GB2630040A

GB2630040A - Drive monitoring system

Info

Publication number: GB2630040A
Application number: GB2307166.5A
Authority: GB
Inventors: O'sullivan Christina; Williams Robbie; Wisbey Octavia
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2023-05-15
Filing date: 2023-05-15
Publication date: 2024-11-20
Also published as: GB202307166D0

Abstract

The present invention relates to drive monitoring systems 100 and methods for monitoring a hybrid drive 20 of a vehicle 250. The hybrid drive comprises an engine 202 and an electric traction motor 216. The present invention comprises receiving a first signal 160 indicating an operating condition of the hybrid drive, determining if the operating condition satisfies a set of predefined conditions, selecting a drive monitoring mode based on the determination, and monitoring the hybrid drive according to the selected drive monitoring mode. The system selects a torque monitoring mode 400 if none of the set of predefined conditions is satisfied and selects an acceleration monitoring mode 500 if at least one of the set of predefined conditions is satisfied. In the torque monitoring mode, the system outputs a torque monitoring alert signal 180 upon detection of a torque demand outside of a permitted torque range. In the acceleration monitoring mode, the system outputs an acceleration monitoring alert signal 180 upon detection of a vehicle acceleration outside of an expected acceleration range.

Description

DRIVE MONITORING SYSTEM

TECHNICAL FIELD

The present disclosure relates to a drive monitoring system. Aspects of the invention relate to a drive monitoring system, to a control system, to a vehicle, and to a method of monitoring a hybrid drive of a vehicle.

BACKGROUND

It is known to provide drive monitoring systems for vehicles with a hybrid drive, i.e. vehicles that comprise at least one internal combustion engine in combination with at least one electric traction motor. Such drive monitoring systems are generally employed to ensure functional safety of the hybrid drive by detecting behaviour which could be indicative of a malfunction in the hardware or software associated with the hybrid drive and, if appropriate, enabling control of the hybrid drive to be modified to mitigate for that malfunction. This can help to avoid or minimise unexpected drive behaviour, such as unintended acceleration or deceleration. In some known systems, a drive monitoring system may monitor a torque demand for the hybrid drive or a component thereof and output a monitoring alert signal upon detection of the torque demand being outside of a permitted torque range. In some alternative known systems, a drive monitoring system may monitor the acceleration of the vehicle and output a monitoring alert signal upon detection of the acceleration being outside of an expected acceleration range.

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a drive monitoring system, a control system comprising such a drive monitoring system, a vehicle, and a method of monitoring a hybrid drive of a vehicle using a drive monitoring system and computer readable instructions which, when executed by a computer, are arranged to perform a method of monitoring a hybrid drive of a vehicle as claimed in the appended claims.

According to an aspect of the present invention there is provided a drive monitoring system for a hybrid drive of a vehicle, the hybrid drive comprising an internal combustion engine and an electric traction motor. The drive monitoring system comprising one or more processors collectively configured to receive a first signal indicating an operating condition of the hybrid drive, determine if the operating condition satisfies at least one of a set of predefined conditions, select a drive monitoring mode based on the determination, wherein a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied. The drive monitoring system monitors the hybrid drive in at least one of the acceleration and torque monitoring modes and outputs a monitoring alert signal if an input to the drive monitoring system is outside an expected or permitted range.

According to an aspect of the present invention there is provided a drive monitoring system for a hybrid drive of a vehicle, the hybrid drive comprising an internal combustion engine and an electric traction motor, the drive monitoring system comprising one or more processors, the one or more processors collectively configured to receive a first signal indicating an operating condition of the hybrid drive, determine if the operating condition satisfies at least one of a set of predefined conditions, select a drive monitoring mode based on the determination, wherein a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied, and monitor the hybrid drive according to the selected drive monitoring mode. When the torque monitoring mode is selected, the one or more processors are collectively configured to detect a demand for torque outside of a permitted torque range and output a torque monitoring alert signal upon detection of the demand for torque outside of the permitted torque range. When the acceleration mode is selected, the one or more processors are collectively configured to detect a vehicle acceleration outside of an expected acceleration range and output an acceleration monitoring alert signal upon detection of the vehicle acceleration being outside of the expected acceleration range.

Advantageously, a drive monitoring system that is capable of selectively monitoring both the requested torque of the vehicle and the acceleration of the vehicle can select the most appropriate monitoring mode based on the operating condition of the hybrid drive of the vehicle. For example, when the hybrid drive is operating in a condition is which simulation of the effects of a certain demand for torque may be computationally complex, the drive monitoring system may select acceleration monitoring. This can be particularly beneficial for hybrid drives in which multiple such operating conditions can occur simultaneously and might otherwise require the operating conditions -such as an engine start and a gear change -to occur consecutively due to the calculational complexity required for accurate torque monitoring. This can result in improved vehicle reaction or faster performance. In many other conditions, it can be beneficial to operate the drive monitoring system in the torque monitoring mode since, unlike acceleration monitoring, this can issue an alert upon detection of a demand which is outside of a permitted range before that demand results in any change to vehicle behaviour.

Torque monitoring of the hybrid drive may be performed by receiving, by the drive monitoring system, a demand signal indicating a demand for torque, ascertaining a calculated permissible torque for one or more components of the hybrid drive, comparing the demand for torque to the calculated permissible torque and outputting a monitoring alert signal if the comparison determines that the magnitude of the demand for torque is greater than the magnitude of the calculated permissible torque.

Acceleration monitoring of the hybrid drive may be performed by receiving an acceleration signal indicating a measured acceleration of the vehicle, ascertaining an expected acceleration of the vehicle, comparing the measured acceleration to the expected acceleration and outputting a monitoring alert signal if the comparison determines that a difference between the magnitude of the measured acceleration and the magnitude of the maximum expected acceleration is greater than a threshold difference.

The set of predefined conditions may comprise the hybrid drive operating in one or more clutch slip modes. These may be modes during which at least one clutch of the hybrid drive is required to gradually transition from an open or partially engaged state to a fully engaged state.

The above set of predefined conditions comprise conditions in which modelling components of the vehicle or the powertrain may be computationally intensive. Thus, in one or more of the predefined conditions, it can be advantageous to activate acceleration monitoring. The one or more clutch slip modes may comprises an engine start mode, a guided launch mode, a gear change mode, or any combination thereof.

The one or more processors of the drive monitoring system may be collectively configured to determine whether one or more handover conditions are satisfied and, in response to determining that one or more handover conditions are not satisfied, inhibit a change from the torque monitoring mode to the acceleration monitoring mode or vice versa.

Advantageously, inhibiting a change between monitoring modes can ensure that the hybrid drive is functioning as expected before switching to a different type of monitoring mode. This can help to ensure accurate monitoring in the initial phases of the 'new' monitoring mode. It can also delay changes to the state of the hybrid drive in situations in which an unexpected hybrid drive behaviour might otherwise occur.

The one or more handover conditions may comprise one or more of determining during torque monitoring that the demand for torque is within the permitted torque range, determining during acceleration monitoring that the vehicle acceleration is within the expected acceleration range and determining that one or more input signals to the drive monitoring system are valid.

The one or more processors may be collectively configured to output the torque monitoring alert signal immediately upon detection of the demand for torque outside of the permitted torque range. The one or more processors may be collectively configured to output the torque monitoring alert signal only once the demand for torque falls outside of the permitted torque range for a threshold period, or "debounce time". This can advantageously reduce the influence of signal noise and reduce unnecessary alerts. The one or more processors may be collectively configured to output a first torque monitoring alert signal immediately upon detection of the demand for torque outside of the permitted torque range and to issue a second torque monitoring alert signal once the demand for torque falls outside of the permitted torque range for a threshold period, or "debounce time". The first and second torque monitoring alert signals can enable the downstream response to differ depending in the duration for which the demand for torque falls outside of the permitted torque range.

The one or more processors may be collectively configured to output the acceleration monitoring alert signal immediately upon detection of the vehicle acceleration being outside of the expected acceleration range. The one or more processors may be collectively configured to output the acceleration monitoring alert signal only once the vehicle acceleration is outside of the expected acceleration range for a threshold period, or "debounce time". This can advantageously reduce the influence of signal noise and reduce unnecessary alerts. The one or more processors may be collectively configured to output a first acceleration monitoring alert signal immediately upon detection of the vehicle acceleration being outside of the expected acceleration range and to issue a second acceleration monitoring alert signal once the vehicle acceleration is outside of the expected acceleration range for a threshold period, or "debounce time". The first and second acceleration monitoring alert signals can enable the downstream response to differ depending in the duration for which the vehicle acceleration is outside of the expected acceleration range.

The drive monitoring system may operate exclusively in the torque monitoring mode or in the acceleration monitoring mode. In some embodiments, the drive monitoring system may operate predominantly in the torque monitoring mode or in the acceleration monitoring mode. For example, when the drive monitoring system is operating in the acceleration monitoring mode, torque monitoring of one or more components of the hybrid drive may be carried out in parallel.

The one or more processors of the drive monitoring system may be collectively configured to disable torque monitoring of at least one component of the hybrid drive when the acceleration monitoring mode is selected; and subsequently reenable torque monitoring of the at least one component of the hybrid drive before changing back from the acceleration monitoring mode to the torque monitoring mode, and wherein the one or more handover conditions may comprise determining, during acceleration monitoring, that torque monitoring has been reenabled.

Advantageously, determining that the modules that enable torque monitoring have been enabled prior to having the drive monitoring system return to torque monitoring mode can help to ensure uninterrupted monitoring of the hybrid drive.

According to another aspect of the present invention there is provided a control system comprising a drive monitoring system as described above. The control system may be configured to control the torque output by at least one of the internal combustion engine and the electric traction motor in response to the torque monitoring alert signal and/or the acceleration monitoring alert signal. For example, the control system may reduce the torque output from at least one of the internal combustion engine and the electric traction motor in response to the torque monitoring alert signal and/or the acceleration monitoring alert signal. The control system may remove the torque output from at least one of the internal combustion engine and the electric traction motor in response to the torque monitoring alert signal and/or the acceleration monitoring alert signal. The control system may reduce or remove power from one or more controllers of the hybrid drive r in response to the torque monitoring alert signal and/or the acceleration monitoring alert signal.

The control system comprises one or more controllers collectively comprising at least one electronic processor having an electrical input for receiving an input signal; and at least one memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to receive a first signal indicating an operating condition of the hybrid drive, determine if the operating condition satisfies at least one of a set of predefined conditions, select a drive monitoring mode based on the determination, wherein a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied, and monitor the hybrid drive according to the selected drive monitoring mode, whereby when the torque monitoring mode is selected, the one or more processors are collectively configured to detect a demand for torque outside of a permitted torque range and output a torque monitoring alert signal upon detection of the demand for torque outside of the permitted torque range, and when the acceleration mode is selected, the one or more processors are collectively configured to detect a vehicle acceleration outside of an expected acceleration range and output an acceleration monitoring alert signal upon detection of the vehicle acceleration being outside of the expected acceleration range.

According to another aspect of the invention, there is provided a vehicle comprising a hybrid drive including an internal combustion engine and an electric traction motor; and the drive monitoring system described above and/or the control system described above.

According to another aspect of the present invention there is provided a method of monitoring a hybrid drive of a vehicle using a drive monitoring system, the hybrid drive comprising an internal combustion engine and an electric traction motor, the method comprising the steps of: receiving a first signal indicating an operating condition of the hybrid drive; determining if the operating condition satisfies at least one of a set of predefined conditions; selecting a drive monitoring mode based on the determination, wherein a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied; and monitoring the hybrid drive according to the selected drive monitoring mode, whereby: when the torque monitoring mode is selected, the monitoring of the hybrid drive is carried out by detecting a demand for torque outside of a permitted torque range and outputting a torque monitoring alert signal upon detection of the demand for torque outside of the permitted torque range; and when the acceleration mode is selected, the monitoring of the hybrid drive is carried out by detecting a vehicle acceleration outside of an expected acceleration range and outputting an acceleration monitoring alert signal upon detection of the vehicle acceleration being outside of the expected acceleration range.

According to another aspect of the present invention there is provided computer readable instructions which, when executed by a computer, are arranged to perform the method described above.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a block diagram illustrating a drive monitoring system according to an embodiment of the present invention; Figure 2A shows a hybrid drive system according to an embodiment of the present invention; Figure 2B shows a schematic illustration of a vehicle according to an embodiment of the present invention; Figure 3 shows a first flow chart showing operations performed by the drive monitoring system of Figure 1 according to an embodiment of the present invention; Figure 4 shows a second flow chart showing operations performed by the drive monitoring system of Figure 1 according to an embodiment of the present invention; Figure 5 shows a third flow chart showing operations performed by the drive monitoring system of Figure 1 according to an embodiment of the present invention; and Figure 6 shows a fourth flow chart showing operations performed by the control system of Figure 1 according to an embodiment of the present invention; Figure 7 shows an example graph of the functions of the drive monitoring system of Figure 1 according to an embodiment of the present invention.

DETAILED DESCRIPTION

A drive monitoring system 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figures 1 to 8. The drive monitoring system 100 is suitable for detecting behaviour which may be indicative of a malfunction in the hardware or software associated with the hybrid drive. The vehicle may comprise a hybrid drive including an internal combustion engine and an electric traction motor. The hybrid drive may be in a variety of operating conditions, as will be described later. In some, but not necessarily all examples, the vehicle is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as commercial vehicles. The vehicle may further comprise a range of other controllers that, for example, may be part of an Advanced Driver Assistance System (ADAS) that may assist the driver in various driving situations, such as adaptive cruise control, lane departure warnings, automatic emergency braking, blind spot detection, and parking assistance, among others. The vehicle may further comprise a powertrain controller, also known as a hybrid powertrain control unit, a battery controller, a thermal management controller and an electric motor controller. In some vehicles any of these controllers may be combined in a single controller.

With reference to Figure 1, there is illustrated a drive monitoring system 100 for a vehicle. The drive monitoring system 100 as illustrated in Figure 1 comprises one or more controller 110, although it will be appreciated that this is merely illustrative. The controller 110 comprises processing means 120 and memory means 130. The processing means 120 may be one or more electronic processing device 120 which operably executes computer-readable instructions. The memory means 130 may be one or more memory device 130. The memory means 130 is electrically coupled to the processing means 120. The memory means 130 is configured to store instructions, and the processing means 120 is configured to access the memory means 130 and execute the instructions stored thereon.

The controller 110 comprises an input means 140 and an output means 150. The input means 140 may comprise an electrical input 140 of the controller 110. The output means 150 may comprise an electrical output 150 of the controller 110.

The input 140 is arranged to receive a first signal 160 indicating an operating condition of the hybrid drive. The operating condition may satisfy any of a set of predefined conditions. The set of predefined conditions may comprise the hybrid drive operating in one or more clutch slip modes during which a clutch of the hybrid drive is required to gradually transition from an open or partially engaged state to a fully engaged state. The one or more clutch slip modes may comprise an engine start mode, a guided launch mode, a gear change mode, or any combination thereof. The set of predefined conditions may comprise any operational mode that enables controlled and coordinated engagement of the electric motor and the internal combustion engine, facilitating a smooth transition during an initial acceleration phase wherein the vehicle transitions from being standstill to moving. The guided launch mode is used to allow the vehicle to pull away smoothly by compensating for inaccuracy in the clutch between the electric traction motor and the torque delivery system. For the vehicle to pull away, the transmission requests a certain speed profile. As an example, if the clutch between the electric traction motor and the torque delivery system transfers less torque to the wheels than it ideally should, the "excess torque" that is not transferred to the wheels will be transferred to the internal combustion engine and/or the electric traction motor, therefore increasing the engine/electric traction motor speed. Guided launch compensates this additional engine/electric traction motor speed by setting a target speed for the engine/electric traction motor, thus, keeping the engine/ electric traction motor speed consistent with the requested speed profile.

The input 140 is also arranged to receive a demand signal 162 indicating a demand of torque for the hybrid drive or a component thereof. Demand signal 162 may be based on driver input, for example driver input provided by a driver via a pedal (not shown). Alternatively or in addition, demand signal 162 may be received from, or supplemented by, a vehicle system, such as an ADAS controller. The input means 140 may receive the demand signal via a controller of the vehicle, e.g., the powertrain controller, that is coupled to the driver input sensor. Alternatively or additionally, the drive monitoring system may by directly coupled to a driver input sensor associated with the driver input, such as a pedal, to receive demand signal 162.

The input 140 is also arranged to receive an acceleration signal 164 indicating a measured acceleration of the vehicle. Acceleration signal 164 may be based on the output of an acceleration sensor. Acceleration signal may be received from one of the vehicle's controllers, e.g., the powertrain controller, that is coupled to the acceleration sensor. Alternatively or additionally, the drive monitoring system may by directly coupled to the driver input sensor to receive demand signal 162.

For the avoidance of doubt, the term "acceleration" is used herein to encompass both positive acceleration and negative acceleration, i.e. deceleration.

In some embodiments the input 140 may be arranged to receive a predicted acceleration signal 166 indicating an expected acceleration of the vehicle. Predicted acceleration signal 166 may be received from one of the vehicle's controllers, e.g., the powertrain controller. Alternatively or additionally, the controller 110 may be arranged to calculate the expected acceleration of the vehicle based on measurements received from various sensors installed on the vehicle, for example, accelerator sensors, speed sensors, torque output sensors, pedal sensors etc. In some embodiments the input 140 may be arranged to receive a permissible torque signal 168 indicating a permitted torque range or calculated maximum magnitude of torque that may be generated by the hybrid drive of the vehicle or a component thereof. Permissible torque signal 168 may be received from one of the vehicle's controllers, e.g., the powertrain controller. Alternatively or additionally, the controller 110 may be arranged to calculate the permissible torque. Calculating the permissible torque range may comprise calculating a maximum magnitude of the torque output generated by the hybrid drive that will ensure that all limitations imposed on the hybrid drive, for example by a stability control system of the vehicle, are satisfied. Additionally or alternatively, calculating the permitted torque range may be based on a simulation of the torque path through various components associated with the hybrid drive and determining their effect on torque output for a given operation condition. For example, auxiliary components external to the primary function of the hybrid drive, such as the air conditioning system, radiator fan or electrical consumers driven by the hybrid drive may need to be simulated in addition to powertrain components to provide an accurate calculation of torque response for a given torque request or operating condition and thereby calculate the permissible torque range. The controller may take the various torques requested (e.g. driver demand, ADAS torque requests, torque losses, etc.) and arbitrate based on hierarchy and/or operating condition to get these into the correct reference frame for the monitoring system and/or for a torque request to the actuator of the electric traction motor and/or engine.

The output 150 is arranged to output a monitoring alert signal 180. Monitoring alert signal 180 may be provided to one of the vehicle's controllers, e.g., the powertrain controller. Monitoring alert signal 180 is indicative of unexpected behaviour which may be indicative of a malfunction in the hardware or software associated with the hybrid drive. The vehicle's controller that receives the monitoring alert signal may in response to receiving the monitoring alert signal cause the powertrain controller to return the status of the powertrain into a safe state reconfiguration, for example by reducing or removing the torque output from the engine and/or the electric traction motor. Alternatively, or additionally, the vehicle's controller that receives the monitoring alert signal may in response to receiving the monitoring alert signal turn off the power to one or more controllers of the hybrid drive, such as a powertrain controller.

Fig 2 illustrates an example hybrid drive system 20 for a parallel hybrid electric vehicle (HEV). The hybrid drive system 20 is controlled by a control system 30. The control system 30 may comprise one or more of: a hybrid powertrain control module; an engine control unit; a transmission control unit; a traction battery management system; and/or the like. The hybrid drive system 20 comprises an engine 202. The illustrated engine 202 is an internal combustion engine. The illustrated engine 202 comprises four combustion chambers, however a different number of combustion chambers may be provided in other examples. The engine 202 is operably coupled to the control system 30 to enable the control system 30 to control output torque of the engine 202. The output torque of the engine 202 may be controlled by controlling one or more of: air-fuel ratio; spark timing; poppet valve lift; poppet valve timing; throttle opening position; fuel pressure; turbocharger boost pressure; and/or the like, depending on the type of engine 202.

The hybrid drive system 20 further comprises an electric traction motor 216. In some embodiments, the hybrid drive system 20 has one electric traction motor. In other embodiments, the hybrid drive system 20 has more than one electric traction motor. The first electric traction motor 216 may be an alternating current induction motor or a permanent magnet motor, or another type of motor. The electric traction motor is also referred to herein as an electric machine (EM). The electric traction motor 216 may be a crankshaft integrated motor generator (CIMG). The electric traction motor 216 is configured to apply positive or negative torque to the crankshaft or to an output shaft connected to the crankshaft, for example to provide functions such as: boosting output torque of the engine 202; deactivating (shutting off) the engine 202 while at a stop or coasting; activating (starting) the engine 202; and regenerative braking in a regeneration mode. In a hybrid electric vehicle mode, the engine 202 and electric traction motor 216 may both be operable to supply positive torque simultaneously to boost output torque. The electric traction motor 216 may be capable of electric only driving. The hybrid drive system 20 comprises a vehicle transmission arrangement 204 for receiving output torque from the engine 202 and/or from the electric traction motor 216. The vehicle transmission arrangement 204 may comprise an automatic vehicle transmission, a semi-automatic vehicle transmission, or a manual vehicle transmission.

The engine 202 is mechanically connected or connectable to the electric traction motor 216 via a first torque path connector in the form of a first clutch 212. The electric traction motor 216 is mechanically connected or connectable to the transmission 204 via a second torque path connector in the form of a second clutch 218.

The second clutch 218 is illustrated in Figure 2A as a single clutch located along the drive shaft between the electric traction motor 216 and the transmission 204. In other embodiments, the second clutch 218 could be integrated with the electric traction motor 216 and/or with the transmission 204. In the latter example, the second clutch could be a core clutch used for gear shifts. The function of the second clutch could be provided by a single clutch, as illustrated, or a by plurality of clutches which are each configured to connect the electric traction motor 216 to the transmission 204 and thereby fulfil the function of the second clutch. For example, the second clutch could comprise a clutch which is operable to connect the electric traction motor 216 to the transmission 204 when the transmission is in one of a first set of gears (e.g., gears 1-4) and one or more further clutches which are operable to connect the electric traction motor 216 to the transmission 204 when the transmission is in one of a second set of gears (e.g. gears 5-8). The electric traction motor 216 is mechanically connected or connectable to a first set of vehicle wheels (RL, RR) via a torque path which extends from an output of the electric traction motor 216 to the second clutch 218 then to the transmission 204, then to the axle/driveshafts 220, and then to the first set of vehicle wheels (RL, RR). The engine 202 is mechanically connected or connectable to the first set of vehicle wheels (RL, RR) via a torque path which extends from an output of the engine 202, then to the first clutch 212, then to the electric traction motor 216, then to the second clutch 218, then to the transmission 204, then to the axle/driveshafts 220, and then to the first set of vehicle wheels (RL, RR). One or both of the engine 202 and the electric traction motor 216 are able to provide torque to a first axle 220 of the vehicle. However, when the torque path between the electric traction motor 216 and the first set of vehicle wheels (RL, RR) is disconnected, the torque path 220 between engine 202 and the first set of vehicle wheels (RL, RR) is also disconnected. In a vehicle overrun and/or friction braking situation, torque may flow from the first set of vehicle wheels (RL, RR) to the electric traction motor 216 and optionally to the engine 202. Torque flow towards the first set of vehicle wheels (RL, RR) is positive torque, and torque flow from the first set of vehicle wheels (RL, RR) is negative torque. The illustrated first set of vehicle wheels (RL, RR) comprises rear wheels. Therefore, the illustrated hybrid drive system 20 is configured for rear wheel drive. In another example, the first set of vehicle wheels may be front wheels (FL, FR). The illustrated front wheels (FL, FR) is a pair of vehicle wheels, however a different number of vehicle wheels could be provided

in other examples.

The hybrid drive system 20 may comprise a differential 217 for receiving output torque from the transmission 204, i.e. from the gear train. The differential may be integrated into the vehicle transmission arrangement 204 as a transaxle, or provided separately.

The illustrated hybrid drive system 20 comprises one electric traction motor 216. In other embodiments, the hybrid drive system 20 may have more than one electric traction motor. The hybrid drive system 20 may further comprise a starter motor 219 which is mechanically connected or connectable to the engine 202. For example, the starter motor 219 may be a belt integrated starter generator (BiSG) or a pinion starter motor. In the illustration, the starter motor 219 is located at an accessory drive end of the engine 202, opposite a vehicle transmission end of the engine 202.

The control system 30 may be configured to disconnect the torque path between the engine 202 and the first set of vehicle wheels (RL, RR) in electric vehicle mode, for example to reduce parasitic pumping energy losses or to operate in an electric vehicle mode. For example, the first clutch 212 may be opened.

In some embodiments, the vehicle comprises another motive power source, or prime mover, arranged to provide torque to at least one wheel (FL, FR) of another axle of the vehicle. For example, the hybrid drive system 20 may further comprise a second electric traction motor (not shown) or a second internal combustion engine (not shown), either of which may provide positive torque alone or in combination with the electric traction motor 216 and/or the engine 202.

In order to store electrical power for the electric traction motor 216, the hybrid drive system 20 comprises a traction battery 221. The traction battery 221 provides a nominal voltage required by electrical power users such as the electric traction motor. The traction battery 221 may be a high voltage (HV) battery. High voltage traction batteries provide nominal voltages in the hundreds of volts, as opposed to traction batteries for mild HEVs which provide nominal voltages in the tens of volts. The traction battery 221 may have a voltage and capacity to support electric only driving for sustained distances. The traction battery 221 may have a capacity of several kilowatt-hours, to maximise range. The capacity may be in the tens of kilowatt-hours, or in the hundreds of kilowatt-hours. Although the traction battery 221 is illustrated as one entity, the function of the traction battery 221 could be implemented using a plurality of small traction batteries in different locations on the vehicle. The hybrid drive system 20 may comprises one or more inverters 214. One inverter 214 is shown, for the electric traction motor 216. In other examples, two or more inverters could be provided.

Although the drive monitoring system 100 is illustrated as connected to the hybrid drive system 20 via the control system 30, the drive monitoring system 100 may be directly connected with one or more of the components of the hybrid drive system 20. Although the drive monitoring system 100 is illustrated as separate to the control system 30, the drive monitoring system 100 may be incorporated into the control system 30.

Figure 2B illustrates a vehicle 250 according to an embodiment of the present invention. The vehicle 250 comprises a drive monitoring system 100 as illustrated in Figure 1. The drive monitoring system 100 is shown as mounted within the vehicle 250 and is in communication with the hybrid drive 20 and with the control system 30 for the hybrid drive 20. The drive monitoring system 100 may be in further communication with one or more of the other controllers installed to the vehicle as mentioned above. Vehicle 250 may be an EGO vehicle, i.e., a vehicle that is equipped with autonomous or semi-autonomous driving technology and is capable of sensing and navigating its environment without direct input from a human driver. Vehicle 250 may comprise a Stability Control System (SCS), that is designed to enhance vehicle stability and mitigate the risk of skidding or loss of control during various driving scenarios. The SCS continuously monitors the vehicle's dynamic parameters, including wheel speed, steering angle, lateral acceleration, and yaw rate, utilizing a suite of sensors and control algorithms.

Figure 3 is a flowchart 300 according to an embodiment of the present invention. The flowchart 300 illustrates steps performed by the drive monitoring system 100 to monitor the hybrid drive of a vehicle, such as the vehicle 250 illustrated in Figure 2B. The memory 130 of the drive monitoring system 100 may comprise computer-readable instructions which, when executed by the processor 120, perform the method 300.

At step 310 the drive monitoring system 100 receives first signal indicating an operating condition of the hybrid drive. This will typically relate to the current operating mode of the hybrid drive or actions or operations which are requested of the hybrid drive, such as a gear change operation, EV only mode, engine creep mode, EV creep mode, a slip start operation by which the engine is started by the electric traction motor, an engine start using auxiliary motor such as a BISG or a pinion starter, engine only mode, or a hybrid operating mode etc. At step 320 the drive monitoring system 100 determines whether the operating condition satisfies any of a set of predefined conditions. The set of predefined conditions may, for example, be any of the conditions described earlier with respect to input 140.

At step 330 the drive monitoring system 100 selects a drive monitoring mode based on the determination of step 320. If the drive monitoring system 100 determines that the operating condition or conditions indicated by the first signal does not satisfy any of the predefined conditions, a torque monitoring mode 400 is selected as the drive monitoring mode and the drive monitoring system proceeds to monitor the hybrid drive using the steps illustrated in Figure 4. If the drive monitoring system 100 determines that the operating condition or conditions indicated by the first signal satisfies any of the predefined conditions, an acceleration monitoring mode 500 is selected as the drive monitoring mode and the drive monitoring system proceeds to monitor the hybrid drive using the steps illustrated in Figure 5.

The torque monitoring mode will typically be the default drive monitoring mode selected by the drive monitoring system 100 under most operating conditions. The acceleration monitoring mode may be particularly suitable for operating conditions of the hybrid drive that are computationally complex to model. For example, the vehicle may have received a first signal indicating the operating condition of the hybrid drive to be a slip start condition. In a slip-start condition the electric traction motor is engaged and provide propulsion, while the internal combustion engine is started and gradually brought up to speed using a clutch of the hybrid drive that gradually transitions from an open or partially engaged state to a fully engaged state. In this example, if the drive monitoring system is set to be in the torque monitoring mode, calculating the permissible torque or permitted torque range for some of the components of the hybrid drive may comprise modelling the behaviour of the components based on a signal that indicates how engaged the clutch of the hybrid drive associated with the internal combustion engine is and also based on a signal indicative of gear shift information. In other examples, other signals indicative of the state of various components of the vehicle may be used to calculate the permissible torque. These signals may be provided by one of the controllers of the vehicle, for example a transmission controller, directly to the drive monitoring system. Alternatively, these signals may be provided to the drive monitoring system via another controller of the vehicle, for example the powertrain controller. Due to various differences between the electric traction motor and the internal combustion engine (e.g., fuel economy may be better for an internal combustion engine at low revs/highest gear, whilst the electric traction motor may run more efficiently or effectively at higher revs/lower gear), it is likely that when the hybrid drive is in a slip-start condition, the transmission will also need to shift to choose a different gear map for efficiency. As such, if the drive monitoring system is set to be in the torque monitoring mode, the drive monitoring system may need to model not just the behaviour of components of the hybrid drive, but also model the effects of a gear change in the behaviour of said components. This increases the computational complexity of the process, which may in turn result in delayed response by the drive monitoring system and/or by the hybrid drive. Conversely, if the acceleration monitoring mode is selected, the computational complexity is simplified while still ensuring functional safety.

In some embodiments, selecting the acceleration monitoring mode may include deactivating components that enable the torque monitoring mode, or in other words activating the acceleration monitoring mode may result in deactivating the torque monitoring mode. In other embodiments, selecting the acceleration monitoring mode may include maintaining active some, or all of the components that enable the torque monitoring mode. For example, in the case wherein a first set of components of the drive monitoring system are used to monitor for acceleration hazards and a second set of components of the drive monitoring system are used to monitor for deceleration hazards, selecting the acceleration monitoring mode may result in deactivating the first set of components but not the second set of components. Thus, the drive monitoring mode may primarily rely on monitoring the acceleration of the vehicle whilst supplementing the drive monitoring system with components that monitor the torque to detect deceleration hazards.

Figure 4 is a flowchart 400 illustrating steps performed by the drive monitoring system 100 to monitor the hybrid drive when the torque monitoring mode is selected.

At step 410 the drive monitoring system 100 receives a demand signal indicating a demand for torque required from the hybrid drive or a component thereof.

At step 420 the drive monitoring system 100 ascertains a permitted torque range for the hybrid drive or one or more components thereof, such as torque sources or components located along one or more torque paths of the hybrid drive. The permitted torque range may be transmitted to the drive monitoring system or calculated by the drive monitoring system 100. Calculating the permissible torque range may comprise calculating a maximum magnitude of the torque output generated by the hybrid drive that will ensure that all limitations imposed on the hybrid drive, for example by a stability control system of the vehicle, are satisfied. Additionally or alternatively, calculating the permitted torque range may comprise simulating the behaviour of various components associated with the hybrid drive and determining their effect on torque output for a given operation condition. For example, auxiliary components external to the primary function of the hybrid drive, such as the air conditioning system, radiator fan or electrical consumers driven by the hybrid drive may need to be simulated in addition to powertrain components to provide an accurate calculation of torque response for a given torque request or operating condition.

At step 430 the drive monitoring system 100 compares the demand for torque to the permitted torque range to determine whether the demand for torque is outside of the permitted torque range.

At step 440 the drive monitoring system 100 outputs a monitoring alert signal in the form of a torque monitoring alert signal if the comparison determines that the demand for torque is outside of the permitted torque range. 25 The monitoring alert signal can be used by a controller of the vehicle, such as the control system 30, to adapt vehicle behaviour. For example, the monitoring alert signal can be used by the control system 30 to adjust the torque output from the hybrid drive 20 to account for the monitoring alert signal. In some instances, the control system 30 can reconfigure the hybrid drive to a reduced power state in response to the monitoring alert signal in order to limit or remove the torque output from the engine and/or the electric traction motor to mitigate unexpected vehicle behaviour. In some instances, the control system 30 can switch off power to one or more controllers of the hybrid drive, such as a powertrain control module, in response to the monitoring alert signal. If the demand for torque is within the permitted torque range, no monitoring alert signal is outputted.

The drive monitoring system can be configured to output the torque monitoring alert signal immediately upon detection of the demand for torque outside of the permitted torque range. Alternatively, the drive monitoring system can be configured to output the torque monitoring alert signal only once the demand for torque has fallen outside of the permitted torque range for a threshold period, or "debounce time". This can advantageously reduce the influence of signal noise and reduce unnecessary monitoring alert signals. In some embodiments, the torque monitoring alert signal can be issued in two stages, with the drive monitoring system outputting a first torque monitoring alert signal immediately upon detection of the demand for torque outside of the permitted torque range and outputting a second torque monitoring alert signal once the demand for torque falls outside of the permitted torque range for a threshold period, or "debounce time". The first and second torque monitoring alert signals enable the downstream response to differ depending in the duration for which the demand for torque falls outside of the permitted torque range. The first torque monitoring alert signal can put the control system on alert that the torque demand is unexpected, with the second torque monitoring alert providing confirmation in response to which mitigating action can be taken by the control system.

An advantage of the torque monitoring mode is that it enables pre-emptive detection of conditions in which the vehicle may exhibit unexpected behaviour. In other words, the process described in flowchart 400 is based on a demand signal, i.e. a requested torque, and the monitoring process takes place before the hybrid drive responds to this signal by producing the requested torque. This enables mitigating action to be taken before the unexpected behaviour is "felt" by the driver in the form of unexpected vehicle behaviour, or at least the mitigation action can be taken more gradually to lessen the effects. However, as explained above, the torque monitoring process can be computationally complex due to the requirement to model complex interactions between various components of the vehicle, such as components of the transmission and the powertrain.

Figure 5 is a flowchart 500 illustrating steps performed by the drive monitoring system 100 to monitor the hybrid drive when the acceleration monitoring mode is selected.

At step 510 the drive monitoring system 100 receives an acceleration signal indicating a measured acceleration of the vehicle. This may be transmitted to the drive monitoring system 100 by one or more acceleration sensors located on the vehicle.

At step 520 the drive monitoring system 100 ascertains an expected acceleration range of the vehicle. The expected acceleration range may be transmitted to the drive monitoring system or calculated by the drive monitoring system 100 itself. The calculation may be based on any suitable parameter or parameters as is known in the art, such as the current speed of the vehicle, the orientation of the vehicle, torque demand, current gear ratio, expected gear ratio, or any combination of the above.

At step 530 the drive monitoring system 100 compares the measured acceleration of the vehicle to the expected acceleration range of the vehicle to determine whether the measured acceleration is within the expected acceleration range.

At step 540 the drive monitoring system 100 outputs a monitoring alert signal in the form of an acceleration monitoring alert signal if the comparison determines that the vehicle acceleration is outside of the expected acceleration range.

The monitoring alert signal can be used by a controller of the vehicle, such as the control system 30, to adapt vehicle behaviour. For example, the monitoring alert signal can be used by the control system 30 to adjust the torque output from the hybrid drive 20 to account for the monitoring alert signal. In some instances, the control system 30 can reconfigure the hybrid drive to a reduced power state in response to the monitoring alert signal in order to limit or remove the torque output from the engine and/or the electric traction motor to mitigate unexpected vehicle behaviour. In some instances, the control system 30 can switch off power to one or more controllers of the hybrid drive, such as a powertrain control module, in response to the monitoring alert signal. If the measured acceleration is within the expected range, no monitoring alert signal is outputted.

The drive monitoring system can be configured to output the acceleration monitoring alert signal immediately upon determination that the vehicle acceleration is outside of the expected acceleration range. Alternatively, the drive monitoring system can be configured to output the acceleration monitoring alert signal only once the vehicle acceleration has been outside of the expected acceleration range for a threshold period, or "debounce time". This can advantageously reduce the influence of signal noise and reduce unnecessary monitoring alert signals. In some embodiments, the acceleration monitoring alert signal can be issued in two stages, with the drive monitoring system outputting a first acceleration monitoring alert signal immediately upon determination that the vehicle acceleration is outside of the expected acceleration range and outputting a second acceleration torque monitoring alert signal once the vehicle acceleration has been outside of the expected acceleration range for a threshold period, or "debounce time". The first and second acceleration monitoring alert signals enable the downstream response to differ depending in the duration for which the vehicle acceleration has been outside of the expected acceleration range. The first acceleration monitoring alert signal can put the control system on alert that the vehicle acceleration behaviour is unexpected, with the second acceleration monitoring alert providing confirmation in response to which mitigating action can be taken.

An advantage of the acceleration monitoring mode, as explained above, is that it is computationally simpler than the torque monitoring mode described above. Tracking the vehicle's physical longitudinal acceleration and comparing it to an expected acceleration reduces the need to model the behaviour of features or functions of the vehicle that do not affect the vehicle's acceleration (such as transmission gear changes or other speed control features). However, because the monitoring is based on the vehicle's current acceleration, it means that the vehicle may already be exhibiting unexpected behaviour by the time the drive monitoring system 100 has identified a fault or malfunction. This means that the mitigating action required to bring the acceleration back to normal can be more severe than for the torque monitoring mode.

If the drive monitoring system outputs a torque monitoring alert signal or an acceleration monitoring alert signal, then the software or hardware components that implement the torque or acceleration monitoring respectively may transition to a "safe state" reconfiguration, which involves reduces or removing torque from the engine and electric traction machine. For acceleration monitoring this may comprise a staged approach to reach the safe state but both in both cases further requests for torque are removed or inhibited. In some embodiments, transitioning the respective monitoring components to the safe state may comprise powering down the components and/or turning off the power to a vehicle controller such as the powertrain controller entirely.

Figure 6 is a flowchart 600 showing a monitoring method according to a further embodiment of the present invention. The flowchart 600 illustrates steps performed by the drive monitoring system 100 to monitor the hybrid drive of a vehicle, such as the vehicle 250 illustrated in Figure 2B. The memory 130 of the drive monitoring system 100 may comprise computer-readable instructions which, when executed by the processor 120, perform the method 600. The method 600 is similar to the method 300 described in relation to Figure 3 and similar reference numerals are used to denote similar steps in the process. Steps 610 to 630 of the method 600 are essentially the same as steps 310 to 330 of the method 300.

At step 640, once the drive monitoring system 100 has selected the appropriate drive monitoring mode based on the operating condition(s) but before any change has been made to the current drive monitoring mode, the drive monitoring system 100 determines whether the selected drive monitoring mode is the same as the current drive monitoring mode. If the current drive monitoring mode is the same as the selected monitoring mode, the drive monitoring system 100 remains in the current drive monitoring mode at step 655. If the current drive monitoring mode is different to the selected monitoring mode -e.g. if the drive monitoring system is currently operating in the torque monitoring mode but the drive monitoring system selects the acceleration monitoring mode in response to the first signal -the method moves to step 650.

At step 650, the drive monitoring system 100 determines whether one or more handover conditions are satisfied. The one or more handover conditions may include determining that, when currently in the torque monitoring mode, that the demand of torque is within the permitted torque range, or when currently in the acceleration monitoring mode, that the measured acceleration is within the expected acceleration range. Additionally, or alternatively to the handover conditions described above, a further handover condition may include determining that one or more input signals to the drive monitoring system are valid, or in other words determining that the input signals are within an acceptable range of values and formats, and have not been corrupted, are incomplete, or erroneous in any way that could cause the controller to malfunction or make incorrect decisions. This determination of signal validity may be implemented using various techniques such as signal processing algorithms or error detection mechanisms. Additionally, or alternatively to the handover conditions described above, a further handover condition may include determining that a minimum period has elapsed since a monitor alert signal was previously output. Additionally, or alternatively to the handover conditions described above, a further handover condition may include determining that all components that are necessary for the functionality of the selected monitoring mode have been enabled.

If the drive monitoring system 100 determines that any of the handover conditions are not satisfied, drive monitoring system 100 will inhibit a change in the monitoring mode and will instead remain in the current monitoring mode at step 655. In other words, even if the monitoring mode selected during step 630 is different to the current monitoring mode, the drive monitoring system will not switch to the "selected" monitoring mode but will continue to operate in the "current" monitoring mode until all handover conditions are satisfied. For example, if the drive monitoring system is currently operating in acceleration monitoring mode and selected the torque monitoring mode at step 630, the drive monitoring system would only switch to the torque monitoring mode if all handover conditions are satisfied, otherwise the drive monitoring system will remain in the acceleration monitoring mode until all handover conditions are satisfied. Some operating conditions or features of the hybrid drive, such as performing a gear change while starting the engine using slip start, may require the appropriate monitoring mode to be in operation before being activated. To achieve this, the drive monitoring system 100 may interface with one or more controllers of the hybrid drive and be configured to confirm that the appropriate drive monitoring mode has been selected before that action is permitted.

At step 660, if the drive monitoring mode determines that the selected drive monitoring mode is different to the current drive monitoring mode and determines that the handover conditions are satisfied, the drive monitoring system 100 will change the drive monitoring mode and proceed with monitoring the hybrid drive using the selected drive monitoring mode. This will either be the torque monitoring mode 400, as discussed above in relation to Figure 4, or the acceleration monitoring mode, as discussed above in relation to Figure 5.

Drive monitoring system 100 may be configured to disable torque monitoring of at least one component of the hybrid drive when the acceleration monitoring mode is selected. Additionally, or alternatively, drive monitoring system 100 may be configured to disable acceleration monitoring mode of the vehicle when the torque monitoring mode is selected.

In some embodiments, the vehicle may comprise a powertrain controller (otherwise known as a Powertrain Control Module or PCM), a transmission controller (otherwise known as a Transmission Control Module or TCM), and an inverter which is arranged to provide signals to the electric traction motor for controlling the torque output of the electric traction motor. These controllers and the inverter may be coupled to each other in a bidirectional or unidirectional manner. These controllers may form part of the control system and may be separate to the drive monitoring system. Alternatively, the drive monitoring system may be integrated in one or more of these controllers, for example in the PCM or the TCM. These controllers may be implemented in a single controller or they be distinct controllers. In some embodiments these controllers may share some processing units, such as processors, with other controllers. As such, the drive monitoring system may comprise hardware of either the TCM, the PCM, or be separate to either of those. In some embodiments, the PCM may be coupled to the inverter and arranged to provide a signal, e.g, an EMTorqueRequest signal, that may indicate a demand for torque from the electric motor. The inverter may output a signal to the electric traction motor to produce the requested torque. Additionally, or alternatively, the TCM may be coupled to the inverter and arranged to provide a signal, e.g, an EMTorqueTarget signal, that may indicate a demand for additional torque. This additional torque may be requested to offset the inertia of the internal combustion engine during, e.g., a slip-start condition. Additionally, or alternatively, the PCM may be coupled to the TCM and arranged to provide a signal, e.g, a SlipStartTypeRequest signal, that may indicate that the hybrid drive is in a slip-start operating condition. Additionally, or alternatively, the TCM may be coupled to the PCM and arranged to provide a signal, e.g, a TCMSafetyHandshake signal, that indicates torque monitoring mode is active and that acceleration monitoring can be safely disabled or disregarded in favour of torque monitoring.

If any of the controllers determines that any of the respectively received signals are not valid, then depending on the signal, the drive monitoring system may remain in the current drive monitoring mode. For example, if after a slip-start operation the PCM receives a corrupted TCMSafetyHandshake signal, the PCM may determine that the torque monitoring mode is fully or partially inactive and therefore remain in the acceleration monitoring mode rather than change to the torque monitoring mode.

If at steps 330 and 630, the drive monitoring system 100 selects a monitoring mode that had been disabled, then drive monitoring system 100 is configured to reenable the disabled monitoring mode before a change in monitoring mode is established. For example, the drive monitoring system 100 may disable torque monitoring of at least one component of the hybrid drive when the acceleration monitoring mode is selected, and, if at a later time drive monitoring system 100 determines that the monitoring mode should be changed back to torque monitoring mode, the drive monitoring system 100 will reenable torque monitoring of the at least one component of the hybrid drive, confirm that torque monitoring of that component has been reenabled and subsequently change back from the acceleration monitoring mode to the torque monitoring mode.

Figure 7 graphically illustrates an example of the functions of the drive monitoring system 100. The example of Figure 7 should not be considered as limiting the invention in general. Figure 7 shows a graph with the x-axis denoting time, T, and the y-axis denoting the combined torque output, Tq, of the hybrid drive 20.

The first period 710, in this example, illustrates the operation of the hybrid drive 20 in an "EV-only" condition in which the combined torque output of the hybrid drive 20 is provided solely by the electric traction motor and the "predefined conditions" for acceleration monitoring are not met. Consequently, the drive monitoring system operates in the torque monitoring mode, according to the process illustrated in Figure 4, by comparing the demand of torque to the permitted torque range. The permitted torque range is illustrated in Figure 7 by area 740. If the demand of torque is outside the permitted torque range and instead lies in area 770, then the drive monitoring system 100 will output a monitoring alert signal. This indicates that, if implemented, the demand of torque in area 770 would result in unintended acceleration of the vehicle. Thus, area 770 can also be considered as a region of unintended acceleration.

The second period 720 illustrates the changing torque profile during a slip start operation in which the electric traction motor provides drive to the transmission and also to the internal combustion engine via a partially closed (i.e. "slipping") clutch between the electric traction motor and the engine, in order to start the engine.

The speed of the engine is then gradually increased to match that of the electric traction motor. Once the speed of the engine is synchronised with the speed of the electric traction motor, the clutch transitions to a fully closed/engaged state. The slip start operation is one of the predefined operating conditions for acceleration monitoring. Thus, during second period 720, the drive monitoring system 100 monitors the hybrid drive in the acceleration monitoring mode according to the process illustrated in Figure 5, by comparing the expected acceleration of the vehicle to a measured acceleration of the vehicle. The torque range by which the expected acceleration would be delivered is illustrated in Figure 7 by area 750. If the measured acceleration exceeds the expected acceleration, as illustrated by the torque range defined in area 770, then the drive monitoring system 100 would output a monitoring alert signal to highlight the unexpected acceleration.

The third period 730 illustrates a "parallel" operating condition following the slip start of the engine during period 720. In the parallel mode, both the internal combustion engine and the electric traction motor provide torque to the transmission of the vehicle. The parallel operating condition is not one of the predefined conditions for acceleration monitoring. Consequently, none of the predefined conditions are satisfied and the drive monitoring system 100 would return to the torque monitoring mode in order to monitor the hybrid drive. Area 760 illustrates the permitted torque range, while upper area 770 illustrates a region of unexpected acceleration and in which the drive monitoring system would output a monitoring alert signal.

In the example of Figure 7, the change from the torque monitoring mode to the acceleration monitoring mode takes place at time ti and the return to the torque monitoring mode occurs at t2. In some embodiments, as described above in relation to Figure 6, before the monitoring mode changes, the drive monitoring system 100 may determine whether various handover conditions are met and, if not, inhibit changing the monitoring mode.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

Claims

CLAIMS1. A drive monitoring system for a hybrid drive of a vehicle, the hybrid drive comprising an internal combustion engine and an electric traction motor, the drive monitoring system comprising one or more processors, the one or more processors collectively configured to: receive a first signal indicating an operating condition of the hybrid drive; determine if the operating condition satisfies at least one of a set of predefined conditions; select a drive monitoring mode in dependence on the determination, wherein: a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied; and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied; and monitor the hybrid drive according to the selected drive monitoring mode, whereby: when the torque monitoring mode is selected, the one or more processors are collectively configured to: detect a demand for torque outside of a permitted torque range; and output a torque monitoring alert signal upon detection of the demand for torque outside of the permitted torque range; and when the acceleration mode is selected, the one or more processors are collectively configured to: detect a vehicle acceleration outside of an expected acceleration range; and output an acceleration monitoring alert signal upon detection of the vehicle acceleration being outside of the expected acceleration range.
2. The drive monitoring system of claim 1, wherein the set of predefined conditions comprises the hybrid drive operating in one or more clutch slip modes during which a clutch of the hybrid drive is required to gradually transition from an open or partially engaged state to a fully engaged state.
3. The drive monitoring system of claim 2, wherein the one or more clutch slip modes comprises an engine start mode, a guided launch mode, a gear change mode, or any combination thereof.
4. The drive monitoring system of any preceding claim, wherein the one or more processors are collectively configured to: determine whether one or more handover conditions are satisfied; and in response to determining that one or more handover conditions are not satisfied, inhibit a change from the torque monitoring mode to the acceleration monitoring mode or vice versa.
5. The drive monitoring system of claim 4, wherein the one or more handover conditions comprises one or more of: determining during torque monitoring that the demand for torque is within the permitted torque range; determining during acceleration monitoring that the vehicle acceleration is within the expected acceleration range; and determining that one or more input signals to the drive monitoring system are valid.
6. The drive monitoring system of claim 4 or claim 5, wherein the one or more processors are collectively configured to: disable torque monitoring of at least one component of the hybrid drive when the acceleration monitoring mode is selected; and subsequently reenable torque monitoring of the at least one component of the hybrid drive before changing back from the acceleration monitoring mode to the torque monitoring mode, and wherein the one or more handover conditions comprises determining, during acceleration monitoring, that torque monitoring has been reenabled.
7. A control system comprising the drive monitoring system according to any preceding claim, wherein the control system is configured to control the torque output by at least one of the internal combustion engine and the electric traction motor in response to the torque monitoring alert signal and/or the acceleration monitoring alert signal.
8. A vehicle comprising: a hybrid drive including an internal combustion engine and an electric traction motor; and the drive monitoring system of any of claims 1 to 6 and/or the control system of claim 7.
9. A method of monitoring a hybrid drive of a vehicle using a drive monitoring system, the hybrid drive comprising an internal combustion engine and an electric traction motor, the method comprising the steps of: receiving a first signal indicating an operating condition of the hybrid drive; determining if the operating condition satisfies at least one of a set of predefined conditions; selecting a drive monitoring mode based on the determination, wherein a torque monitoring mode is selected as the drive monitoring mode if none of the set of predefined conditions is satisfied and an acceleration monitoring mode is selected as the drive monitoring mode if at least one of the set of predefined conditions is satisfied; and monitoring the hybrid drive according to the selected drive monitoring mode, whereby: when the torque monitoring mode is selected, the monitoring of the hybrid drive is carried out by detecting a demand for torque outside of a permitted torque range and outputting a torque monitoring alert signal upon detection of the demand for torque outside of the permitted torque range; and when the acceleration mode is selected, the monitoring of the hybrid drive is carried out by detecting a vehicle acceleration outside of an expected acceleration range and outputting an acceleration monitoring alert signal upon detection of the vehicle acceleration being outside of the expected acceleration range.
10. The method of claim 9, wherein the set of predefined conditions includes the hybrid drive operating in one or more clutch slip modes during which a clutch of the hybrid drive is required to gradually transition from an open or partially engaged state to a fully engaged state.
11. The method of claim 10, wherein the one or more clutch slip modes includes an engine start mode, a guided launch mode, a gear change mode, or any combination thereof.
12. The method of any of claims 9 to 11, comprising the steps of: determining whether one or more handover conditions are satisfied; and in response to determining that one or more handover conditions are not satisfied, inhibiting a change from the torque monitoring mode to the acceleration monitoring mode or vice versa.
13. The method of claim 12, wherein the one or more handover conditions comprises one or more of determining during torque monitoring that the demand for torque is within the permitted torque range; determining during acceleration monitoring that the vehicle acceleration is within the expected acceleration range; and determining that one or more inputs to the drive monitoring system are valid.
14. The method of claim 12 or claim 13, comprising the steps of: disabling torque monitoring of at least one component of the hybrid drive when the acceleration monitoring mode is selected; and subsequently reenabling torque monitoring of the at least one component of the hybrid drive before changing back from the acceleration monitoring mode to the torque monitoring mode, and wherein the one or more handover conditions comprises confirming, during acceleration monitoring, that torque monitoring has been reenabled.
15. Computer readable instructions which, when executed by a computer, are arranged to perform a method according to any of claims 9 to 14.