JP3295566B2 - Automatic driving vehicle braking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic traveling vehicle braking method suitable for an automatic traveling vehicle having two systems of brake devices.

[0002]

2. Description of the Related Art Conventionally, various types of automatic traveling vehicles have been developed which are used as golf carts for carrying luggage such as golf bags and people in golf courses. As this type of automatic traveling vehicle, for example, one disclosed in Japanese Patent Application Laid-Open No. 5-73144 is known. The self-driving vehicle disclosed in this publication has two types of brake devices, a brake using regenerative braking (including resistance braking by a resistor) by a starter dynamo connected to an engine and an electromagnetic brake, and a starter. The vehicle is decelerated for speed control during traveling by regenerative braking by a dynamo, and the vehicle is stopped using an electromagnetic brake for parking immediately before stopping.

FIG. 9 is a graph showing the operation when the above-mentioned automatic traveling vehicle stops. FIG. 9 (a) shows the change over time of the vehicle speed (theoretical value), and FIGS. 9 (b) and 9 (c) show the starter. FIG. 4 shows a change over time of a braking command value supplied to each of a dynamo and an electromagnetic brake. As shown in this figure, when a stop instruction is given to the vehicle at the time point P1 in the figure,
A braking command value starts to be supplied to the starter dynamo to decelerate the vehicle, and the value changes as shown in G1 in the figure. As a result, the vehicle speed gradually decreases (G2 in the figure). When the vehicle speed at the time of the illustrated P2 becomes V ₁ (low speed as not shown V-belt automatic transmission is not expired) a constant low speed (shown G3), constant braking command value to the electromagnetic brake (for parking The braking force command value) is supplied (G4 in the figure), and the electromagnetic brake is turned on. At this time, at the same time, the braking command value to the starter dynamo is set to "0" (G5 in the figure), and the regenerative braking is released. Thereafter, the vehicle speed further decreases due to the braking force of the electromagnetic brake, and the vehicle stops (G6 in the figure).

[0004] As described above, the braking by the electromagnetic brake is turned on immediately before the stop and the regenerative braking is released at the same time. This is because the control is easy and the regenerative braking immediately before the stop is small. It is due to.

[0005]

In the above-mentioned conventional automatic traveling vehicle, since there is a slight delay in response to the starter dynamo and the electromagnetic brake, it is necessary to obtain a braking force corresponding to a given braking command value. Takes a certain amount of time. Therefore, as shown in FIG. 10, the braking force (regenerative braking force) by the starter dynamo is such that the braking command value is “0” when the vehicle speed becomes a constant low speed V ₁ (P2 in the drawing).
Does not immediately become the value "0", but becomes "0" after decreasing at a predetermined gradient (G1 'in the figure). Similarly, the braking force by the electromagnetic brake, rather than rises quickly at the illustrated P2, a constant value after rising at a predetermined gradient (after a period T _E) (shown G
2 '). For this reason, when shifting from the regenerative braking by the starter dynamo to the braking by the electromagnetic brake, FIG.
As shown in (1), the braking force applied to the vehicle (that is, the combined braking force of the regenerative braking and the electromagnetic braking) temporarily drops. Due to the drop in the braking force, the vehicle speed at the time of the transition temporarily increases as shown in FIG. 10A (G3 'in FIG. 10), so that the running immediately before the stop becomes unstable, and the ride comfort is hindered. Will come.

The present invention has been made in view of such a background, and provides a method of braking an automatic traveling vehicle that can prevent speed fluctuations immediately before the vehicle stops and improve riding comfort. It is an object.

[0007]

According to the first aspect of the present invention, there is provided a first-system brake device for applying a braking force for braking control during vehicle running, and a parking braking force for stopping the vehicle. The present invention is applied to a self-driving vehicle including a second system brake device for providing vehicle speed and vehicle speed detection means for detecting vehicle speed, and the first system brake device decelerates the vehicle in response to a stop instruction, In the method of braking an automatic traveling vehicle, wherein the vehicle is stopped by the second system brake device when the value detected by the vehicle speed detection means reaches "0" or a low speed in the vicinity thereof, the second system brake device
The braking force is variably controlled, and the first system
Braking for braking control while the vehicle is running with the rake device
A force is also applied, and after the braking by the second system brake device is started, the braking by the first system brake device is continued for a predetermined period, and the braking periods by both systems are overlapped.

[0008]

[0009]

According to the first aspect of the present invention, immediately before the vehicle stops, the first and second brake systems are provided.
It is possible to prevent a drop in braking force when shifting from braking by the second system to braking by only the second system brake .

[0010]

[0011]

Embodiments of the present invention will be described below with reference to the drawings. (1) Configuration of the Embodiment Configuration of an Autonomous Vehicle FIG. 1 is a block diagram showing the configuration of an autonomous vehicle to which the present invention is applied. The self-driving vehicle shown in FIG. 1 is used, for example, as a golf cart used in a golf course, and is equipped with an engine 1 as in a normal car, and is transmitted from the engine 1 via a V-belt type automatic transmission 1a. A transmission 3 for transmitting the supplied driving force to rear wheels 2a and 2b as driving wheels, a steering wheel 4 for steering front wheels 2c and 2d, and an accelerator pedal 5 for adjusting a throttle opening to change a vehicle speed. And a governor 6, a brake pedal 7 for applying a brake to the vehicle, and mechanical brake mechanisms such as drum brakes 8a to 8d.

The self-propelled vehicle is capable of self-traveling in addition to normal manual operation (hereinafter referred to as "manual traveling"). A controller 9, a steering driver 10, A steering motor 11, a throttle motor 12, a brake motor driver 13, a brake motor 14, an electromagnetic brake 15, a sensor group such as an induction line sensor 16, a fixed point sensor 17, a steering clutch 18 for switching between manual traveling and automatic traveling, and a throttle. Various switching mechanisms 20, 21 such as a clutch 19 are provided.

The steering driver 10 supplies a driving current corresponding to a steering instruction signal output from the controller 9 during automatic traveling to the steering motor 11 to rotate the steering shaft 22. At this time,
The steering wheel 4 is separated from the steering shaft 22 by the steering clutch 18, and manual operation is disabled.

The throttle motor 12 is driven in response to an opening instruction signal output from the controller 9 during automatic traveling, and the throttle clutch 19 is connected in response to an ON instruction signal output from the controller 9 in the same manner. You. At this time, the switching device 21 switches the drive system of the engine 1 from the governor 6 to the throttle motor 12. Thus, during automatic running, the throttle opening is adjusted according to the driving amount of the throttle motor 12 instead of the operation amount of the accelerator pedal 5.

The brake motor driver 13 supplies a drive current corresponding to the braking command value output from the controller 9 to the brake motor 14 during automatic traveling. Thus, the brake motor 14 is controlled by the gear 23 and the switching mechanism 2.
The brakes 8a to 8d provided on each of the four wheels 2a to 2d are driven via 0 to brake the vehicle. In addition, the brake pedal 7 is connected to the drum brakes 8 a to 8
It is in a state of being connected to d, and can be controlled by manual operation.

The electromagnetic brake 15 is a stop brake device that is turned on / off by the controller 9, and is spline-fitted to a rotation shaft 24 that transmits the rotation of the engine 1 to the transmission 3, as shown in the figure. And a fixed platen 15b fixed to an outer wall or the like of the transmission 3 so as not to contact the rotating shaft 24 and to face the disk 15a. Since the disc 15a is spline-fitted to the rotating shaft 24, the disk 15a rotates integrally with the rotating shaft 24 and is movable in the axial direction of the rotating shaft 24. In addition, fixed board 1
Reference numeral 5b denotes a permanent magnet that generates a magnetic field for attracting the disk 15a, and an electromagnet that is excited by the controller 9 to cancel the magnetic field of the permanent magnet.

That is, in the electromagnetic brake 15, the excitation of the electromagnet is turned on during traveling, and the magnetic field of the permanent magnet is canceled by this magnetic field, so that the attractive force against the disk 15a is eliminated, and as a result, the rotation shaft 24 On the other hand, braking is not effective. On the other hand, if the excitation of the electromagnet is turned off immediately before the stop,
The disk 15a is fixed to the fixed plate 15b by the magnetic force of the permanent magnet.
And the rotation shaft 24 is braked.

The controller 9 controls the electromagnetic brake 1
If the magnitude of the exciting current supplied to the electromagnet is made variable and the magnitude of the braking force to be applied to the vehicle is controlled instead of simply controlling the on / off control of the vehicle 5, the electromagnetic brake as an automatic traveling brake device is provided. Drum brakes 8a to 8d driven by a brake 15 and the aforementioned brake motor 14
And can be used in combination. For example, the electromagnetic brake 15 is mainly used as a first-system brake device that supplies a small braking force for speed control during traveling, and the drum brakes 8a to 8d mainly supply a large braking force for stopping the vehicle. You may make it use as a 2nd system brake device.

The guide line sensor 16 is attached to a T-shaped arm 25 which is attached to the front end of the vehicle so as to be rotatable in the horizontal direction.
It is arranged at three places so as to face the ground. The guide line sensor 16 magnetically detects a guide line (not shown) embedded in a course of a golf course or the like, and outputs a detection signal corresponding to a distance from the guide line to the controller 9. The controller 9 controls the traveling based on the output of the guide line sensor 16 so that the vehicle does not deviate from the course.

The fixed point sensor 17 is mounted at a predetermined position of the vehicle so as to face the ground, and magnetically detects a fixed point composed of a plurality of permanent magnets (not shown) embedded at predetermined intervals in a golf course or the like. To detect. For example, assuming that this fixed point is constituted by the magnetic poles of three permanent magnets, and the arrangement thereof is an S pole, an N pole, and an N pole, the fixed point sensor 17
Outputs a detection signal corresponding to the magnetic pole arrangement pattern to the controller 9. The pattern of the arrangement of the magnetic poles is used as an instruction signal for the controller 9 to perform traveling control such as stopping, starting, and speed of the vehicle.

The operation panel 26 is provided in the vicinity of the driver's seat, and includes a main switch, a manual / auto switch for instructing switching between manual traveling and automatic traveling, and a start / stop for instructing start and stop. It is composed of various switches such as switches and a display unit for displaying a warning. When automatic driving is selected by the manual / auto switch of the operation panel 26, the controller 9
Switches the traveling mode of the vehicle from manual traveling to automatic traveling, and performs control for automatic traveling described later.

The transmission 3 includes a vehicle speed sensor 30 for detecting a vehicle speed, the engine 1 includes a throttle potentiometer 31 for detecting a throttle opening, a steering driver 10 and a brake motor driver 13. Thermistors 32 and 33 for detecting the respective temperatures, the current sensor 34 for detecting the amount of current supplied to the brake motor 14 for the brake motor driver 13, and the drum brakes 8a to 8d and the braking force transmission path for the gear 23. Brake limit switches 35 are provided to detect whether the rotation speed of the brake motor 14 has exceeded a certain limit value due to an abnormality in the mechanical brake mechanism including the brake limit switches.

Next, the configuration of the controller 9 will be described. The controller 9 is configured by hardware such as a CPU (Central Processing Unit) and a memory. The software configuration includes a target vehicle speed setting section 91, a driving force calculation section 92, a throttle drive calculation section, as shown in FIG. Unit 93, braking force calculation unit 94, braking state switching determination unit 95, current command value calculation unit 9
6, excitation voltage calculation unit 97, abnormality determination / abnormality processing unit 98,
It comprises input interfaces 99a to 99g for receiving various sensor outputs and switch outputs, and output interfaces 99h to 99l for outputting control signals such as various command values to the outside.

When start is instructed on the operation panel 26, the target vehicle speed setting section 91 outputs a set value of the target vehicle speed based on speed instruction information read from the memory in response to an instruction signal supplied from the fixed point sensor 17. I do. Driving force calculator 9
2 calculates the required driving force to be applied to the vehicle based on the difference between the set value of the target vehicle speed and the current vehicle speed detection value output from the vehicle speed sensor 30 installed in the transmission 3.

The throttle drive calculator 93 outputs an on / off instruction signal for the throttle clutch 19 in accordance with the running mode, and based on the calculation result of the required driving force and the detection result of the throttle opening by the throttle potentiometer 31, A throttle drive pulse corresponding to the drive amount of the throttle motor 12 is output.

The braking force calculation unit 94 calculates the required braking force based on the difference between the set value of the target vehicle speed and the current detected vehicle speed and the amount of current supplied to the brake motor 14 detected by the current sensor 34.

The braking state switching determination unit 95 determines whether or not the vehicle is in an appropriate braking state based on the difference between the set value of the target vehicle speed and the current vehicle speed detection value and the detection result of the throttle opening. The result is output to the braking force calculator 94. In other words, if the throttle opening is accelerating even though the vehicle speed substantially matches the target vehicle speed, the balance is maintained by performing acceleration and braking simultaneously, and the fuel This leads to waste and wear of the brake shoes. Here, a determination is made to avoid such an inappropriate braking state.

The braking force calculation unit 94 outputs the calculated required braking force to the current command value calculation unit 96 as it is if the result of the determination is an appropriate braking state. On the other hand, if the result of the determination is an inappropriate braking state, the required braking force is output to the current command value calculating section 96 while gradually decreasing the required braking force until it becomes “0”. Accordingly, the throttle opening gradually becomes an appropriate value, and the improper balancing state described above is released.

The current command value calculation unit 96 includes a braking force calculation unit 9
4 to output a current command value to be given to the brake motor driver 13 based on the value of the required braking force calculated by (4). When the electromagnetic brake 15 is used only as an on-off type parking brake, the excitation voltage calculation unit 97 outputs a binary signal indicating either on or off, but when the braking force by the electromagnetic brake 15 is made variable. Outputs an excitation command value to be given to the electromagnetic brake 15 based on the value of the braking force output from the braking force calculation unit 94.

The abnormality judging / abnormality processing section 98 includes temperature detection values of the thermistors 32 and 33 provided in the steering driver 10 and the brake motor driver 13, an output of the brake limit switch 35, a current vehicle speed detection value, and a necessary control value, respectively. An abnormality is determined based on the calculation result of the power. When it is determined that the vehicle is abnormal, a warning signal for notifying the abnormality is output, and an instruction to stop the vehicle is issued. The current command value calculator 96, the excitation voltage calculator 97, and the throttle drive calculator 93 receive the above stop processing instruction and output a value for stopping the vehicle.

(2) Operation of Embodiment Next, the operation when the braking method according to the present invention is applied to an automatic traveling vehicle having the above-described configuration will be described. Hereinafter, a case where the first to third braking methods according to the present invention are respectively applied to the automatic traveling vehicle will be described separately.

FIG. 3 is a graph for explaining the operation when the first braking method is applied. FIG. 3A shows the vehicle speed (vehicle speed detection value).
FIG. 4B shows the change over time of the braking force of the drum brakes 8a to 8d driven by the brake motor 14, and FIG. 4C shows the change over time of the electromagnetic brake 15 which is turned on and off as a parking brake. Changes in braking force over time
Each is shown.

As shown in this figure, when a stop instruction is given to the vehicle at the point P1 in the figure, the brake motor 14 is energized to decelerate the vehicle, and the drum brakes 8a to 8
A braking force of d is applied. This braking force value changes based on the vehicle speed control, for example, as shown in C1 in the figure. This allows
Vehicle speed gradually decreases (shown C2), the constant low speed becomes V ₁ (V belt automatic transmission 1a low speed so as not expired) at the time of drawing in P2 (shown C3), the electromagnetic brake 15
Is turned on (that is, the excitation of the electromagnet is stopped). Thereafter, the braking force of the electromagnetic brake 15 rises at a gradient corresponding to the response speed, and becomes constant at a predetermined value (C4 in the figure). During this time, the power supply to the brake motor 14 is continued, and the braking by the drum brakes 8a to 8d is continued (C5 in the figure).

When the vehicle speed further decreases and the vehicle speed detection value becomes "0", the power supply to the brake motor 14 is stopped, and the braking force of the drum brakes 8a to 8d decreases at a gradient corresponding to the response speed. After that, the value becomes “0” (C6 in the figure).

As described above, according to the first braking method, when the vehicle speed decreases to the constant low speed V ₁ , the electromagnetic brake 15
Even after turning on the braking by the brake, the braking by the drum brakes 8a to 8d is continuously performed, and the braking by the drum brakes 8a to 8d is released only when the vehicle speed detection value becomes “0”. Thereby, the drum brakes 8a to 8
d to the electromagnetic brake 15, the braking forces of the two are reliably overlapped, and the braking force of the drum brakes 8 a to 8 d falls before the braking force of the electromagnetic brake 15 rises. can do. As a result, fluctuations in speed immediately before the vehicle stops are prevented, and riding comfort is improved.

Next, an operation in a case where the second braking method is applied will be described. In this method, as shown in FIG. 4, the vehicle speed becomes "0" in order to further increase the period in which the braking force of the drum brakes 8a to 8d and the braking force of the electromagnetic brake 15 overlap with each other as compared with the first method. the energization of the brake motor 14 is continued for a certain period of time T _W even after. Other operations are the same as those in the first method.

That is, in the second braking method, since the vehicle may actually be moving even if the detected vehicle speed becomes "0", the braking period by the drum brakes 8a to 8d is set to the time T. It is an extension of _W. This makes it possible to more reliably prevent speed fluctuations immediately before the vehicle stops.

Next, the operation when the third braking method is applied will be described. In this method, as shown in FIG. 5, in order to stop the vehicle more smoothly than the second method, the braking by the electromagnetic brake 15 is turned on when the vehicle speed becomes "0". Other operations are the same as those in the second method.
Thus, in the third braking method, it is possible to reliably prevent a change in speed immediately before the vehicle stops, and to smoothly stop the vehicle.

(3) Modified Example In the above-described embodiment, an example is shown in which the braking method of the present invention is applied to a configuration in which the electromagnetic brake 15 is simply used as a parking-only brake device whose on / off control is performed. The braking method of the present invention is not limited to the configuration in which the electromagnetic brake 15 is used exclusively for parking, but is also applicable to the case where the braking force of the electromagnetic brake 15 is variably configured so as to be used for braking control during traveling as described above. is there.

FIG. 6 shows an operation when the above-described first braking method is applied when the braking force of the electromagnetic brake 15 is variably controlled. In this figure,
It is assumed that a stop command is issued while the vehicle is traveling downhill. In the figure, when the vehicle enters a downhill at the point of time P1 'shown in FIG.
5 is applied by a predetermined amount (illustrated C1 '). When there is a stop command at the point of time P2 'in the figure, the brake motor 14 is energized, and the braking force by the drum brakes 8a to 8d is applied (C2' in the figure).

In this way, the vehicle speed is gradually reduced due to the large braking applied to the vehicle (C3 'in the figure), and P3' in the figure.
If at the time of a constant low velocity V ₁ (shown C4 '), excitation command value to the electromagnetic brake 15 is set to "0", the braking force becomes maximum (shown C5').

Thereafter, the braking by the drum brakes 8a to 8d is continued while the braking force of the electromagnetic brake 15 rises as described above (C6 'in the figure), and is released when the vehicle speed detection value becomes "0". (C7 'in the figure). Thereby, the same effect as in the case described above can be obtained.

When the above-described second and third braking methods are applied, the operation is performed as shown in FIGS. 7 and 8, respectively. These operations can be easily inferred from the above-described contents, and thus description thereof is omitted.

The first and second embodiments to which the present invention is applied
The brake device of the system is not limited to the electromagnetic brake 15 and the drum brakes 8a to 8d of the above-described embodiment. For example, instead of the drum brakes 8a to 8d, another mechanical brake such as a disk brake may be driven by a motor.

[0045]

As described above, according to the present invention, it is possible to eliminate a drop in the braking force when shifting from braking control during vehicle running to parking braking for stopping the vehicle. Fluctuations in vehicle speed immediately before can be prevented, and riding comfort is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an automatic traveling vehicle to which the present invention is applied.

FIG. 2 is a block diagram showing a software configuration of a controller of the self-driving vehicle.

FIGS. 3A and 3B are graphs showing an operation of the embodiment when the first braking method of the present invention is applied, wherein FIG. 3A shows a change over time in vehicle speed, and FIG. 3B shows a change over time in braking force of a drum brake. (C) shows the change over time of the braking force of the electromagnetic brake.

FIGS. 4A and 4B are graphs showing the operation of the embodiment when the second braking method of the present invention is applied, wherein FIG. 4A shows the change over time of the vehicle speed, and FIG. 4B shows the change over time of the braking force of the drum brake; (C) shows the change over time of the braking force of the electromagnetic brake.

FIGS. 5A and 5B are graphs showing an operation of the embodiment when the third braking method of the present invention is applied, wherein FIG. 5A shows a change over time of the vehicle speed, and FIG. 5B shows a change over time of the braking force of the drum brake. (C) shows the change over time of the braking force of the electromagnetic brake.

FIGS. 6A and 6B are graphs showing an operation of a modified example when the first braking method of the present invention is applied, wherein FIG. 6A shows a change over time in the vehicle speed, and FIG. 6B shows a change over time in the braking force of the drum brake. (C) shows the change over time of the braking force of the electromagnetic brake.

FIGS. 7A and 7B are graphs showing an operation of a modified example when the second braking method of the present invention is applied, wherein FIG. 7A shows a change over time in vehicle speed, and FIG. 7B shows a change over time in braking force of a drum brake. (C) shows the change over time of the braking force of the electromagnetic brake.

FIGS. 8A and 8B are graphs showing an operation of a modified example when the third braking method of the present invention is applied, wherein FIG. 8A shows a change over time in vehicle speed, and FIG. 8B shows a change over time in braking force of a drum brake. (C) shows the change over time of the braking force of the electromagnetic brake.

9A and 9B are graphs showing a conventional method of braking an automatic traveling vehicle, in which FIG. 9A shows a change in vehicle speed (theoretical value) with time, and FIG.
Shows the change over time of the braking command value of regenerative braking, and (c) shows the change over time of the braking command value of the electromagnetic brake.

10A and 10B are graphs showing a conventional method of braking an automatic traveling vehicle, wherein FIG. 10A shows a change over time of an actual vehicle speed, FIG. 10B shows a change over time of a braking force of regenerative braking, and FIG. The change with time of the braking force of the electromagnetic brake is shown.

FIG. 11 is a graph showing a temporary drop in a combined braking force in a conventional method of braking an automatic traveling vehicle.

[Explanation of symbols]

8a to 8d: drum brake (first system brake device), 9: controller, 10: steering driver, 11: steering motor, 12: throttle motor, 13: brake motor driver (first system brake device), 14: Brake motor (brake device of first system), 15: electromagnetic brake (brake device of second system), 30: vehicle speed sensor (vehicle speed detecting means), 91: target vehicle speed setting unit, 92: driving force calculation unit, 93 ... Throttle drive calculation unit, 94: braking force calculation unit, 95: braking state switching determination unit, 96: current command value calculation unit, 97: excitation voltage calculation unit, 98: abnormality determination / abnormal processing unit, 99a to 99l: interface.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-73144 (JP, A) JP-A-63-130453 (JP, A) JP-A-4-197857 (JP, A) 41072 (JP, U) Japanese Utility Model 3-91273 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B60T ⁷ /12-7/22 B60T 8/00 B60T 8/32- 8/96 B60T 13/74

Claims (1)

(57) [Claims] A first system brake device for applying a braking force for braking control during running of a vehicle, a second system brake device for applying a parking braking force for stopping the vehicle, and a vehicle speed. The present invention is applied to an autonomous vehicle having a vehicle speed detecting means for detecting, wherein the vehicle is decelerated by the first system brake device in response to a stop instruction, and a detection value by the vehicle speed detecting means is "0" or near. When the low speed is reached, the second
In a braking method for an automatic traveling vehicle in which a vehicle is stopped by a system brake device, the second system brake device variably controls a braking force.
The vehicle travels together with the first brake system.
After applying the braking force for the braking control during the braking and starting the braking by the braking device of the second system,
A method for braking an automatic traveling vehicle, wherein the braking by the first system brake device is continued for a predetermined period, and the braking periods by both systems are overlapped.