Method for monitoring an automated guided vehicle

Abstract

Method for operating a driverless transport vehicle, wherein the transport vehicle has an electric drive system with a control device (10) for controlling the electric drive system, wherein the drive system is controlled by means of the control device (10), wherein the control device (10) generates setpoint values ​​of at least one operating variable of the electric drive system and detects actual values ​​of at least one operating variable of the drive system, wherein the transport vehicle further comprises a monitoring device (12), in particular a safety controller, wherein the monitoring device (12) and the control device (10) are connected by a data connection (14), wherein data packets containing the generated setpoint values ​​and / or the detected actual values ​​are generated by the control device (10) and transmitted to the monitoring device (12) via the data connection (14) and evaluated by the monitoring device (12) in order to detect errors in the operation of the drive system, in particular errors in the control of the drive system by means of the control device (10), characterized in that the data packets each contain a counter value generated by the monitoring device (12) and transmitted to the control device (10), which counter value is checked by the monitoring device (12) after receipt of the respective data packet in order to detect errors in the operation of the drive system.

Description

[0001] The invention relates to a method for monitoring a driverless transport vehicle.

[0002] Automated guided vehicles are known from the state of the art. These types of vehicles are used to transport loads. Automated guided vehicles are used primarily in confined spatial areas, for example, within a production facility and / or a warehouse.

[0003] Such automated guided vehicles pose a significant risk to people. Persons who enter the path of such automated guided vehicles can suffer severe and, in extreme cases, fatal injuries if the vehicle is not stopped before physical contact occurs between the person and the vehicle. The same naturally applies to other objects that may be in the path of the vehicle and that could be damaged by the vehicle and / or sustain damage. However, it is the potential risk to people, in particular, that leads to the highest demands being placed on the operational safety of such vehicles.

[0004] Transport vehicles of the type in question are typically moved by electric drive systems controlled by a control device of the transport vehicle. For this purpose, the control device can be connected to the electric drives of the drive system, for example, via a bus system. Target values ​​generated by the control device can be transmitted to the drive system via this bus system, and actual values ​​of operating variables of the electric drive system can be received by the control device. The drive system, in particular the control device of the drive system, but also other components such as actuators and / or sensors of the drive system, represent components of a safety function of the transport vehicle with regard to the personal hazards described above.Faults in the drive system, particularly in the control system, can cause a transport vehicle to continue moving without restriction in a critical situation, for example, where a person is in its path of movement, even if the person is correctly detected by the transport vehicle's corresponding sensors. This can be the case, for example, if a sensor failure fails to detect that the transport vehicle is still moving, causing a brake to fail to be triggered.

[0005] This problem can be addressed by selecting components for the electric drive system, and especially for its control system, that offer an appropriate level of functional and operational safety. Such components are designed to offer, in particular, the highest level of reliability.

[0006] However, the disadvantage of using such high-quality components is the associated costs.

[0007] EP 2 639 790 A1 describes a driverless vehicle with a control unit and at least one ultrasonic sensor. The ultrasonic sensor includes an evaluation unit. The evaluation unit is designed such that altered portions of the ultrasonic signals can be identified as a test signal.

[0008] AT 525 002 A2 describes a driverless transport unit in which a control signal for activating a driving unit is sent from a controller in the transport unit, wherein the driving operation is preferably monitored by a safety controller, wherein a blocking device is activated upon detection of a malfunction.

[0009] The invention is therefore based on the object of demonstrating a method for operating an automated guided vehicle which enables a high functional safety of the drive system of the automated guided vehicle while at the same time keeping costs as low as possible.

[0010] The object is achieved by a method for monitoring a driverless transport vehicle having the features of independent claim 1. The features of the dependent claims relate to advantageous embodiments.

[0011] The transport vehicle, the operation of which is the subject of the method, has an electric drive system with a control device for controlling the electric drive system of the transport vehicle. The method provides that the drive system is controlled by means of the control device, wherein the control device generates setpoint values ​​of at least one operating variable of the electric drive system and records actual values ​​of at least one operating variable of the drive system.

[0012] The transport vehicle also has a monitoring device. This monitoring device can, in particular, be a safety controller. The monitoring device and the control device are connected by a data link.

[0013] To achieve this objective, the method provides, in particular, that the control device generates data packets containing the generated setpoints and / or the detected actual values ​​and / or, if applicable, further information and transmits them to the monitoring device via the data connection. The monitoring device evaluates the data packets to detect errors in the operation of the drive system. The errors in the operation of the drive system can, in particular, be errors in the control of the drive system by means of the control device and / or errors in the drive device.

[0014] In connection with the present invention, it has been shown that such monitoring of a control device by means of a monitoring device enables the use of comparatively simple and cost-effective components for the drive system, in particular the control device. Errors that occur during operation of the drive system can be detected by the monitoring device through the evaluation of the data packets by the monitoring device, which enables the monitoring device, in particular, to intervene in the operation of the driverless transport vehicle upon detection of an error in the operation of the drive system.

[0015] The method can provide that the data packets comprise actual value data packets containing actual values ​​and / or setpoint value data packets containing setpoint values. The distribution of setpoint values ​​and actual values ​​across different data packets offers the possibility of processing setpoint values ​​and actual values ​​more independently of one another within the framework of the method. In particular, the actual value data packets contain no setpoint values ​​and / or the setpoint value data packets contain no actual values. In particular, the discrete distribution of actual values ​​and / or setpoint values ​​across different data packet types enables at least largely independent processing of actual values ​​and setpoint values, in particular with regard to the structuring of the software used for this purpose. Alternatively and / or additionally, setpoint values ​​and actual values ​​can be generated and transmitted in different data formats.

[0016] The method can provide for the data packets to be generated by the control device at a specific time-dependent rate, for example, every 10 ms. Furthermore, the method can provide for the data packets to be generated by the control device at a specific time-dependent rate, for example, every 10 ms, and sent to the monitoring device via the data connection. Such generation or transmission of data packets is also referred to as cyclical generation or transmission of data packets. Compared to other methods, such as event-driven generation or transmission, this method has the advantage that the monitoring device can detect an absence of data packets over a specific period of time as an error in the operation of the drive system.

[0017] The method can provide that data packets contain setpoints and / or actual values ​​of calculated positions or sensors independently of the The method can provide that data packets contain setpoints and / or actual values ​​of operating variables from which the actual and / or controlled time-dependent trajectory of the transport vehicle can be determined. Accordingly, the operating variables can be in particular steering angle and speed(s) and / or rpm(s) and / or operating variables that are dependent on the above operating variables, in particular proportionally. The monitoring of operating variables from which the time-dependent trajectory can be determined makes it possible to safeguard the essential functions of the drive system control, namely those that have a direct impact on the movement of the transport vehicle.

[0018] In particular, the actual value data packets contain actual values ​​of operating variables from which the actual time-dependent trajectory of the transport vehicle can be determined. Alternatively and / or additionally, the setpoint value data packets contain setpoint values ​​of operating variables from which the controlled time-dependent trajectory of the transport vehicle can be determined. Such an organization of the values ​​in the packets ensures that the actual and / or controlled trajectory can be determined from an actual value data packet and / or a setpoint value data packet, respectively.

[0019] The method can in particular provide that the monitoring device checks the integrity of the transmitted data packets. Such a check of the integrity of the transmitted data packets can prevent errors in the data transmission from the control device to the monitoring device from resulting in errors in the operation of the electric drive system not being detected by the monitoring device. The check of the integrity of the transmitted data packets can in particular be carried out by means of a check value generated for the data packets by the control device. For this purpose, the check value can be transmitted to the monitoring device via the data connection. The check value can be transmitted as part of the respective data packet. The check value can be a checksum, for example.

[0020] The method provides that the data packets each contain a counter value generated by the monitoring device, which is checked by the monitoring device after receipt of the respective data packet. The counter value is transmitted to the control device, in particular via the data connection. In this case, the method can provide, in particular, that the actual value data packets each contain an actual value counter value generated by the monitoring unit and / or the setpoint value data packets each contain a setpoint counter value generated by the monitoring device. The actual value counter value and / or the setpoint counter value are transmitted to the control device, in particular via the data connection. The actual value counter value and / or the setpoint counter value are checked by the monitoring device after receipt of the respective data packet.Checking the counter value can be used in particular to detect errors in the operation of the control device.

[0021] The counter values ​​can be checked, in particular, by checking whether the counter value corresponds to an expected value and / or lies within an expected value range. The counter value can be generated by the monitoring device and sent to the control device, in particular at a specific time-dependent rate. In particular, if the data packets are generated at a specific time-dependent rate, the method can provide that each data packet generated and sent by the control device contains the last counter value received by the control device. An expected value range can be useful in such a method in order to avoid immediately triggering operational intervention in the event of merely momentary disturbances that, for example, lead to a minimal time delay in the transmission of a data packet by the control device.However, if, for example, a so-called "stuck at" error occurs in the control device, in which identical data packets are continuously sent to the monitoring device at constant time intervals, the monitoring device can easily detect a malfunction from the counter value that then remains constant. This constant counter value of the identical data packets would, after a short time, no longer be within the expected value range for the counter range contained in the data packet received at a specific time.

[0022] The method can provide that data packets contain first actual values. The data packets containing the first actual values ​​are in particular the actual value data packets. Furthermore, the data packets containing the first actual values, i.e. in particular the actual value data packets, contain in particular first counter signal values. The first actual values ​​can be detected by a first sensor. The first sensor can in particular be an incremental encoder. The incremental encoder detects in particular the angular changes of a travel drive of the transport vehicle. The first actual values ​​are detected in particular by means of a first detection device of the control device. The first detection device can be a first input / output unit, for example in the form of an I / O card and / or an input / output module.

[0023] The first detection device can have two signal inputs. The method can provide for a signal from the first sensor to be detected via one signal input. The signal can be an HTL signal, for example. The method can provide for the first actual values ​​to be determined from the signal from the first sensor. The method can provide for a first counter signal, from which the first counter signal values ​​are determined, to be detected via the other signal input.

[0024] The method may provide that the first counter signal values ​​are checked by the monitoring device after receipt of the respective data packet in order to detect errors in the operation of the drive system. In particular, the first counter signal values ​​may be checked to detect errors in the first detection device.

[0025] The first counter signal values ​​can be checked, in particular, by checking whether the first counter signal value corresponds to an expected value and / or is within an expected value range. The first counter signal values ​​can be determined, in particular, from the first counter signal at a specific time-dependent rate. In particular, when the data packets are generated at a predetermined time rate, the method can provide that each data packet generated and sent by the control device contains the last counter signal value determined by the first detection device. The monitoring unit can check the first counter signal values, for example, to determine whether the first counter signal value of a data packet received by the monitoring unit is greater or lesser than the second counter signal value of a data packet previously received by the control device.If the first counter signal value remains unchanged from packet to packet, this may indicate a fault in the detection device, which leads to the repeated generation of data packets with the same content.

[0026] The method can provide for data packets to contain second actual values. The data packets containing the second actual values ​​are, in particular, the actual value data packets. Furthermore, the data packets containing the second actual values, i.e., in particular, the actual value data packets, contain, in particular, second counter signal values. The second actual values ​​can be detected by a second sensor.

[0027] In one variant of the method, the second sensor can be, in particular, an incremental encoder. The incremental encoder detects, in particular, the angular changes of another drive of the transport vehicle. The transport vehicle can, particularly in this context, be a transport vehicle with a differential drive. The second actual values ​​are detected, in particular, by means of a second detection device of the control device. The second detection device can be a second input / output unit, for example in the form of an I / O card and / or an input / output module.

[0028] According to this variant of the method, the second detection device can have two signal inputs. The method can provide that a signal from the second sensor is detected via one signal input. The signal can be an HTL signal, for example. The method can provide that the second actual values ​​are determined from the signal from the second sensor. The method can provide that a second counter signal, from which the second counter signal values ​​are determined, is detected via the other signal input.

[0029] According to an alternative variant of the method, the second sensor can be, in particular, an absolute value encoder. The absolute value encoder detects, in particular, the steering angle of the transport vehicle. The transport vehicle can be, particularly in this context, a transport vehicle with a turntable drive. The second actual values ​​are detected, in particular, by means of a second detection device of the control device. The second detection device can be a second input / output unit, for example in the form of an I / O card and / or an input / output module.

[0030] According to this variant of the method, the second detection device can have two signal inputs. The method can provide that a first signal from the second sensor is detected by means of one signal input. The first signal can be, for example, a DATA signal from a synchronous serial interface (SSI). The method can provide that the second actual values ​​are determined from the first signal from the second sensor. The method can provide that a second signal from the first sensor, from which the second counter signal values ​​are determined, is detected by means of the other signal input. The signal can be, for example, a CLOCK signal from a synchronous serial interface (SSI).

[0031] The method may provide that the second counter signal values ​​are checked by the monitoring device after receipt of the respective data packet in order to detect errors in the operation of the drive system. In particular, the second counter signal values ​​may be checked to detect errors in the second detection device.

[0032] The second counter signal values ​​can be checked, in particular, by checking whether the counter signal value corresponds to an expected value and / or is within an expected value range. The second counter signal values ​​can be determined, in particular, from the second counter signal at a specific time-dependent rate. In particular, when the data packets are generated at a predetermined time rate, the method can provide that each data packet generated and sent by the control device contains the last counter signal value determined by the second detection device. The second counter signal values ​​can be checked by the monitoring unit, for example, to determine whether the second counter signal value of a data packet received by the monitoring unit is greater or lesser than the second counter signal value of a data packet previously received by the control device.If the second counter signal value remains unchanged from packet to packet, this may indicate, in particular, an error in the detection device, which leads to the repeated generation of data packets with the same content.

[0033] The method can provide for the first counter signal values ​​and the second counter signal values ​​to exhibit time-dependent curves with opposite signs. This enables a reliable differentiation between the first and second counter signal values. In particular, the first and second counter signal values ​​can each exhibit time-dependent increasing values ​​with opposite signs of the first and second counter signal values. This enables a simple verification of the counter signal values.

[0034] The first and second counter signals can be identical. In this case, the identical counter signals can be generated, in particular, using a counter signal generating device whose signal output is connected, in particular, to a signal input of each of the first and second detection devices. The first and second counter signal values ​​can then be determined, in particular, by determining first and second counter signal values ​​with opposite signs from identical counter signals.

[0035] The method can provide that the actual values ​​transmitted in the data packets from the control device to the monitoring device are compared by the monitoring device with the setpoint values ​​transmitted in the data packets from the control device to the monitoring device in order to detect errors in the operation of the drive system.

[0036] The method can, in particular, provide for the monitoring device to compare actual values ​​from an actual value data packet with target values ​​from a target value data packet. The comparison is carried out, in particular, between values ​​or data packets that were generated or transmitted to the monitoring device within a specific time interval. This ensures that the actual values ​​and target values ​​compared are so closely related in time that a comparison can be made in a meaningful way, because it is ensured that, within this close temporal relationship, the trajectory of the automated guided vehicle or the operating variables of the drive system leading to this trajectory cannot have changed so significantly that a comparison would no longer produce meaningful results.

[0037] The comparison can be carried out in particular by checking whether any differences between actual values ​​and target values ​​relating to the same operating variable lie within a specific tolerance range. In other words, it can be checked, for example, whether an actual speed lies within a defined tolerance range around a target speed with which the actual speed is compared. In this way, the monitoring device can be used to check whether the controlled operating variables specified by the control device are actually converted by the drive system into real movements of the corresponding elements of the drive system. If this is not the case, this can be detected by the monitoring device as an error in the operation of the drive system and, in particular, if such an error in the operation of the drive system is detected, operational intervention can be carried out by the monitoring device.

[0038] The method can, in particular, provide for the control device to have software structured using program organization units. In this context, program organization units are understood to mean, in particular, so-called program organization units, also referred to as POUs, of a programmable logic controller. In particular, these include POUs as defined in the IEC 61131-3 standard.

[0039] In this context, the method can in particular provide that the acquisition of an actual value and / or the generation of a target value takes place in the same program organization unit, in particular the same POU, as the generation of a data packet containing this value, in particular in order to keep the time offset between the acquisition of an actual value and the generation of a target value as small as possible and to reduce the complexity of the program structure.

[0040] In particular, the acquisition of actual values ​​and the generation of actual value data packets can take place in the same program organizational unit, and / or the generation of setpoint values ​​and the generation of setpoint data packets can take place in the same program organizational unit. This creates a corresponding encapsulation of the acquisition or generation of the respective values ​​with the generation of the corresponding data packets in the program flow. If errors are detected during the monitoring device's review of the data packets, they can be specifically assigned to the program organizational units.

[0041] The transport vehicle can have a sensor arrangement for detecting obstacles within a monitoring area around the transport vehicle. The sensor arrangement can comprise at least one laser scanner for monitoring the monitoring area and / or a portion of the monitoring area. The method can provide for the signals generated by the sensor arrangement to be evaluated. The evaluation of the signals generated by the sensor arrangement can be performed, in particular, by the monitoring unit. The method can provide for the monitoring unit to initiate an operational intervention if an obstacle is detected by the sensor arrangement.

[0042] The method can, in particular, provide for the size and / or shape of the monitoring area to be selected depending on the operating parameters of the drive system. The size and / or shape of the monitoring area is selected, in particular, depending on a movement path of the transport vehicle determined, in particular calculated, from the operating parameters. In this context, the movement path of the transport vehicle is calculated or the size and / or shape of the monitoring area is selected, in particular, by the monitoring device and / or based on the actual values ​​contained in the data packets.

[0043] Such a procedure enables the monitoring area to be selected appropriately depending on the respective operating situation. In this way, the monitoring area is selected in such a way that, on the one hand, safe operation is guaranteed, but on the other hand, the risk of unnecessary shutdowns of the transport vehicle due to detected obstacles is avoided. For example, only a very limited monitoring area can be selected, thus avoiding unnecessary operational interventions when the transport vehicle is at a standstill due to people being in the detection area. Even people who are not in the path of the transport vehicle in relation to the direction of movement of the transport vehicle, e.g. when cornering, are not usually at risk from the moving transport vehicle, so it is sensible for these people not to cause operational interventions.Furthermore, the distance from the transport vehicle at which an obstacle must be located to trigger an operational intervention can be adjusted to the transport vehicle's speed. A very slowly moving transport vehicle can be stopped in a much shorter distance than a fast-moving transport vehicle. Therefore, a more "predictive" operating mode is required for the latter.

[0044] The method can provide that an operational intervention, in particular by the monitoring device, takes place upon detection of an error in the operation of the drive system, in particular by a monitoring device, and / or upon detection of an obstacle within the monitoring area, in particular by the monitoring device. In this context, the method can in particular provide that the driverless transport vehicle is transferred into a safe operating state by the operational intervention. The safe operating state can in particular be an operating state in which the transport vehicle is brought to a standstill, for example by closing a brake or a plurality of brakes and / or stopping the supply of electrical energy to the drive or drives of the transport vehicle, for example by means of a contactor or a plurality of contactors.Consequently, the operational intervention may in particular involve closing at least one brake and / or disconnecting at least one electric drive from its power supply.

[0045] In particular, the monitoring device and / or the sensor arrangement meets at least safety requirements corresponding to a Category 3 and Performance Level d architecture according to DIN EN ISO 13849-1:2016-06. Alternatively and / or additionally, the monitoring device can meet higher safety requirements, particularly with regard to Category 3 and Performance Level d according to DIN EN ISO 13849-1:2016-06, than the control device and / or the first and / or second sensor. In this way, the highest level of functional safety can be ensured, even if some components of the transport vehicle, and in particular the drive system, only meet operational requirements and are therefore significantly more cost-effective.

[0046] Further practical embodiments and advantages of the invention are described below in connection with the drawing. Fig. 1 shows a simplified process diagram of an exemplary method for operating a driverless transport vehicle.

[0047] The Fig. The simplified process diagram shown in Figure 1 shows a method for operating an automated guided vehicle having an electric drive system with a control device 10 for controlling the electric drive system. The method provides that the drive system is controlled by the control device 10, wherein the control device 10 generates setpoint values ​​of at least one operating variable of the electric drive system and detects actual values ​​of at least one operating variable of the drive system.

[0048] The transport vehicle also has a monitoring device 12. This can be a safety controller, as in the example shown. The monitoring device 12 and the control device 10 are connected by a data link 14.

[0049] The method provides for the control device 10 to generate data packets. As in the example shown, these can be setpoint data packets containing the generated setpoints and actual value data packets containing the acquired actual values. The data packets are transmitted via the data connection 14 to the monitoring device 12. The monitoring device 12 evaluates the data packets to detect errors in the operation of the drive system.

[0050] As in the exemplary method, the generation of the data packets and the transmission of the data packets via the data connection 14 by the control device 10 can occur at a specific time-dependent rate. The setpoint data packets can contain setpoint values ​​of operating variables from which the controlled time-dependent trajectory of the transport vehicle can be determined. Accordingly, the actual value data packets can contain actual values ​​of operating variables from which the actual time-dependent trajectory of the transport vehicle can be determined.

[0051] For example, the transport vehicle can have a drive system with a first drive 16 and a second drive 18, as shown. The first drive 16 and the second drive 18 can be used to implement a differential drive of the driverless transport vehicle. With such a differential drive, the first and second drives 16, 18 can each drive a wheel of the transport vehicle, wherein the wheels driven by the drives 16, 18 are arranged on different sides of the transport vehicle. The wheels are driven in particular such that the speed of a drive 16, 18 during operation of the transport vehicle is always in a fixed ratio to the speed of the wheel driven by this drive 16, 18. The speed of a drive 16, 18 is thus proportional to the speed of the wheel driven by this drive 16, 18.The movement path of the transport vehicle can therefore be determined from the speeds of both drives 16, 18.

[0052] As in the example shown, the control device 10 can be connected to the drives 16, 18 of the drive system via a data bus 20, for example, a CAN bus. The data bus 20 can, as in the example shown, transmit setpoints for the rotational speeds of the first drive 16 and the second drive 18 to the drives 16 and 18. The method can also provide for actual values ​​of the rotational speeds of the drives 16 and 18 to be transmitted to the control device 10 via the data bus 20. These values ​​can be used, in particular, to control the drives 16, 18 by the control device 10.

[0053] The method may further provide that the monitoring device 12 performs a check of the integrity of the data packets transmitted via the data connection 14. This can be done, for example, by means of a checksum generated for each data packet by the control device 10 and transmitted to the monitoring device 12 via the data connection 14 as part of the respective data packet.

[0054] The method can further provide that the monitoring device 12 generates counter values ​​and transmits them to the control device 10 via the data connection 14. As in the example shown, the data packets transmitted from the control device 10 to the monitoring device 12 can contain these counter values. In particular, each data packet contains the last counter value received from the control device 10 before its generation. The monitoring device 12 can detect errors in the operation of the drive system based on the counter values, in particular by the monitoring device 12 checking whether the respective counter value in a specific data packet lies within an expected value range.

[0055] As in the example shown, the actual value data packets can contain first actual values ​​and second actual values. The first actual values ​​can be detected at a first sensor 22 by means of a first detection device 24. The first sensor 22 can be an incremental encoder, and the first detection device 24 can be an I / O card of the control device 10. The first detection device 24 can have two signal inputs, with one signal input detecting a signal 26 from the first sensor 22. A first counter signal 28 can be detected by means of the other signal input. First counter signal values ​​can be determined from the first counter signal 28.

[0056] The second actual values ​​can be detected at a second sensor 30 by means of a second detection device 32. The second sensor 30 can be an incremental encoder, and the second detection device 32 can be an I / O card of the control device 10. The second detection device 32 can have two signal inputs, with one signal input detecting a signal 34 from the second sensor 30. A second counter signal 36 can be detected by means of the other signal input. Second counter signal values ​​can be determined from the second counter signal 36.

[0057] In an alternative to the illustrated embodiment, it could, for example, be a driverless transport vehicle with a turntable drive. The method could then differ from the one described in Fig. 1 in particular in that the second drive 18 and the second sensor 30 would be replaced by a steering angle adjustment device controlled by the control device 10 and a steering angle sensor. The steering angle sensor can be an absolute value encoder. Such an absolute value encoder would in particular generate both a first signal with which the second actual values ​​are determined, and a second signal from which the second counter signal values ​​would be determined. Both signals would in particular be detected by means of two inputs of the second detection device 32 and the second actual values ​​and second counter signal values ​​determined from these signals would be transmitted by means of the actual value data packets analogously to the above with reference to the Fig. 1 described example to the monitoring device 12.

[0058] The method may provide that the actual value data packets contain the first and second actual values ​​as well as the first and second counter signal values. By checking the counter signal values ​​after receipt, errors in the operation of the drive system can be detected by the monitoring device 12.

[0059] Furthermore, the transport vehicle can have a sensor arrangement. This can comprise at least one or, as shown by way of example, two laser scanners 38 and 40. For example, a first laser scanner 38 can be oriented forward relative to the transport vehicle and a second laser scanner 40 can be oriented rearward relative to the transport vehicle, thus each monitoring a part of a monitoring area. The laser scanners 38, 40 can be connected to the monitoring device 12 by means of a further data connection 42, as shown by way of example. The signals generated by the sensor arrangement formed in the example shown by the first laser scanner 38 and the second laser scanner 40 can be evaluated by the monitoring device 12 in order to detect obstacles within the monitoring area around the transport vehicle.In this case, the method can, in particular, provide for the size and / or shape of the monitoring area to be adjusted depending on the operating parameters of the drive system. This can be done, in particular, by the monitoring device 12. In the example shown, this can be done, for example, by the monitoring device 12 evaluating either the signal generated by the first laser scanner 38 or the second laser scanner 40, depending on the direction of travel (forward or reverse), in order to detect obstacles within the monitoring area and thus, in particular, the travel path of the transport vehicle.

[0060] The method can provide for an operational intervention by the monitoring device 12 upon detection of a fault in the operation of the drive system or upon detection of an obstacle within the monitoring area. The operational intervention can, for example, involve triggering a contactor 44 to disconnect the drives 16 and 18 from their power supply. Alternatively and / or additionally, the operational intervention can involve triggering a brake 46.

[0061] As in the example shown, the driverless transport vehicle can have a network connection device 48, for example a switch. This can be used to establish a connection between external data processing devices 50, 52, for example a data processing device 50 for carrying out fleet management of a fleet of driverless transport vehicles or a localization data processing device 52 for localizing driverless transport vehicles, and components of the transport vehicle. In particular, access to the control device 10 can be enabled by means of the network connection device 48. Alternatively and / or additionally, it is also possible, for example, to connect components of the sensor arrangement, such as the first laser scanner 38 and the second laser scanner 40 shown as an example, to external data processing devices via the network connection device 48.

[0062] The features of the invention disclosed in the present description, the drawings, and the claims may be essential, both individually and in any combination, for the realization of the invention in its various embodiments. The invention is not limited to the described embodiments. It may be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art. List of reference symbols 10 Control device 12 Monitoring device 14 Data connection 16 first drive 18 second drive 20 data bus 22 first sensor 24 first recording device 26 Signal of the first sensor 28 first counter signal 30 second sensor 32 second detection device 34 Signal of the second sensor 36 second counter signal 38 first laser scanner 40 second laser scanner 42 additional data connections 44 contactor 46 Brake 48 Network connection device 50 data processing facility 52 Data processing facility

Claims

[1] Method for operating a driverless transport vehicle, wherein the transport vehicle has an electric drive system with a control device (10) for controlling the electric drive system, wherein the drive system is controlled by means of the control device (10), wherein the control device (10) generates setpoint values ​​of at least one operating variable of the electric drive system and detects actual values ​​of at least one operating variable of the drive system, wherein the transport vehicle further comprises a monitoring device (12), in particular a safety controller, wherein the monitoring device (12) and the control device (10) are connected by a data connection (14), wherein data packets containing the generated setpoint values ​​and / or the detected actual values ​​are generated by the control device (10) and transmitted to the monitoring device (12) via the data connection (14) and evaluated by the monitoring device (12) in order to detect errors in the operation of the drive system, in particular errors in the control of the drive system by means of the control device (10), characterized by that the data packets each contain a counter value generated by the monitoring device (12) and transmitted to the control device (10), which is checked by the monitoring device (12) after receipt of the respective data packet in order to detect errors in the operation of the drive system. [2] Method according to claim 1, characterized bythat the data packets include actual value data packets that contain actual values ​​and in particular no setpoint values, and setpoint data packets that contain setpoint values ​​and in particular no actual values. [3] Method according to claim 1 or 2, characterized by that the data packets are generated by the control device (10) at a specific time-dependent rate and are sent to the monitoring device (12) in particular via the data connection (14). [4] Method according to one of the preceding claims, characterized bythat data packets contain target values ​​and / or actual values ​​of operating variables from which the actual and / or controlled time-dependent trajectory of the transport vehicle can be determined, in particular wherein the actual value data packets contain actual values ​​of operating variables from which the actual time-dependent trajectory of the transport vehicle can be determined and / or the target value data packets contain target values ​​of operating variables from which the controlled time-dependent trajectory of the transport vehicle can be determined. [5] Method according to one of the preceding claims, characterized by that the monitoring device (12) checks the integrity of the transmitted data packets, in particular by means of a test value generated for each data packet by the control device (10) and transmitted to the monitoring device (12) via the data connection (14), in particular as a component of the respective data packet. [6] Method according to one of the preceding claims, characterized by that the actual value data packets each contain an actual value counter value generated by the monitoring device (12) and / or the setpoint value data packets each contain a setpoint counter value generated by the monitoring device (12). [7] Method according to one of the preceding claims, characterized byin that data packets, in particular the actual value data packets, contain first actual values ​​and first counter signal values ​​which are detected at a first sensor (22) by means of a first detection device (24) of the control device (10), wherein the first detection device (24) has two signal inputs, wherein a signal from the first sensor (26), from which the first actual values ​​are determined, is detected by means of one signal input, and a first counter signal (28), from which the first counter signal values ​​are determined, is detected by means of the other signal input, wherein the first counter signal values ​​are checked by the monitoring device (12) after receipt of the respective data packet in order to detect errors in the operation of the drive system. [8] Method according to claim 7, characterized bythat data packets, in particular the actual value data packets, contain second actual values ​​and second counter signal values ​​which are detected at a second sensor (30) by means of a second detection device (32) of the control device (10), wherein the second detection device (32) has two signal inputs, wherein a signal from the second sensor (34), from which the second actual values ​​are determined, is detected by means of one signal input, and a second counter signal (36), from which the second counter signal values ​​are determined, is detected by means of the other signal input, wherein the second counter signal values ​​are checked by the monitoring device (12) after receipt of the respective data packet in order to detect errors in the operation of the drive system. [9] Method according to claim 7 in conjunction with claim 8, characterized byin that the first counter signal values ​​and second counter signal values ​​have time-dependent curves, in particular time-dependent increasing amounts, with opposite signs, in particular wherein the first and the second counter signal (28, 36) are identical and the determination of the first and second counter signal values ​​from identical counter signals (28, 36) takes place in such a way that first and second counter signal values ​​with opposite signs result. [10] Method according to claim 7, characterized bythat data packets, in particular the actual value data packets, contain second actual values ​​and second counter signal values ​​which are detected at a second sensor (30), in particular an absolute value encoder, by means of a second detection device (32) of the control device, wherein the second detection device (32) has two signal inputs, wherein a first signal from the second sensor (30), from which the second actual values ​​are determined, is detected by means of one input, and a second signal from the second sensor (30), from which the second counter signal values ​​are determined, is detected by means of the other input, wherein the second counter signal values ​​are checked by the monitoring device (12) after receipt of the respective data packet in order to detect errors in the operation of the drive system. [11] Method according to one of the preceding claims, characterized bythat the actual values ​​transmitted in the data packets from the control device (10) to the monitoring device (12) are compared by the monitoring device (12) with the setpoint values ​​transmitted in the data packets from the control device (10) to the monitoring device (12) in order to detect errors in the operation of the drive system. [12] Method according to one of the preceding claims, characterized by that the control device (10) has software structured by means of program organization units (POU) and the detection of an actual value and / or generation of a target value takes place in the same program organization unit as the generation of a data packet containing this value, in particular wherein the detection of the actual values ​​and the generation of the actual value data packets takes place in the same program organization unit and / or the generation of the target values ​​by and the generation of the target value data packets takes place in the same program organization unit. [13] Method according to one of the preceding claims, characterized by that the transport vehicle has a sensor arrangement, in particular wherein the sensor arrangement comprises at least one laser scanner (38, 40) for monitoring a monitoring area and / or a part of the monitoring area, and the signals generated by the sensor arrangement are evaluated by the monitoring device (12) in order to detect obstacles within the monitoring area around the transport vehicle. [14] Method according to claim 13, characterized by that the size and / or shape of the monitoring area, in particular by the monitoring device (12), is selected as a function of operating variables of the drive system, in particular as a function of a movement path of the transport vehicle determined from the operating variables. [15] Method according to one of the preceding claims, characterized bythat upon detection of an error in the operation of the drive system and / or upon detection of an obstacle within the monitoring area, an operational intervention is carried out by the monitoring device (12), in particular wherein the driverless transport vehicle is transferred into a safe operating state by the operational intervention.

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