WO2007074197A1 - Gps- and wireless-communication-assisted device for controlling a motor vehicle, which enables the vehicle to travel in congested traffic - Google Patents

Abstract

The invention relates to a GPS- and wireless-communication-assisted device for controlling a motor vehicle, which enables the vehicle to travel in congested traffic. The purpose of the device is to enable a road vehicle to be controlled automatically, with the speed thereof being adapted to that of the vehicle in front such that a safe distance is maintained. The inventive device can be used to control the vehicle such that it follows pre-determined routes in structured environments, by managing the three main actuators of the vehicle, namely the accelerator, the brake and the steering wheel, and by maintaining a safe distance with the vehicles in front, within a range of speeds varying from 0 km/h to the maximum speed of the vehicle.

Description

 TITLE:

CONTROL UNIT OF A CAR, WITH GPS ASSISTANCE AND WIRELESS COMMUNICATIONS, THAT ALLOWS TRAFFIC CIRCULAR WITH RETENTIONS

SECTOR OF THE TECHNIQUE

The device presented is framed from the point of view of its application in the automotive engineering sector as it is a driving aid. Attending to its construction, it is a computer system composed of a computer and various peripherals specifically designed as an electronic control element and helps driving in traffic conditions in traffic with retentions.

STATE OF THE TECHNIQUE

The number of traffic accidents and casualties on the road have been stimulating, both by governments and car manufacturers, solutions to reduce both one and the other. One of the paths chosen to achieve this objective is the introduction into the vehicles of driving aids that inform the driver of situations that may have escaped his knowledge or that control certain specific aspects of driving in order to reduce the number of elements that require continuous driver attention. One of the functions that most interest is currently collected by the automobile industry is the maintenance of the safety distance from the previous vehicle within the same lane, better known as

Adaptive Cruise Control,

ACC), also called by other ICC authors (Intelligeht

Cruise Control) or AICC (Autonomous Intelligent Cruise Control) and considered an extension of cruise control

(CC) conventional. Its purpose is to avoid the most common traffic accidents today, the so-called rear-end crashes or scopes behind (RR Knipling et.al., "Rear-End Crashes: Problem Size Assessment and Statistical Description", DOT Report HS 807 994.), as well as optimizing the use of road infrastructure, automatically maintaining a user-defined safety distance, by automating speed control- (Willie D.

Jones, "Keeping Cars from Crashing," IEEE Spectrum,

September 2001, pp. 40-45.)

At present, some commercial houses offer ACC systems as an option for luxury vehicles ^' in their range. The first manufacturer that had it available was

Mitsubishi, with its "Preview Distance Control" for its Diamond model, in 1995. Toyota, Nissan, Jaguar, Mercedes,

Lexus, BMW and some manufacturers of automobile components among others have been incorporating it to the present (Jesse Crosse, "Tomorrow's World," Automotive

World, January / February 2000, p. 46-48). However, all these commercial systems have several limitations: the first is that their operating range is above 40 km / h, which means that they only have the capacity to operate on interurban roads, preferably highways with fluid traffic, leaving out of service in situations of slow traffic or retentions, which, in addition to being tremendously tedious for drivers, cause a lot of scope. The second limitation is that at present they only act on the accelerator pedal, the maximum deceleration caused by the motor brake itself in the vehicle, which limits its operation to maintenance situations, from distance in speed situations stationary without major decelerations The third limitation lies in the method to calculate the distance from the previous vehicle. Commercially, there are only two alternatives: those based on microwave radars or laser scanners, operating separately or in a coordinated manner.

The purpose of an ACC system is to automatically adjust the speed of the vehicle that houses it, in order to maintain a safety distance preset by the user with respect to the vehicle that is driving ahead. There are currently two strategies to carry out this task, depending on the final operation you want to achieve.

• Constant distance: it is based on forcing the system to maintain a constant distance from the previous vehicle (Shahab Sheikholeslam and Charles A. Desoer, ^' "Longitudinal Control of a Platoon of Vehicles I: Linear Model", PATH Research Report UCB-ITS- PRR-89-3, 1989 .; Shahab Sheikholeslam and Charles A. Desoer, "Longitudinal Control of a Platoon of Vehicles; II: First and Second Order Time Derivatives of Distance Deviations", PATH Research Report UCB-ITS-PRR-89- 6, 1989; Shahab Sheikholeslam and Charles A. Desoer, "Longitudinal Control of a Platoon of Vehicles; 111: Nonlinear Model", UCB-ITS-PRR-90-1, 1990; SE Shladover, "Longitudinal Control of Automated Guideway Transit Vehicle within Platoons ", ASME Journal of Dynamic System, Measurement and Control. VoI. 100, December, 1978; S. Sheikholelslam and CA Desoer," A System Level Study of the Longitudinal Control ", of a Platoon of Vehicles, ASME Journal on Dynamic Systems, Measurement, and Control, 1991; Y. Zhang et al., "Auto nomous Intelligent Cruise Control Using Front and Back Information for Tight Vehicle Following

Maneuvers ", IEEE Transactions on Vehicular Technology, vol. 48, No. 1, January 1999; R. Rajamani et al.,

"Demonstration of integrated Longitudinal and Lateral Control for the Operation of Automated Vehicles in

Platoons ", IEEE Transactions on Control Systems

Technology, VoI. 8, No. 4, July 2000, pp. 695-708).

• Speed-dependent distance (headway control): it is the most common method to maintain safety distance ([H]), in which, the space between vehicles is variable according to the speed of movement, and is the way of driving more similar to human (L. Evans and P. Wasielewski, "Risky driving related to driver and Vehicle Characteristics", Accident Analysis and Preventions, 15, pp. 121-136, 1983; J. Piao and M. McDonald, "Low Speed Car Following Behavior from Floating Vehicle Data ", Proceedings of the IEEE Intelligent Vehicles Symposium 2003, Columbus, Ohio, USA, June, 2003; PA Ioannou and CC. Chien," Autonomous Intelligent Cruise Control ", IEEE Transactions on Vehicular Technology, VoI . 42, No. 4, November 1993, pp. 657-672; A. Higashimata et al., "Design of a Headway Distance Control System for ACC"; H. Holzmann et al., "Longitudinal and Lateral Control and Supervision of Autonomous Vehicles ", Control Engineering Practice, VoI. 5, No. 11, 1997, pp. 1 599-1605 JSAE Review, 22, 2001, pp. 15-22; D. Maurel and S. Donikian, "ACC Systems - Overview and Examples", Intelligent Vehicle Technologies, SAE International, 2001, pp. 423-441; G. Sala and E. Morello, UDC URBAN DRIVE CONTROL, Telematics Applications Program, Transport Sector, Project TR1060, Deliverable No. D8.01, Version 1.1, Draft Evaluation Plan, 1998.).

DESCRIPTION OF THE INVENTION Brief description of the invention

The objective that is proposed is the development of an apparatus that allows the automatic control of a car that circulates in regulated environments with retention. This device will be based on a computer that runs a fuzzy control program. • The computer will receive as data the position itself, through a GPS, the position of the preceding vehicle through wireless Ethernet communication and CAN protocol. It will be able to act on the throttle, brake and steering wheel mechanisms.

Detailed description of the invention

The device object of the invention uses GPS to perform a vehicle position control and keep it behind the preceding vehicle at a safe distance, which depends on the speed. A wireless ethernet system that communicates at all times the position of the preceding vehicle. The apparatus includes control algorithms that have been developed and validated as described in the attached bibliography.

- Components

• 1 GPS

• 1 Ethernet wireless network communication »1 communication with the vehicle's CAN bus to read data from it and in particular the speed

• 1 computer

• 1 analog output for steering wheel control • 1 analog output for throttle control

• 1 analog output for brake control

- Operation of the device The device consists of a computer in which a specific software is responsible for performing the following functions: 1. Analyze the data of the GPS itself and those received by the wireless ethernet network to find the distance to the previous vehicle. 2. Obtain vehicle speed from the information on your CAN data bus.

3. Apply the fuzzy control algorithms developed by the authors to, with the preceding data: «Find the actions for the steering wheel so that the vehicle remains centered in its lane.

• Find the actions for the accelerator and brake so that the safety distance, dependent on the speed, is maintained with the preceding vehicle. * If the speed is greater than a preset value, notify by means of an acoustic signal of the cessation of the automatic operation of the device.

A necessary element for the use of this invention is the GPS system or Global Positioning System (its most correct name is NAVSTAR GPS), which is a Global Satellite Navigation System (GNSS), which allows worldwide determination of the Position of an object, a person, a vehicle or a ship, with an accuracy up to centimeters using differential GPS, although the usual are a few meters, was developed and installed and is currently used by the United States Department of Defense. The device of the invention uses this information obtained from the GPS system to perform the position control of a vehicle equipped with said device and keep it in its path. Through wireless Wi-Fi Ethernet communication in particular, which is a trademark of the Wi-Fi Alliance (formerly the Wireless Ethernet Compatibility Alliance), the commercial organization that tests and certifies that the equipment complies with IEEE 802. Hx standards. The unit receives information on the presence of other nearby vehicles and through the use of new fuzzy control algorithms, developed for the present invention, identifies all its trajectories and speeds and, if the situation allows, performs the appropriate operations on analog or digital driving elements and means such as steering wheel, accelerator and brake to perform a maneuver in case the conditions and safety of the maneuver allow it, as are the cases of being the left lane free in case of use of a highway or there are no vehicles in the opposite direction in the case of two-way roads.

Another necessary element in the use of the devices is the CAN communications protocol provides the following benefits: a) It is a standardized communications protocol, which simplifies and saves the task of communicating subsystems of different manufacturers on a common network or bus. b) The host processor delegates the communications load to an intelligent peripheral, therefore the host processor has more time to execute its own tasks. c) Being a multiplexed network, considerably reduces wiring and eliminates point-to-point connections. d) To simplify the car electronics even further, a simpler subnet can be used, which connects to the CAN network, called LIN.

CAN is based on the producer / consumer model, which is a concept, or data communications paradigm, that describes a relationship between a producer and one or more consumers. CAN is a message-oriented protocol, that is, the information to be exchanged is broken down into messages, to which an identifier is assigned and encapsulated in frames for transmission. Each message has a unique identifier within the network, with which the nodes decide whether or not to accept said message. Among its main features are:

• Message priority,

• Latency time guarantee, • Configuration flexibility,

• Multicast reception with time synchronization,

• Robust system in terms of data consistency, • Multi-master system,

• Error detection and signaling,

• Automatic retransmission of erroneous frames,

• Distinction between temporary errors and permanent failures of the network nodes, and autonomous disconnection of defective nodes,

CAN was developed, initially for applications in automobiles and, therefore, the protocol platform is a result of the existing needs in the automotive area. The International Organization for Standardization (ISO, International Organization for Standardization) defines two types of CAN networks: a high-speed network (up to 1 Mbps), under the ISO 11898-2 standard, intended to control the motor and interconnect the electronic control units (ECU) ); and a fault-tolerant low speed network (less than or equal to 125 Kbps), under the standard ISO 11519-2 / ISO 11898-3, dedicated to the communication of the internal electronic devices of a car such as door control, roof sliding, lights and seats.

CAN is a serial communications protocol that supports distributed control in real time with a high level of security and multiplexing. The establishment of a CAN network to interconnect the internal electronic devices of a vehicle is intended to replace or eliminate wiring. ECUs, sensors, non-slip systems, etc. they are connected via a CAN network at data transfer rates of up to 1 Mbps. According to the OSI reference model (Open Systems Interconnection), the CAN protocol architecture includes three layers: physical, data link and application, in addition to a special layer for management and control of the node called supervisor layer.

• Physical layer: defines the aspects of the physical environment for the transmission of data between nodes of a network

CAN, the most important are signal levels, representation, synchronization and times in which the bits are transferred to the bus. The CAN protocol specification does not define a physical layer, however, ISO 11898 standards establish the characteristics that applications must meet for high and low speed transfer.

• Data link layer: defines the tasks independent of the method of access to the medium, In addition, because a CAN network provides support for real-time processing to all the systems that comprise it, the exchange of messages that such processing requires requires a high frequency transmission system and minimum delays. In multi-master networks, the media access technique is very important since every active node has the rights to control the network and monopolize resources. Therefore the data link layer defines the method of access to the medium as well as the types of frames for sending messages

When a node needs to send information through a CAN network, it can happen that several nodes try to transmit simultaneously. CAN resolves the above by assigning priorities through the identifier of each message, where said assignment is made during the design of the system in the form of binary numbers and cannot be modified dynamically. The identifier with the lowest binary number is the one with the highest priority.

The method of access to the medium used is Access

Carrier Detection Multiple, with Detection of

Collisions and Arbitration by Message Priority

(CSMA / CD + AMP, Carrier Sense Multiple Access with Collision Detection and Arbitration Message Priority). According to this method, the nodes in the network that need to transmit information must wait for the bus to be free

(carrier detection); when this condition is met, said nodes transmit a start bit (multiple access). Each node reads the bitwise bus during frame transmission and compares the transmitted value with the received value; as long as the values are identical, the node continues with the transmission; if a difference is detected in the values of the bits, the arbitration mechanism is carried out.

CAN establishes two formats of data frames (data frames) that differ in the length of the identifier field, standard frames (standard frame) with an 11-bit identifier defined in the CAN 2.0A specification, and extended frames (extended frame ) with a 29-bit identifier defined in the CAN 2.0B specification. For the transmission and control of CAN messages, four types of frames are defined: data, remote (remote frame), error (error frame) and overload (overload frame). Remote frames are also set in both standard and extended formats, and both data and remote frames are separated from previous frames by spaces between frames (interfraine space).

As for the detection and handling of errors, a CAN controller has the ability to detect and handle errors that arise in a network. Any error detected by a node is immediately notified to the rest of the nodes.

• Supervisor layer: The replacement of conventional wiring with a serial bus system presents the problem that a faulty node can block the operation of the entire system. Each active node transmits an error flag when it detects some type of error and can cause a defective node to monopolize the physical environment. To eliminate this risk, the CAN protocol defines an autonomous mechanism to detect and disconnect a faulty node from the bus, this mechanism is known as fault isolation.

• Application layer: There are different standards that define the application layer; some are very specific and related to their fields of application. Among the most commonly used application layers are CAL, CANopen, DeviceNet, SDS (Smart Distributed System), OSEK, CANKingdom. The function of a data bus (d) is to move the data between the hardware devices: input; outbound; and storage such as hard disk or Flash memory, these transfers that occur through the data bus are governed by various devices and methods, of which the PCI controller, "Peripheral Component Interconnect", Interconnection of Peripheral components, is one of the main.

None of the devices described herein is specifically designed to solve the problem that solves the device 'object of the invention that is specifically designed to avoid the reach of a vehicle to its immediate predecessor in a low-speed traffic lane characterized by cruising speeds. under 45 km / h. The applicability and utility of the device object of the invention resides in that the specific use of fuzzy logic methods ensures the reliability of the trajectory calculation process with this procedure. Blurred or multivalued logic is based on the following principle: Multivalued logic includes logical systems that support several possible truth values. Fuzzy logic (fuzzy logic) is one of them, characterized by wanting to quantify this uncertainty: If P is a proposition, a number v (P) can be associated in the interval [0,1] such that :

• If v (P) = 0, P is false.

• If v (P) = 1, P is true.

• The veracity of P increases with v (P). There are similarities with the theory of probability, although fuzzy logic and the latter theory pursue different ends. Fuzzy or fuzzy logic is based on the "Everything is a matter of degree" principle. Thus, for example, if a measure of 2 meters is defined as a long length (it is long with grade 1) and a length of 1 meter is defined as being not long length at all (it is long with grade 0). On an intermediate basis it can be said that a length measuring 1.82 m is long with a grade of 0.75, indicating that it is "quite long". On the contrary, classical logic would only define whether the length is long or not, defining the difference between belonging to one group or another a simple centimeter.

EXAMPLE OF EMBODIMENT OF THE INVENTION

A prototype based on a serial computer has been built that runs a program developed for this application by the authors, in particular equipped with the following peripherals: - Serial input

Ethernet wireless network card - CAN network card

Analog output card

The system also includes a GPS.

The device is used to automatically control a vehicle along a road. To do this, it has the database of existing roads. The passenger must indicate the destination point and the device calculates the trajectory and controls the vehicle until it reaches the destination point, taking into account the presence of the other vehicles on the road. For this you have the GPS that It allows you to know your own position and the wireless network input, which allows you to know the position of the other vehicles.

The GPS is connected to the serial input of the computer and continuously sends frames in which it specifies the position of the vehicle. The program developed reads these frames, as well as others from the CAN bus, (which carries vehicle data) to obtain its speed, and others from the wireless network to know the position of the previous vehicle. The rule-based fuzzy control program uses the values thus obtained to determine from the position of the vehicle given by the GPS the deviation from the preset trajectory and act on the steering wheel according to the intuitive driving rules, (which thanks to the blurred control can be quantified, obtaining concrete values to act)

If you are on the left, turn the steering wheel to the right If you are on the right, turn the steering wheel to the left

The program knows the speed and position of the preceding vehicle, therefore calculates the safety distance, and if the control is activated, using rules analogous to the example set for speed, decides if the safety distance is too large to reduce it and if it is too Small expand it. To do this, it uses the analog outputs to act on the accelerator and the brake. The mode of action is to stop accelerating and, if not enough, slow down. When you drive the three actuators of the vehicle, steering wheel, accelerator and brake you have in fact full control of it.

Claims

1.- Automatic control procedure of a vehicle that is characterized by the following stages: a. Stage of identification of trajectory to follow, through manual instructions of the passenger that indicates his destination point; b. Stage of obtaining the position of the vehicle through the GPS and location of this point within the trajectory, which is done by comparing the. position given by the • GPS with the trajectory and locating the point of the path closest to the real position of the vehicle; C. Calculation stage of the errors produced in the tracking of the trajectory, both in distance and in angle, which are obtained by measuring the distance of the point given by the GPS to the desired trajectory and from two consecutive positions of the GPS the vehicle angle is deducted with the desired trajectory; d. Stage for obtaining the actual speed of vehicle movement through the CAN bus, which is read directly from the vehicle bus through the CAN network card; and. Stage of obtaining the position of the preceding vehicle through the wireless network, which is read directly by the wireless network card; F. Reading stage of the desired safety distance by the user or set by the traffic rules, which is obtained from the internal database of the program and depends on the road, the point within it and the actual speed of the vehicle; g. Stage, based on stages d, e and f, to determine the distance in time to the preceding vehicle, applying a simple mathematical formula; h. Stage based on stages a, b and c to determine the control signal that must act on the steering wheel to maintain the desired trajectory, applying the fuzzy control algorithms developed by the authors, which. they consist of applying the fuzzy rules according to the values of the input variables and applying said signal to the servo that controls the steering wheel; i. Stage based on stage g to determine the control signal that must act on accelerator to maintain the desired safety distance from the preceding vehicle, applying in the fuzzy control algorithms developed by the authors, which consist of applying the fuzzy rules as they are the values of the input variables and apply said signal to the motor controller as if it were the accelerator signal generated by the vehicle itself; j. Stage based on stage g to determine the control signal that must act on brake to maintain the desired safety distance from the preceding vehicle, applying the fuzzy control algorithms developed by the authors, which consist of applying the fuzzy rules as they are values of the input variables and apply said signal to the brake controller. 2. ~ Apparatus that executes the procedure described in section 1 consisting of the following elements: 1 GPS, 1 Ethernet wireless network communication, 1 communication with the vehicle CAN bus to read data from it and in particular the speed, 1 computer, 1 analog output for steering wheel control, 1 analog output for throttle control, 1 analog output for control brake which is characterized by: a) Identify the trajectory and drive the vehicle to the destination point; b) Allow speed control over the entire legally permitted speed range, and especially between 0 and 45 km / h for having the ability to control the brake; c) Use a sensory system based on Global Satellite Navigation Systems (GNSS) and wireless Ethernet communications to know the positions of the vehicle itself and other vehicles; and d) Automatically handle the three fundamental actuators of the vehicle, accelerator, brake and steering wheel.