JP5045338B2 - Lower limb drive device - Google Patents

Description

  The present invention relates to a rehabilitation assisting device used for restoring the function of a limb and a limb driving device for driving a lower limb in a limb driving device such as a training device.

Conventional leg driving devices have been developed in which a doctor or a physical therapist directly moves a patient's leg while the patient is placed on the device to memorize (teach) the trajectory during training. (For example, refer to Patent Document 1). This apparatus enables teaching by causing an arm to follow the movement of a leg during teaching using impedance control. Further, by performing impedance control during training, it is possible to perform training without imposing an excessive load on the patient's leg.
As a rehabilitation device intended to lighten (eliminate) a teacher's load, a device in which a magnetic torque sensor is attached between an arm and a motor speed reducer has been developed (see, for example, Patent Document 2). .
In addition, as a technique related to direct teaching of robots other than rehabilitation equipment, a technique for canceling the robot's own weight to reduce the operating force of the instructor (for example, see Patent Document 3), A device that cancels the influence of gravity even when the gravity increases (see, for example, Patent Document 4) has been developed. An example of performing impedance control for realizing such a function is also disclosed (see, for example, Patent Documents 5 and 6).
FIG. 5 is an operation flow diagram of the lower limb drive device showing a conventional example.
In FIG. 5, the operation procedure of the lower limb driving apparatus is performed by attaching the patient's leg to the apparatus (step 101), teaching the apparatus to memorize the trajectory for moving the leg (step 102), and memorizing by the teaching of step 102. Training is performed according to the trajectory (step 103).

FIG. 6 is a block diagram of a lower limb driving apparatus showing a first conventional example.
In FIG. 6, 201 is a patient, 202 is a hip joint, 203 is a thigh, 204 is a knee joint, and 205 is a lower leg. Reference numeral 210 denotes a drive shaft of the thigh arm, which can rotate the thigh 203 around the hip joint 202 via the angle detector 208 and the force detector 206. Reference numerals 211 and 212 denote drive shafts of the crus arms, which can rotate the crus part 205 around the knee joint 204 via the angle detector 209 and the force detector 207.
The thigh arm control device receives a signal from the force detector 206 and the angle detector 208, amplifies or processes the signal, and converts the signal into a signal corresponding to the force or angle, and an impedance control unit 215, The servo amplifier 217 is configured. Since the thigh arm has one degree of freedom, impedance control using the following equation can be performed.
Fe = Mαe + BVe + K (θ-θ0) (1)
Where Fe is the force acting between the thigh and the thigh arm, M, B and K are target impedances (M is the inertia coefficient, B is the viscosity coefficient, K is the spring coefficient), and θ is the angle of the thigh arm drive shaft. , Θ0 is a balance point of the spring stiffness of the thigh arm, Ve is an angular velocity (differential value of the angle θ) of the thigh arm drive shaft, and αe is an angular acceleration (second-order differential value of the angle θ) of the thigh arm drive shaft. Since control using this equation is a known technique, detailed description thereof is omitted. In this control system, when the signals detected by the force detector 206 and the angle detector 208 are amplified by the detector converter 213 and sent to the impedance control unit 215, the impedance control unit 215 satisfies the expression (1). Thus, a motion command is generated and the motor of the drive shaft 210 is driven via the servo amplifier 217.
The control device for the lower leg arm receives a signal from the force detector 207 and the angle detector 209, amplifies or processes the signal, and converts the signal into a signal corresponding to the force or angle, an impedance control unit 216, It is composed of servo amplifiers 218 and 219. Since the lower arm has two degrees of freedom, the control of the control device can be impedance control using the following equation.
Fx = Mαx + BVx + K (x-x0) (2)
Where Fx is the force acting between the lower leg and the lower leg arm, M, B, K are target impedances (M is an inertia coefficient, B is a viscosity coefficient, K is a spring coefficient), and x is an XY coordinate system in FIG. X0 is the spring stiffness equilibrium point of x, Vx is the differential value of x, and αx is the second-order differential value of x. Since control using this equation is a known technique, detailed description thereof is omitted. In this control system, when the force signal and the angle signal detected by the force detector 207 and the angle detector 209 are amplified by the detector converter 214 and sent to the impedance control unit 216, the impedance control unit 216 represents the equation (2). The motion command is generated so as to satisfy (2), and the motors of the drive shaft 211 and the drive shaft 212 are driven via the servo amplifiers 218 and 219.
The lower limb drive device as described above has a mechanism section with multiple degrees of freedom, and performs impedance control so that a complicated pattern can be trained without applying an excessive load on the lower limb.

FIG. 7 is a block diagram of a lower limb driving apparatus showing a second conventional example.
In FIG. 7, 701 is a torque sensor, 702 is an arm, 703 is a motor, 704 is a speed reducer, 705 is an angle detector, 706 is a dynamic characteristic model, 707 is a memory, 708 is a servo controller, and 710 is an object or limb. is there. When teaching the operation of the arm 702, the command value 723 of the angle to the servo controller 708 is calculated by a force control system based on the external force 722 detected by the torque sensor 701 and the dynamic characteristic model 706. The servo controller 708 calculates the deviation of the angle 721 detected by the angle detector 705 from the angle command value 723, and commands the motor drive torque 724 to the motor so that the actual angle follows the angle command value 723. The motor 703 moves the arm 702 via the speed reducer 704. At this time, the operation of the arm 702 is taught by storing the angle command value 723 and the external force 722 in the memory 707 at regular intervals. In the conventional leg driving device, a torque sensor 701 is disposed between the speed reducer 704 and the arm 702, and the force from the object or the limb 710 is detected. It is possible to make the arm 702 move with a light operational feeling by reducing the value of each parameter of impedance which is a dynamic characteristic model of the force control system.
Japanese Patent Laid-Open No. 11-347081 Japanese Patent Laid-Open No. 10-291182 JP-A-9-38877 Japanese Patent Laid-Open No. 5-192885 JP-A-10-231100 Japanese Patent Laid-Open No. 10-249769

The conventional lower limb drive device was able to adjust each parameter of impedance control so that the arm of the device itself moved with a light operational feeling, but did not consider the weight of the patient's leg For this reason, the weight of the leg must be supported by the instructor who teaches, which is a burden on the instructor. In addition, as a technology related to direct teaching of robots other than rehabilitation equipment, there is a technology that reduces the robot's own weight by reducing the robot's own weight, or when the gravity applied to the robot increases by gripping the workpiece during teaching. Although the example of canceling the influence of gravity and performing impedance control to realize these functions is disclosed, there are individual differences in the length and weight of the patient's leg placed on the lower limb drive device, and the bed Since the legs are bent and stretched in the sleeping position, there is a problem that the load applied to the apparatus changes depending on the posture of the legs, and there is no other example in which such a complicated weight is canceled.
The present invention has been made in view of such problems, and provides a lower limb drive device that can estimate the weight of the leg and compensate for the weight of the leg, thereby reducing the load when the teacher teaches. The purpose is to do.

In order to solve the above problem, the present invention is configured as follows.
The invention of the lower limb drive device according to claim 1 includes a drive unit that moves the thigh and the lower leg, a force detector that detects a load from the thigh and the lower leg, and the force detector. a lower leg drive system including an impedance controller for flexible control of the drive unit from the load information,
A lower limb weight estimation unit that estimates the weight of the thigh and the lower leg, and a lower limb weight compensation unit that calculates an offset value corresponding to the respective weights of the thigh and the lower leg. In the lower limb drive device that cancels the weight of the thigh and the lower leg at the time of teaching and training ,
The lower limb weight estimation unit calculates the weight of the thigh and the weight of the crus, outputs of the angle detectors of the thigh and the crus, and outputs of the thighs and the crus. Based on the output and position of each force detector and the length of the thigh, from the following formulas (A) and (B):
M1 · g = [L1 (S1 / C1-a2 · S3 / l2 · C3) f2x
-L1 (l-a2 / l2) f2z
-(A1 / C1) f1z] / l1 Formula (A)
M2 · g = a2 · [(S3 / C3) f2x−f2z] / l2... Formula (b)
here,
α: Horizontal crotch angle detected by thigh angle detector
γ: Angle of the lower leg that is detected by the angle detector of the lower leg and the horizontal direction
β: Knee angle calculated from α and γ (β = γ-α)
L1: The length of the thigh measured by inputting the length of the patient's thigh into the device
M1: Weight of the thigh
M2: Weight of the lower leg
g: Gravity acceleration
l1: Distance between the center of gravity of the hip joint and thigh
l2: Distance between the center of gravity of knee joint and lower leg
f1z: Value from thigh force detector
f2x, f2z: horizontal and vertical values from the lower leg force detector
a1: Position of thigh force detector (known)
a2: position of the force sensor of the lower leg (known)
S1 = sinα
C1 = cosα
S3 = sinγ
C3 = cosγ,
The weight M1 of the thigh is estimated from the formula (A),
It is characterized by estimating the weight M2 of the lower leg from the formula (b) .
According to a second aspect of the present invention, in the lower limb drive device according to the first aspect, the lower limb weight compensation section is based on the estimated weight M1 · g of the thigh and the estimated weight M2 · g of the crus. From the following formulas (c) to (e)
f1z_offst = −C1 · M1 · g (C)
f2x_offst ≒ 0 ... (d)
f2z_offst = -M2 · g (e)
Each offset value of the thigh and crus is calculated .

According to the first aspect of the present invention, the lower limb weight estimation unit that estimates the weight of the thigh and the lower leg, and the lower limb weight compensation unit that calculates an offset value corresponding to the weight of the thigh and the lower leg. Therefore, the teacher does not need to support the weight of the patient's leg, and the teaching can be performed while reducing the conventional burden.
According to the second to fifth aspects of the present invention, since the weights of the thighs and lower legs (self-weight of the lower limbs) are estimated simply by inputting the length of the patient's thighs in advance, it is extremely easy to use. A good lower limb drive.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an operation flow diagram of the lower limb drive device of the present invention.
First, the patient's leg is attached to the apparatus (step 101).
Next, the dead weight of the leg is estimated. In the dead weight estimation of the leg (step 104), the dead weight of the thigh and the dead weight of the lower leg are calculated from each data of the patient and the value of the sensor of the apparatus.
Further, using the weight data (106) of the thigh and crus estimated by the weight estimation of the leg in step 104, the weight of the leg is compensated (step 105).
In the leg weight compensation in step 105, an offset value (107) corresponding to the leg weight detected by the force detectors of the thigh arm and the lower leg arm is calculated. In the teaching of step 102, the trajectory for moving the leg is memorized in the same way as in the conventional example, but at this time, the teaching is performed by canceling the weight of the leg using the offset value calculated in the weight compensation of the leg in step 105. It is possible to reduce the burden on the teacher at the time.
Training is performed in accordance with the trajectory learned in the teaching of step 102 (step 103). In this case as well, if the offset value (107) calculated by the leg weight compensation in step 105 is used, impedance control is used during training. When the legs are moved by flexibly controlling the thigh arm and lower leg arm, it is possible to prevent the thigh arm and lower leg arm from sinking due to the weight of the leg, and training can be performed at the balance point of the impedance control spring. It becomes possible.
A specific method for estimating the weight of the leg and compensating for the weight will be described later.

FIG. 2 is a block diagram of the lower limb drive device showing the present invention.
In FIG. 2, 201 is a patient, 202 is a hip joint, 203 is a thigh, 204 is a knee joint, and 205 is a lower leg. Reference numeral 210 denotes a drive shaft of the thigh arm, which can rotate the thigh 203 around the hip joint 202 via the angle detector 208 and the force detector 206. Reference numerals 211 and 212 denote drive shafts of the crus arms, which can rotate the crus part 205 around the knee joint 204 via the angle detector 209 and the force detector 207.
The thigh arm control device receives a signal from the force detector 206 and the angle detector 208, amplifies or processes the signal, and converts the signal into a signal corresponding to the force or angle, and a self-weight estimating unit 222, The self-weight compensator 220, the impedance controller 215, and the servo amplifier 217 are included. Since the thigh arm has one degree of freedom, impedance control using the following equation can be performed.
Fe = Mαe + BVe + K (θ-θ0) (1)
Where Fe is the force acting between the thigh and the thigh arm, M, B and K are target impedances (M is the inertia coefficient, B is the viscosity coefficient, K is the spring coefficient), and θ is the angle of the thigh arm drive shaft. , Θ0 is a balance point of the spring stiffness of the thigh arm, Ve is an angular velocity (differential value of the angle θ) of the thigh arm drive shaft, and αe is an angular acceleration (second-order differential value of the angle θ) of the thigh arm drive shaft.
Since control using this equation is a known technique, detailed description thereof is omitted.

In this control system, signals detected by the force detector 206 and the angle detector 208 are amplified by the detector converter 213 and sent to the self-weight compensator 220. The own weight estimation unit 222 estimates the own weight of the thigh when the leg is put on and stores it in a memory (not shown).
The self-weight compensator 220 reads the thigh's own weight data 223 estimated by the self-weight estimator 222 from the memory, and uses the thigh's own weight data 223 to obtain a thigh unloading amount (offset value). . Further, the thigh offset value is subtracted from the output value of the detector converter 213 and sent to the impedance control unit 215. When sent to the impedance control unit 215, the impedance control unit 215 generates a motion command so as to satisfy Expression (1), and drives the motor of the drive shaft 210 via the servo amplifier 217.
The control device for the lower leg arm receives a signal from the force detector 207 and the angle detector 209, amplifies or processes the signal, and converts the signal into a signal corresponding to the force or angle, an impedance control unit 216, It is composed of servo amplifiers 218 and 219. Since the lower arm has two degrees of freedom, the control of the control device can be impedance control using the following equation.
Fx = Mαx + BVx + K (x-x0) (2)
Where Fx is the force acting between the lower leg and the lower leg arm, M, B, K are target impedances (M is an inertia coefficient, B is a viscosity coefficient, K is a spring coefficient), and x is an XY coordinate system in FIG. X0 is the spring stiffness equilibrium point of x, Vx is the differential value of x, and αx is the second-order differential value of x.
Since control using this equation is a known technique, detailed description thereof is omitted.

In this control system, the force signal and the angle signal detected by the force detector 207 and the angle detector 209 are amplified by the detector converter 214 and sent to the self-weight compensator 221.
The own weight estimating unit 222 estimates the own weight of the lower leg when putting a leg on, and stores it in a memory (not shown).
The self-weight compensator 221 reads the crus weight data 224 estimated by the self-weight estimator 222 from the memory, and uses the crus weight data 224 to obtain the crus free weight (offset value). . Further, the offset value of the lower leg is subtracted from the output value of the detector converter 214 and sent to the impedance control unit 216. When sent to the impedance control unit 216, the impedance control unit 216 generates a motion command so as to satisfy Expression (2), and drives the motors of the drive shaft 211 and the drive shaft 212 via the servo amplifiers 218 and 219. .
The lower limb drive device as described above has a mechanism section with multiple degrees of freedom, and performs impedance control so that a complicated pattern can be trained without applying an excessive load on the lower limb.
In addition, the weight of the leg is estimated when the leg is put on the device, and the estimated weight is used to compensate for the weight of the leg to drive the thigh arm and the lower leg arm. It becomes possible, and the burden on the teacher can be reduced.
Also, during training, when the legs are moved by flexibly controlling the thigh and crus arms using impedance control during training, the thigh and crus arms can be prevented from sinking due to the weight of the legs. Training can be performed at the balance point of the control spring.
The present invention is different from the prior art in that (1) a leg weight estimation unit 222 and (2) a leg weight compensation unit 220, 221 are provided.

A specific method for estimating the dead weight of the leg performed by the dead weight estimation unit 222 of the leg will be described.
FIG. 3 and FIG. 4 are auxiliary diagrams for explaining the calculation formulas for the dead weight estimation and the dead weight compensation.
FIG. 3 is a diagram showing the definition of the leg's own weight and torque, and FIG. 4 is a diagram showing the definition of the external force and torque.
here,
τ1: Torque generated around the hip joint τ2: Torque generated around the knee joint α: Crotch angle formed by the horizontal direction (X direction in FIGS. 3 and 4) detected by the angle detector 208 (FIG. 3) γ: Angle detector Angle formed with the horizontal direction (X direction in FIGS. 3 and 4) detected by 209 (FIG. 2) β: Knee angle calculated from α and γ (β = γ−α)
L1: Length of thigh (value input to the device after measuring the length of the patient's thigh)
M1: Weight of the thigh M2: Weight of the lower leg g: Gravity acceleration l1: Distance between the center of gravity of the hip joint and the thigh 12: Distance between the center of gravity of the knee joint and the thigh flz: Thigh Values from the force detector 206 (FIG. 2) f2x, f2z: in the horizontal direction (X direction in FIGS. 3 and 4) and the vertical direction (Y direction in FIGS. 3 and 4) from the force sensor 207 of the lower leg Value a1: Position of the thigh force detector 206 (FIG. 2) based on the XY coordinate system of FIGS. 3 and 4 (known)
a2: position based on the XY coordinate system of FIGS. 3 and 4 of the crus force detector 207 (FIG. 2) (known)
It is.
From the values shown in FIGS. 3 and 4 and these values, the weights of the thigh and crus can be estimated.
M1 * g = {L1 (S1 / C1-a2 / S3 / l2 * C3) f2x-L1 (1-a2 / l2) f2z- (a1 / C1) f1z} / l1 (3)
M2 · g = a2 · {(S3 / C3) f2x−f2z} / l2 (4)
Here, S1 = sin α, C1 = cos α, S3 = sin γ, and C3 = cos γ.
α, β, and γ are values obtained from the angle detector of the device, l1 and l2 are values obtained from the posture of the device when L1 and the device are attached, f1z, f2x, and f2z are values obtained from the force detector of the device, a1 , A2 is a value obtained from a parameter such as the link length of the apparatus. Therefore, according to Equation (3) and Equation (4), it is necessary to input only the length L1 of the patient's thigh beforehand. It is possible to estimate the weight M1 · g of the limb and the weight M2 · g of the crus.

A specific method of leg weight compensation performed by the leg weight compensation units 220 and 221 will be described.
The offset value corresponding to the weight of the leg can be obtained from the estimated weight of the leg M1 · g, M2 · g by the following formula.
f1z_offst = −C1 · M1 · g (5)
f2x_offst ≒ 0 (6)
f2z_offst = −M2 · g (7)
In order to compensate for the weight of the leg, that is, to adjust the lifting amount of the leg, the value of the equation (5) or the equation (7) may be subtracted from the value of the force detector 206 or 207 converted to the absolute coordinate system.
f1z ′ = f1z−f1z_offst (8)
f2z ′ = f2z−f2z_offst (9)
Since f1z_offst and f2z_offst are negative values as can be seen from the equations (5) and (7), f1z ′> f1z and f2z ′> f2z.
If impedance control is performed using the values of Equation (8) and Equation (9) as the left sides of Equation (1) and Equation (2), respectively, control that compensates for the weight of the leg is possible. As a result, the weight of the leg is canceled at the time of teaching, and the burden on the teacher can be reduced. In addition, when performing training, impedance control is performed in consideration of the weight of the leg, so that the thigh arm and lower leg arm will not sink due to the weight of the leg, and the impedance control is performed with the position of the leg as the equilibrium point of the impedance spring. It becomes possible.

It is an operation | movement flowchart of the leg drive device which shows the Example of this invention. It is a control block diagram of the lower limb drive device showing an embodiment of the present invention. It is an auxiliary figure for explaining a computing equation of the present invention, and is a figure showing a definition of a leg's own weight and torque. It is an auxiliary figure for explaining a computing equation of the present invention, and is a figure showing a definition of external force and torque. It is an operation flow figure of the conventional leg drive device. It is a control block diagram of the conventional leg drive device. It is a control block diagram of the conventional leg drive device.

Explanation of symbols

101 Leg Attachment 102 Teaching 103 Training 104 Leg Weight Estimation 105 Leg Weight Compensation 106 Weight Data 107 Offset Value 201 Patient 202 Hip Joint 203 Thigh 204 Knee Joint 205 Lower Thigh 206, 207 Force Detector 208, 209 Angle Detection Device 210 thigh arm drive shaft 211 crus arm drive shaft 212 crus arm drive shafts 213, 214 detector converters 215, 216 impedance control unit 217 servo amplifier 218, 219 servo amplifier 220, 221 self-weight compensation unit 222 self-weight estimation unit 223 Thigh weight data 224 Lower leg weight data 501 Hip joint 502 Knee joint 503 Thigh arm 504 Lower leg arm 701 Torque sensor 702 Arm 703 Motor 704 Decelerator 705 Angle detector 706 Dynamic characteristic model 707 Memory 708 Server Bocontroller 710 Object or limb 721 Detected angle 722 Detected external force 723 Angle command value 724 Motor drive torque

Claims (2)

A drive unit that moves the thigh and crus, a force detector that detects a load from the thigh and the crus, and a flexible control of the drive unit based on load information from the force detector A lower limb drive device comprising an impedance control unit ,
A lower limb weight estimation unit that estimates the weight of the thigh and the lower leg, and a lower limb weight compensation unit that calculates an offset value corresponding to the respective weights of the thigh and the lower leg. In the lower limb drive device that cancels the weight of the thigh and the lower leg at the time of teaching and training ,
The lower limb weight estimation unit calculates the weight of the thigh and the weight of the crus, outputs of the angle detectors of the thigh and the crus, and outputs of the thighs and the crus. Based on the output and position of each force detector and the length of the thigh, from the following formulas (A) and (B):
M1 · g = [L1 (S1 / C1-a2 · S3 / l2 · C3) f2x
-L1 (l-a2 / l2) f2z
-(A1 / C1) f1z] / l1 Formula (A)
M2 · g = a2 · [(S3 / C3) f2x−f2z] / l2... Formula (b)
here,
α: Horizontal crotch angle detected by thigh angle detector
γ: Angle of the lower leg that is detected by the angle detector of the lower leg and the horizontal direction
β: Knee angle calculated from α and γ (β = γ-α)
L1: The length of the thigh measured by inputting the length of the patient's thigh into the device
M1: Weight of the thigh
M2: Weight of the lower leg
g: Gravity acceleration
l1: Distance between the center of gravity of the hip joint and thigh
l2: Distance between the center of gravity of knee joint and lower leg
f1z: Value from thigh force detector
f2x, f2z: horizontal and vertical values from the lower leg force detector
a1: Position of thigh force detector (known)
a2: position of the force sensor of the lower leg (known)
S1 = sinα
C1 = cosα
S3 = sinγ
C3 = cosγ,
The weight M1 of the thigh is estimated from the formula (A),
A lower limb drive device characterized by estimating the own weight M2 of the lower leg from the formula (b) . The lower limb weight compensation section is based on the following weight (M) to (E) based on the estimated weight M1 · g of the thigh and the estimated weight M2 · g of the lower leg.
f1z_offst = −C1 · M1 · g (C)
f2x_offst ≒ 0 ... (d)
f2z_offst = -M2 · g (e)
2. The lower limb drive device according to claim 1, wherein each offset value of the thigh and the lower leg is calculated .

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