SETTING METHOD OF TURNING CHARACTERISTICS OF AUTOMATED VEHICLE DRIVING SYSTEM AND AUTOMATED VEHICLE DRIVING SYSTEM

Abstract

In a setting method of turning characteristics of an automated vehicle driving system, driving patterns for acquisition of a parameter of turning characteristics are generated automatically. Data concerning the turning characteristics of a vehicle is acquired through automated driving of the vehicle with the generated driving patterns. The parameter is set based on the acquired data.

Description

TECHNICAL FIELD

The present disclosure relates to a setting method of turning characteristics of an automated vehicle driving system and an automated vehicle driving system.

BACKGROUND

Known is an automated vehicle driving system as disclosed in an Internet web page “NaviControl: GPS-controlled real vehicle driving test robot, manufactured by HI-TEC s.r.l., dealt (in Japan) by TOYO Corporation, [retrieved Feb. 19, 2022], <URL: https://www.toyo.co.jp/mecha/products/detail/navicontrol.html>” (Non-patent Literature 1). The system disclosed in the Non-patent Literature 1 includes a robot that operates a steering wheel, a robot that operates an accelerator pedal and a brake pedal, a robot that operates a gear selector, and a controller that controls these robots. These robots are used by being attached to a vehicle and can be removed from the vehicle.

Also known is an automated vehicle driving system as disclosed in JP 2017-177847 A (Patent Literature 1). In the Patent Literature 1, an automated steering control related to vehicle turning is mainly disclosed.

SUMMARY OF THE INVENTION

In an automated steering control of an automated driving system, an actuator steers steered road wheels for turning. In the system disclosed in the Non-Patent Literature 1, when an actuator of the robot rotates a steering wheel, steered road wheels are steered through a steering mechanism including a steering column shaft and a steering gear box. In practical application of such a system, a calibration process is needed. More specifically, it is needed to set a parameter of an automated steering control concerning turning characteristics of a vehicle.

An object of the present disclosure is to provide a setting method of turning characteristics of an automated vehicle driving system and an automated vehicle driving system, which can efficiently set a parameter of an automated steering control concerning turning characteristics of a vehicle in a calibration process of the automated steering control.

In a setting method of turning characteristics of an automated vehicle driving system according to the present disclosure, driving patterns for acquisition of a parameter of turning characteristics are automatically generated, data concerning the turning characteristics of a vehicle is acquired through automated driving of the vehicle with the generated driving patterns, and the parameter is set based on the acquired data.

Here, the automated vehicle driving system is configured by installing an automated driving robot on the vehicle.

In addition, a driving area for the automated driving with the driving patterns may be acquired by driver's driving of the vehicle along a perimeter of the driving area before automatically generating the driving patterns to generate the driving patterns automatically in the driving area.

Here, the parameter may be a turning curvature or a turning radius of the vehicle relative to a steering angle of a steering wheel of the vehicle.

The parameter may be a yaw rate of the vehicle relative to a steering angle of a steering wheel of the vehicle.

The parameter may be a time constant for a response delay of a yaw rate of the vehicle.

The parameter may be a stability factor concerning turning of the vehicle.

And, an automated vehicle driving system according to the present disclosure includes a steering robot that rotates a steering wheel of a vehicle, a self-position detecting device that detects a self-position of the vehicle, and a controller that controls the automated vehicle driving system, wherein the controller is configured to automatically generate driving patterns for acquisition of a parameter of turning characteristics, to acquire data concerning the turning characteristics of the vehicle by using the self-position detecting device while driving the vehicle automatedly with the generated driving patterns by controlling the steering robot, and to set the parameter based on the acquired data.

Here, the steering robot may be post-installed on the vehicle.

According to the setting method of turning characteristics of an automated vehicle driving system or the automated vehicle driving system in the present disclosure, a parameter of an automated steering control concerning turning characteristics of a vehicle can be set efficiently in a calibration process of the automated steering control.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a configuration of an automated vehicle driving system according to an embodiment;

FIG. 2 is a plan view showing steps of a setting method of turning characteristics for the system (setting of a driving area);

FIG. 3 is a plan view showing the steps (travelling to a start position);

FIG. 4 is a plan view showing the steps (automated driving step: large turning curvature);

FIG. 5 is a plan view showing the steps (automated driving step: small turning curvature);

FIG. 6 is a graph showing a parameter of an automated steering control that has been set (turning curvature with respect to steering angle);

FIG. 7 is a flowchart of the above setting method; and

FIG. 8 is a graph showing a parameter of an automated steering control in another example (yaw rate with respect to steering angle).

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of an automated vehicle driving system and a setting method of turning characteristics that uses the system will be described with reference to the drawings.

The automated vehicle driving system according to the present embodiment is a system in which post-installed automated driving robots like those described in the above [Non-patent Literature 1] are installed on an existing vehicle 1. In other words, since the post-installed type automated driving robots are installed on the vehicle 1, a calibration process of the automated steering control is needed after the automated driving robots are installed. The calibration process sets a parameter of the automated steering control concerning turning characteristics of the vehicle 1. The turning characteristics are the characteristics relating to the turning of the vehicle 1, and specifically, various state quantities relating to the turning of the vehicle 1, such as a turning curvature, a turning radius, a yaw rate, its time constant or a stability factor, or various intrinsic values that affect the turning performance of the vehicle 1.

The vehicle 1 in the present embodiment has a configuration shown in FIG. 1. Automated driving robots that can be post-installed on a vehicle to enable remote driving or automated driving are installed on the vehicle 1. The automated driving robots include a steering robot 2 that rotates a steering wheel, a pedal robot 3 that operates an accelerator pedal and a brake pedal, a self-position detecting device 4 that detects a self-position of the vehicle 1 and a controller 5 that controls these robots. The steering robot 2, the pedal robot 3 and the self-position detecting device 4 are connected to the controller 5.

The controller 5 is also connected to a Graphical User Interface (GUI) unit 6, which displays various information about the system and serves as an input device for various instructions to the controller 5. The controller 5 is also connected to obstacle detection sensors 7. The system in the present embodiment is also equipped with a gear robot (not shown) that operates a gear selector, and the gear robot is also connected to controller 5. These robots are cooperatively controlled by the controller 5.

The vehicle 1 is capable of performing remote driving or automated driving by the above-mentioned automated driving robot without a passenger on board. However, a passenger, i.e., a driver, can ride in a driver's seat of the vehicle 1 while the automated driving robot is still installed, or a driver can drive it without activating the automated driving robot. The driver can also drive it with the automated driving robot activated, and various data can be recorded at that time.

The steering robot 2 can take various forms, but in the present embodiment, for example, it includes a ring member that is attached to a rim of the steering wheel to be rotated together with the steering wheel. When the driver drives the vehicle 1 as described above, the driver operates the ring member as if it were the rim of the steering wheel. The ring member is fixed to the vehicle body via a bracket or the like and is rotated by an actuator of the steering robot 2. As mentioned above, the steering robot 2 can take various forms, so it can be attached to the steering wheel or directly manipulate the rim of the steering wheel.

The pedal robot 3 can also take various forms, but in the present embodiment it includes actuators for pushing the pedals and is fixed between a seat cushion of the driver's seat and the pedals. The actuators of the steering robot 2 and the pedal robot 3 are controlled by the controller 5.

The self-position detecting device 4 is generally a device that combines a satellite positioning system, such as a GPS (Global Positioning System) and so on, with an Inertial Measurement Unit (IMU), for example. The controller 5 is an electronic device including a CPU, a ROM, a RAM, a storage such as an SSD or an HDD and I/O devices. The GUI unit 6 in the present embodiment is a tablet-type terminal with a touch screen. The obstacle detection sensors 7 are ultrasonic sensors mounted on a front end of the vehicle 1 in the present embodiment, but other types of sensors may be used, and their mounting positions are not limited to the front end of the vehicle 1.

Next, parameter setting for the automated steering control during the above-mentioned calibration process of the system will be explained with reference to the plan views in FIGS. 2 to 5, the flowchart in FIG. 7 and so on.

First, in the present embodiment, the above-mentioned post-installed type automated driving robots are installed on the vehicle 1. That is, the steering robot 2, the pedal robot 3, the gear robot, the controller 5, the GUI unit 6 and so on, which are described above, are installed on vehicle 1. Next, various specifications inherent in the vehicle 1, such as a wheelbase and so on, are input into the system from the GUI unit 6. Here, a default turning radius estimated from the vehicle specifications is also input (step S1 in FIG. 7). The input information is stored in the storage of the controller 5.

Note that the specifications of the vehicle 1 may be input as numerical values or, if the system stores a vehicle database, the vehicle type may be input. In this case, the controller 5 retrieves the vehicle specifications compatible with the vehicle type from the database based on the input vehicle type. In addition, if a maximum steering angle of the steering wheel and a minimum turning radius are known, these values are also input.

In the present embodiment, the default turning radius is calculated by using an Expression (1) shown below that is a two-wheeled vehicle kinematics model, or the like. It is well known to study vehicle dynamics by using the two-wheeled vehicle kinematics model in a simulated manner instead of a four-wheeled vehicle kinematics model, and the default turning radius is calculated by using the two-wheeled vehicle kinematics model in the present embodiment.

δs=K tan⁻¹(L/R)=K tan⁻¹(κL)  Expression (1)

Here, δs is the steering angle, K is a steering gear ratio, L is the wheelbase value, R is the turning radius, and K is a turning curvature. The turning radius R and turning curvature K have an inverse relationship. Note that, in a case where a steered angle of the steered road wheel, i.e., the front wheels, can be obtained and the steering gear ratio K is obvious, the default turning radius may be determined by using the steered angle δ of the steered road wheels (Kδ=δs) instead of the steering angle δs of the steering wheel. In this way, the initial settings for the calibration process are made.

Then, data concerning the turning characteristics of the vehicle 1 is acquired automatically through the automated driving of the vehicle 1, and the parameter of the automated steering control is set based on the acquired data. However, it is needed for the automated driving to input a driving area X for the automated driving to the system. Therefore, the driver actually drives the vehicle 1 along a perimeter Y of the driving area X as shown in FIG. 2 (step S2 in FIG. 7). At this time, a travelling path of the vehicle 1 is detected by the self-position detecting device 4 and becomes a closed path. The inside of the closed path is determined as the driving area X in which the automated driving of the vehicle 1 is done for the calibration process through the automated driving.

At this time, the vehicle 1 is driven at a slow speed (about 5 km/h), for example. In FIG. 2, the driving area X is a simple rectangle, but even if the driving area X has a more complicated shape, the driving area X can be set accurately and simply by driving the vehicle 1 along its perimeter. Both the self-position detection of the vehicle 1 for setting the driving area X and the self-position detection of the vehicle 1 during the automated driving done just after that are performed by the same self-position detecting device 4. Therefore, the automated driving done just after setting the driving area X can be done reliably. In addition, during actual driving by the driver along this perimeter Y, data concerning the acceleration/deceleration characteristics of the vehicle 1 in response to the pedal operation is also simultaneously acquired and stored in the controller 5.

After the driving area X has been set, the vehicle 1 is maneuvered to a start position S as shown in FIG. 3. Specifically, a map of the driving area X is shown on the GUI unit 6 as in a navigation system to show the vehicle 1 and the start position S in the map, and the driver carries the vehicle 1 to the start position S by referring to the GUI unit 6 (step S3 in FIG. 7). A position where a circular travelling path having a maximum radius can be placed within the driving area X is determined as the start position S through the calculation of the controller 5. However, the start position S can also be set arbitrarily by the driver (user) through the GUI unit 6.

Next, plural driving patterns are automatically generated to acquire the data concerning the turning characteristics of the vehicle 1 within the driving area X (step S4 in FIG. 7). For example, in the present embodiment, the turning curvature relative to the steering angle of the steering wheel is acquired as the turning characteristics, and driving patterns are generated for every 10 degrees of the steering angle as shown in [Table 1] below. Note that positive values for the steering angle in the Table 1 indicate a right turn and negative values indicate a left turn. In addition, the above-mentioned default turning radii are also shown in the [Table 1].

TABLE 1
	Turning	Turning	Turning
	Radius [m]	Radius [m]	Curvature [m−1]
Steer	(Default	(Measured	(Measured
Angle [deg]	Value)	Value)	Value)
720	4.80	4.91	0.20
710	4.88	4.85	0.21
.	.	.	.
.	.	.	.
.	.	.	.
45	85.91	Not Measured	Not Measured
.	.	.	.
.	.	.	.
.	.	.	.
−710	4.88	Not Measured	Not Measured
−720	4.80	Not Measured	Not Measured

Each travelling route is automatically generated so that the route fits within the predetermined driving area X. For example, as shown by a driving route R1 in FIG. 4, if the steering angle is large and the turning radius is small, it is possible to make a full circle within the driving area X and return to the start position S. However, as shown by a travelling route R2 in FIG. 5, if the steering angle is small and the turning radius is large, it is not possible to make a full circle within the driving area X. In such a case, travelling routes Z1-Z3 are generated by using a route generation method with straight lines and arcs, such as Dubins path, for a return to the start position S done after the travelling route R2 by which a turn with a predetermined steering angle is done for the data acquisition. Here, the semicircular travelling route Z1, the straight travelling route Z2 and the semicircular travelling route Z3 constitute the return route to the start position S. When shifting from a right-turn travelling route to a left-turn travelling route, the return route is generated so that the travel direction from the start position S is made reversed. In this way, all the travelling routes are automatically generated.

Once all the travelling routes have been determined, automated driving based on the travelling routes is sequentially done by unmanned driving, i.e., automated driving, to acquire the data concerning the turning characteristics (steps S5 and S6 in FIG. 7). The automated driving starts from the travelling route with a large steering angles, i.e., a small turning radius. By these processes, the unmeasured data in the above-mentioned [Table 1] is sequentially measured to fill the table.

After all the data has been acquired, the parameter for automated turning control is calculated based on the acquired data as shown in FIG. 6 (step S7 in FIG. 7). In the present embodiment, the parameter to be calculated is a characteristic curve on a graph showing the relationship between the steering angle and the turning curvature as shown in FIG. 6. As mentioned above, the acquired data is made for every 10 degrees of the steering angle. Therefore, in generating the map shown in FIG. 6, the characteristic curve is generated by using the least-squares method or the like. Note that, based on the generated parameter, the coefficients and the eigenvalues in the above Expression (1) may be modified to re-set the default values for which no data was acquired. In addition, in the present embodiment, the data was acquired for both right and left turns, but the data for one may be used to generate data for the other.

In addition, in the steps S5 and S6, deviation between the acquired data and the default values may be monitored, and if the deviation is large, the data acquisition may be interrupted. Furthermore, in the steps S5 and S6, the self-position of the vehicle 1 is always known by the controller 5 via the self-position detecting device 4 for the above-mentioned data acquisition. Therefore, the controller 5 may output an error if deviation from the driving area X occurs or if an obstacle is detected by the obstacle detection sensors 7. If an error is output in this manner, the user is presented with a request for a return of the vehicle 1 to the start position S. As explained above, the calibration process for the automated turning control is completed, and then the automated driving is properly performed.

Note that, in the above embodiment, the characteristic curve of the turning curvature with respect to the steering angle shown in FIG. 6 is set as the parameter of the automated steering control. However, other parameters may be set. For example, as shown in FIG. 8, a characteristic curve of a yaw rate with respect to the steering angle may be set as the parameter of the automated steering control. In this case, the yaw rate is also acquired as the data in the above-mentioned automated driving in the steps S5 and S6. In the present embodiment, the yaw rate can be detected by the self-position detecting device 4 that includes the GPS and the IMU.

Alternatively, a time constant for a response delay of the yaw rate may be set as the parameter for the automated turning control. Especially in the system using the post-installed type automated driving robots like in the present embodiment, the response delay is likely to occur. Therefore, the automated driving can be performed appropriately by setting the time constant for the response delay as the parameter and using the parameter for the subsequent automated turning control. Also in this case, the yaw rate is acquired as the data in the automated driving of the steps S5 and S6, and the time constant is calculated based on the data.

Alternatively, a stability factor of the vehicle 1 may be set as the parameter of the automated turning control. The stability factor A can be calculated from an Expression (2) shown below.

R=(1+AV²)KL/δs  Expression (2)

Here, A is the stability factor, V is a travel speed, δs is the steering angle, K is the steering gear ratio, L is the wheelbase value, and R is the turning radius.

The stability factor A is an indicator of the steer characteristics of the vehicle 1, and its value can tell whether the vehicle 1 has a tendency to oversteer or understeer. In this case, the turning radius is acquired while the travelling speed is changed by controlling the accelerator pedal in the above-mentioned automated driving in the steps S5 and S6. Note that the parameter of the automated turning control to be set is not limited to one, and two or more parameters may be set at the same time.

According to the setting method of the turning characteristics of the automated vehicle driving system in the present embodiment, (a) driving patterns for acquisition of the parameter of the turning characteristics are automatically generated. Then, (b) the data concerning the turning characteristics of the vehicle 1 is acquired through the automated driving of the vehicle 1 with the generated driving patterns. (c) The parameter concerning the turning characteristics is set based on the acquired data. Thus, the parameter of the automated steering control concerning the turning characteristics of the vehicle 1 can be set efficiently in the calibration process of the automated steering control.

For example, if a company owns a large number of vehicles and wishes automated driving of these vehicles, it becomes possible to perform a calibration process for each vehicle efficiently. Even if vehicle types are not identical and are different, the calibration process can be performed efficiently for each vehicle.

In particular, in a case where an automated driving system is configured by installing an automated driving robot, such as the steering robot 2, on a vehicle 1 like in the above embodiment, its calibration process has to be done for each vehicle 1. Therefore, its parameter of turning characteristics can be set for each vehicle 1 very efficiently by using the above-mentioned procedures (a) to (c).

According to the setting method of the turning characteristics of the automated vehicle driving system in the above embodiment, the driving area X for the automated driving with the driving patterns is acquired by driver's driving of the vehicle 1 along a perimeter Y of the driving area X before automatically generating the driving patterns. Then, the driving patterns are automatically generated in the driving area X. There is no problem in a case where a very large flat area can be prepared as the driving area X used in the calibration process, but in many cases it is difficult to prepare such a driving area X. In addition, the shape of the driving area X may vary, but the subsequent automatic generation of the travelling routes can also be done reliably because the driving area X can be determined easily and reliably.

In a case where the parameter is the turning curvature or the turning radius of the vehicle 1 relative to the steering angle of the steering wheel of the vehicle 1, the output of the automated steering control, i.e., the turning curvature or the turning radius, can be reliably controlled in relation to the input of the automated steering control, i.e., the steering angle.

In a case where the parameter is the yaw rate of the vehicle 1 relative to the steering angle of the steering wheel of the vehicle 1, the output of the automated steering control, i.e., the yaw rate, can be reliably controlled relative to the input of the automated steering control, i.e., the steering angle.

In a case where the parameter is the time constant for the response delay of the yaw rate of the vehicle 1, reliable automated steering control can be performed in consideration of the response delay. The system using the post-installed type automated driving robots is prone to response delays as described above, so the automated driving can be performed appropriately by setting the time constant for the response delay as the parameter and using this parameter for the subsequent automated turning control.

In a case where the parameter is a stability factor concerning the vehicle's turning, the automated steering control can be performed reliably in consideration of the steer characteristics of the vehicle 1.

The automated vehicle driving system according to the above embodiment includes the steering robot 2 that rotates the steering wheel of the vehicle 1, the self-position detecting device 4 that detects the self-position of the vehicle 1, and the controller 5 that controls the system. The controller 5 automatically generates the driving patterns for the acquisition of the parameter of the turning characteristics. The controller 5 acquires the data concerning the turning characteristics of the vehicle 1 by using the self-position detecting device 4 while driving the vehicle 1 automatedly with the generated driving patterns by controlling the steering robot 2. The controller 5 sets the parameter based on the acquired data. Therefore, according to the automated vehicle driving system in the above embodiment, the parameter of the automated steering control concerning the turning characteristics of the vehicle 1 can be set efficiently in the calibration process of the automated steering control.

In particular, in a case where a steering robot is post-installed on a vehicle like in the above embodiment, its calibration process has to be done for each vehicle 1. Therefore, according to the automated vehicle driving system in the above embodiment, the parameter of the turning characteristics can be set for each vehicle 1 very efficiently.

Note that the automated vehicle driving system is realized by installing the post-installed type automated driving robot on the vehicle in the above embodiment. However, the automated vehicle driving systems of the present disclosure also include a system in which an automated driving system is integrated into a vehicle itself. Even for such a system integrated into a vehicle, its calibration process, i.e., setting of a parameter of its automated driving control concerning turning characteristics, is needed. In this case, since an automated driving robot is not installed, an operated angle of a steering wheel and operated strokes of an accelerator pedal and a brake pedal are detected by respective detection sensors installed in the vehicle when setting the parameter of the automated steering control.

The yaw rate is acquired by the self-position detecting device 4 having the GPS and the IMU in the above embodiment, but the yaw rate may be detected by a yaw rate sensor installed in the vehicle 1. The self-position detecting device 4 is a device having the GPS and the IMU in the above embodiment, but it may also be a device using SLAM (Simultaneous Localization And Mapping). In a case of the self-position detecting device 4 using the SLAM, the self-position detecting device 4 has a three-dimensional scanner or camera that scans its surrounding environment.

In addition, according to the present disclosure, safety of automated driving can be improved by properly performing its calibration process for automatic turning control of a vehicle. Thus, for example, it contributes to the Goal 9 of the Sustainable Development Goals (SDGs) initiated by the United Nations. “Develop resilient infrastructure, promote inclusive and sustainable industrialization, and expand technological innovation.”

Claims

1. A setting method of turning characteristics of an automated vehicle driving system, the method comprising: automatically generating driving patterns for acquisition of a parameter of turning characteristics;acquiring data concerning the turning characteristics of a vehicle through automated driving of the vehicle with the generated driving patterns; andsetting the parameter based on the acquired data.

2. The setting method of turning characteristics according to claim 1, wherein the automated vehicle driving system is configured by installing an automated driving robot on the vehicle.

3. The setting method of turning characteristics according to claim 1, wherein a driving area for the automated driving with the driving patterns is acquired by a driver's driving of the vehicle along a perimeter of the driving area before automatically generating the driving patterns, and thenthe driving patterns are automatically generated in the driving area.

4. The setting method of turning characteristics according to claim 3, wherein the parameter is a turning curvature or a turning radius of the vehicle relative to a steering angle of a steering wheel of the vehicle.

5. The setting method of turning characteristics according to claim 3, wherein the parameter is a yaw rate of the vehicle relative to a steering angle of a steering wheel of the vehicle.

6. The setting method of turning characteristics according to claim 3, wherein the parameter is a time constant for a response delay of a yaw rate of the vehicle.

7. The setting method of turning characteristics according to claim 3, wherein the parameter is a stability factor concerning turning of the vehicle.

8. An automated vehicle driving system comprising: a steering robot that rotates a steering wheel of a vehicle;a self-position detecting device that detects a self-position of the vehicle; anda controller that controls the automated vehicle driving system,wherein the controller is configured to automatically generate driving patterns for acquisition of a parameter of turning characteristics, to acquire data concerning the turning characteristics of the vehicle by using the self-position detecting device while driving the vehicle automatedly with the generated driving patterns by controlling the steering robot, and to set the parameter based on the acquired data.

9. The automated vehicle driving system according to claim 8, wherein the steering robot is post-installed on the vehicle.