JP2014184087A - Support device and support program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the torque outputted by an actuator properly.SOLUTION: A walking support device 1 determines whether motion of a knee joint actuator 18 (motor 81) is active or passive from an energized direction of the motor 81 of the knee joint actuator 18 to rotate and an actually rotating direction of a knee joint pitch axis 86 as an output axis. Current torque characteristics of the knee joint actuator 18 is different between in the active case and in the passive case, and the walking support device 1: uses the active current torque characteristics when the motion of the knee joint actuator 18 is active to calculate a current value; and uses passive current torque characteristics when it is passive to calculate a current value.

Description

  The present invention relates to a support device and a support program, for example, to support movement of a leg joint.

In recent years, a wearable walking support device (wearable mobility) that is worn by a pedestrian and supports (assist) the walking motion of the pedestrian with an actuator or the like has been actively researched. A device has been proposed.
The walking assist device described in Patent Document 1 has a structure that supports a part of the body weight by lifting the seating portion upward by controlling the angle between the upper thigh frame and the lower thigh frame with an assisting actuator.

  In these walking support devices, the movement of the wearer and the torque generated in the joint are detected using a myoelectric sensor or a torque sensor, and a part of the torque is assisted by an actuator composed of a motor and a gear, for example. About the movement by a wearer's will, it can respond by the said sensor.

However, when a person wears, back drivability that operates by receiving external force (gravity, inertial force, force from a third party, etc.) not depending on the wearer's will may be important.
In such a case, the actuator rotates in the direction opposite to the driving direction, but in the actuator including the gear mechanism, the active movement (when the motor rotates the output shaft) and the passive movement (the motor The present inventor has found that the current torque characteristics are different in the case where is rotated around the output shaft.
For this reason, when the assist force is torque-controlled, if the motor is current-controlled without distinguishing between active and passive, there is a problem that the output torque is different from the desired torque.

Japanese Patent Laid-Open No. 2007-616

  An object of this invention is to control appropriately the torque which an actuator outputs.

In order to achieve the above object, according to the first aspect of the present invention, in the invention according to claim 1, an actuator that supports movement of a joint of a leg of a support target, and a torque that acquires torque to be output to the actuator at the joint The acquisition means, the detection means for detecting the operation direction of the actuator, the determination means for determining whether the detected operation direction and the direction of the acquired torque are the same, and the determination means are determined to be the same In this case, the current torque characteristic when the actuator outputs torque in the operation direction is selected, and the current torque characteristic when the actuator outputs torque in the direction opposite to the operation direction when the determination means determines NO And a current corresponding to the acquired torque is supplied to the actuator according to the selection means for selecting and the selected current torque characteristic. Providing a support device which is characterized by comprising a sheet means.
According to a second aspect of the present invention, the actuator includes a gear head, and the detection unit detects the operation direction on the output shaft side that outputs torque to the joint with respect to the gear head. A support device according to claim 1 is provided.
According to a third aspect of the present invention, there is provided the support device according to the second aspect, wherein the detection means detects the movement direction by the output shaft.
According to a fourth aspect of the present invention, there is provided a support program for a support device including an actuator for supporting the motion of a joint of a leg of a support target person, wherein torque acquisition for acquiring torque to be output to the actuator at the joint is obtained. A function, a detection function for detecting the operation direction of the actuator, a determination function for determining whether or not the detected operation direction is the same as the acquired torque direction, and the determination function is the same The current torque characteristic when the actuator outputs torque in the operation direction is selected, and the current torque characteristic when the actuator outputs torque in the direction opposite to the operation direction is selected when the determination function determines NO Supply current corresponding to the acquired torque to the actuator according to the selection function and the selected current torque characteristic. To provide a support program to implement a supply function that, at the computer.

  According to the present invention, the torque output from the actuator can be appropriately controlled by using a plurality of current torque characteristics corresponding to the situation.

1 shows a configuration of a weight support type walking support device. It is a figure for demonstrating an active direction and a passive direction. It is a figure for demonstrating the current torque characteristic of an active direction and a passive direction. It is the figure which showed the system configuration | structure of the walking assistance apparatus. It is a flowchart for demonstrating an electric current correction process.

(1) Outline of Embodiment In the assistance device of the present embodiment, a walking assistance device 1 that performs walking assistance will be described as an example.
As shown in FIG. 2, the walking assist device 1 includes the knee joint actuator 18 (from the direction in which the motor 81 of the knee joint actuator 18 wants to rotate and the direction in which the knee joint pitch shaft 86 that is actually the output shaft rotates. It is determined whether the movement of the motor 81) is active or passive.
The current torque characteristics of the knee joint actuator 18 are different depending on whether the knee joint actuator 18 is active or passive. The walking assist device 1 has a current torque characteristic for active when the operation of the knee joint actuator 18 is active. If it is passive, the current value is calculated using the passive current torque characteristic.
The walking assist device 1 can output a desired torque regardless of active or passive by supplying the knee joint actuator 18 with the current corrected by active or passive.
Further, when detecting the rotation direction of the output shaft, the rotation of the output shaft can be directly detected by detecting with the encoder 20 installed on the output shaft side of the gear head 82, and the direction in which the motor 81 is to rotate is actually set. In addition, it is easy to detect the direction in which the output shaft is rotating, and the number and types of sensors can be suppressed.

(2) Details of Embodiment FIG. 1 shows a configuration of a weight support type walking support apparatus 1.
Fig.1 (a) is the figure which showed the place which looked at the structure of the walk assistance apparatus 1 which concerns on this Embodiment from the side surface (lateral direction with respect to the advancing direction).
FIG. 1B is a diagram in which the walking support device 1 in the state shown in FIG. 1A is viewed from the front (traveling direction) and the lower body part of the wearer 100 is represented by dotted lines.
As shown in FIG. 1, the walking support device 1 supports (burdens) a part of the weight of the wearer 100 and reduces the load on the wearer 100 when the wearer 100 rides over the rider. . Part of the weight is applied by generating an upward force on the seating portion 61 by driving an actuator described later.
Moreover, in the walking assistance apparatus 1, since the wearer 100 does not need to fix a waist | hip | lumbar part, an upper leg part, and a lower leg part, attachment / detachment becomes easy.

  As shown in FIGS. 1 (a) and 1 (b), the walking support device 1 is bent at the knee joint portion when the wearer 100 indicated by the dotted line is in a state where the leg is extended (upright state). Thereby, even in an upright state, an upward force can be generated in the seating portion 61 to bear a part of the body weight.

  Returning to FIG. 1A, the walking assist device 1 includes a seating portion 61, a connecting member 63, a plate 62, guide rails 64 and 65, a load sensor 67, a hip joint pitch axis mechanism 17, a knee joint actuator 18, and an ankle joint pitch axis. The mechanism 19 includes an upper leg connecting member 26, a lower leg connecting member 27, a foot connecting member 28, a foot mounting portion 24, a floor reaction force sensor 241, an encoder 20, a knee joint pitch shaft 86, and the like.

Note that the hip joint pitch axis mechanism 17, the knee joint actuator 18, the encoder 20, the knee joint pitch axis 86, the ankle joint pitch axis mechanism 19, the upper thigh connection member 26, the lower thigh connection member 27, the foot connection member 28, the foot mounting portion 24, As for the floor reaction force sensor 241, there are members for the right leg and the left leg as shown in FIG. 1 (b). A description will be given separately with LR.
Although not shown, in the present embodiment, the control device 2 and the battery are disposed in the seating portion 61 or on the lower side of the seating portion 61. However, the control device 2 and the battery are disposed at other positions, for example, the upper thigh connection member 26. You may make it install.
In FIG. 1A, the right side (toe side of the foot mounting portion 24) is the front as viewed in the drawing.

The seating part 61 is a member on which the wearer 100 sits down.
A load sensor 67 that detects the pressure received by the wearers 100 to 61 is disposed on the upper surface of the seating portion 61. In the present embodiment, the output of the knee joint actuator 18 is controlled so that the detection value of the load sensor 67 becomes a predetermined target value (referred to as support load).
As a result, the wearer 100 always receives an upward urging force from the seating portion 61 so as to bear a part of his weight.

  The seating portion 61 supports at least a part of the weight of the wearer 100 from below. Since the seating portion 61 is pressed against the crotch portion of the wearer 100 from below, the upper portion of the walking support device 1 is thereby fixed to the waist portion of the wearer 100.

The connecting member 63 extends to the rear of the seat portion 61, and two left and right plates 62 are fixed to the extended portion. The connecting member 63 fixes the position of the seating portion 61 with respect to the plate 62.
The two plates 62 are disposed so as to be rotatable about the axis of the connecting member 63, so that the connecting member 63 functions as an opening / closing shaft for the two plates 62. As a result, the two plates 62 are also opened and closed around the axis of the connecting portion 63 as the legs of the wearer 100 are opened and closed.

The plate 62 is a fan-shaped member that is formed from the rear end side of the seating portion 61 to the lower portion of the front end side of the seating portion 61 and is convex toward the lower limb side. The plate 62 is a member that holds the seat portion 61 with respect to the movement of the lower limbs, and has rigidity that can withstand it.
On the surface of the plate 62, guide rails 64 and 65 (hereinafter, referred to as guide rails 65) are formed concentrically around a hip joint pitch axis center (position of the hip joint) K located above the seat portion 61. ing.
The guide rail 65 defines a trajectory in which the hip joint pitch axis mechanism 17 moves in the front-rear direction as the wearer 100 moves.

The hip joint pitch axis mechanism 17 is configured to freely move on the track by the guide rail 65, and the hip joint pitch axis mechanism 17 freely moves on the path by the guide rails 64, 65 as the wearer 100 walks. To do.
For example, in a state where the center of gravity moves forward by the wearer 100 moving the right leg forward, the right hip joint pitch shaft mechanism 17R freely moves forward on the track in conjunction with the movement of the leg, and the left on the standing leg side. The left hip joint pitch shaft mechanism 17L freely moves backward on the track in conjunction with the movement of the leg backward from the center of gravity.
As described above, the hip joint pitch axis mechanism 17 freely moves in the front-rear direction on the track by the force (movement) of the wearer 100 moving the leg in the front-rear direction, and is driven in the front-rear direction by the actuator. Absent.
The hip joint pitch shaft mechanism 17 is provided with a position sensor that detects the position of the guide rails 64 and 65. Since the value of the position sensor can be used to calculate the hip joint angle of the wearer 100, the position sensor functions as a joint angle sensor related to the hip joint.

One end of an upper thigh coupling member 26 composed of a rigid member (for example, a columnar member) is fixed to the hip joint pitch shaft mechanism 17, and the knee joint actuator 18 is connected to the other end of the upper thigh coupling member 26. ing.
Since one end of the upper thigh connecting member 26 is fixed to the hip joint pitch axis mechanism 17, the angle with respect to the hip joint pitch axis mechanism 17 does not change, but the hip joint pitch axis mechanism 17 moves on the guide rail 65 on the arc. Thus, the angle of the upper thigh connecting member 26 with respect to the horizontal plane changes while keeping the angle θ with the tangent to the guide rail 65 constant.
That is, as the hip joint pitch shaft mechanism 17 moves forward on the guide rail 65 with the operation of raising the knee of the wearer 100, the angle between the upper thigh connecting member 26 and the horizontal plane becomes small (approaches horizontal).

Then, the knee joint actuator 18 located on the other end side of the upper thigh coupling member 26 moves back and forth on an arc centering on the hip joint pitch axis center K which is the central axis of the guide rail 65. That is, the knee joint actuator 18 performs an arc motion while maintaining a certain distance from the hip joint pitch axis center K as the hip joint pitch axis mechanism 17 freely moves.
The lower leg connection member 27 is connected to the other end side of the upper leg connection member 26 via a knee joint pitch shaft 86.

The knee joint actuator 18 is controlled by an input current, and is configured to change the knee joint angle between the upper leg connecting member 26 and the lower leg connecting member 27 based on the knee joint pitch axis 86 by the output. Yes.
That is, the knee joint actuator 18 increases the knee joint angle (closer to a straight line) so as to generate an upward biasing force on the seat 61 connected to the upper thigh coupling member 26 via the plate 62 or the like. Thus, a part of the weight of the wearer 100 is supported by the upper biasing force.
The knee joint actuator 18 functions as an actuator that supports the movement of the joints of the legs of the walking support target person.

  The knee joint actuator 18 of the present embodiment will be described in the case where it is disposed at the position of the knee joint pitch axis 86 (the connection point between the upper thigh connecting member 26 and the lower thigh connecting member 27). Alternatively, they may be arranged in other positions such as in the seating portion 61, under the seating portion 61, and behind the hip joint pitch axis mechanism 17. In this case, the output of the knee joint actuator 18 may be applied to the upper thigh connecting member 26 and the lower thigh connecting member 27 by arranging a pulley at a necessary position and using a transmission mechanism using a wire or a belt or other force transmission mechanism. .

  Although not shown, the encoder 20 is installed so as to be coaxial with the knee joint pitch axis 86 and detects the rotation angle of the knee joint pitch axis 86. The encoder 20 functions as a joint angle sensor related to the knee joint.

The crus connecting member 27 is formed of a rigid member (for example, a columnar member), and an ankle joint pitch axis mechanism 19 is attached to the other end opposite to the knee joint actuator 18.
The ankle joint pitch shaft mechanism 19 is attached with a foot connecting member 28 made of a rigid member (for example, a columnar member).
A foot mounting portion 24 into which the foot of the wearer 100 is inserted is fixed to the foot connecting member 28 so that the position of the ankle joint pitch axis mechanism 19 is substantially the same height as the ankle joint of the wearer 100.
In the ankle joint pitch axis mechanism 19, the foot connecting member 28 and the foot mounting portion 24 freely pitch with respect to the crus connecting member 27.
Although not shown, the ankle joint pitch axis mechanism 19 is also provided with an encoder for detecting the angle of the ankle joint, and functions as a joint angle sensor for detecting the angle of the ankle joint.

The foot mounting portion 24 is disposed outside the pair of opposing foot connecting members 28, so that FIG.
), Each member other than the foot mounting portion 24 fits between both legs.
Floor reaction force sensors 241R and 241L for detecting a reaction force from the walking surface are disposed on the bottom surface of the foot mounting portion 24 in order to obtain a weight ratio of the weight supported by each leg.
In the present embodiment, one floor reaction force sensor 241 is disposed at a substantially central portion of the bottom surface of each foot mounting portion 24. However, in order to more accurately determine the state of the standing leg and the free leg, You may make it arrange | position a floor reaction force sensor in multiple places (for example, two places of a toe and a heel).

The wearing procedure of the walking support device 1 is as follows.
First, the power of the walking support device 1 is turned off and the upper thigh connecting member 26 and the lower thigh connecting member 27 are folded.
Then, the wearer 100 wears the foot attachment unit 24 on the left and right legs in a sitting posture.
Next, the wearer 100 stands up, extends the upper thigh connecting member 26 and the lower thigh connecting member 27, and puts the seating portion 61 on the crotch.

Next, when the power is turned on, the walking support device 1 drives the knee joint actuator 18 so that the detection value of the load sensor 67 matches the support load, and the seat portion 61 supports the weight of the wearer 100. When taking off the walking support device 1, the reverse procedure is performed.
Thus, the walking support device 1 is easy to attach and detach.

When the power is turned on, until the load sensor 67 of the seating section 61 detects the load, the knee joint actuator 18 applies a torque corresponding to the load at the time of wearing that is smaller than the output torque corresponding to the support load. By outputting, the seating part 61 slowly rises below the waist of the wearer 100.
When the power is turned off, the knee joint actuator 18 outputs torque corresponding to a load at the time of attachment / detachment that is smaller than the load at the time of attachment, so that the seating portion 61 is slowly lowered downward.

  In the present embodiment, the knee joint actuator 18 is used as the walking assist actuator. However, in addition to this, the ankle joint pitch axis mechanism 19 is provided with an ankle joint actuator, or the hip joint pitch axis mechanism 17 is connected to the guide rail 64. , 65 may be provided.

In the following, the torque control of the actuator will be described by taking the knee joint actuator 18 as an example, but the same processing can be performed when an ankle joint actuator or a hip joint actuator is provided.
In this embodiment, the walking support device 1 of the type that is mounted on the inner side of both legs will be described. For example, the walking support device 1 is mounted on the outer side of both legs and is driven while holding the waist, thigh, lower leg, and the like. The present invention can also be applied to a type of walking support device.

Each drawing in FIG. 2 is a view for explaining the active direction and the passive direction of the knee joint actuator 18 (motor 81).
The knee joint actuator 18 includes a motor 81 that generates a driving force and a gear head 82 formed at the tip of the motor.
The motor 81 rotates a motor output shaft (spindle, spindle) (not shown) by a direct current from the control device, thereby driving the gear head 82.
A gear output shaft 83 extends from the tip of the gear head 82.
A gear mechanism is provided inside the gear head 82, and the gear head 82 converts the rotational speed and rotational torque of the motor output shaft by the gear mechanism and outputs them from the gear output shaft 83.

The gear 85 is attached to the tip of the gear output shaft 83 coaxially with the gear output shaft 83, and when the gear output shaft 83 rotates, the gear 85 also rotates accordingly.
The gear 87 is attached to a knee joint pitch shaft 86 parallel to the gear output shaft 83 and meshes with the gear 85.

Therefore, when the gear output shaft 83 rotates, the knee joint pitch shaft 86 rotates in the opposite direction.
By the transmission mechanism using these gears, the knee joint actuator 18 can generate torque on the knee joint pitch shaft 86 and rotate the lower leg connecting member 27 relative to the upper leg connecting member 26. Thus, the knee joint pitch shaft 86 is an output shaft that outputs the torque generated by the knee joint actuator 18 to the joint (drive target).
Note that the above gear configuration is an example, and various modifications are possible.

The encoder 20 is provided at the end of the knee joint pitch axis 86 and detects the angle of the knee joint pitch axis 86.
In general, the encoder 20 is attached to the rear end of the motor 81 and detects the rotation of the motor output shaft. However, in this embodiment, since rotation of the knee joint pitch shaft 86 is used for motor control, if the encoder 20 is installed on the motor output shaft, a detection delay due to mechanical play of the gear mechanism occurs. Therefore, in the walking support device 1, the encoder 20 is installed on the knee joint pitch shaft 86 (that is, directly installed on the output shaft that outputs torque to the drive target).

In FIG. 2A, the knee joint pitch axis 86 is rotated leftward toward the paper surface. The rotation direction of the knee joint pitch axis 86 is detected by the encoder 20. This rotation direction is defined as forward rotation, and the reverse direction is defined as negative rotation.
In this figure, the motor 81 is supplied with a current for rotating the knee joint pitch shaft 86 in the forward direction. In this way, when a current for forward rotation is supplied to the motor 81 and the knee joint pitch shaft 86 is rotating forward, there is no difference in the operation direction, so the motor 81 (in other words, the knee joint actuator 18) is Suppose that it is operating in the active direction.
The operation in the active direction is also performed when a current for negative rotation is supplied to the motor 81 and the knee joint pitch shaft 86 rotates negatively.

In FIG. 2B, the motor 81 is supplied with a current that rotates the knee joint pitch axis 86 in the forward direction, whereas the knee joint pitch axis 86 rotates in the opposite negative direction.
In this way, when a current for positive rotation is supplied to the motor 81 and the knee joint pitch shaft 86 rotates negatively, there is a difference in the operation direction, so the motor 81 (in other words, the knee joint actuator 18) is Suppose that it is operating in a passive direction.
In addition, when the current for negative rotation is supplied to the motor 81 and the knee joint pitch shaft 86 is rotating in the positive direction, the operation is in the passive direction.
The knee joint actuator 18 operates in the passive direction when, for example, the wearer 100 applies a force in the extending direction to the leg portion and the leg portion is bent by gravity or by a force from a third party. There is a case where the joint bends in the opposite direction to the direction of movement.

FIG. 3 is a diagram for explaining current torque characteristics of the motor 81 in the active direction and the passive direction.
More specifically, the motor 81 drives the output shaft (the knee joint pitch shaft 86) via a gear mechanism such as the gear head 82 and the gears 85 and 87.
The current torque characteristics described below are characteristics of the current supplied to the motor 81 and the torque transmitted to the output shaft through the gear mechanism, and include the gear mechanism.

FIG. 3A is a diagram showing an experimental apparatus for measuring the characteristics of the motor 81. The figure has shown the figure which looked at the knee joint pitch axis | shaft 86 from the axial direction.
The bar 91 is fixed in a plane perpendicular to the knee joint pitch axis 86, and rotates around the axis together with the knee joint pitch axis 86. A measuring instrument 93 is attached to a position of the bar 91 at a distance L from the center of the knee joint pitch axis 86 via a string-like connecting member 92.
The measuring instrument 93 is composed only of a spring or the like, and measures the force (tension) that the string-like connecting member 92 pulls the bar 91.

In the experimental apparatus configured as described above, an experiment was performed according to the following procedure.
As an initial state, while the knee joint pitch shaft 86 is driven by supplying a predetermined current to the motor 81, the measuring instrument 93 is rotated while the string-like connecting member 92 is perpendicular to the bar 91. Is pulled in the opposite direction with a force F and stopped at a balanced position.
Thus, the torque in the active direction is measured from the balanced state as follows.
First, the force F is gradually weakened while keeping the current value constant. Even if the force is slightly reduced, the reverse rotation regeneration of the gear mechanism such as the gear head 82 and the motor 81 becomes a resistance force, and the knee joint pitch shaft 86 does not rotate immediately.
Then, the force F is weakened and the force F−ΔF1 at the moment when the knee joint pitch axis 86 rotates is recorded. As a result, the torque at which the knee joint pitch shaft 86 starts to rotate in the active direction is obtained with the current value. The torque value (torque magnitude) is (F−ΔF1) × L. Then, the torque for each current value is measured while changing the current value.

On the other hand, the torque measurement in the active direction is performed as follows.
First, similarly, the measuring instrument 93 is stopped at a balanced position.
Next, the force F is gradually increased while keeping the current value constant. Even if the force is slightly increased, the forward rotation of the gear mechanism such as the gear head 82 and the motor 81 becomes a resistance force, and the knee joint pitch shaft 86 does not rotate immediately.
Then, the force F is increased and the force F + ΔF2 at the moment when the knee joint pitch axis 86 rotates is recorded. As a result, the torque at which the knee joint pitch shaft 86 starts to rotate in the passive direction is obtained with the current value. The torque value is (F + ΔF2) × L. Then, the torque for each current value is measured while changing the current value.

FIG. 3B is a graph showing the above experimental results.
The vertical axis represents torque, and the horizontal axis represents current. This graph represents current torque characteristics representing torque output from the output shaft through the gear mechanism with respect to the current supplied to the motor 81.
The ideal characteristic 97 is an ideal current torque characteristic (IT characteristic) when the resistance due to the gear mechanism, the characteristic of the motor 81, or the like is ignored.
The passive characteristic 98 is obtained by plotting measured torque values in the passive direction against current.
The active characteristic 99 is obtained by plotting measured torque values in the active direction against current.

When it is desired to output N to the knee joint actuator 18 with such characteristics, it is necessary to supply the current I1 in the passive direction, I2 in the active direction, and I3 in the ideal direction to the knee joint actuator 18. . Here, I1 <I3 <I2.
In this way, when outputting a certain torque, the current in the passive direction requires less current than in the ideal case, and the current in the active direction requires a larger current than in the ideal case.
Incidentally, since control was performed with the ideal characteristic 97 regardless of whether it is active or passive, the torque actually output was excessive or insufficient according to the active / passive relative to the desired torque.

The walking assist device 1 calculates the current supplied to the motor 81 by the following equation (1).
Motor input current = (output torque) / (effective torque ratio) × (torque constant of motor 81) (Equation 1).
Here, the output torque is an ideal torque ignoring the effective torque ratio, and is a torque that is actually output to the knee joint pitch shaft 86.

The effective torque ratio is a ratio between ideal torque and actually output torque. Since the ideal characteristic 97, the passive characteristic 98, and the active characteristic 99 are all linear, in the case of the active direction, the value is obtained by dividing the inclination of the active characteristic 99 by the inclination of the ideal characteristic 97, for example, about 0.7. is there.
On the other hand, in the case of the passive direction, a value obtained by dividing the inclination of the passive characteristic 98 by the inclination of the ideal characteristic 97 is, for example, about 1.5.

The torque constant of the motor 81 is a torque output from the output shaft by the motor 81 per unit current in an ideal case, and is an inclination of the ideal characteristic 97.
If the passive characteristic 98 or the active characteristic 99 is not a straight line, an approximate expression is used, or a map of torque and current is prepared.

FIG. 4 is a diagram illustrating a system configuration of the walking support device 1.
The control device 2 is an electronic control unit including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a storage unit, various interfaces, and the like (not shown). Electronically controlled.

  The control device 2 is configured by executing various programs such as a walking support program stored in a storage unit by a CPU, and includes a sensor information acquisition unit 3, a joint moment calculation unit 4, an actuator output torque calculation unit 8, and a correction unit 7. , Device parameter storage unit 5, human body parameter storage unit 6 and the like.

The sensor information acquisition unit 3 acquires the angle of each joint from the joint angle sensor 9 (such as the encoder 20), acquires the floor reaction force from the floor reaction force sensor 241, and acquires the load from the load sensor 67.
The joint moment calculation unit 4 uses the joint angles, the detection values of the floor reaction force sensor 241, and the parameters stored in the device parameter storage unit 5 and the human body parameter storage unit 6 to use the joint moment of the knee joint of the wearer 100. Is calculated.
The actuator output torque calculation unit 8 calculates an output torque to be output as an assist force to the knee joint pitch shaft 86 as an output shaft with respect to the joint moment calculated by the joint moment calculation unit 4.

The output torque is a concept including the value (magnitude) of the output torque and the direction of the torque (drive direction of the knee joint actuator 18), and is a vector quantity.
Thus, the knee joint actuator 18 functions as a torque acquisition unit that acquires torque to be output to the actuator at the joint.

The correction unit 7 acquires the output torque (the output torque value and the driving direction of the knee joint actuator 18) from the actuator output torque calculation unit 8, and further, the current rotation direction of the knee joint pitch axis 86 from the sensor information acquisition unit 3. To get.
Here, the rotation direction corresponds to the operation direction of the actuator. Therefore, the correction unit 7 functions as detection means for detecting the operation direction of the actuator.

Then, the correction unit 7 determines whether the operation of the knee joint actuator 18 is the active direction or the passive direction from the driving direction of the knee joint actuator 18 and the rotation direction of the knee joint pitch axis 86.
In this way, the correction unit 7 determines whether or not the detected motion direction (the rotation direction of the knee joint pitch axis 86) and the acquired torque direction (the motion direction of the knee joint actuator 18) are the same. It functions as a means.

After the determination, the correction unit 7 adopts the active effective torque ratio or the passive effective torque ratio in accordance with the active / passive.
As described above, when the determination unit determines that the determination unit is the same, the correction unit 7 selects a current torque characteristic (active effective torque ratio) when the actuator outputs torque in the operation direction, and the determination unit determines NO. In this case, the actuator functions as a selection means for selecting a current torque characteristic (passive effective torque ratio) when the actuator outputs torque in the direction opposite to the operation direction.

Further, the correction unit 7 substitutes the adopted effective torque ratio and output torque into the equation (1), calculates the current input to the knee joint actuator 18, and supplies the current to the knee joint actuator 18.
Thus, the correction unit 7 functions as a supply unit that supplies a current corresponding to the acquired torque to the actuator in accordance with the selected current torque characteristic.
As described above, the correction unit 7 corrects the current supplied to the knee joint actuator 18 by selecting the active / passive effective torque ratio.

The device parameter storage unit 5 includes parameters necessary for calculating the joint moment, such as the length between the joints of the walking support device 1, the weight of each part, and the center of gravity, as well as the effective torque ratio for active and passive. Parameters necessary for correcting the current according to the equation (1) such as the torque constant of the motor 81 are stored.
The human body parameter storage unit 6 stores data representing physical characteristics such as the height and weight of the wearer.
Thus, the device parameter storage unit 5 and the human body parameter storage unit 6 store various parameters necessary for calculating the joint moment and the like.

FIG. 5 is a flowchart for explaining current correction processing performed by the walking support device 1.
The walking support device 1 performs the following processing on the left and right knee joint actuators 18.
Further, when the walking support device 1 includes actuators at other locations such as a hip joint and an ankle joint, these are also sequentially performed.

First, the correction unit 7 obtains the operation direction of the knee joint actuator 18 from the actuator output torque calculation unit 8 (that is, whether the direction in which the knee joint pitch axis 86 is rotated is positive or negative) (step 5).
Next, the correction unit 7 acquires the rotation direction of the output shaft (the knee joint pitch axis 86) from the detection value of the encoder 20 of the sensor information acquisition unit 3 (step 10).
Then, the correction unit 7 determines whether or not the operation direction of the knee joint actuator 18 and the rotation direction of the knee joint pitch axis 86 are the same (step 15).

When the operation direction of the knee joint actuator 18 and the rotation direction of the knee joint pitch axis 86 are the same (step 15; Y), the correction unit 7 determines that the direction is the active direction.
Then, the correction unit 7 adopts the active current torque characteristic, reads the active effective torque ratio from the device parameter storage unit 5, and substitutes it into the equation (1) (step 25).

Next, the correction unit 7 obtains the output torque from the actuator output torque calculation unit 8 (step 30), substitutes the output torque into the equation (1), and calculates the current input to the motor 81 (step 35). .
Then, the correction unit 7 inputs the calculated current to the motor 81 and drives the knee joint actuator 18 (step 40).

Next, the control device 2 determines whether or not to continue the walking support operation (step 45). When the operation is continued (step 45; Y), the control device 2 returns to step 5 and when not continued (step 45; N). ) End the process.
For example, the walking support device 1 can select the start and end of the walking support operation by the wearer 100 pressing a switch or the like, and the control device 2 can perform the walking support operation when the switch is on. If the switch is off, it is determined that the walking support operation is to be terminated.

Note that the operation switch for starting and ending this operation may be the same as or different from the above-described power on / off operation.
In the case of common use, when the operation end switch (= power switch) is turned off, the knee joint actuator 18 outputs an output torque corresponding to the load at the time of attachment / detachment, so that the seat portion 61 slowly descends downward.
On the other hand, when separate from the power switch, the knee joint actuator 18 continues to output the output torque corresponding to the support load.

On the other hand, when the operation direction of the knee joint actuator 18 and the rotation direction of the knee joint pitch axis 86 are different (step 15; N), the correction unit 7 determines that the direction is the passive direction.
Then, the correction unit 7 adopts the passive current torque characteristic, reads the passive effective torque ratio from the device parameter storage unit 5, and substitutes it into the equation (1) (step 50).

Next, the correction unit 7 obtains the output torque from the actuator output torque calculation unit 8 (step 55), substitutes the output torque into the equation (1), and calculates the current input to the motor 81 (step 60). .
Then, the correction unit 7 inputs the calculated current to the motor 81 and drives the knee joint actuator 18 (step 40).

  As described above, the walking assist device 1 corrects the drive current according to whether the operation of the knee joint actuator 18 is active or passive so that an appropriate torque is output from the knee joint pitch shaft 86.

  The walking assist device 1 performs the above processing independently for the left and right knee joint actuators 18 with respect to the left and right knee joint actuators 18.

  In the embodiment described above, the knee joint actuator 18 has been described as an example. However, various actuators other than the knee, for example, a hip joint actuator, an ankle joint actuator, and various support devices in an assisting device that supports operations of an elbow, a shoulder wrist, and the like. It is also possible to apply to an actuator.

According to the embodiment described above, the following effects can be obtained.
(1) The current supplied to the knee joint actuator 18 can be corrected depending on whether the operation direction of the knee joint actuator 18 (motor 81) is active or passive.
(2) By correcting the current, the knee joint actuator 18 can output a desired torque regardless of active or passive.
(3) Since the encoder 20 is installed on the output shaft, detection delay due to mechanical play of the gear mechanism can be prevented.

DESCRIPTION OF SYMBOLS 1 Walking assistance apparatus 2 Control apparatus 3 Sensor information acquisition part 4 Joint moment calculation part 8 Actuator output torque calculation part 9 Joint angle sensor 17 Hip joint pitch axis mechanism (slide mechanism)
18R Right knee joint actuator 18L Left knee joint actuator 19 Ankle joint pitch axis mechanism 20 Encoder 24 Foot mounting part 241R Right floor reaction force sensor 241L Left floor reaction force sensor 26 Upper thigh connection member 27 Lower thigh connection member 28 Foot connection member 61 Seating portion 62 plate 63 connecting member 64 guide rail 65 guide rail 67 load sensor 81 motor 82 gear head 83 gear output shaft 85, 87 gear 86 knee joint pitch shaft 91 bar 92 connecting member 93 measuring instrument 97 ideal characteristic 98 passive characteristic 99 active characteristic 100 Wearer K hip pitch axis center

Claims (4)

An actuator for supporting the movement of the joint of the leg of the support target,
Torque acquisition means for acquiring torque to be output to the actuator at the joint;
Detecting means for detecting an operating direction of the actuator;
A judging means for judging whether or not the detected operation direction and the acquired torque direction are the same;
When the determination means determines that the same is selected, a current torque characteristic is selected when the actuator outputs torque in the operation direction. When the determination means determines no, the actuator outputs torque opposite to the operation direction. Selecting means for selecting current torque characteristics when
Supply means for supplying a current corresponding to the acquired torque to the actuator according to the selected current torque characteristic;
A support apparatus comprising: The actuator includes a gear head,
The support device according to claim 1, wherein the detection unit detects the operation direction on an output shaft side that outputs torque to the joint with respect to the gear head.   The support device according to claim 2, wherein the detection unit detects the movement direction with the output shaft. A support program for a support device including an actuator that supports movement of a joint of a leg of a support target,
A torque acquisition function for acquiring torque to be output to the actuator in the joint;
A detection function for detecting the operating direction of the actuator;
A determination function for determining whether or not the detected operation direction and the acquired torque direction are the same;
When it is determined that the determination function is the same, the current torque characteristic when the actuator outputs torque in the operation direction is selected, and when the determination function is determined to be negative, the actuator outputs torque opposite to the operation direction. Selection function to select current torque characteristics when
A supply function for supplying a current corresponding to the acquired torque to the actuator according to the selected current torque characteristic;
Support program that realizes with a computer.

Images