DE102023211163A1 - Articulated arm robot and method for monitoring an articulated arm robot - Google Patents

Abstract

The articulated arm robot (20) has a plurality of robot members (22) which are each connected to one another via a joint (24) and each driven by an electric motor (28), and is designed for redundant monitoring of its operation and for this purpose has two independent monitoring devices, namely a first monitoring device (34A, 40A, 44A) and a second monitoring device (34B, 40, 44B), each of the monitoring devices having
- a respective motion sensor, namely a first and a second motion sensor (34A, 34B) for detecting a current position of the respective robot member (22),
- a device for detecting a force momentarily acting on the robot member (22), namely a first and a second device (40A, 40B), the two devices being based on different measuring principles,
- an evaluation unit in each case, namely a first evaluation unit (44A) for processing data from the first motion sensor (34A) and data from the first device (40A) and a second evaluation unit (44B) for processing data from the second motion sensor (34B) and data from the second device (40B).
This enables redundant monitoring of the articulated arm robot via two separate monitoring paths.

Description

The invention relates to an articulated arm robot with a plurality of robot links which are each connected to one another via a joint and driven by electric motors, wherein the articulated arm robot is designed for redundant monitoring of its operation.

Such an articulated arm robot is, for example, from the EP 1 445 075 B2 can be found.

An articulated-arm robot generally has several robot links, each connected to one another by a joint. The various robot links form a link chain and are mounted to one another via the joints, allowing each robot link to perform a rotational movement relative to its neighboring robot link. The respective rotational movement is controlled by an electric motor, which may be located directly in the joint. For example, a motor shaft runs parallel to a joint axis.

Especially for articulated arm robots that come into contact with or in close proximity to people, especially for medical robots that work on patients, for example, highly precise positioning as well as reliable, trouble-free operation of the robot and its movements are important in order to prevent any danger to people.

In the aforementioned EP 1 445 075 B2 Within the framework of a redundant measuring system, several different physical measurement variables are determined and compared with each other. In particular, the strain of a robot structure, position data, and the motor current are evaluated.

Based on this, the invention is based on the object of providing an articulated arm robot, in particular for medical applications, and a method for monitoring such an articulated arm robot, whereby a high level of functional reliability is ensured.

• - jeweils einen Bewegungssensor, nämlich einen ersten sowie einen zweiten Bewegungssensor zur Erfassung einer momentanen Position und insbesondere auch einer momentanen Geschwindigkeit des jeweiligen Robotergliedes,
• - jeweils eine Einrichtung zur Erfassung einer auf das Roboterglied momentan einwirkenden Kraft oder auch eines Kraftmoments, nämlich eine erste sowie eine zweite Einrichtung, wobei die beiden Einrichtungen auf unterschiedlichen Messprinzipien beruhen, sowie
• - jeweils eine Auswerteeinheit, nämlich eine erste Auswerteeinheit zur Verarbeitung von Daten des ersten Bewegungssensors sowie von Daten der ersten Einrichtung und eine zweite Auswerteeinheit zur Verarbeitung von Daten des zweiten Bewegungssensors und von Daten der zweiten Einrichtung. Die beiden Auswerteeinheiten sind insbesondere unabhängig und vollständig getrennt voneinander ausgebildet und sind beispielsweise durch zwei verschiedenen Baueinheiten gebildet. Eine jede der Auswerteeinheiten ist geeignet für die Auswertung und Datenverarbeitung ausgestaltet und weist jeweils eine Rechnereinheit, insbesondere einen Mikrochip, einen Speicher sowie ein ausführbares Programm zur Verarbeitung und Auswertung der Daten auf.

The object is achieved according to the invention by an articulated-arm robot with several robotic elements connected to one another via a joint and each driven by an electric motor. The articulated-arm robot is designed for redundant monitoring of its operation. For this purpose, two independent monitoring devices, namely a first and a second monitoring device, are provided. Each of the monitoring devices has the following elements:

• - a motion sensor, namely a first and a second motion sensor for detecting a current position and in particular also a current speed of the respective robot limb,
• - a device for detecting a force or moment of force currently acting on the robot limb, namely a first and a second device, the two devices being based on different measuring principles, and
• - an evaluation unit, namely a first evaluation unit for processing data from the first motion sensor and data from the first device, and a second evaluation unit for processing data from the second motion sensor and data from the second device. The two evaluation units are, in particular, designed to be independent and completely separate from one another and are formed, for example, by two different structural units. Each of the evaluation units is designed to be suitable for evaluation and data processing and has a computer unit, in particular a microchip, a memory, and an executable program for processing and evaluating the data.

The object is further achieved according to the invention by a method for monitoring a multi-axis articulated-arm robot, which is monitored during operation using the two monitoring devices described above. The advantages and preferred embodiments described below with regard to the articulated-arm robot also apply analogously to the method.

It is important to note that monitoring is carried out using two independent and separate monitoring devices, so that the operation of the articulated arm robot is monitored reliably and redundantly.

The articulated arm robot generally preferably has a redundant system for detecting a collision.

It is particularly important that each monitoring device evaluates both movement data and instantaneous data on the force applied. The evaluation of data regarding the instantaneous force acting on the robotic limb or the instantaneous force moment is particularly important for medical robots. to detect collisions immediately and, if necessary, stop the movement immediately. This device for detecting the instantaneous force is part of the collision detection system.

To achieve a particularly high level of redundant safety, two different devices for detecting the currently acting force are installed for the two monitoring devices. This means that the currently acting force is determined using two different measuring principles. The selection of different measuring principles further increases operational safety.

The use of different measuring principles means that the two devices evaluate different physical measurement variables, which allow conclusions to be drawn about the force currently exerted.

For example, according to a preferred embodiment, the currently exerted force is determined directly by a force measuring device, specifically by a suitable direct force sensor, for example a force load cell.

According to another operating principle, a deformation, for example an extension or compression of a structural component of the articulated arm robot, specifically a deformation of the robot limb, is detected. Mechanical forces acting on the robot limb regularly lead to a mechanical deformation of the robot member, which can be detected, and the deformations allow conclusions to be drawn about the current force. With this measuring principle, suitable strain sensors are therefore provided to measure the deformation. This can be achieved, for example, using optical sensors, specifically fiber optic cables. In the case of fiber optic cables, a strain of the same is detected. Fiber optic cables are in particular attached directly to the robot limb and are deformed with it. Alternatively, at least one and preferably several strain gauges are preferably attached to the robot limb.

According to another measurement principle, it is possible, for example, to evaluate the motor current of the electric motor that generates the movement of the robot limb. If a mechanical force acts on the robot limb, this leads to a measurable change in the motor current.

To ensure operational safety, the two monitoring devices evaluate the received data—both the motion data and the force data. As soon as one of the monitoring devices detects a critical operating condition, it initiates a safety measure, such as stopping the movement of the articulated-arm robot or returning it to a safe operating position. Preferably, the evaluated data from the two monitoring devices are also compared. For this purpose, they can communicate with each other or with a higher-level control unit.

According to a preferred embodiment, the first monitoring device comprises at least one strain sensor attached to the robot limb, which is particularly designed as a strain gauge. This strain sensor forms the first device for detecting the force or moment of force currently acting on the robot limb. Expediently, several strain sensors, specifically strain gauges, are mounted around the circumference of the articulated-arm robot so that deformations in different directions can be reliably detected.

Alternatively or optionally in addition to the at least one strain sensor, a force measuring device - as described above - is arranged as the first device for detecting the instantaneous force. This force measuring device is mounted in particular between a last robot link, in particular between the so-called robot hand, and a processing tool (end effector) attached to it. Depending on the application, these end effectors may vary. In medical applications, for example, this may be a patient couch with which the patient is moved into a therapy or diagnostic facility, or a diagnostic or therapy device (e.g., radiation device) which is moved relative to the patient, or even a medical instrument for treating the patient.

In a preferred embodiment, the second monitoring device comprises a current sensor for determining the motor current of the motor driving the robot limb. This current sensor forms the second device for detecting the force or moment of force currently acting on the robot limb. The measured instantaneous motor current is then used in a conventional manner to determine the currently acting force or moment of force.

In particular, the combination of the use of strain sensors or a force Measuring device with evaluation of the motor current enables high operational reliability of the articulated arm robot.

Preferably, the two motion sensors are encoders that detect the rotational movement of a motor shaft. Such encoders ensure reliable position detection of the robot's current position. In addition, the current speed can usually also be derived from the data from such encoders. The design and function of such encoders are generally known.

According to a preferred embodiment, the data acquired by the motion sensors is also used for collision detection. For this purpose, the data acquired by the motion sensors is evaluated, e.g., with regard to the current position and/or speed and/or acceleration, and these determined variables are evaluated with regard to a potential collision.

Independently of the evaluation with regard to collisions, the data from the motion sensors are used to determine the current position and/or speed and/or acceleration, whereby these data are preferably used for the control and regulation of the movements of the articulated arm robot.

In a preferred embodiment, the motion sensors are arranged at different locations, i.e., the first motion sensor is located away from the second motion sensor. This facilitates independent recording of the current motion data.

In particular, it is provided that the motion sensors are mounted on opposite sides of the electric motor. Specifically, the first motion sensor is mounted on the input side of the motor, in particular on an input shaft, and the second motion sensor is mounted on the output side, in particular on an output shaft of the motor. The monitoring robot element is driven via the output shaft. This typically occurs with the interposition of a gearbox. The second motion sensor is preferably arranged downstream of the gearbox.

To ensure the most independent recording of movement data possible, the two motion sensors are also designed differently. This also further improves operational reliability. Therefore, different measurement principles are used in both the motion data and force data recording systems, thus achieving a high level of redundant protection precisely through the use of different measurement principles.

Specifically, it is provided that one motion sensor, for example the first or the second motion sensor, is designed as an incremental encoder and thus as an incremental encoder and the other motion sensor, i.e. the second or the first motion sensor, is designed as an absolute encoder and thus as an absolute value encoder.

Alternatively or additionally, the two encoders also differ in the number of read heads. These encoders detect movement, specifically rotational movement, via such read heads. Preferably, one encoder has only one read head, while the other has two.

In a useful embodiment, several, and in particular all, of the robot elements are each assigned a first and a second motion sensor, as well as a first and a second device, as previously described. The data from all first motion sensors and the data from all first devices are evaluated by the first evaluation unit, and the data from all second motion sensors and second devices are evaluated by the second evaluation unit. This measure creates two completely separate monitoring paths, which are based, in particular, on different measurement principles for recording both the motion data and the force data.

Preferably, the two evaluation units are designed differently. This means that at least some, and preferably all, components of the evaluation units differ from each other. Alternatively or additionally, the two evaluation units come from different manufacturers.

For data communication and data transmission between individual components, a bus system (data bus) is preferably used, i.e. the data transmission takes place according to a predetermined data protocol. Different bus systems are preferably used in the articulated arm robot, in particular the data connection with the evaluation units takes place via two different bus systems. One of the bus systems is preferably based on an Ethernet protocol and the other bus system on a non-Ethernet protocol. The other bus system is designed, for example, for serial data transmission and is preferably based on an ElA-xxx standard (also known as RS-xxx standard). standard). Specifically, the other bus system is based on the EIA-485 standard.

Preferably, a respective drive unit and thus a respective motor is further assigned a redundant braking device with two brakes, each of which is designed to exert a currentless braking force, wherein the two brakes are preferably based on different operating principles, so that the respective braking force of the two brakes is exerted by different operating principles.

This means that the forces required to generate the braking force are generated through various physical means. The different operating principles are based, for example, on the application of a magnetic force, a pneumatic force, a hydraulic force, or a mechanical spring force.

Such a braking device is described in detail in the applicant's German patent application entitled "Gelenkarmroboter" (Joint Arm Robot), filed concurrently with the present application. The disclosure of this application is hereby incorporated into the present application. In particular, this concerns the description of the figures therein. 2 and 3 , as well as these 2 and 3 , which are hereby incorporated into the present application

Each brake regularly has two braking partners, namely in particular a movable and a fixed braking partner, whereby the braking force or a braking torque is suitably transferred from the fixed braking partner to the other braking partner.

Typically, the two braking partners are mechanically pressed against each other to generate the braking force, so that the braking effect is generated by friction between the two braking partners. This pressing force, which generates the braking force, is generated in particular by one of the above-mentioned operating principles.

By using different operating principles, the risk of failure is reduced and functional reliability is increased.

In a preferred embodiment, one brake is a spring-actuated brake, meaning the braking force is generated by a spring force. The two brake partners are pressed against each other by spring force.

In a preferred embodiment, the other brake is a magnetic brake, in which the braking force is generated by magnetic force. In a preferred embodiment, a permanent magnet is used for this purpose. Here, one braking partner is preferably pressed against the other braking partner by means of the magnetic force—similar to the spring-actuated brake.

The operating principles of the two currentless brakes permanently exert a force on the braking partners, which leads to the braking effect. In order to control the braking effect during normal operation, in a preferred embodiment, each brake is assigned an electromagnet via which the braking force of the respective brake can be controlled and via which a respective brake can be transferred to an open position. An electrically controlled magnetic force is therefore generated via the electromagnet, which acts on one of the braking partners at a time. The electrically controlled force counteracts the permanent, currentless force. This electromagnet therefore allows the braking force to be dosed and, in particular, the braking effect can be completely canceled.

In a preferred embodiment, the brakes are attached to a shaft of the drive unit. The braking force therefore acts on the shaft of the drive unit.

Preferably, at least one of the brakes, and preferably both brakes, each has a brake disc that is movable along the shaft and interacts with a stationary brake disc that is firmly connected to the shaft. The movable brake disc and the stationary brake disc are the two braking partners of the respective brake. The currentless force acts on the movable brake disc in the direction of the stationary brake disc. The effect of the previously described electromagnet is opposite, so that the movable brake disc is pulled away from the stationary brake disc by the electromagnet when it is activated. The movable brake discs are mounted, for example, on the motor shaft or otherwise displaceably.

The stationary brake disc is mechanically firmly connected to the shaft, for example via a mounting flange or a welded joint. However, the stationary brake disc is preferably a monolithic section of at least part of the shaft.

In a preferred embodiment, the stationary brake disc is arranged between the two movable brake discs. The stationary brake disc therefore forms a common brake disc for both brakes.

Preferably, the shaft of the drive unit is designed as a hollow shaft, at least in the region of the brakes. This provides, in particular, an additional internal cavity that can be used. In a preferred embodiment, the shaft is designed as a hollow shaft only in the region of the brakes. In this case, the hollow shaft is connected in a rotationally fixed manner to at least one further section of the shaft (which, in particular, is not designed as a hollow shaft), for example via a flange connection or welded connection. Alternatively, the entire shaft of the drive unit is designed as a hollow shaft.

In a practical design, the electrical wires connected to the electromagnet are routed through the hollow shaft. These electrical wires serve to control the electromagnet.

In addition, the hollow shaft also offers the possibility of integrating additional functions, such as the arrangement or design of sensors, cooling elements, etc.

The drive unit has an output shaft, which controls the positioning movements of the respective robot limb. In addition to the electric motor, the drive unit typically also has a gearbox connected downstream of the motor.

• Gemäß einer bevorzugten Ausführungsvariante sind die beiden Bremsen gemeinsam auf einer Seite des Motors angeordnet. Beispielsweise auf der Eingangsseite, also gegenüberliegend zu der Abtriebswelle und insbesondere auch gegenüber liegend zum Getriebe. Alternativ hierzu sind die beiden Bremsen gemeinsam auf der Abtriebsseite also nachfolgend zum Motor angeordnet, wobei sie bevorzugt zwischen Motor und Getriebe positioniert sind.

Different positioning options are available for the two brakes:

• According to a preferred embodiment, the two brakes are arranged together on one side of the motor. For example, on the input side, i.e., opposite the output shaft and, in particular, also opposite the transmission. Alternatively, the two brakes are arranged together on the output side, i.e., downstream of the motor, preferably positioned between the motor and the transmission.

As an alternative to being positioned together on one side of the motor, the two brakes are arranged spaced apart on opposite sides of a component of the drive unit. Specifically, they are positioned on opposite sides of the motor or, alternatively, on opposite sides of the gearbox. Preferably, one of the brakes is positioned on the input side of the motor and the other brake is positioned on the output side of the motor, specifically between the motor and gearbox.

In a preferred embodiment, two redundant position sensors are assigned to each brake to detect the current position of the respective brake. This redundancy ensures reliable detection. Preferably, the two position sensors are designed differently. This ensures a high level of reliability. For example, the two position sensors are based on different (physical) operating principles and/or are connected in opposite directions, so that one sensor is normally closed and the other is normally open.

According to the invention, the object is further achieved by an articulated-arm robot having a redundantly designed system for its operation. Each redundantly designed system comprises several system components. To ensure high reliability, the two redundant systems are generally designed differently from one another according to a further aspect of the invention.

This fundamental design principle, whereby redundant systems are not identical but different, achieves a high level of reliability, so that, for example, design errors, programming errors, etc., which could lead to a failure in one redundant system, cannot occur in the other, differently designed system due to the design. Non-identical systems are understood here to mean that at least functionally identical and thus redundant system components of the two systems are designed differently. Preferably, several, and in particular all, functionally identical system components of the two systems are designed differently.

In a preferred embodiment, the differently designed system components are based on different operating principles, as previously explained in more detail in connection with, for example, the braking device, the motion sensors and/or the devices for detecting the currently acting force.

Alternatively or additionally, the various system components differ in that they come from different manufacturers, for example.

In particular, it is also provided that the articulated arm robot is assigned a redundant controller and/or a redundant evaluation unit, as already explained above The articulated-arm robot is controlled via the control unit. Such control units and/or evaluation units are also designed redundantly and, preferably, are different from one another. This means that the individual components, such as the hardware and/or software, are designed differently. The software and/or hardware are supplemented or alternatively supplied by different manufacturers.

Preferably, several system components, and preferably all system components of the two redundant systems, are designed differently from one another. This ensures a high level of fail-safe redundancy overall.

This basic principle is not limited to the application of an articulated arm robot, but can be applied generally to devices and machines.

1. a. die redundant ausgelegte Bremseinrichtung mit den zwei Bremsen, die auf einem unterschiedlichen Wirkprinzip beruhen,
2. b. die redundante Überwachung des Betriebs des Gelenkarmroboters mit zwei Überwachungseinrichtungen, die sich voneinander unterscheiden,
3. c. unterschiedliche Steuer- oder Auswerteeinheiten,
4. d. unterschiedlich ausgebildete Bewegungssensoren zur Erfassung einer momentanen Position des jeweiligen Robotergliedes,
5. e. unterschiedliche Einrichtungen zur Erfassung einer auf das Roboterglied momentan einwirkenden Kraft,
6. f. unterschiedliche Positionssensoren zur Erfassung von Positionen von Teilen einer Bremseinrichtung,
7. g. unterschiedliche Bussysteme zur Datenübertragung.

The system components are in particular at least one, several or all of the components already explained above, in particular

1. a. the redundant braking system with two brakes based on a different operating principle,
2. b. redundant monitoring of the operation of the articulated robot with two different monitoring devices,
3. c. different control or evaluation units,
4. d. differently designed motion sensors for detecting the current position of the respective robot limb,
5. e. different devices for detecting a force acting momentarily on the robot limb,
6. f. different position sensors for detecting the positions of parts of a braking device,
7. g. different bus systems for data transmission.

• 1 eine vereinfachte Seitenansicht eines Gelenkarmroboters,
• 2 eine schematisierte Blockbilddarstellung eines Gelenkarmroboters mit zwei unabhängigen Überwachungseinrichtungen,
• 3 eine schematisierte ausschnittsweise Blockbilddarstellung eines Gelenkarmroboters mit zwei unabhängigen Überwachungseinrichtungen gemäß einer alternativen Ausführungsvariante,
• 4, 5 alternative Varianten eines Gelenkarmroboters sowie
• 6 eine vereinfachte Seitenansicht einer Antriebseinheit mit einer Bremseinrichtung mit zwei unterschiedlich ausgestalteten Bremsen.

An embodiment of the invention is explained in more detail below with reference to the figures, which show, in simplified representations:

• 1 a simplified side view of an articulated arm robot,
• 2 a schematic block diagram of an articulated arm robot with two independent monitoring devices,
• 3 a schematic partial block diagram of an articulated arm robot with two independent monitoring devices according to an alternative embodiment,
• 4 , 5 alternative variants of an articulated arm robot and
• 6 a simplified side view of a drive unit with a braking device with two differently designed brakes.

In 1 as well as in the 4 and 5 Each of these shows an articulated-arm robot 20, which is used in particular as a medical robot for medical applications. The articulated-arm robot 20 is a multi-axis robot with several robot links 22, each of which is connected to one another via joints 24.

In the exemplary embodiment, the articulated arm robot 20 has, for example, a base 26 on which a base is arranged as a first robot link 22 and can rotate about a vertical axis of rotation via a first joint 24. On this base, a rocker arm, as a second robot link 22, is pivotable about a horizontal axis about a second joint 24. At the end, a robot arm, as a further robot link 22, is mounted on the rocker arm so as to be rotatable about a third joint 24. Finally, a robot hand, as a further robot link 22, is mounted on the robot arm so as to be rotatable about a further joint 24. At its front end, this hand has a rotatable fastening flange which is used to attach a tool. In the case of a medical robot, this can be, for example, a medical instrument or a patient bed.

During operation, the individual robot links 22 are adjusted relative to one another about the respective joints 24. For this purpose, each joint is assigned an individual electric drive unit to execute the adjustment movement. The articulated-arm robot 20 is generally controlled via a control unit not shown in detail here.

In addition to or as an alternative to a rotational adjustment about a rotational axis, at least one robot member 22 can also be adjusted translationally. This is achieved in particular with an additional translational drive unit or with a combined drive unit that is designed to perform both a rotational movement and a translational movement. 5 shows a variant in which a robot link 22 (right half of the image) can be moved translationally, for example along a guide.

For safety reasons, the movement sequence of such articulated-arm robots 20 is monitored. A high level of functional reliability must be ensured, particularly for articulated-arm robots 20 that work near people or even on patients, as is the case with medical robots.

• Bei dem in 2 sowie 3 vereinfacht in einer Blockbild-Darstellung gezeigten Gelenkarmroboter 20 sind die einzelnen Gelenke 24 schematisiert durch Boxen dargestellt, in dem mehrere Komponenten gezeigt sind. Die Gelenke 24 sind wiederum über vereinfacht dargestellte Roboterglieder 22 miteinander verbunden. Im Ausführungsbeispiel sind insgesamt lediglich drei Gelenke 24 dargestellt.

In connection with 2 as well as 3 The monitoring of the operation of the articulated arm robot 20 and the equipment required for this purpose are explained in more detail below:

• In the 2 as well as 3 In the articulated arm robot 20, shown in a simplified block diagram, the individual joints 24 are schematically represented by boxes in which several components are shown. The joints 24 are in turn connected to one another via simplified robot links 22. In the exemplary embodiment, only three joints 24 are shown.

In the actual implementation, 24 different components are typically arranged within each joint.

This particularly concerns an electric motor 28, to which a gear 30 is connected on the output side. The respective robot element 22 is driven via an output shaft 32.

On the output side, a first encoder 34A is mounted as a first motion sensor downstream of the gear 30. This encoder detects the movement of the output shaft 32 in order to determine the position and/or speed of the respective robot link 22. In the variant according to 3 This first encoder 34A is represented by two boxes, above which an embodiment with two reading heads is illustrated.

On the input side of the motor 28 opposite the gearbox 30, 2 A braking device with two redundant brakes 64A, B and a second encoder 34B as a second motion sensor are attached to an incoming shaft of the motor 28 (not shown in detail here). This has, in the variant according to 3 preferably has only one reading head. Furthermore, in this embodiment, the braking device with the two brakes 64A, B is arranged between the motor 28 and the gear 30.

Motor 28, gear 30, output shaft 32 and the braking device together with the encoders 34A, 34B form a respective drive unit 62 (cf. 6 ). A tool 38 is typically attached to the last joint 24 via a mounting flange.

The two encoders 34A, 34B are preferably designed differently, with one encoder 34A preferably being designed as an incremental encoder 34A and the other encoder 34B as an absolute encoder 34B. While the incremental encoder 34A only detects and transmits relative position changes, the absolute encoder 34B provides absolute positions of the robot member 22 as measurement results.

Within the box representing the joint 24, structural components of the robot link 22 are also schematically illustrated by way of example, with strain gauges 40A attached thereto as strain sensors, which form a first device for detecting a force acting on the respective robot link 22. In the exemplary embodiment, three strain gauges 40A are schematically illustrated by triangles. In the exemplary embodiment, the strain gauges 40A are connected to an associated transducer 42. Alternatively or additionally, in an alternative exemplary embodiment, a force measuring device is arranged as the first device or as a further first device for detecting the instantaneous force. The force measuring device is arranged between a last robot link, in particular between the so-called robot hand, and a processing tool (end effector) attached thereto.

Furthermore, a current sensor 40B is assigned to each motor 28, via which the instantaneous motor current of the motor 28 is detected. The current sensor 40B forms a second device for detecting the force acting on the respective robot link 22.

The individual drive units assigned to a respective joint 24, including the first and second motion sensors (encoders 34A, 34B) as well as the first and second devices (strain gauges 40A and current sensor 40B), are preferably identical for all joints 24.

Two evaluation units 44A, 44B are also configured for monitoring. The first evaluation unit 44A receives the (measurement) data from all first encoders 34A and all strain gauges 40A. Based on this data, the first evaluation unit 44A performs an evaluation with regard to the current position and/or speed of the respective robot link 22 and, in particular, with regard to the force currently acting on the robot link 22.

Analogously, the second evaluation unit 44B receives the (measurement) data of all second encoders 34B as well as all current sensors 40B and carries out the evaluation on the basis of this data analogously to the first evaluation unit 44A.

In the variant according to 3 Within the joint 24 represented by the box, two separate data paths are formed, each leading to a joint-specific interface 46A, B. These are, in particular, data or communication interfaces that communicate with the two evaluation units 44A, 44B. Specifically, the first system components (first encoder 34A, first brake 64A, first device (strain gauge 40A)) are connected to the first interface 46A. In contrast, the second system components (second encoder 34B, second brake 64B, second device (current sensor 40B)) are connected to the second interface 46B.

Each interface 46A, 46B is further connected to its associated evaluation unit 44A, B. The two interfaces 46A, B and/or the two evaluation units 44A, B are preferably connected to each other via a communication connection, in particular in order to compare the respective data with each other.

In an expedient further development, the data communication takes place in particular between the interfaces 46A, B and the evaluation units 44A, B via different bus systems 48A, 48B, in particular via a first bus system 48A designed as an Ethernet bus and via a second bus system 48B designed as an RS-485 bus.

The first evaluation unit 44A together with the first motion sensor (first encoder 34A) and the first device (strain gauge 40A) as well as in the variant according to 3 with the first interface 46A and the first bus system 48A form a first monitoring device. Correspondingly, the second evaluation unit 44B together with the second motion sensor (second encoder 34B) and the second device (current sensor 40B) as well as in the variant according to 3 with the second interface 46B and the second bus system 48B, a second monitoring device.

Overall, two redundant monitoring paths are created, ensuring reliable monitoring. It is particularly important to note that the individual sensor devices for the two monitoring paths are independent of each other and, in particular, are based on different measurement principles.

Furthermore, it should be emphasized that, as an overarching design principle for safe operation of the articulated-arm robot 2, it has a redundant system with multiple system components that are designed to be redundant to one another. Redundant system components are each designed to perform the same function and, in particular, enable the (continued) operation of the articulated-arm robot 2 if one of the two redundant system components fails.

The system components in this case are the previously mentioned first components of the first monitoring device and the first brake 64B or the previously mentioned second components of the second monitoring device and the second brake 64B.

At least some, preferably several and in particular all of these system components are designed differently from one another, as already explained above.

• Die redundante Bremseinrichtung 60 ist jeweils als Teil einer Antriebseinheit 62 ausgebildet. Über eine jeweilige Antriebseinheit 62 wird die Verstellbewegung eines jeweiligen Roboterglieds 22 ausgeübt. Die Antriebseinheit 62 ist insbesondere unmittelbar in einem Gelenk 24 angeordnet.

In connection with the 6 The redundant braking device 60 with the two brakes 64A, 64B, which function according to different physical principles, is explained below:

• The redundant braking device 60 is designed as part of a drive unit 62. The adjustment movement of a respective robot link 22 is carried out via a respective drive unit 62. The drive unit 62 is arranged, in particular, directly in a joint 24.

The redundant braking device 60 has two brakes 64A, 64B, each designed to exert a braking force without current. The two brakes 64A, 64B and the generation of the braking force are based on different operating principles.

In the illustrated embodiment, the drive unit 62 comprises the electric motor 28 on a common shaft 66 and the transmission 30 connected downstream of the electric motor on an output side. A portion of the shaft 66, referred to as the output shaft 32, drives the robot member 22 and is connected to it via a suitable, for example, flexible, shaft connection.

In the exemplary embodiment, the braking device 60 is arranged on a section of the shaft 66 formed on the input side and thus opposite the output side.

Alternatively, according to a preferred variant, the braking device is arranged between the motor 28 and the transmission 30.

In the exemplary embodiment, the shaft 66 has a section designed as a hollow shaft 72, to which the braking device 60 is attached. The hollow shaft 72 is connected to the remaining shaft 66 in a suitable manner, for example via flanges.

In the center of the hollow shaft 72, it has a stationary brake disc 74 firmly connected to it. Positioned on either side of this is a movable brake disc 76A, 76B, each mounted so as to be displaceable in the longitudinal direction of the hollow shaft 72.

Each of these movable brake discs 76A, 76B is assigned an electromagnet 78A, 78B.

A currentless force acts on each of the movable brake discs 76A, 76B, directed toward the stationary brake disc 74. For one movable brake disc 76A, this force is exerted by means of a spring element 80. For the other movable brake disc 76B, this force is exerted by means of a permanent magnet 82. This is, for example, embedded in the movable brake disc 76B or forms a carrier on which a brake pad is arranged.

The two electromagnets 78A, 78B are used to control the braking force, which can generate a counterforce to the spring force or the force of the permanent magnet.

The two electromagnets 78A, 78B are controlled via electrical lines 84. The electrical lines 84 run within a cavity of the hollow shaft 72 to the electromagnets 78A, 78B.

Furthermore, position sensors 86 are preferably arranged, which detect the respective position of the movable brake disc 76A, 76B in relation to the stationary brake disc 74. Depending on these position sensors 86A, B, the electromagnets 78A, 78B, for example, are controlled.

Preferably, two position sensors 86A, 86B are assigned to each movable brake disc 76A, 76B. These are preferably not only redundant but also differently configured. Specifically, the position sensors 86 monitor an air gap between the movable brake disc 76A, 76B and the stationary brake disc 74. The two redundant position sensors 86A, 86B, each assigned to a brake 64A, 64B, are preferably configured to operate in opposite directions, so that one sensor is normally closed and the other sensor is normally open.

List of reference symbols

20

Articulated arm robot

22

robot limb

24

joint

26

base

28

Motor

30

Gearbox

32

Output shaft

34A

first encoder

34B

second encoder

38

Tool

40A

strain gauges

40B

Current sensor

42

Transducer

44A

first evaluation unit

44B

second evaluation unit

46A

first interface

46B

second interface

48A

first bus system

48B

second bus system

60

braking device

62

drive unit

64A, B

brake

66

Wave

72

hollow shaft

74

stationary brake disc

76A, B

movable brake disc

78A, B

electromagnet

80

spring element

82

permanent magnet

84

Line

86A, B

Position sensors

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1 445 075 B2 [0002, 0005]

Claims (17)

Articulated arm robot (20) with a plurality of robot links (22) each connected to one another via a joint (24) and each driven by an electric motor (28), which is designed for redundant monitoring of its operation, characterized in that two mutually independent monitoring devices, namely a first monitoring device (34A, 40A, 44A) and a second monitoring device (34B, 40, 44B), are designed and each of the monitoring devices has - a respective motion sensor, namely a first and a second motion sensor (34A, 34B) for detecting a current position of the respective robot link (22), - a respective device for detecting a force currently acting on the robot link (22), namely a first and a second device (40A, 40B), wherein the two devices are based on different measuring principles, - a respective evaluation unit, namely a first evaluation unit (44A) for processing data from the first motion sensor (34A) and data from the first device (40A) and a second evaluation unit (44B) for processing data from the second motion sensor (34B) and data from the second device (40B). Articulated arm robot (20) according to the preceding claim, wherein the first monitoring device (34A, 40A, 44A) has, as the first device for detecting the instantaneous force, at least one strain sensor attached to the robot member (22), which is designed in particular as a strain gauge (40A) or alternatively as a force measuring device. Articulated arm robot (20) according to the preceding claim, wherein the second monitoring device (34B, 40, 44B) has a current sensor (40B) for determining the motor current of the motor (28) as a device for detecting the instantaneous force. Articulated arm robot (20) according to one of the preceding claims, wherein the two motion sensors are encoders (34A, 34B) for detecting the rotational movement of a shaft of the motor (28). Articulated arm robot (20) according to one of the preceding claims, wherein the motion sensors (34A, 34B) are arranged at different locations, in particular on opposite sides of the motor (28). Articulated arm robot (20) according to one of the preceding claims, wherein the motion sensors (34A, 34B) are designed differently. Articulated arm robot (20) according to one of the preceding claims, wherein one motion sensor is designed as an incremental encoder (34A) and the other motion sensor is designed as an absolute encoder (34B) and/or the encoders (34A, 34B) differ with regard to the number of read heads. Articulated arm robot (20) according to one of the preceding claims, wherein a first and a second motion sensor (34A, 34B) and a first and a second device (40A, 40B) are each assigned to several and in particular all robot members (22), and the data of all first motion sensors (34A) and first devices (40A) are evaluated by the first evaluation unit (44A) and the data of all second motion sensors (34B) and second devices (40B) are evaluated by the second evaluation unit (44B). Articulated arm robot (20) according to one of the preceding claims, wherein the two evaluation units (44A, 44B) are designed differently and in particular originate from different manufacturers. Articulated arm robot (20) according to one of the preceding claims, wherein different bus systems are used for data communication, in particular with the evaluation units (44A, 44B). Articulated arm robot (20) according to one of the preceding claims, wherein the robot members (22) are driven by electric drive units (62), each having an electric motor (28), wherein at least one drive unit (62) has a redundant braking device (60) with two brakes (64A, B), each designed to exert a currentless braking force, characterized in that the two brakes (64A, B) are based on different operating principles, so that the respective braking force of the two brakes (64A, B) is exerted by different operating principles. Method for monitoring a multi-axis articulated arm robot (20) which has a plurality of robot members (22) which are each connected to one another via a joint (24) and each driven by an electric motor (28), wherein the monitoring is carried out by means of a first monitoring device (34A, 40A, 44A) and a second monitoring device (34B, 40B, 44B), and each of the monitoring devices has - in each case a motion sensor, namely a first and a second motion sensor (34A, 34B), via which a current position of the respective robot member (22) is detected, - in each case a device for detecting a force currently acting on the robot member (22), namely a first and a second device (40A, 40B), wherein the two devices (40A, 40B) are based on different measuring principles and a force currently acting on the robot member (22), in particular a deformation, is measured via the two devices (40A, 40B), - in each case an evaluation unit, namely a first evaluation unit (44A), which evaluates the data of the first motion sensor (34A) and the data of the first device (40A), and a second evaluation unit (44B), which evaluates the data of the second motion sensor (34B) and the data of the second device (40B). Articulated arm robot (20), in particular according to one of the preceding claims, with a redundantly designed system for operating the articulated arm robot (20), wherein the respective redundant system has a plurality of system components, characterized in that at least one of the system components of the two redundant systems is designed differently. Articulated arm robot (20) according to the preceding claim, characterized in that the differently designed system components are based on different operating principles. Articulated arm robot (20) according to one of the two preceding claims, characterized in that a respective redundant system has a control unit and/or evaluation unit, wherein the control units and/or evaluation units of the two redundant systems are different from one another and in particular originate from different manufacturers. Articulated arm robot (20) according to one of the Claims 11 until 13 , characterized in that preferably several system components and in particular all system components of the two redundant systems are different from one another. Articulated arm robot (20) according to one of the Claims 11 until 14 , characterized in that the system components are one or more, and preferably all, of the following components: a. a redundantly designed braking device (60) with two brakes (64A, 64B) which are based on a different operating principle, b. redundant monitoring of the operation of the articulated arm robot (20) with two monitoring devices which differ from one another, c. different control or evaluation units (44A, B), d. differently designed movement sensors (34A, 34B) for detecting a current position of the respective robot member (22), e. different devices for detecting a force currently acting on the robot member (22), f. different position sensors (86A, B) for detecting positions of parts of a braking device (60), g. different bus systems for data transmission.

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