JPH05153701A - Brake controller for motor drive vehicle - Google Patents

Abstract

PURPOSE:To realize smooth brake control causing no slip and matching, at all times, to the feeling of driver regardless of the stepping of brake or the difference of load by applying fuzzy control on the brake control of motor drive vehicle. CONSTITUTION:Stepping amount of brake BK, vehicle speed LW, and load LM are fed to a fuzzy controller 11. The fuzzy controller 11 is set with a predetermined fuzzy rule based on the braking state for a vehicle corresponding to the brake operation of a driver. In other words, the fuzzy controller 11 performs fuzzy inference based on the fuzzy control rule according to the step amount of brake BK, the vehicle speed V and the load LM to determine a regenerative brake amount RB which is fed to a base drive circuit 2. The base drive circuit 2 controls the voltage to be applied on a motor 5 based on the regenerative brake amount RB thus braking the vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake control device for a motor-driven vehicle suitable for use in brake control of a vehicle such as a forklift truck that is driven by a motor.

[0002]

2. Description of the Related Art Vehicles such as forklifts are known which are driven by a battery-powered motor. In a vehicle driven by such a motor, the brake control is performed by a brake control device as shown in FIG. In the figure, when an ON signal BS of a brake switch (not shown) operated by a driver is supplied, a CPU (Central Processing Unit) 1 can perform regenerative control for brake control based on a motor current MC. Check whether or not

If regenerative is possible, the regenerative mode is set, and the regenerative brake amount RB corresponding to the brake depression amount BK is supplied to the base drive circuit 2 in order to apply the regenerative brake to the mechanical brake. This regenerative braking amount RB
Is the brake depression amount B as shown by the hatching in FIG.
It is set to increase according to K (brake force).

The base drive circuit 2 has a regenerative braking amount RB.
Is supplied to the base B of the transistor Q1. The transistor Q1 is
It controls the voltage of the battery 4 applied to the motor 5.

[0005]

However, the above-described brake control device for a motor-driven vehicle has a problem that the brake suddenly works or slips depending on how the brake is depressed. In addition, there is a difference in the effectiveness of the braking depending on the difference in load, which causes a problem of danger.

The present invention has been made in view of the above-mentioned circumstances, and a smooth brake control that does not cause a slip that always matches the driver's sensation is provided regardless of the conditions such as how the brake is depressed and the difference in load. An object of the present invention is to provide a brake control device for a motor-driven vehicle that can be used.

[0007]

In order to solve the above-mentioned problems, in the present invention, a regenerative braking amount corresponding to the depression amount of a brake pedal is applied to a motor for driving the vehicle, so that In a brake control device for a motor-driven vehicle that controls a braking force, the regenerative brake amount is obtained by fuzzy inference based on a stepping amount of the brake pedal, a traveling speed of the vehicle and a load applied to the motor, and the regenerative brake amount. A fuzzy controller for controlling the motor is provided.

[0008]

According to the present invention, by the fuzzy controller,
The regenerative braking amount is obtained by fuzzy reasoning based on the amount of depression of the brake pedal, the traveling speed of the vehicle and the load on the motor, and the motor is controlled by the regenerative braking amount.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram showing a control system of an embodiment of the present invention. In this figure, the same components as those shown in FIG. 8 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the brake depression amount BK, the vehicle speed V and the load LW are supplied to the fuzzy controller 11. In the fuzzy controller 11, a fuzzy control rule based on a braking state for the vehicle according to a driver's braking operation is set. That is, the fuzzy controller 1
1 performs a fuzzy inference based on the fuzzy control rule in accordance with the brake depression amount BK, the vehicle speed V and the load LW to obtain the regenerative brake amount RB and supplies it to the base drive circuit 2.

Next, the membership function for the above fuzzy control rule will be described. 2 is a membership function of the brake depression amount BK, FIG. 3 is a membership function of the vehicle speed V, FIG. 4 is a membership function of the load LW, and FIG. 5 is a membership function of the regenerative braking amount. Here, S, M, B, N, Z, P, Z, SS, S,
M, B, and BB are labels of membership functions, respectively. The respective meanings are that the label S is "small", the label M is "medium", and the label B is "large" for the membership function with respect to the brake depression amount BK. Next, regarding the membership function of the vehicle speed V, the label S is “slow”, the label M is “medium”,
Label B is "fast". Regarding the membership function of the load LW, the label S is “light” and the label B is
Is "heavy". Regarding the membership function of the regenerative braking amount, the label Z is "zero" and the label SS is
Is "very small", label S is "small", label M
Is "medium", label B is "large", and label BB is "very large". In addition, in the present embodiment, all the membership functions described above are triangular functions. Further, the following 13 rules are used for the above fuzzy control rules.

Fuzzy control rule Rule A1: IF vehicle speed = S THEN regenerative braking amount = Z Rule A2: IF brake depression amount = S and vehicle speed =
M and load = S THEN Regenerative braking amount = SS Rule A3: IF Brake step amount = S and vehicle speed =
M and load = B THEN Regenerative brake amount = S Rule A4: IF Brake step amount = S and vehicle speed =
B and load = S THEN regenerative braking amount = S Rule A5: IF brake depression amount = S and vehicle speed =
B and load = B THEN Regenerative braking amount = M

Rule A6: IF brake depression amount = M and vehicle speed =
M and load = S THEN Regenerative braking amount = S Rule A7: IF brake depression amount = M and vehicle speed =
M and load = B THEN Regenerative braking amount = M Rule A8: IF Brake step amount = M and vehicle speed =
B and load = S THEN regenerative braking amount = M Rule A9: IF brake depression amount = M and vehicle speed =
B and load = B THEN Regenerative braking amount = B

Rule A10: IF brake depression amount = B and vehicle speed = M and load = S THEN regenerative braking amount = M Rule A11: IF brake depression amount = B and vehicle speed = M and load = B THEN regenerative braking amount = B rule A12: IF brake depression amount = B and vehicle speed = B and load = S THEN regenerative braking amount = B Rule A13: IF brake depression amount = B and vehicle speed = B and load = B THEN regenerative braking amount = BB

In the above-mentioned rules, for example, the rule A1 means "if the vehicle speed V is S (slow), set the regenerative braking amount RB to Z (zero)". In addition, according to the rule A2, "If the brake depression amount BK is S
(Small), the vehicle speed V is M (medium), and the load LM is S (light), the regenerative braking amount RB
To SS (very small) ". In the control in this embodiment, the most general "MIN-MAX centroid method" is adopted as the inference method, but other inference methods may be used.

Next, the brake control using the above-mentioned fuzzy inference rule will be described with reference to FIGS. 6 and 7. [Operation of Embodiment] Here, for example, the brake depression amount BK
Is 0.25, the vehicle speed V is 0.1, and the load LW is 0.5, rule A1 and rule A2 will be evaluated as an example.

First, in rule A1, as shown in FIG. 6, the degree of conformity of the brake depression amount BK is 0.5 and the degree of conformity of the vehicle speed V is 0.8, while the degree of conformity of the load LW is a conditional part. Since it is not written in, it becomes 1.0. Therefore,
If the MIN (minimum value) is taken, it becomes 0.5. Therefore, a figure obtained by cutting off the membership function Z of the regenerative braking amount RB at the position of height 0.5 is obtained.

Next, in rule A2, as shown in FIG. 7, the degree of conformity of the brake depression amount BK is 0.5, the degree of conformity of the vehicle speed V is 0.2, and the degree of conformity of the load LW is 0.5. Become. Therefore, if we take their MIN (minimum value), we get 0.2
Therefore, a figure obtained by cutting off the membership function SS of the regenerative braking amount RB at the position of height 0.2 is obtained.

The above calculation is performed for all the fuzzy control rules A1 to A13, and the resulting graphics are MAX (maximum value) synthesized (not shown). The result is defuzzified, that is, the synthesized graphics. When the center of gravity of is taken, this value becomes the regenerative braking amount RB (new control amount). This center of gravity is supplied to the base drive circuit 2 as the regenerative braking amount RB. The base drive circuit 2 controls the base current of the transistor Q1 according to the regenerative braking amount RB. As a result, smooth brake control that matches the driver's feeling can be performed.

In the above-mentioned embodiment, the steering angle may be used as the input signal, and if the steering angle is large, knowledge such as applying a small brake may be described as a fuzzy control rule. According to this, the skid of the vehicle body can be reduced.

[0020]

As described above, according to the present invention, the fuzzy controller obtains the regenerative braking amount by the fuzzy inference based on the depression amount of the brake pedal, the traveling speed of the vehicle and the load applied to the motor. Since the motor is controlled by the amount of regenerative braking, it is possible to always perform smooth brake control that does not cause slipping that matches the driver's senses, regardless of conditions such as how the brake is depressed and the difference in load. Is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a control system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a membership function of a brake depression amount BK in the present embodiment.

FIG. 3 is a diagram showing a membership function of a vehicle speed V in the embodiment.

FIG. 4 is a diagram showing a membership function of a load LW in the example.

FIG. 5 is a diagram showing a membership function of a regenerative braking amount RB in the same embodiment.

FIG. 6 is a diagram showing a goodness of fit of a brake depression amount BK, a goodness of fit of a vehicle speed V, a goodness of fit of a load LW, and a goodness of fit of a regenerative braking amount RB based on these results with respect to a rule A1.

FIG. 7 is a diagram showing the fitness of the brake depression amount BK, the fitness of the vehicle speed V, the fitness of the load LW, and the fitness of the regenerative braking amount RB based on these results with respect to the rule A2.

FIG. 8 is a block diagram showing a configuration of a control system of a conventional brake control device for a motor-driven vehicle.

9 is a diagram illustrating a regenerative brake amount RB of the brake control device shown in FIG.

[Explanation of symbols]

 2 Base drive circuit 4 Battery 5 Motor 11 Fuzzy controller BK Brake depression amount V Vehicle speed LW load RB Regenerative braking amount

Claims (1)

[Claims] 1. A brake control device for a motor-driven vehicle, which controls a braking force of a vehicle by applying a regenerative braking amount corresponding to a depression amount of the brake pedal to a motor that drives the vehicle. A motor comprising a fuzzy controller that obtains the regenerative braking amount by fuzzy inference based on a stepping amount, a traveling speed of the vehicle, and a load applied to the motor, and controls the motor by the regenerative braking amount. Brake control device for driving vehicle.