JP2002078752A - Motor controller for motor-driven assist device for wheelchair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an operation burden of a user and to prevent a wheelchair rider from feeling uneasy or lost by a rapid change in a traveling speed by holding the traveling speed of a wheelchair at an almost fixed value regardless of conditions on the surface of a traveling road (such as road surface gradient or presence/no-presence of step, for example,) in a motor-driven assist device for wheelchair. SOLUTION: This device is provided with an operating part 5 capable of setting and operating an arbitrary target speed, a voltage control part C1 for controlling a driving voltage to be impressed to an electric motor M corresponding to the target speed set by this operating part 5, a current detecting means 7 for detecting the load current of the motor M and a feedback means 8 for feeding the load current detected by that current detecting means 7 back to the input side of the voltage control part C1 and the voltage control part C1 controls the driving voltage on the basis of the target speed and the load current so that the actual traveling speed of a wheelchair EV can be converged to the set target speed regardless of the level of the load current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for an electric assist device for a wheelchair, comprising an electric motor for outputting at least a part of the driving power of the wheelchair to driving wheels when the wheelchair runs.

[0002]

2. Description of the Related Art The above-mentioned electric assist device applies a rotational driving force to a driving wheel from an electric motor thereof, thereby enabling a user (ie, a passenger trying to run a wheelchair by himself / herself,
Or a caregiver trying to push the wheelchair from behind, to reduce the labor.

[0003] In this kind of conventional apparatus, the drive voltage to be applied to the electric motor is arbitrarily increased or decreased by manual operation of the user so that the motor rotation speed (the wheelchair traveling speed) can be adjusted at any time. I was

[0004]

In the conventional electric assist device described above, when the load of the electric motor temporarily becomes excessively large due to traveling uphill, climbing over a step, etc., the load current value flowing through the motor increases. The rotation speed decreases. Therefore, conventionally, in such a case, the user adjusts the driving speed of the wheelchair by increasing the driving voltage of the motor each time.

[0005] However, after the adjustment, when the motor load suddenly decreases due to the wheelchair shifting to a flat road or a downhill, or the stepping over is completed, the rotation speed of the motor (accordingly, the running of the wheelchair is reversed). In such a case, it is necessary to readjust (reduce) the drive voltage of the motor.

As described above, in the conventional device, the traveling speed of the wheelchair may be unstable depending on the traveling road surface condition.
In such a case, there are problems such as the user being frequently forced to perform an operation for correcting the speed, and feeling uneasy or confused.

[0007] The present invention has been proposed in view of the above,
An object of the present invention is to provide a motor control device in an electric assist device for a wheelchair, which can solve the problems of the conventional device at once.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 comprises an electric motor for a wheelchair provided with an electric motor for outputting at least a part of the running power to a driving wheel when the wheelchair runs. In the assist device, an operation unit capable of setting and operating an arbitrary target speed, a voltage control unit for controlling a drive voltage applied to the electric motor according to the target speed set by the operation unit, Current detecting means for detecting the load current of the voltage control section, and feedback means for feeding back the load current detected by the current detecting means to the input side of the voltage control section. The voltage control section determines whether the load current is large or small. The driving voltage is controlled based on the target speed and the load current such that the actual running speed of the wheelchair converges on the set target speed regardless of the driving speed.

According to a second aspect of the present invention, there is provided an electric assist device for a wheelchair provided with an electric motor for outputting at least a part of the traveling power to a driving wheel when the wheelchair is traveling. An operation unit, a voltage control unit for controlling a drive voltage applied to the electric motor according to the target speed set by the operation unit, speed detection means for detecting an actual traveling speed of the wheelchair, and the speed Feedback means for feeding back the actual traveling speed detected by the detection means to the input side of the voltage control unit, wherein the voltage control unit controls the actual traveling speed to converge on the set target speed. The driving voltage is controlled based on a deviation between a target speed and an actual traveling speed.

According to the above features of the invention, a change in the running load (accordingly, a change in the load current value flowing through the electric motor) occurs due to a running road surface condition (for example, a change in the road surface gradient or the presence or absence of a step). In addition, since the motor drive voltage is feedback controlled so that the actual running speed of the wheelchair converges to the target speed set by the operator, the running speed of the wheelchair can be set to a substantially constant value (target speed) regardless of the road surface conditions Therefore, there is no need to worry about the user being forced to operate excessively or feeling uneasy or confused due to fluctuations in the traveling speed.

[0011] In particular, according to the feature of the invention of claim 1,
In the feedback control of the motor drive voltage, the load current value of the electric motor is fed back, so that a speed sensor for the motor is not particularly required, and the speed control can be further simplified.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on embodiments of the present invention illustrated in the accompanying drawings.

In the accompanying drawings, FIG. 1 is a partially cutaway side view of a wheelchair according to an embodiment of the present invention, FIG. 2 is a rear view of the wheelchair (a view taken in the direction of arrow 2 in FIG. 1), and FIG. FIG. 4 is a block diagram of the motor drive circuit according to the first embodiment, FIG. 5 is a control flowchart, and FIG. 6 is a motor drive circuit according to the second embodiment. FIG. 7 is a block diagram of a motor drive circuit according to a third embodiment, and FIG. 8 is a block diagram of a motor drive circuit according to a fourth embodiment.

First, a first embodiment will be described. FIG.
1 to 3, a wheelchair EV includes a body frame F formed by framed metal pipes, and a pair of left and right relatively small-diameter front wheels Wf attached to the front of the body frame F so as to be rotatable and steerable by 360 degrees. And a pair of left and right relatively large-diameter rear wheels Wr which are rotatably and non-steerably mounted to the rear portion of the vehicle body frame F.
A seat S provided at a central portion of the vehicle body frame F; a footrest step 1 provided at a front lower portion of a front end of the vehicle body frame F; And a pair of handle portions 2.

The handle portion 2 is used by a caregiver to grasp them by hand and push the wheelchair EV from behind. A caregiver brake lever 3 that pushes a wheelchair is disposed at an appropriate position of the vehicle body frame F (near each handle portion 2 in the illustrated example), and the rear wheel Wr is braked by strongly pressing the lever 3. A brake (not shown) can be activated at any time. Although not shown, a brake lever operated by a passenger sitting in a wheelchair is provided at an appropriate position of the vehicle body frame F.

Outside the wheel rim of the rear wheel Wr, a hand rim 4 for use by the occupant when the occupant runs on the wheelchair EV by himself is integrally connected, and the occupant grasps the hand rim 4 by hand. By forcibly rotating, the rear wheel Wr can be rotated. The above is the same structure as a conventionally known wheelchair.

The vehicle body frame F bears a part or all of the running power of the wheelchair EV when the wheelchair EV is running (ie, a passenger who tries to run the wheelchair EV by himself or a caregiver who wants to push the wheelchair EV). ) Is provided with an electric assist device A for reducing the operation effort of the person.

In the illustrated example, the electric assist device A includes a single drive wheel Wa, an electric motor M connected to the drive wheel Wa to drive the wheels in rotation, and an electric motor M
A control circuit C for controlling a drive voltage to be applied to the control circuit C, a battery B as a power supply connected to the control circuit C, and a control circuit C connected to the control circuit C via a connection line (not shown). And an operation panel 5 for remotely controlling the remote control from the user.

The operation panel 5 constitutes an operation section of the present invention, and is provided at an appropriate position of the vehicle body frame F (for example, around the handle section 2 as shown by a solid line in FIG. 1 or an armrest section 2 as shown by a chain line). ′ Around). On the outer surface of the operation panel 5, a main power switch SW1, a traveling switch SW2 for issuing a traveling command, and a traveling speed of the wheelchair EV are set to arbitrary target speed values within a predetermined range (for example, 0 to 4 km / H). Speed setting volume switch SW3 for
Are provided. Further, an output circuit unit (not shown) capable of outputting a control signal voltage to the control circuit C in accordance with an input operation to each of the switches SW1 to SW3 is accommodated inside the operation panel 5.

The control circuit C and the battery B are housed in a common unit case 6 detachably mounted on the vehicle body frame F. The drive wheel Wa is rotatably supported on the outer wall of the unit case 6 and a motor case of the electric motor M is fixed. Therefore, the electric assist device A has most components except the operation panel 5. The elements are collectively configured as one drive unit U.

When the drive unit U is set on the vehicle body frame F, the drive unit Wa has a contact position where the drive wheel Wa contacts the road surface (the position shown in FIGS. 1 and 2) and a storage position where the drive wheel Wa rises above the road surface by a predetermined height (see FIG. (Not shown). It should be noted that the drive wheels Wa may always be held at the ground contact position while the drive unit U is set on the vehicle body frame F.

The wheelchair EV is provided with the drive unit U.
Can be used as an electric wheelchair when the unit U is set on the vehicle body frame F, and can be used as a normal human powered wheelchair when the unit U is removed from the vehicle body frame F.

Next, referring to FIG.
An example of the control circuit C will be described. By manually operating the speed setting volume switch SW3, a set voltage Eo corresponding to the set speed is output from the operation panel 5 to the input side of the voltage control drive circuit C1 in the control circuit C.
The voltage control drive circuit C1 constitutes the voltage control unit of the present invention, and includes a power supply, an amplifier circuit, a ground, and the like, and has a size corresponding to an input voltage (ie, a set speed) to the drive circuit C1. Is output to the electric motor M. In this case, in the illustrated example, the input voltage is linearly amplified in the voltage control drive circuit C1 and applied to the electric motor M.

The electric motor M and the voltage control drive circuit C1
A current sensor 7 (Hall element current sensor in the illustrated example) as current detecting means is interposed in the motor energizing circuit connecting the motor M and the sensor 7 to detect a load current flowing through the motor M. Is done. The detected current is fed back to the input side of the voltage control drive circuit C1 through a feedback circuit 8 as feedback means connecting the current detection sensor 7 and the input side of the voltage control drive circuit C1.

The feedback circuit 8 is provided with conversion means 9 for converting the load current value detected by the current detection sensor 7 into a voltage signal Ef for feedback.

When the resistance of the electric motor M is R, the load current flowing through the motor M is I, the motor speed is w, and the motor drive voltage is V, the relational expression is as follows: V = Ks · w + I · R (where Ks is a constant), and if the motor drive voltage V is constant, the load current I
The motor rotation speed w decreases as the load current I increases. However, the motor rotation speed w can be prevented from lowering by increasing the motor drive voltage V in accordance with the increase in the load current I.

Therefore, in this embodiment, the set voltage Eo set by the speed setting volume switch SW3 is set as an initial value, and the load current I is converted (multiplied by a constant Ks in the illustrated example) by the conversion means 9. The obtained correction voltage Ef is used as a feedback value, and the sum (Eo + E
By applying the motor drive voltage corresponding to f) to the electric motor M from the voltage control drive circuit C1, the motor rotation speed w can be maintained at a substantially constant value regardless of a change in the load current I.

Thus, the voltage control drive circuit C1 as a voltage control unit controls the actual running speed of the wheelchair EV to the target speed set by the speed setting volume switch SW3 regardless of the change in the load current I flowing through the electric motor M. The motor drive voltage can be controlled based on the target speed and the load current so as to converge.

Next, the operation of the first embodiment will be described. When the wheelchair EV is run using the electric assist device A, as shown in FIG. 5, first, the power switch SW1 of the operation panel 5 is turned on (step S1), and then the run switch SW2 is turned on (step S2). ), And further operates the speed setting volume switch SW3 to output a set voltage Eo corresponding to the set target speed to the voltage control drive circuit C1,
A motor drive voltage corresponding to the set voltage Eo is applied from the voltage control drive circuit C1 to the electric motor M (step S
3). As a result, the electric motor M rotationally drives the drive wheels Wa at a rotational speed corresponding to the motor drive voltage, so that part or all of the user's (wheelchair occupant or caregiver) labor during wheelchair travel is reduced. Is done.

During the running of the wheelchair, the electric motor M
Is detected by the current detection sensor 7, and a correction voltage Ef corresponding to the load current value is fed back to the input side of the voltage control drive circuit C1 (step S5).
4) A motor drive voltage corresponding to the sum of the correction voltage Ef and the set voltage Eo corresponding to the target speed is applied from the voltage control drive circuit C1 to the electric motor M (step S).
5). Such control is continued as long as the travel switch SW2 is on (step S6). When the travel switch SW2 is turned off, the rotation of the electric motor M, and thus the travel of the wheelchair EV, is stopped (step S7).

Thus, even if the running load increases or decreases (accordingly, the load current value of the electric motor M changes) due to the running road surface condition (for example, a change in the road gradient or the presence or absence of a step), the actual running speed of the wheelchair EV does not change. However, since the motor drive voltage is feedback-controlled so as to approach the target speed initially set by the speed setting volume switch SW3, the traveling speed of the wheelchair EV is maintained at a substantially constant value (target speed) regardless of the traveling road surface condition. Becomes possible. As a result, there is no need to worry about the user being anxious or confused by the fluctuations in the running speed or being excessively burdened with the operation burden for correcting the speed, and the operability and usability of the wheelchair are improved and handling is extremely difficult. It becomes simple.

FIG. 6 shows a second embodiment of the present invention. In this embodiment, a voltage control drive circuit C1 'as a voltage control section includes a PWM signal conversion circuit 10 for outputting a pulse-like voltage signal having a pulse width changed according to the magnitude of an input signal; An open / close switch means 12 is provided for opening and closing an energizing circuit 11 of the electric motor M in accordance with a pulse signal output from the conversion circuit 10 to control the amount of energization. In the illustrated example, the open / close switch means 12 is interposed in the motor energizing circuit 11 and receives a pulse signal from the PWM signal conversion circuit 10 as a base, thereby closing the energizing circuit 11 for the ON pulse period of the input signal. Is used.

The above-mentioned "PWM control" is an abbreviation of pulse width modulation (Palus Width Modulation) control, and an output is performed according to the magnitude of an input signal (DC level) while keeping a switching frequency (period) constant. This is a well-known control method in which the pulse width (i.e., the on-pulse conduction width) is changed to thereby control the energy supplied to a control target such as a motor to control the operation of the control target.

At the input side of the PWM signal conversion circuit 10, a set voltage Eo corresponding to the set speed is output from the operation panel 5 by an input operation to the speed setting volume switch SW3, and further detected by the current detection sensor 7. The voltage signal Ef corresponding to the load current value fed back is fed back through the feedback circuit 8. The feedback circuit 8 includes a smoothing circuit 1 including a low-pass filter for smoothing a detection signal output from the current detection sensor 7.
3, and a conversion means 9 for converting a detection signal from the current detection sensor 7 into a voltage signal for feedback as in the previous embodiment are provided in series.

The PWM signal conversion circuit 10 outputs to the on / off switch means 12 a pulse-like voltage signal having a constant cycle in which the pulse width is changed in accordance with the sum of the input voltages (Eo + Ef). The switch circuit 12 controls the rotation of the electric motor M by energizing the energizing circuit 11 of the electric motor M only during the on-pulse period of the pulse-shaped voltage signal. To be able to hold.

Thus, the voltage control drive circuit C1 'as the voltage control unit sets the actual traveling speed of the wheelchair EV to the target speed set by the speed setting volume switch SW3 regardless of the change in the load current flowing through the electric motor M. The motor drive voltage is PWM-controlled based on the target speed and the load current so as to converge. By controlling the motor drive voltage by the PWM control in this way, efficiency can be increased and heat generation can be suppressed.

FIG. 7 shows a third embodiment of the present invention. In this embodiment, the current detection sensor 7 of the first embodiment is used.
Instead, a speed detection sensor 17 as speed detection means is provided on the output rotation shaft of the electric motor M. A voltage signal corresponding to the motor rotation speed detected by the speed detection sensor 17 is fed back to the input side of the voltage control drive circuit C2 via a feedback circuit 18 as feedback means. The feedback circuit 18 is provided with a conversion means 19 for converting a detection signal of the speed detection sensor 17 into a voltage signal Ef 'for feedback.

In this embodiment, the voltage control drive circuit C
2, the set voltage Eo (corresponding to the target speed) set by the speed setting volume switch SW3 and the voltage signal Ef ′ fed back from the speed detection sensor 17
(Corresponding to the actual traveling speed) and their deviations (Eo
−Ef ′) is corrected and applied to the electric motor M in accordance with the deviation so that the motor rotation speed can be kept constant regardless of the change in the motor load. Like that.

Thus, the voltage control drive circuit C2 as the voltage control unit causes the actual running speed of the wheelchair EV to converge on the target speed set by the speed setting volume switch SW3 regardless of the change in the load current flowing through the electric motor M. So that the motor drive voltage is controlled based on the target speed and the actual traveling speed. Therefore, this embodiment can also exhibit the same effect as the previous embodiment.

FIG. 8 shows a fourth embodiment of the present invention. In this embodiment, the current detection sensor 7 of the second embodiment is used.
Instead, a speed detection sensor 17 as speed detection means is provided on the output rotation shaft of the electric motor M. A voltage signal corresponding to the motor rotation speed detected by the speed detection sensor 17 is fed back to the input side of the voltage control drive circuit C2 'via a feedback circuit 18 as feedback means. This feedback circuit 18 includes:
Conversion means 19 is provided for converting the detection signal of the speed detection sensor 17 into a voltage signal Ef 'for feedback.

In the present embodiment, in the voltage control drive circuit C2 'as a voltage control section, the PWM signal conversion circuit 10 includes a set voltage Eo (corresponding to the target speed) set by the speed setting volume switch SW3, The voltage signal Ef '(corresponding to the actual traveling speed) fed back from the detection sensor 17 is compared, and their deviation (Eo-E
A pulse-like voltage signal having a constant period and a pulse width changed in accordance with the deviation is output to the on / off switch means 12 so that f ') becomes small. And the open / close switch circuit 12
The energizing circuit 11 of the electric motor M is energized during the on-pulse period of the pulse-shaped voltage signal to control the rotation of the electric motor M, so that the motor rotation speed can always be maintained at a constant value irrespective of a change in the motor load. ing. Therefore, this embodiment can also exhibit the same effect as the previous embodiment.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, and various small design changes can be made. For example, in the above-described embodiment, the electric assist device A is detachably attached to the vehicle body frame F. However, in the present invention, the electric assist device is permanently attached to the vehicle body frame (that is, it is not easily detachable). You may.

In the above embodiment, the electric assist device A
The electric motor M drives the drive wheel Wa dedicated to the assist device A. However, in the present invention, the electric motor of the electric assist device A is normally mounted on a wheelchair. The wheel Wr) may be directly driven.

[0044]

As described above, according to the invention of each claim,
Road surface conditions (for example, change in road gradient, presence or absence of steps, etc.)
The motor drive voltage is feedback controlled so that the actual running speed of the wheelchair converges to the target speed set by the operator even if the running load changes (and thus the load current value flowing through the electric motor changes). Therefore, the running speed of the wheelchair is almost constant (target speed) regardless of the running road surface condition
It is possible to prevent the user from being forced to operate excessively due to fluctuations in the traveling speed or to worry about wheelchair occupants being anxious or confused, thereby improving the operability and usability of the wheelchair. The handling becomes very simple.

In particular, according to the features of the first aspect of the present invention,
When the feedback control of the motor drive voltage is performed, the load current value of the electric motor is fed back, so no special speed sensor is required for the motor and the speed control can be further simplified, resulting in a simple structure and contributing to cost reduction. can do.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view of a wheelchair according to an embodiment of the present invention.

FIG. 2 is a rear view of the wheelchair (a view taken in the direction of arrow 2 in FIG. 1).

FIG. 3 is an enlarged view of a main part of the operation panel (an enlarged view as viewed in the direction of arrow 3 in FIG. 1).

FIG. 4 is a block diagram of a motor drive circuit according to the first embodiment.

FIG. 5 is a flowchart of control.

FIG. 6 is a block diagram of a motor drive circuit according to a second embodiment.

FIG. 7 is a block diagram of a motor drive circuit according to a third embodiment.

FIG. 8 is a block diagram of a motor drive circuit according to a fourth embodiment.

[Explanation of symbols]

 5 Operation panel (operation section) 7 Current detection means (current detection sensor) 8 Feedback circuit (feedback means) 17 Speed detection means (speed detection sensor) 18 ... feedback circuit (feedback means) A ... electric assist device C1, C1 '... voltage control drive circuit (voltage control unit) C2, C2' ... voltage control drive circuit (voltage control unit) M ... ...... Electric motor SW3 Speed setting volume switch EV Wheelchair Wa Driving wheel

Claims (2)

[Claims] 1. An electric power assist device for a wheelchair, comprising: an electric motor (M) for outputting at least a part of the traveling power to a driving wheel (Wa) during traveling of a wheelchair (EV). An operable operation unit (5);
According to the target speed set by the operation unit (5),
A voltage controller (C1, C1 ') for controlling a drive voltage applied to the electric motor (M); a current detector (7) for detecting a load current of the motor (M); 7) the load current detected by the voltage controller (C
, C1 ′), and feedback means (8) for feeding back to the input side of the voltage control section (C1, C1 ′).
1 ') is a wheelchair (E) regardless of the magnitude of the load current.
V) controlling the drive voltage based on the target speed and the load current so that the actual running speed of V) converges to the set target speed. . 2. An electric power assist device for a wheelchair, comprising: an electric motor (M) for outputting at least a part of the running power to a driving wheel (Wa) when the wheelchair (EV) runs. An operable operation unit (5);
According to the target speed set by the operation unit (5),
A voltage controller (C2, C2 ') for controlling a drive voltage applied to the electric motor (M); a speed detector (17) for detecting an actual traveling speed of the wheelchair (EV); Feedback means (18) for feeding back the actual traveling speed detected in (17) to the input side of the voltage control section (C2, C2 '), and the voltage control section (C2, C2') comprises A motor control device for an electric assist device for a wheelchair, wherein the driving voltage is controlled based on a deviation between the target speed and the actual traveling speed so that the speed converges to the set target speed.