JP2003070849A - Control device for electric wheelchair - Google Patents

Abstract

[PROBLEMS] To provide a control device for an electric wheelchair capable of obtaining a good braking performance by preventing slipping of drive wheels and the like. When performing braking control from a turning state such as a stationary turning state, a controller 20 executes a turning braking duty ratio calculation routine and performs feedback control based on the yaw rate Yaw to turn the electric wheelchair 1. Cancel the direction component. As a result, the left and right drive wheels 1
0L, 10R slips and the like can be prevented, and the electric wheelchair 1 can be prevented from overshooting. Thereafter, when the component in the turning direction becomes minute, the controller 20 executes a normal braking duty ratio calculation routine and performs feedback control based on the left and right driving wheel speeds VelL and VelR, thereby ensuring reliable braking performance. Get.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric wheelchair in which left and right drive wheels are driven by individual electric motors.

[0002]

2. Description of the Related Art In general, an electric wheelchair has a pair of electric motors, and each electric motor independently drives and controls the left and right driving wheels to realize straight traveling or turning traveling. Things are widely adopted.
In the control of this type of electric wheelchair, it is general that the instruction speed for each electric motor is feedback-controlled using the actual traveling state.
In Japanese Patent No. 88065, the proportional-integral control is performed so that the actual turning angular velocity becomes equal to the turning command value, and the proportional-integral control is performed such that the actual center-of-gravity velocity becomes equal to the center-of-gravity velocity command value, and these results are used. A technique for calculating speed command values for the left and right driving wheels is disclosed. According to such a technique, it is possible to reduce the shock to the occupant at the time of starting / stopping by delaying the response of the center of gravity speed control.

[0003]

However, as in the technique disclosed in Japanese Unexamined Patent Publication No. 11-188065 mentioned above, it is sufficient to simply delay the response of the center-of-gravity velocity control to perform the braking control. It may be difficult to obtain proper braking performance. For example, when performing braking control from a turning state in which the left and right driving wheels are driven in opposite directions, such as a stationary turning, the driving wheels slip because inertia force in the turning direction is generated in the electric wheelchair. In some cases, the electric wheelchair may be braked while moving overshooting. In particular, in an electric wheelchair that is configured such that the auxiliary drive device is detachably attached to the wheelchair body, the left and right drive wheels have a narrow tread width and a small drive wheel diameter. .

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a control device for an electric wheelchair capable of preventing slipping of driving wheels and obtaining good braking performance.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 is a control device for an electric wheelchair that feedback-controls a pair of electric motors for individually driving the left and right drive wheels based on the running state. In a turning determination means for determining a turning state of the electric wheelchair during braking control, and when the electric wheelchair is in a turning state, feedback control based on an angular velocity of the electric wheelchair is performed to control the braking of the electric wheelchair. And a second braking means for controlling the braking of the electric wheelchair by performing feedback control based on the left and right driving wheel speeds when the electric wheelchair is not in a turning state.

According to a second aspect of the invention, in the first aspect of the invention, the turning determination means is in a turning state when the left and right drive wheels are rotated in opposite directions. It is characterized by determining that.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic configuration diagram of an electric wheelchair, FIG. 2 is a configuration diagram of a power control system, FIG. 3 is a flowchart of an overall control routine, and FIG. 4 is a flowchart of a joystick signal processing routine. 5, FIG. 5 is a flowchart of a straight traveling correction control routine, FIG. 6 is a flowchart of a normal braking duty ratio calculation routine, FIG. 7 is a flowchart of a turning braking duty ratio calculation routine, and FIG. 8 is a straight traveling instruction speed signal limiter value calculation method. FIG.

In FIG. 1, reference numeral 1 indicates an electric wheelchair. In the present embodiment, the electric wheelchair 1 is configured with an existing folding manual wheelchair main body 2 to which an auxiliary drive device 3 is detachably attached to form a main part.

The wheelchair body 2 includes a pipe frame-shaped frame 5 which is substantially symmetrical on both left and right sides, a pair of left and right casters 6 and wheels 7.
The front and rear parts are supported by and to form the main part.

The frame 5 includes a main frame pipe 5a to which casters 6 and wheels 7 are rotatably mounted, a seat frame pipe 5b extending forward from the middle of the main frame pipe 5a, and a seat frame pipe 5b.
And a stay 5d that integrally connects the front ends of the seat frame pipe 5b and the armrest pipe 5c to the main frame pipe 5a. There is. Further, the upper end of the main frame pipe 5a is bent backward, and this portion is formed as a grip 5e for an assistant.

The auxiliary drive device 3 is mounted on the wheelchair body 2 by crimping a clamp mechanism (not shown) having a hydraulic cylinder or the like to the left and right main frame pipes 5a. Left and right drive wheels 10L, 10R
And a single caster 11 arranged in front of it.

The left and right drive wheels 10L and 10R are individually driven and controlled by the built-in controller 20 shown in FIG. 2, whereby the auxiliary drive device 3 causes the wheelchair body 2 to move forward and backward, turn, and stop. Is possible.

Specifically, as shown in FIG. 2, the controller 20 is connected to electric motors 19L and 19R for independently driving the left and right drive wheels 10L and 10R, respectively.

Further, the controller 20 includes rotary encoders 13L and 13R for detecting rotations of the left and right driving wheels 10L and 10R, and an angular velocity sensor (yaw rate sensor) for detecting a rotational angular velocity (yaw rate) of the electric wheelchair 1. ) 14 and the tilt angle signal x indicating the operation amount of the joystick 15 in the front-back direction (X-axis direction) and the operation amount in the left-right direction (Y-axis direction) when the user operates the joystick 15 as an operation switch. Potentiometer 1 for detecting each tilt angle signal y shown
5a and 15b are connected. Then, the controller 20 controls the left and right electric motors 19 based on the respective input signals.
The duty ratio for L and 19R is calculated, and the PWM control (pulse wide modulator control) based on these is performed.

As shown in FIG. 1, the joystick 15 is fixed to the armrest pipe 5c, and signals from the potentiometers 15a and 15b are input to the controller 20 via a cable. Further, the rotary encoders 13L and 13R and the angular velocity sensor 14 are built in the auxiliary drive device 3.

The controller 20 has the functions of the turning determination means, the first braking means, and the second braking means according to the present invention. Specifically, the functions of the respective means are determined by the routines shown in FIGS. To be realized. Hereinafter, the processing relating to the control of the auxiliary drive device 3 executed by the controller 20 will be described with reference to the flowcharts of FIGS. 3 to 7.

In FIG. 3, a main switch (not shown) is turned on.
This is an overall control routine that is started upon start. This routine is executed every predetermined time (for example, every 8 msec), and the controller 20 first executes step S10.
At 1, the signals from various switches and sensors are read. Specifically, the controller 20 reads the output pulses from the rotary encoders 13L and 13R, the angular velocity (yaw rate) signal Yaw from the angular velocity sensor 14, the tilt angle signals x and y from the potentiometers 15a and 15b, and the like. In this case, the yaw rate signal Yaw has a positive value when the yaw rate of the right turn is detected, and has a negative value when the yaw rate of the left turn is detected. Further, the rectilinear direction tilt angle signal x shows a positive value when the joystick 15 is tilted forward and a negative value when it is tilted backward. Further, the turning direction tilt angle signal y shows a positive value when the joystick 15 is tilted to the right, and a negative value when the joystick 15 is tilted to the left.

In the following step S102, the controller 20 follows the joystick signal processing routine, which will be described later, based on the signals from the rotary encoders 13L and 13R and the potentiometers 15a and 15b, and outputs the straight advance instruction speed signal Spd and the turning instruction speed signal. R
Calculate ot. Here, the straight traveling instruction speed signal Spd is
When the value is positive, the auxiliary drive unit 3 (that is, the electric wheelchair 1) is instructed to move forward, and when the value is negative, the auxiliary drive unit 3 is moved backward. Further, the turn instruction speed signal Rot indicates a right turn of the auxiliary drive device 3 when it is a positive value, and indicates a left turn of the auxiliary drive device 3 when it is a negative value.

When the process proceeds from step S102 to step S103, the controller 20 calculates the straight ahead instruction speed signal Spd and the turning instruction speed signal Ro calculated in step S102.
It is checked whether both t are "0". Then, in step S103, at least one of the straight-ahead instruction speed signal Spd and the turning instruction speed signal Rot is "0".
If it is determined that it is not, the controller 20 controls the traveling of the auxiliary drive device 3 by the processing from step S104. On the other hand, when it is determined in step S103 that the straight-ahead instruction speed signal Spd and the turning instruction speed signal Rot are both "0", the controller 20 performs the braking control of the auxiliary drive device 3 by the processing from step S111.

When the process proceeds from step S103 to step S104, the controller 20 determines the turning instruction speed signal Rot.
Is checked to see if it is "0".

When it is determined in step S104 that the turning instruction speed signal Rot is "0", the controller 20 proceeds to step S105 to perform the straight-ahead control of the auxiliary drive device 3, and the straight-ahead correction control described later is performed. The straight-ahead correction value Str is calculated according to a routine. afterwards,
The controller 20 proceeds to step S106 and sets the left and right motor command speeds SpdL and SpdR by SpdL = Spd + Str (1) SpdR = Spd-Str (2). That is, during the straight ahead control, the controller 20 corrects the left and right motor command speeds (= Spd) calculated based on the signal from the joystick 15 with the straight travel correction value Str, so that the final motor command speed SpdL, Set SpdR. In this case, (1)
As is clear from the equation (2), the straight traveling correction value Str is
When it is a positive value, the motor command speed SpdL of the left electric motor 19L is increased and corrected, and when it is a negative value, the motor command speed SpdR of the right electric motor 19R is increased and corrected.

On the other hand, when it is determined in step S104 that the turning instruction speed signal Rot is not "0",
The controller 20 proceeds to the process of step S107 to calculate the left and right motor command speeds SpdL and SpdR by SpdL = Spd + Rot (3) SpdR = Spd-Rot (4).

Step S106 or step S107
From step S108, the controller 20
Feedback (PID) control for the left and right motor command speeds SpdL and SpdR is performed based on the left and right drive wheel speeds VelL and VelR calculated from the output pulses from the rotary encoders 13L and 13R. That is, the controller 20 calculates the proportional component LP, the integral component LI, and the differential component LD of the speed of the left electric motor 19L as follows: LP = SpdL-VelL (5) LI = LIf + LP (6) LD = LPf-LP (7) ), The proportional component RP, the integral component RI, and the differential component RD of the speed of the right electric motor 19R are calculated as follows: RP = SpdR-VelR (8) RI = RIf + RP (9) RD = RPf-RP (10) ). LPf and RPf represent the previous proportional components, and LIf and RIf represent the previous integral components.

Then, the controller 20 executes step S
Proceeding to the processing of 109, the left and right electric motors 19L, 19R
The duty ratios DutyL and DutyR with respect to are calculated by: DutyL = LP.GeinP + LI.GeinI + LD.GeinD (11) DutyR = RP.GeinP + RI.GeinI + RD.GeinD. Here, GeinP, GeinI,
Also, GeinD is a preset gain constant.

In the following step S110, the controller 20 determines the left and right duty ratios DutyL and Duty.
After performing the PWM control of the electric motors 19L and 19R based on R, the routine exits.

On the other hand, steps S103 to S1
11, the controller 20 determines that the left and right drive wheel speed Ve
Whether or not both IL and VelR are positive values, or
By checking whether the left and right drive wheel speeds VelL and VelR are both negative values, it is checked whether the auxiliary drive device 3 is in the normal traveling state. Here, the normal traveling state refers to a case where the auxiliary drive device 3 is in a straight traveling state or in a traveling state while making a minute turn.

When it is determined in step S111 that the auxiliary drive device 3 is in the normal traveling state, the controller 20 proceeds to step S112, where the left and right electric motors are operated during normal braking according to a normal braking duty ratio calculation routine described later. The duty ratios DutyL and DutyR for the motors 19L and 19R are calculated.

On the other hand, in step S111, it is determined that the auxiliary drive device 3 is not in the normal traveling state, and therefore, in step S111.
Proceeding to 113, the controller 20 determines the left and right drive wheel speed V
It is checked whether or not the auxiliary drive device 3 is in a turning state by checking whether or not elL and VelR are equal to or higher than a predetermined speed and have speed components in opposite directions. Here, the turning state determined in step S113 is a turning state in which the left and right drive wheels are driven in opposite directions, such as stationary turning.

When it is determined in step S113 that the auxiliary drive device 3 is in the turning state, the controller 20 proceeds to step S114 and moves to the left and right during turning braking according to a turning braking duty ratio calculation routine described later. The duty ratios DutyL and DutyR for the electric motors 19L and 19R are calculated.

Step S112 or step S114
Duty ratio DutyL, DutyR when braking
Is calculated, the controller 20 determines in step S11.
5, the duty ratio DutyL for the left electric motor 19L and the limiter value ± Brake of the duty ratio DutyL are compared. That is, step S11
5, the controller 20 determines that the duty ratio Dut
It is checked whether yL is −Brake <DutyL <Brake.

When it is determined in step S115 that the duty ratio DutyL is out of the range of the limiter value ± Brake, the controller 20 determines in step S115.
The duty ratio DutyL calculated in step 112 or step S114 is maintained as it is, and the process proceeds to step S119.

On the other hand, when it is determined in step S115 that the duty ratio DutyL is within the limiter value ± Brake, the controller 20 determines in step S1.
16, the positive / negative of the duty ratio DutyL is checked, and when the duty ratio DutyL is a negative value, the value is reset to −Brake (step S117), and when the duty ratio DutyL is a positive value, the value is set. Br
After resetting to ake (step S118), the process proceeds to step S119.

Similarly, in step S119, the controller 20 checks whether or not the duty ratio for the right electric motor 19R is -Brake <DutyR <Brake. Then, when it is determined in step S119 that the duty ratio DutyR is outside the range of the limiter value ± Brake, the controller 20 maintains the duty ratio DutyR calculated in step S112 or step S114 as it is, and then in step S110.
Go to processing.

On the other hand, when it is determined in step S119 that the duty ratio DutyR is within the limiter value ± Brake, the controller 20 determines in step S1.
In step 20, whether the duty ratio DutyR is positive or negative is checked, and when the duty ratio DutyR is a negative value, the value is reset to −Brake (step S121), and when the duty ratio DutyR is a positive value, the value is set. Br
After resetting to ake (step S122), the process proceeds to step S110.

That is, the controller 20 performs the processes of steps S115 to S118 and step S11.
In the processing from 9 to step S122, step S11
2 or the duty ratio Du calculated in step S114
Limiter value for values of tyL and DutyR ± Brac
e is provided, and when the components of the duty ratios DutyL and DutyR are below the limiter value, the duty ratio Duty
By limiting the lower limit of L and DutyR to the limiter value, effective braking performance is maintained.

Next, step S10 of the overall control routine.
The calculation of the straight ahead instruction speed signal Spd and the turning instruction speed signal Rot in 2 is performed according to the joystick signal processing routine shown in FIG. In this case, the joystick signal processing routine sets the upper limit by the limiter value SpdT of the straight advance instruction speed signal calculated based on the traveling state of the auxiliary drive device 3 with respect to the primary straight advance instruction speed signal SpdP calculated based on the tilt angle signal x. By setting the final straight ahead instruction speed signal Spd by adding the regulation, it is possible to prevent the auxiliary drive device 3 from suddenly starting and to secure the turning ability when climbing a slope or accelerating. Further, the joystick signal processing routine directly calculates the turning instruction speed signal Rot based on the tilt angle signal y, thereby improving the responsiveness at the time of turning.

When the routine shown in FIG. 4 is started, in step S201, the controller 20 detects the tilt angle signal detected at each sampling cycle within a predetermined time in order to prevent hunting due to a minute movement when the joystick 15 is operated. The tilt angle signal X, which is obtained by averaging x and y
Calculate Y.

In subsequent step S202, the controller 20 determines that the turning direction tilt angle signal Y is -Fy≤Y≤Fy.
If it is determined that −Fy ≦ Y ≦ Fy, the turning instruction speed signal Rot is set to “0” (step S203). That is, ± Fy is for defining the dead band of the operation in the left-right direction (turning direction) by the joystick 15, and the turning instruction speed signal Rot when the turning direction tilt angle signal Y is in the dead band.
Joystick 15 by setting to "0"
Prevents unintentional turning due to minute blurring and misalignment during operation.

On the other hand, when it is determined in step S202 that the turning direction tilt angle signal Y is outside the dead band of ± Fy, the controller 20 proceeds to step S204 and determines whether the turning direction tilt angle signal Y is positive. Find out.

If it is determined in step S204 that the turning direction tilt angle signal Y is positive, the controller 20 determines that Rot = RotMax. (Y-Fy) / (YMax-Fy) (13). The turning instruction speed signal Rot is set by (step S205). On the other hand, when it is determined in step S204 that the turning direction tilt angle signal Y is negative, the controller 20 determines that the turning instruction speed signal is Rot = RotMax · (Y + Fy) / (YMax−Fy) (14). Rot is set (step S206). Here, in the equations (13) and (14), R
otMax indicates the maximum value of the turning instruction speed signal, and YMax indicates the maximum tilt angle of the joystick 15 in the Y-axis direction.

When the process proceeds from step S203, step S205, or step S206 to step S207,
The controller 20 calculates the primary straight ahead instruction speed signal SpdP by the processing up to step S211.

That is, in step S207, the controller 20 determines that the rectilinear direction tilt angle signal X is -Fx≤X.
If it is determined that −Fx ≦ X ≦ Fx, it is determined whether or not ≦ Fx, and the primary straight ahead instruction speed signal SpdP is set to “
It is set to 0 "(step S208). That is, ± F
x is for defining the dead zone of the operation of the joystick 15 in the front-back direction (straight ahead direction),
By setting the primary straight-ahead instruction speed signal SpdP to "0" when the straight-ahead direction tilt angle signal X is within the dead band, it is possible to prevent an unintended straight-ahead movement due to a slight blur or displacement of the joystick 15 operation.

On the other hand, if it is determined in step S207 that the rectilinear direction tilt angle signal X is outside the dead band of ± Fx, the controller 20 proceeds to the process of step S209 to determine whether the rectilinear direction tilt angle signal X is positive. Check whether or not.

If it is determined in step S209 that the straight-ahead tilt angle signal X is positive, the controller 20 proceeds to step S210, where SpdP = SpdMax.multidot. (X-Fx) / (XMax-Fx ) (15) sets the primary straight ahead instruction speed signal SpdP. On the other hand, in step S209, the receding direction tilt angle signal X
Is determined to be negative, the controller 20
Advances to step S211, and the primary straight-ahead instruction speed signal SpdP is set by SpdP = SpdMax.multidot. (X + Fx) / (XMax-Fx) (16). In the equations (15) and (16), SpdMax represents the maximum value of the straight-ahead instruction speed signal, and XMax represents the maximum tilt angle of the joystick 15 in the X-axis direction.

When the process proceeds from step S208, step S210, or step S211 to step S212,
The controller 20 calculates the limiter value SpdT of the straight ahead instruction speed signal by the processing up to step S221.

Here, in the present embodiment, as shown in FIG. 8, the limiter value SpdT is a speed step SpdStep that equally divides the straight-ahead instruction speed signal area from -SpdMax to SpdMax into, for example, 10 forward and backward steps. Is set based on. In this case, the initial value of the speed stage SpdStep at the start of forward movement is set to, for example, "1", and the initial value of the speed stage SpdStep at the start of reverse movement is set to, for example, "-1". When the limiter value SpdT is calculated, the first lower limit value is one step lower than the limiter value SpdT.
2 than the speed threshold SpdTa and the limiter value SpdT of
The second speed threshold value SpdTd on the lower speed side is set, and the speed step SpdStep is updated by the left and right drive wheel speeds VelL, V.
The actual traveling speed V of the auxiliary drive device 3, which is the average value of elR
Is compared with the first and second speed thresholds SpdTa and SpdTd.

More specifically, in step S212, the controller 20 determines whether or not the absolute value of the speed V is equal to or less than the absolute value of the second threshold value SpdTd for a certain time (for example, 0.5 sec) or more. Find out. Here, when the state of | V | <| SpdTd | continues for a certain time or longer, for example, when the user attempts to decelerate by returning the joystick 15 to the neutral position side, or the electric wheelchair 1 approaches an uphill road. It is possible that

Then, in step S212, | V |
When it is determined that the state of <| SpdTd | has continued for a certain period of time or more, the controller 20 determines in step S213.
Then, it is checked whether the absolute value of the speed stage SpdStep is smaller than "2". In step S212, | S
If it is determined that pdStep | <2, then the controller 20 proceeds to step S215, where SpdSt
When ep> 0, the speed stage SpdStep is set to "1".
, And if SpdStep <0, the speed stage S
Set pdStep to "-1". On the other hand, step S
When it is determined that | SpdStep | ≧ 2 in 212, the controller 20 determines in step S214.
Then, the speed stage SpdStep is updated to the value on the one side lower speed side.

On the other hand, in step S212, | V | <
When it is determined that the state of | SpdStep | has not continued for the fixed time or more, the process proceeds to step S216. In step S216, the controller 20 keeps the turning instruction speed signal Rot = 0 and the absolute value of the speed V is equal to or more than the absolute value of the first threshold value SpdTa for a certain time (for example, 0.5 sec) or more. Check whether or not.

Then, in step S216, the turning instruction speed signal Rot = 0 and | V |> | Sp.
When it is determined that the state of dTa | has continued for a certain period of time or more, the controller 20 proceeds to step S217,
It is checked whether or not | SpdStep | <| StepMax | −1. In step S217 | SpdSte
If it is determined that p | <| StepMax | −1, the controller 20 proceeds to step S218, where Sp
When dStep> 0, the speed stage SpdStep is set to StepMax-1, and when SpdStep <0, the speed stage SpdStep is set to StepMax + 1. On the other hand, in step S217 | SpdSt
When it is determined that ep | ≧ | StepMax | −1, the controller 20 proceeds to step S219,
The speed stage SpdStep is updated to the value on the higher side by one stage.

On the other hand, in step S216, it is determined that the turning instruction speed signal Rot ≠ 0, or | V |> | S
If at least one of the determinations that pdTa | has not continued for a certain period of time or more is made, the controller 20 proceeds to step S220 and proceeds to the current speed stage Spd.
Maintain Step.

Upon proceeding from step S214, step S215, step S218, step S219, or step S220 to step S221, the controller 20 determines, based on the set speed stage SpdStep.
The limiter value SpdT, the first threshold value SpdTa, and the second threshold value SpdTd are calculated.

These calculations are carried out according to the speed stage SpdStep>
In the case of 0, it is calculated by the following equations (17), (18) and (19). SpdT = SpdMax. (SpdStep + 1) / StepMax (17) SpdTa = SpdMax.SpdStep / StepMax ... (18) SpdTd = SpdMax. (SpdStep-1) / StepMax. , Are calculated by the following equations (20), (21) and (22). SpdT = SpdMax * (SpdStep-1) / StepMax (20) SpdTa = SpdMax * SpdStep / StepMax ... (21) SpdTd = SpdMax * (SpdStep + 1) / StepMax ... (22) That is, for example, as shown in FIG. Stage SpdSt
When ep = 5, SpdT = 6/10 · Spd
Max, SpdTa = 5 / 10.SpdMax, SpdTd =
It becomes 4/10 · SpdMax.

Upon proceeding from step S221 to step S222, the controller 20 determines the primary straight ahead instruction speed signal S
The absolute value of pdP and the absolute value of the limiter value SpdT are compared, and if | SpdP | <| SpdT |, the final straight-travel instruction speed signal Spd is changed to the primary straight-travel instruction speed signal S.
After setting to pdP (step S223), the routine exits. On the other hand, when | SpdP | ≧ | SpdT |, the final straight ahead instruction speed signal Spd is set to the limiter value S.
After setting to pdT (step S224), the routine exits.

As described above, in the joystick signal processing routine, the controller 20 goes straight on the basis of the tilt angle signals X and Y obtained by averaging the tilt angle signals x and y calculated for each sampling period within a predetermined time. Since the instruction speed signal Spd and the turning instruction speed signal Rot are calculated, it is possible to prevent hunting or the like due to a slight movement when the joystick 15 is operated.

Also, the dead zone (± F
By providing (x, ± Fy), it is possible to prevent unintended going straight or turning due to a slight blur or distortion when the user operates the joystick 15.

Further, the controller 20 sets the limiter value SpdT based on the actual traveling speed V of the auxiliary drive unit 3 (that is, the electric wheelchair 1), and calculates the straight traveling instruction speed calculated based on the leaning angle signal X in the straight traveling direction. Since the signal (primary straight ahead instruction speed signal SpdP) is subjected to the upper limit regulation by the limiter value SpdT to set the final straight ahead instruction speed signal Spd, it is possible to prevent sudden acceleration of the electric wheelchair 1.

Therefore, the operability of the joystick 15 can be improved such that sudden acceleration can be prevented without requiring the skill of the user. In addition, setting the final straight-travel instruction speed signal Spd by adding the upper limit regulation by the limiter value SpdT to the primary straight-travel instruction speed signal Spd causes the electric motors 19L and 19R to drive at the maximum output, and thus the vehicle travels straight. This can be prevented, and sufficient turning response can be ensured even during acceleration traveling or traveling on an uphill road.

Further, the controller 20 determines the limiter value S
The first threshold value SpdTa is set on the lower speed side than pdT,
When the actual traveling speed V is higher than the first threshold value SpdTa for a certain period of time or more, the limiter value SpdT is shifted to the high speed side, so that the acceleration state of the electric wheelchair 1 is restricted more than necessary by the limiter value SpdT. This can be prevented, and smooth acceleration control can be performed.

Further, the controller 20 uses the first threshold value S
The second threshold value SpdTd is set to a lower speed side than pdTa, and the limiter value SpdT is shifted to a lower speed side when the actual traveling speed V continues to be lower than the second threshold value SpdT for a certain period of time. The limiter value SpdT can be gently shifted to the low speed side when traveling on a road or the like, and excessive deceleration can be prevented.

Further, when the turning instruction speed Rot ≠ 0, the controller 20 does not shift the limiter value SpdT to the high speed side and limits the acceleration during the turning.
The turning response can be improved more effectively.

Further, since the controller 20 directly calculates the turning instruction speed signal Rot based on the tilt angle signal Y, the turning response can be improved more effectively.

Next, step S10 of the overall control routine.
The straight ahead correction control in 5 is performed according to the straight ahead correction control routine shown in FIG. Here, in the controller 20, for example, the left and right drive wheels 10L and 10L from the start of the auxiliary drive device 3 are based on the left and right drive wheel speeds VelL and VelR.
The travel distance components KyoriL and KyoriR by R are continuously calculated, and the straight travel correction control routine calculates the straight travel correction value Str based on the travel distance components KyoriL and KyoriR. Further, in the straight-ahead correction control routine, immediately after the turning traveling state is switched to the straight-ahead traveling state and immediately after S1 seconds have elapsed, the integral components LI and RI of the speed calculated in step S108 of the overall control routine are corrected in order to correct the integral components. LI and RI are set separately. In this case, the straight-line correction control routine is used to perform integration components LI and RI.
Is set, this set value is used to set the duty ratio Dut in step S109 of the overall control routine.
yL and DutyR are calculated.

When the routine shown in FIG. 5 starts, the controller 20 checks in step S301 whether the current routine is the first routine immediately after the start of straight traveling.

When it is determined in step S301 that the current routine is a routine immediately after the start of straight traveling, the process proceeds to step S302, and the controller 20 is the traveling distance used for calculating the straight traveling correction value Str. Straight control distance StrKyoriL, StrKyo
Straight travel correction reference value b which is a reference value for calculating riR
Set aseL and baseR. For these straight travel correction reference values baseL and baseR, the travel distance components KyoriL and KyoriR of the left and right drive wheels 10L and 10R from the start of the auxiliary drive device 3 to the present time are used, respectively.

After proceeding from step S302 to step S303, the controller 20 sets integral components LI and RI. These integral components LI and RI are the integral components LIf and RI set in the previous overall control routine.
It is set using f, and is set by LI = RIf / HoseiS (23) RI = LIf / HoseiS (24). HoseiS is HoseiS.
It is a constant set to S ≧ 1. That is, in order to prevent the responsiveness of straight-ahead correction from being deteriorated due to a strong turning moment remaining during a turning run immediately after the turning traveling state is switched to the straight-ahead traveling state, the controller 20 controls
Immediately after switching to straight running, the integral component of PID control is exchanged on the left and right to correct reverse rotation.

On the other hand, if it is determined in step S301 that it is not immediately after the start of straight traveling, the controller 20
In step S304, it is determined whether or not this routine is the time when S1 second (for example, 0.5 sec) has elapsed from the start of straight traveling.

When it is determined in step S304 that the routine this time is after the elapse of S1 seconds from the start of straight traveling, the controller 20 proceeds to step S305 and proceeds to the straight traveling correction reference values baseL, base.
Update eR. These straight travel correction reference values baseL, b
aseR is the travel distance component Kyor of the left and right drive wheels 10L and 10R from the start of the auxiliary drive device 3 to the present time.
iL and KyoriR are used respectively.

After proceeding from step S305 to step S306, the controller 20 sets integral components LI and RI. These integral components LI and RI are the integral components LIf and RI set in the previous overall control routine.
It is set using f, and is set by LI = RI = (LIf + RIf) / 2 (25). That is, the controller 20 averages and corrects the left and right integral components LI and RI evenly after the passage of S1 seconds from the start of straight travel, so that the integral components LI and RI set by the reverse correction for the first time are used for the subsequent PID control. Prevent it from affecting more than necessary.

On the other hand, if it is determined in step S304 that the routine this time does not occur when S1 seconds have elapsed from the start of straight traveling, the controller 20 determines in step S304.
The routine proceeds to step 307, where the current routine is the straight-ahead correction reference value bas.
After updating eL and baseR, S2 seconds (for example, 0.
It is checked whether it is after 5 seconds).

If it is determined in step S307 that the current routine has updated the straight-ahead correction reference values baseL, baseR after S2 seconds have passed, the controller 20 advances to step S308. It is checked whether or not the previously set straight-ahead correction value Str is within a predetermined correction value range (-HoseiM <Str <HoseiM).

Here, the case where the straight-ahead correction value Str is outside the predetermined correction value range means that a relatively large amount of straight-ahead correction is being performed, and the maximum amount of such a large amount of straight-ahead correction is being made. It is not preferable to update the straight travel correction reference values baseL and baseR that are the basis of the straight travel correction value Str setting while maintaining straightness. Therefore, step S30
When it is determined that the straight travel correction value Str is out of the predetermined correction value range in 8, the controller 20 proceeds to step S309 and proceeds to the straight travel correction reference values baseL and base.
The current value is reset as it is without updating eR.

On the other hand, if it is determined in step S308 that the straight travel correction value Str is within the predetermined correction value range, the controller 20 proceeds to step S310.
The straight-ahead correction reference values baseL and baseR are updated. These straight traveling correction reference values baseL and baseR are set to the left and right drive wheels 10 from the start of the auxiliary drive device 3 to the present time.
L, 10R travel distance components Kyori L, Kyori
R is used respectively.

Step S303, step S306, step S307, step S309, or step S
When the process proceeds from step 310 to step S311, the controller 2
0 is the current traveling distance components KyoriL and KyoriR of the left and right drive wheels 10L and 10R and the straight travel correction reference value bas.
Differences from eL and baseR are calculated, and these values are set as straight-ahead control distances StrKyoriL and StrKyoriR, respectively.

Upon proceeding from step S311 to step S312, the controller 20 directs the straight ahead instruction speed signal Spd.
If it is determined that the straight traveling instruction speed signal Spd is a positive value, the straight traveling correction gain constant StrGein (when traveling forward) is calculated by the following equation: StrGein = Spd · StrGeinF (26) (step S313). ). On the other hand, if it is determined in step S311 that the straight travel instruction speed signal Spd is a negative value, then the straight travel correction gain constant StrGein (reverse travel) is calculated by StrGein = -Spd · StrGeinB (27) (step S31). S314).

When the process proceeds from step S313 or step S314 to step S315, the controller 20 calculates the straight-ahead correction value Str by Str = (StrKyoriR-StrKyoriL) .StrGein ... (28) and then exits the routine.

As described above, in the straight-ahead correction control routine, the controller 20 determines that the straight-ahead control distance StrKyor is
When calculating the straight travel correction value Str using iL, StrKyoriR, the straight travel control distance StrKyoriL, S
Straight-ahead correction reference value b that is a reference value for calculating trKyoriR
By updating the asL and the baseR at predetermined time intervals, the straight traveling control distances StrKyoriL and StrKyor are obtained.
It is possible to prevent the iR from being strongly affected by a disturbance or the like, and it is possible to calculate an appropriate straight-ahead correction value Str.
In this case, when it is determined that the straight-ahead correction value Str is outside the predetermined correction value range, the straight-ahead correction reference values baseL and base.
By not updating R, the straight-ahead correction reference value bas
It is possible to prevent the straight-ahead correction value Str from largely changing due to the update of eL and baseR, and to obtain good straight-ahead controllability.

Further, the controller 20 reversely corrects the integral components LI and RI, which are hard to change rapidly in the PID control immediately after the turning control is switched to the straight ahead control, so that the turning moment during the turning travel remains strong. This can be prevented, and the responsiveness of switching to the straight traveling state can be improved. Further, by averaging the integral components LI and RI after S1 seconds from the start of straight traveling, it is possible to prevent the integral components LI and RI set by the reverse rotation correction from unnecessarily affecting the subsequent PID control. it can.

Next, step S11 of the overall control routine.
Left and right electric motors 19L and 19R during normal braking in 2
Calculation of the duty ratios DutyL and DutyR is performed according to the normal braking duty ratio calculation routine shown in FIG.

When the routine shown in FIG. 6 starts, the controller 20 checks in step S401 whether or not this routine is the first routine immediately after the start of braking.

When it is determined in step S401 that the current routine is the first routine immediately after the start of braking, the controller 20 determines in step S40.
After proceeding to step 2 and resetting the integral components LI and RI to "0", proceed to step S403. That is, in step S402, the controller 20 improves the responsiveness of the braking operation by setting the integral component of the feedback control set in step S105 or step S108 of the overall control routine at the time of the previous traveling control to "0". . In other words, in feedback control, the integral components LI and RI, which are less likely to change rapidly, are set to "0" to improve the response of the braking operation.

On the other hand, when it is determined in step S401 that the current routine is not the first routine immediately after the start of braking, the controller 20 directly proceeds to the processing of step S403.

Step S401 or step S402
From step S403, the controller 20
The left and right motor command speeds SpdL and SpdR are set to "0", and in step S404, the left and right drive wheel speed Vel is set.
Left and right motor command speeds Spd based on L and VelR
Feedback (PID) control for L and SpdR is performed. Note that the PID performed in step S404
The control is performed using the above formulas (5) to (10).

Then, from step S404 to step S
When proceeding to 405, the controller 20 proceeds to (11) above.
After calculating the duty ratios DutyL and DutyR for the left and right electric motors 19L and 19R using the equation (12), the routine exits.

Next, step S11 of the overall control routine.
Left and right electric motors 19L and 19R at the time of turning braking in 4
Calculation of the duty ratios DutyL and DutyR is performed in accordance with the turning braking duty ratio calculation routine shown in FIG. 7. The turning braking duty ratio calculation routine is performed by the drive wheels 1 when the turning traveling state is changed to the braking state.
In order to prevent the electric wheelchair 1 from being overshooted due to a slip of 0L or 10R,
This is for canceling the component in the turning direction of the electric wheelchair 1. Therefore, in this routine, feedback using the left and right drive wheel speeds VelL, VelR (PI
D) The proportional components LPy and RPy of the yaw rate are calculated by feedback (P) control using the yaw rate Yaw of the electric wheelchair 1 instead of the control, and these proportional components L are calculated.
Duty ratios DutyL and Dut using Py and RPy
Calculate yR. When the component in the turning direction becomes small during braking, the above-described normal braking duty ratio calculation routine is executed by the determination in step S111 in the overall control routine.

When the routine shown in FIG. 7 is started, the controller 20 determines in step S501 the proportional components LP, R of the feedback control based on the left and right wheel speeds.
P, integral components LI and RI, and differential components LD and RD
In step S502, the left and right motor command speeds SpdL and SpdR are set to "0", and the flow proceeds to step S503.

Then, the controller 20 performs step S
In step 503, the target angular velocity YawT is set to "0", and in step S504, the yaw rate (angular velocity) is set.
Proportional component LPy of feedback control based on Yaw,
RPy is calculated by LPy = YawT−Yaw (29) RPy = YawT + Yaw (30). In this case, since the target angular velocity YawT is set to "0" in step S503,
LPy = -Yaw and RPy = Yaw.

When the process proceeds from step S504 to step S505, the controller 20 determines the left and right electric motors 19
Duty ratios for L and 19R Duty L and Duty
After calculating R by: DutyL = LPy · GeinY (31) DutyR = RPy · GeinY (32), the routine exits. Where Ge
inY is a preset gain constant.

As described above, when the braking control is performed from the turning state such as the stationary turning state, the controller 20 executes the duty ratio calculation routine during the turning braking and performs the feedback control based on the yaw rate Yaw to perform the electric wheelchair. By canceling the component of the turning direction of 1, the left and right drive wheels 10L and 10R can be prevented from slipping, and the electric wheelchair 1 can be prevented from overshooting.

When the component in the turning direction becomes small, the controller 20 executes a normal braking duty ratio calculation routine to determine the left and right drive wheel speeds VelL, VelR.
By performing feedback control based on, it is possible to obtain reliable braking performance.

In the above embodiment, the electric wheelchair in which the auxiliary drive device is detachably attached to the existing folding manual wheelchair body has been described as an example of the electric wheelchair, but the present invention is not limited to this. Instead, the above control can be applied to, for example, an electric wheelchair in which the left and right wheels of the wheelchair body are driven by electric motors.

Further, in the above-mentioned embodiment, the operation switch is not limited to the joystick, but may be a handle having a throttle lever or the like.

The detection of the yaw rate Yaw in the above embodiment is not limited to the one using the angular velocity sensor. For example, the yaw rate is the difference between the left and right driving wheel speeds detected by using the rotary encoder or the like. It is also possible to substitute as.

[0094]

As described above, according to the present invention, it is possible to provide a control device for an electric wheelchair which can prevent slipping of driving wheels and obtain good braking performance.

[Brief description of drawings]

FIG. 1 Schematic diagram of an electric wheelchair

FIG. 2 is a block diagram of a power control system

FIG. 3 is a flowchart of an overall control routine

FIG. 4 is a flowchart of a joystick signal processing routine.

FIG. 5 is a flowchart of a straight-ahead correction control routine.

FIG. 6 is a flowchart of a duty ratio calculation routine during normal braking.

FIG. 7 is a flowchart of a duty ratio calculation routine during turning braking.

FIG. 8 is an explanatory diagram showing a method of calculating a straight ahead instruction speed signal limiter value.

[Explanation of symbols]

1 ... Electric wheelchair 10L ... Left side drive wheel 10R ... Right side drive wheel 15 ... Joystick (operation switch) 20 ... Controller (turn determination means, first braking means, second braking means) 19L ... Left electric motor 19R ... Right side electric motor

Claims (2)

[Claims] 1. A control device for an electric wheelchair that feedback-controls a pair of electric motors for individually driving left and right drive wheels based on a running state, and a turning determination means for determining a turning state of the electric wheelchair during braking control. First braking means for performing feedback control based on the angular velocity of the electric wheelchair to control the braking of the electric wheelchair when the electric wheelchair is in a turning state; and the left-right driving when the electric wheelchair is not in a turning state A control device for an electric wheelchair, comprising: second braking means for performing feedback control based on wheel speed to control the braking of the electric wheelchair. 2. The electric wheelchair according to claim 1, wherein the turning determination means determines that the electric wheelchair is in a turning state when the left and right drive wheels are rotated in mutually opposite directions. Control device.