CONTROL DEVICE FOR AUTONOMOUS DRIVING

Abstract

Control device for autonomous driving, comprising: a higher-level control device that outputs a control target value of an actuator group based on an action plan of a vehicle; and a subordinate control device (2) which controls the actuator group of the vehicle based on a command from the superordinate control device, wherein the subordinate control device (2) maintains the control target value of the vehicle provided by the superordinate control device for a certain period of time, wherein, if the higher-level control device does not fulfill a desired function, the lower-level control device (2) is designed to be controlled on the basis of the maintained control setpoint, and the action plan is followed by determining and correcting a difference between an actual action value and the control target value of the vehicle, and wherein a plurality of subordinate control devices (2) are provided, wherein one of the subordinate control devices (2) monitors the other subordinate control device (2), and, when a deviation of the vehicle from the action plan is detected, the one subordinate control device (2) corrects the control target value of the other subordinate control device (2).

Description

Technical field

[0001] The present invention relates to a control device for autonomous driving. State of the art

[0002] To achieve an advanced autonomous driving system, a higher-level control device (electronic control device) that controls autonomous driving is required to continue operation for a certain period of time until the operation is handed over to the driver, even if, for example, a fault occurs in the device itself.

[0003] To realize the continuation of operation for a predetermined period of time, redundancy through system multiplexing and operation monitoring can be considered.

[0004] On the other hand, a higher-level control device usually has a high computing load.

[0005] To solve this problem, Patent Literature 1 proposes a method of continuing the control of a plurality of multiplexed actuator driving devices (group of subordinate control devices) for a certain period of time by pre-accumulating control command values ​​in a superordinate control device (electronic control device) without providing redundancy to the electronic control device.

[0006] PTL 2 discloses that a subsystem controller of a vehicle is configured to receive a first message and a second message, wherein the first message includes at least one command for the controller and the second message includes at least one target value to be achieved by the controller. An error related to the first message can be detected, and an adjustment of the subsystem can be determined locally in the subsystem controller to achieve the target value. List of referencesPatent literature Patent Literature 1: JP 2016-38689 A Patent literature 2: DE 10 2015 108 286 A1 Summary of the inventionTechnical problem

[0007] On the other hand, in a situation where the higher-level control device fails to perform its function, it becomes difficult to achieve the coordinated operation of the lower-level control device group.

[0008] Since the subordinate control device group continues control based on the control command values ​​it independently maintains within itself, a control error will occur in each control system. This may result in an operation that deviates from the driving mode determined in advance by the higher-level control device.

[0009] The present invention has been made in view of the above-described points, and an object thereof is to increase the reliability of an autonomous driving system. Solution to the problem

[0010] To solve the above problems, the present invention includes, for example, a higher-level control device that outputs a control target value of an actuator group based on an action plan of a vehicle; and a lower-level control device that controls the actuator group of the vehicle based on a command from the higher-level control device. The lower-level control device retains the control target value of the vehicle provided by the higher-level control device for a predetermined period of time. When the higher-level control device fails to perform a desired function, the lower-level control device is configured to be controlled based on the retained control target value. Following the action plan, a difference between an actual action value and the control target value of the vehicle is determined and corrected.A plurality of subordinate control devices are provided, wherein one of the subordinate control devices monitors the other subordinate control device, and, when a deviation of the vehicle from the action plan is detected, the one subordinate control device corrects the control setpoint of the other subordinate control device. Advantageous effects of the invention

[0011] According to the present invention, it is possible to increase the reliability of the autonomous driving system. Short description of the drawings Fig. 1 is a block diagram illustrating a configuration of an autonomous driving system according to an example of the present invention. Fig. 2 is an example of output data from a trajectory planning device in the example of the present invention. Fig. 3 is a diagram illustrating an intended own-vehicle trajectory according to the example of the present invention. Fig. 4 is a diagram illustrating steering angle values ​​and speed values ​​corresponding to the intended own vehicle trajectory in the example of the present invention. Fig. 5 is a diagram illustrating a divergence between the intended own-vehicle trajectory and an actual travel trajectory in the example of the present invention. Fig. 6 is a diagram illustrating steering angle values ​​and speed values ​​corresponding to the actual traveling trajectory in the example of the present invention. Fig. 7 is a diagram illustrating a correction trajectory in the example of the present invention. Fig. 8 is a diagram illustrating steering angle values ​​and speed values ​​corresponding to the correction trajectory in the example of the present invention. Fig. 9 is a diagram illustrating a method for calculating the steering angle values ​​and speed values ​​corresponding to the correction trajectory in the example of the present invention. Description of embodiments

[0012] Hereinafter, an autonomous driving control device according to an example of the present invention will be described with reference to the drawings. In the present example, when the results of a calculation based on input signals from various sensors mounted on a control target are output to an electronic control device, the corresponding calculation results can be output.

[0013] Fig. 1 illustrates an overall configuration of an autonomous driving system in the present example. This system includes a trajectory planning device 1 as a higher-level control device that, upon receiving inputs of self-vehicle state amount observation values ​​from an external information observation device such as a sensor (not shown) and from a self-vehicle state amount observation device installed in a self-vehicle, converts a self-vehicle traveling trajectory including a speed command value, a steering angle command value, and other parameters of the self-vehicle into a steering angle and a speed, and outputs these values.

[0014] This system also includes a subordinate control device 2 including a steering control device 21 that controls an actuator based on the speed command value, the steering command value, and other quantities output from the trajectory planning device 1, a brake control device 22, a powertrain control device, and a chassis control device (not shown).

[0015] With regard to the present example, coordinated operations of the two control devices, ie, the steering control device 21 and the brake control device 22, will be described for the sake of simplicity. However, the present example is not limited to this, but can be applied to coordinated operations of two or more control devices.

[0016] The subordinate control device 2 receives a predetermined command value data group 3 containing command values ​​for the steering angle and the speed for a certain upcoming period, as shown in Fig. 2, which is generated by the trajectory planning device 1 as the upper-level control device. The lower-level control device 2 stores the command value data group 3 in a storage medium formed by a random access memory (RAM) or the like configured in the lower-level control device group 2. In the present example, the system is based on the assumption that the trajectory planning device 1 outputs steering angle and speed command values ​​for the next 10 seconds at intervals of 100 milliseconds. In addition, Fig. 2 shows an example in which the command value data group 3 is generated with time information. However, the command value data group 3, which has no time information and is sorted and output in chronological order, can be processed in the same manner as described below.

[0017] The command value data group is updated in each operation period of the trajectory planning device 1. In the present example, a steering angle command value data group 31 is retained in a steering angle storage medium 211 formed inside or outside the steering control device 21, and the steering angle command value data group 31 and a speed command value data group 32 are retained in a steering angle storage medium 221 and a speed storage medium 222, respectively, formed inside or outside the brake control device 22.

[0018] When the trajectory planning device 1 fulfills the required trajectory generation function, the steering control device 21 and the braking control device 22 control the steering and braking of the host vehicle using control command values ​​to be output from the steering angle command value group 31 and the speed command value group 32 transmitted from the trajectory planning device 1 every certain period.

[0019] However, when the trajectory planning device 1 cannot fulfill the required trajectory generation function due to, for example, a failure of an internal calculation, the steering control device 21 is controlled according to the steering angle command value group 31 retained in the steering angle storage medium 211, and the braking control device 22 is controlled according to the speed command value group 32 retained in the speed storage medium 222, thereby continuing the steering and braking of the host vehicle. Accordingly, even when the trajectory planning device 1 fails to fulfill the desired function, the use of the steering angle command value group 31 and the speed command value group 32 previously generated by the trajectory planning device 1 and stored in the steering angle storage medium 211 and 222, respectively, enables the steering and braking of the host vehicle.Speed ​​storage medium 222, the continuation of autonomous driving for a certain period of time, even though the control function is impaired.

[0020] In the autonomous driving system configuration that performs such control, as long as the trajectory planning device 1 operates properly, the steering angle of the host vehicle, which is controlled by the steering control device 21, and the speed of the host vehicle, which is controlled by the braking control device 22, can be coordinated by the trajectory planning device 1. On the other hand, if the trajectory planning device 1 fails to perform the desired function, the steering angle and speed of the host vehicle are independently controlled according to the steering angle command value group 31 and the speed command value group 32 provided by the steering control device 21 and the braking control device 22, respectively, making it difficult to implement coordinated operation.The steering angle and speed are subject to the influences of control errors, road gradients that are difficult to determine in advance by the trajectory planning device 1, road surface conditions, and other factors. This causes a divergence from an intended own-vehicle trajectory 4 as the own-vehicle trajectory generated in advance by the trajectory planning device 1. To correct such a divergence, in the present example, the right and left speeds are independently calculated by the brake control device 22, and corrections are superimposed on the own-vehicle steering angle control performed by the steering control device 21, thereby implementing coordinated operation even in the absence of the trajectory planning device 1 as the master control device.The following provides an overview of the error determination of a trajectory planned in advance by the trajectory planning device 1 and the correction of the error.

[0021] An example of a situation in which a correction is to be performed is described below. It is assumed that the trajectory planning device 1 is now failing to perform a desired function at a time T0 while the host vehicle is traveling along a curved trajectory. Here, the previous operation result of the trajectory planning device 1 at this time indicates that the steering angle command value data group 31 and the speed command value data group 32 stored in the steering angle storage medium 211 and the speed storage medium 222, respectively, were outputted, which correspond to the Fig. 3 correspond to the intended own vehicle trajectory 4 shown, and the degeneration control is started accordingly. Fig. 4 illustrates an example of the steering angle command value data group 31 and the speed command value data group 32 at this time.

[0022] As described above, the command value groups shown in Table 2 are not necessarily met due to environmental influences such as control system errors, road gradients, and road friction. Fig. 5 and Fig. 6 illustrate the driving condition without correction operation. It is assumed that the speed described in Table 3 at time 0.2 is different from the condition of Fig. 4, which illustrates the specified command value group, has changed. At this time, due to the change in the Fig. 6 described speed at time 0.2, a feedback is applied to the speed controlled by the brake control device 22 from time 0.3 and the speed from time 0.3 as in Fig. 6. However, since the steering control device 21 performs control independent of the braking control device 22 and its control system, an actual travel trajectory 5 is used that deviates from the intended own-vehicle trajectory 4 set by the trajectory planning device 1, so that it may be considered difficult to track the original intended own-vehicle trajectory 4.

[0023] Therefore, as described above, the right and left speeds are independently controlled by the speed control to effect a change in steering, and the correction of the command values ​​according to a Fig. 7 shown correction trajectory 6 as in Fig. 8, in order to achieve that the originally set own vehicle trajectory is followed again. As an example, the correction trajectory 6 can be formed from correction steering angles Θ_corA 61 and Θ_corB 62 and a correction speed V_cor 63. The correction steering angles Θ_corA 61 and Θ_corB 62 and the correction speed V_cor 63 are specified, for example, by the following correction method 1. An intended own vehicle trajectory steering angle Θ_ref 64, which in Fig.9 has a steering angle command value prescribed in advance by the trajectory planning device 1 immediately after a divergence from the intended own-vehicle trajectory 4 occurs at a control timing, and a speed V_diff 65 different from the intended own-vehicle trajectory has an error value between the intended own-vehicle trajectory 4 and the actual own-vehicle speed due to environmental influences such as an error in a control system, road gradients, and road friction. <korrekturverfahren>

[0024] Based on the positional relationship (distance) between a correction target point 68 and a correction start position, V_cor 63 is determined.

[0025] By determining V_cor63, Θ_corA61 and Θ_corB62 can be obtained by the following equations 1 and 2: Θ_corA=arcsin(Vref*sinΘ_refA / V_cor) Θ_corB=Θ_refB−Θ_refA+Θ_corA

[0026] According to the above method, it is possible to generate the correction trajectory 6 for modifying the actual trajectory to the intended own vehicle trajectory 4.

[0027] The correction steering angles Θ_corA 61 and Θ_corB 62 can be generated at the own vehicle speed, which is maintained at the correction speed V_cor 63 by the brake control device 22 that individually controls the right and left speeds.

[0028] In the present example, the self-vehicle deviates from the intended self-vehicle trajectory 4 at time T0 + 0.3 and returns to the intended self-vehicle trajectory 4 at time T0 + 0.4, that is, in 100 ms as one control cycle of the autonomous driving control device. However, in the present example, only the steering control device 21 and the braking control device 22 are operated in cooperation, and no powertrain control device or the like is used. This may make it difficult to increase the speed. In such a case, for example, it is necessary to continue the correction for a time corresponding to several control cycles in order to reduce the divergence from the intended self-vehicle trajectory 4 along the time axis.The same applies to a case where the owner's vehicle is unlikely to return in one control cycle, from the point of view of passenger comfort and the like.

[0029] Furthermore, the present example has been described based on the assumption that the divergence from the intended own-vehicle trajectory 4 is caused by a difference between the speed command value data group 32 held by the brake control device 22 and the actual speed value measured by the speed sensor. However, the divergence may also be caused by a difference between the steering angle command value data group 31 held by the steering control device 21 and the actual measured value of the steering angle measured by the steering angle sensor, or by simultaneous differences in the steering angle and speed.In the case where a difference occurs between the steering angle command value data group 31 and the actual measured value of the steering angle, the difference from the steering angle command value data group 31 held in the steering angle storage medium 221 in the brake control device 22 is detected via a speed sensor mounted on the brake control device 22 or a yaw motion sensor mounted on the vehicle body, so that the host vehicle can track the intended host vehicle trajectory 4 via the same measures as described above.

[0030] The above example includes: a higher-level control device that outputs a control target value of an actuator group based on an action plan of a vehicle; and a lower-level control device that controls the actuator group of the vehicle based on a command from the higher-level control device. The lower-level control device retains the vehicle control target value provided by the higher-level control device for a specified period of time. When the higher-level control device fails to perform a desired function, the lower-level control device is configured to be controlled based on the retained control target value. Following the action plan, a difference between an actual action value and the vehicle control target value is determined and corrected.

[0031] Additionally, several subordinate control devices are provided. One of the subordinate control devices monitors the other subordinate control device. If a deviation of the vehicle from the action plan is detected, one subordinate control device corrects the control setpoint of the other subordinate control device.

[0032] In addition, a brake controller, as one of the subordinate control devices, monitors the behavior of a steering controller as the other subordinate control device. Upon detecting a vehicle deviation from the action plan, the brake controller corrects the steering control target by controlling the right and left speeds.

[0033] According to the example described above, even if the trajectory planning device 1 fails to perform the desired function, the coordinated operations of the steering control device 21 and the braking control device 22 can be implemented, so that the vehicle can continuously track the intended self-vehicle trajectory 4 specified by the trajectory planning device 1. This makes it possible to eliminate the redundancy of the trajectory planning device 1 without losing the reliability of the autonomous driving system, thereby achieving the autonomous driving system at a low cost.

[0034] In this example, an advanced autonomous driving system can be implemented at low cost. Furthermore, implementing the coordinated operations of subordinate systems in the concept of command value accumulation in the group of subordinate control devices enables the implementation of an advanced autonomous driving system at low cost and with high reliability.

[0035] In this example, the collaborative operations can be performed solely through the cumulative control command values ​​maintained between the subordinate controllers, without the intervention of the higher-level controller. This makes it possible to implement a cumulative command value safety concept for functional safety, eliminate multiplexing of the higher-level electronic control device without compromising the reliability of the implementation of the advanced autonomous driving system, and implement the system cost-effectively.

[0036] The above-described embodiments and various modifications are only examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. List of reference symbols 1 trajectory planning device (higher-level control device) 2 subordinate control device 21 Steering control device 22 Brake control device 23 Steering drive device 24 Brake drive device< / korrekturverfahren>

Claims

[1] Control device for autonomous driving, comprising: a higher-level control device that outputs a control target value of an actuator group based on an action plan of a vehicle; and a subordinate control device (2) which controls the actuator group of the vehicle on the basis of a command from the superordinate control device, wherein the subordinate control device (2) maintains the control target value of the vehicle provided by the higher-level control device for a certain period of time, wherein, if the higher-level control device does not fulfill a desired function, the lower-level control device (2) is designed to be controlled on the basis of the maintained control setpoint, and the action plan is followed by determining and correcting a difference between an actual action value and the control target value of the vehicle, and wherein a plurality of subordinate control devices (2) are provided, wherein one of the subordinate control devices (2) monitors the other subordinate control device (2), and, when a deviation of the vehicle from the action plan is detected, the one subordinate control device (2) corrects the control target value of the other subordinate control device (2). [2] The autonomous driving control device according to claim 1, wherein, when a brake controller as the one subordinate control device (2) monitors the behavior of a steering controller as the other subordinate control device (2) and a deviation of the vehicle from the action plan is detected, the brake controller corrects the control target value of the steering controller by controlling the left and right speeds.

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