JPH0323065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a control method for a rehabilitation support device used to restore functions of limbs such as upper or lower limbs that have decreased muscle strength. The present invention relates to a control system for a rehabilitation support device that supports rehabilitation by attaching a limb that has deteriorated to an angularly movable arm.

BACKGROUND ART A typical prior art is shown in Japanese Patent Publication No. 57-30509, etc., and in order to realize isotonic control of the rocking motion of an angularly displaceable arm to which a limb is attached,
Muscles apply force to the gear shafts of multiple speed-increasing gears that are meshed with each other to rotate them, and this rotation is transmitted to and controlled by the powder brake.Also, the gears are rotated in a controlled state by a motor, and the muscles It has a mechanism that exerts force on the With this configuration, during patient rehabilitation training,
The subject performs an action such as pulling up a weight, and the load on the muscles is set to a constant value depending on the weight of the weight, and training is performed using anti-gravity.

Problems to be Solved by the Invention This type of prior art has a problem in that it is equipped with a powder brake, has a relatively complicated structure, and is large in size.

An object of the present invention is to provide a control method for a rehabilitation support device that has a simple configuration and can be downsized.

Means for Solving the Problems The present invention is a control method for a rehabilitation support device for restoring the functions of limbs with decreased muscle strength by attaching a limb to an arm capable of angular displacement. A power amplifier for driving the servo motor; A rotation speed/drive current detector for detecting the rotation speed or drive current of the servo motor; A force/torque detector for detecting the force or torque applied to the arm from the limb. a detector, a setting circuit that derives a signal representing a predetermined force or torque, and a first circuit that calculates a difference between the output of the force/torque detector and the output of the setting circuit and derives a signal representing the difference.
Rehabilitation characterized by comprising: a subtracter; and a second subtracter that calculates the difference between the output of the first subtracter and the output of the rotational speed/drive current detector and supplies a signal representing the difference to the power amplifier. This is a control method for stationary support equipment.

A preferred embodiment is characterized in that a first-order low-pass filter is interposed between the first and second subtracters.

A further preferred embodiment includes: an angle detector for detecting the angle of the arm; and a dead band element responsive to the output of the angle detector to derive an output having a predetermined large level when the arm exceeds a predetermined range of movement. interposed between the first and second subtractors, calculating the difference between the output of the first subtractor and the output of the dead zone element;
and a third subtracter that supplies a signal representing the difference to the second subtractor.

Effect According to the present invention, the force or torque applied from the limb to the arm is detected by a force/torque detector that detects force or torque, and a predetermined force from the force/torque detector and the setting circuit is detected. The first subtractor calculates the difference between the output signal and the torque signal, and the output of the first subtracter is given to the second subtractor to drive the servo motor. The set force or torque will always be applied. Therefore, when performing rehabilitation training, the patient can perform an action such as pulling up a weight, and isotonic control is achieved.

Embodiment FIG. 1 is a block diagram of one embodiment of the present invention. In order to restore the function of a limb with reduced muscle strength, a control method for a rehabilitation support device according to the present invention is implemented. The upper or lower limbs are
It is attached to the end 2 of the arm 1. This arm 1
The proximal end 3 of is fixed to a rotating shaft 4 having a horizontal axis. The output shaft 6 of the servo motor 5 is connected to a reducer 7
The rotational speed of the output shaft 6 of the servo motor 5 is reduced and transmitted to the rotating shaft 4. The rotational speed of the output shaft 6 of the servo motor 5 is detected by a rotational speed detector 8. This rotational speed detector 8 has a characteristic that as the rotational speed of the output shaft 6 increases, the level of the output delivered to the line 9 increases as shown in FIG. Servo motor 5
is driven by a power amplifier 10.

A force detector 11 is attached to the arm 1 and can detect the force acting on the arm 1. This force detector 11 produces an output corresponding to the force acting on the arm 1 on a line 12, the characteristics of which are as shown in FIG. The force detector 11 is realized by, for example, a strain gauge. The output signal of the force detector 11 is input to a coefficient multiplier 14 via a line 12, and is multiplied by a predetermined constant value k1.

The output from the coefficient unit 14 is given to one input of the subtracter 15. The other input of the subtracter 15 is given an output from a setting circuit 16 that derives a signal having a level corresponding to a predetermined force. The subtracter 15 subtracts the level of the output of the setting circuit 16 from the level of the output of the coefficient unit 14, and provides a signal representing the difference to the subtracter 17.
The output of the subtracter 17 is applied to a first-order low-pass filter 18, and the output of the filter 18 is applied to a subtracter 19.
given to. The subtracter 19 performs an operation by subtracting the level of the output from the rotational speed detector 8 from the level of the output from the filter 18, and provides a signal representing the difference to the power amplifier 10.

The amount of angular displacement of arm 1 is detected by angle detector 21 . The angle detector 21 derives an output corresponding to the angle of the shaft 4 fixed to the arm 1, as shown in FIG. This angle detector 21
The output from is input to deadband element 23 via line 22.

The dead zone element 23, as shown in FIG.
The level of the input provided via line 22 is
When it is in the range of a predetermined value θ _MAX to θ _MIN , the level of the output derived to line 24 is zero, and when the level of the input is equal to or higher than the upper limit value θ _MAX , and when it is the lower limit value. When the value θ _MIN or less,
Derive the output of the slope kp. When the input level is above the value θ _MAX and below the value θ _MIN , the amount of change in the output level corresponding to the amount of change in the input level, that is, the slope kp, is extremely large, and the angle α shown in FIG. 5 is , a value close to 90 degrees. The output derived from deadband element 23 to line 24 is
It is applied to the coefficient unit 25, multiplied by a constant _kE , and inputted to the subtracter 17. The subtracter 17 subtracts the output of the coefficient multiplier 25 from the output of the subtracter 15 described above, and provides a signal having a level corresponding to the difference to the filter 18.

It is assumed that the angular displacement position of the arm 1 is within a movable range corresponding to preset values θ _MAX to θ _MIN in the dead zone element 23 . When a force is applied to arm 1 by a limb, the force is detected by force detector 11 .

The servo motor 5, the rotational speed detector 8, the power amplifier 10, and the subtractor 19 constitute a speed feedback loop, and the actual output shaft 6 detected by the rotational speed detector 8 is The rotational speed θ〓 follows the rotational speed command value θ〓r input from the filter 18 to the subtracter 19. In the following explanation, θ〓 and θ〓r
The deviation from that shall be sufficiently small.

The setting of the movable range of the arm 1 will be explained. When the level of the signal applied from the subtracter 15 to the subtracter 17 is A, when the signal is applied from the angle detector 21 to the dead zone element 23, the following first
Equations to Equation 5 hold true.

θ〓r＝θ〓=A (θ _MIN ≦θ≦θ _MAX ) …(1) θ〓r＝θ〓=A−kp・kE (θ−θ _MAX ) (θ _MAX <θ) …(2) θ 〓r＝θ〓=A−kp・kE(θ−θ _MIN ) (θ＜θ _MIN ) …(3) Level θ of the signal input to the dead band element 23
is in the range of values θ _MAX to θ _MIN , isotonic control is performed as described later.

When the second or third equation holds true, that is, when the angle of arm 1 exceeds θ _MAX or is less than θ _MIN , a position feedback operation is performed, and arm 1 moves vertically between θ _MAX and _{θ MIN} . This will prevent you from going too far out of range. Dead band element 23
In this case, when the output of the angle detector 21 input from the line 22 is greater than or equal to θ _MAX and less than or equal to θ _MIN , the output changes greatly in response to a change in the input.
For example, it has a large slope α that is close to 90 degrees but not 90 degrees. Therefore, when isotonic control is performed by applying force to the arm position using the limbs, the arm position is prevented from suddenly stopping at the angular displacement position corresponding to the values θ _MAX and θ _MIN . Therefore, impact force can be prevented from being applied to the limbs.

Next, the operation of isotonic control will be explained. Force detector 1
1, coefficient unit 14, subtracter 15, force setting circuit 16,
In the feedback loop including the filter 18, etc., the transfer function W of the first-order low-pass filter 18 is
is expressed by the fourth equation. Here, s is a Labrasian operator, and J and D are constants.

W=1/Js+D (4) Therefore, when the output of the coefficient unit 14 is T and the output of the force setting circuit 16 is _T0 , the rotational speed θ of the output shaft 6 of the servo motor 5 is determined by the filter 18. Assuming that the deviation from the output θ〓r is sufficiently small, Equation 5 holds true.

θ=1/Js+D(T−T ₀ ) (5) When the fifth equation is inversely transformed by Labras, the sixth equation holds true.

Jθ¨+Dθ〓+T ₀ =T …(6) Referring to this sixth equation, we can see that the inertial force J
The load of frictional force D plus a constant force T ₀ corresponds to a patient undergoing rehabilitation training generating a force T to angularly displace the arm 1.

Therefore, if the inertial force J and the frictional force D are sufficiently small, T=T ₀ (7), which results in isotonic motion. Also the values J, D, T ₀
By changing the force, force can be generated in the arm 1 in various ways, and the impact force can be alleviated.

The specific configuration of the primary low-pass filter 18 is as follows:
For example, as shown in FIG. The output from subtractor 17 is provided on lines 26 and 27. A resistor 28 is connected in series to the line 26, and a capacitor 30 is connected between the connection point 29 and the line 27. Following the capacitor 30, an amplifier circuit 31 with high input impedance
is connected. The output of the amplifier circuit 31 is sent to the subtracter 1
given to 9. The amplifier circuit 31 is an operational amplifier 3
2 and resistors R1 and R2, and its gain K is as shown in equation 8.

K=1+R2/R1 (8) In the filter 18 having such a configuration, the above-mentioned values J and D are as shown in Equations 9 and 10. The resistance value of the resistor 28 is represented by R, and the capacitance of the capacitor 30 is represented by C.

J=C.R/K (9) D=1/K (10) FIG. 7 is a block diagram of another embodiment of the present invention. This embodiment is similar to the previous embodiment, and corresponding parts are given the same reference numerals. What should be noted is that in place of the rotational speed detector 8 in the previous embodiment, a current transformer 35 and a drive current detector 36 are used in this embodiment. Servo motor 5, current transformer 35, drive current detector 36, and power amplifier 1
0 and the subtractor 19 constitute a feedback loop, and the current transformer 35 and the drive current detector 36
The output current of the power amplifier 10 detected by , that is, the field current i of the servo motor 5 follows the rotational speed command value θ〓r input from the filter 18 to the subtracter 19 .

A detector that detects the torque of arm 1 may be used instead of force detector 11, and in this case, instead of force setting circuit 16, a setting circuit that derives a signal representing a predetermined torque is used.

Effects As described above, according to the present invention, the configuration can be simplified and downsized, and can be realized using commercially easily available components.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
3 shows the characteristics of the force detector 11, FIG. 4 shows the characteristics of the angle detector 21, and FIG. 5 shows the characteristics of the dead zone element 23.
FIG. 6 is an electric circuit diagram showing a specific configuration of the first-order low-pass filter 18, and FIG. 7 is a block diagram of another embodiment of the present invention. 1...Arm, 4...Rotating shaft, 5...Servo motor, 7...Reducer, 8...Rotation speed detector, 9
... Power amplifier, 11 ... Force detector, 14, 25
...Coefficient unit, 15, 17, 19...Subtractor, 16
...Force setting circuit, 23...Dead zone element, 35...
Current transformer, 36... Drive current detector.

Claims (1)

[Scope of Claims] 1. A control method for a rehabilitation support device for restoring the functions of limbs with reduced muscle strength by attaching limbs to arms capable of angular displacement, comprising: a servo motor for driving the arm for angular displacement; , a power amplifier that drives the servo motor, a rotation speed/drive current detector that detects the rotation speed or drive current of the servo motor, and a force/torque detector that detects the force or torque applied to the arm from the limb. a setting circuit that derives a signal representing a predetermined force or torque; and a first circuit that calculates a difference between the output of the force/torque detector and the output of the setting circuit and derives a signal representing the difference.
Rehabilitation characterized by comprising: a subtracter; and a second subtracter that calculates the difference between the output of the first subtracter and the output of the rotational speed/drive current detector and supplies a signal representing the difference to the power amplifier. Control method for stationary support equipment. 2. A control system for a rehabilitation support apparatus according to claim 1, characterized in that a first-order low-pass filter is interposed between the first and second subtracters. 3 an angle detector that detects the angle of the arm; a dead band element that responds to the output of the angle detector and derives an output having a predetermined large level when the arm exceeds a predetermined movable range; interposed between the second subtractor, calculating the difference between the output of the first subtractor and the output of the dead zone element;
and a third subtractor that supplies a signal representing the difference to the second subtractor.
Control method for the rehabilitation support device described in Section 3.