JPH10291800A - Assistant arm provided with power assist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an assistant arm provided with a power assist, capable of conveying a workpiece in the direction in which an operator tends to move it. SOLUTION: A speed command V is calculated by multiplying detected operating force F by a gain K (S1, S2). Next, speed commands θof motors for each shaft are calculated by multiplying the speed command V by the Jacobian matrix (S3). Whether the calculated speed commands θ1, θ2,... exceed the maximum speeds θ1max, θ2max,... set to respective motors or not is judged. If the speeds of all motors do not exceed respective maximum speeds, the motors are rotated by the speed commands θ (S4-S6). While, if the speeds of any one of motors exceeds the maximum speeds, a new gain is found by multiplying the Jacobian matrix Jsin<-1> (θ) by the speed command V and the dividing the speed command θ by the calculated result, and the speeds of the other motors are decreased while the speeds of the motor exceeding the maximum speed is kept to the maximum speed (S7-S9).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assist arm with power assist which can be lightly conveyed regardless of the weight of a work.

[0002]

2. Description of the Related Art Conventionally, an assisting arm as shown in FIG. 7 has been used in order to reduce a burden when a heavy object is carried. The assisting arm includes a cylinder 12 attached to the arm 10 (in some cases, a motor is used).
Thus, the weight of the work can be offset.

[0003] This arm 10 can move up and down,
Further, it can turn with respect to the main shaft 14, and its tip can slide forward and backward. For this reason, the worker can freely convey the work with a light operation using the assisting arm.

However, when the work becomes heavy, the weight of the heavy object (work) is offset by the action of the cylinder 12, but when the work is transported, the inertia force corresponding to the work weight is increased. Another problem arises in that the transportation takes considerable effort.

[0005]

In order to solve this problem, a motor is attached to each arm, and a sensor for detecting the acting force applied by the operator to the arm is provided. It is conceivable that the work force is applied to the work so that the work is conveyed by a lighter operation.

However, in the case of such a configuration,
Depending on the speed at which the work is moved, the arm may not be able to follow the speed.In such a case, the work will not move in the direction in which the worker is going to move, and the worker will be unable to carry the work. You will feel uncomfortable. Therefore, in the case of such a configuration, it is necessary to control the work to move in a direction in which the worker tries to move the work.

The present invention has been made in order to meet such a conventional demand, and has as its object to provide a power-assisted assisting arm capable of transporting a work in a direction in which an operator intends to move. .

[0008]

The present invention for achieving the above object is constituted as follows. The invention according to claim 1 is an assisting arm including a plurality of arms for transporting a work to a desired position and a gravitational balance mechanism acting on one of the arms to balance the weight of the work with gravity. An actuation force detection sensor for detecting a magnitude of a force in a three-dimensional direction and a torsion direction in each dimension that an operator acts on the work; driving means provided on each of the plurality of arms; Based on the magnitude and direction of the force detected by the force detection sensor, each drive unit is controlled so that the work moves at a speed desired by the worker in a desired direction. If the operating speed of the driving means of the
Control means for controlling the operating speed of each drive means so that the moving direction is in the direction desired by the operator.

According to a second aspect of the present invention, there are provided a plurality of arms for transferring a work to a desired position, and a gravitational balance mechanism which acts on one of the arms to balance the weight of the work with gravity. An assisting arm, an acting force detecting sensor that detects a magnitude of a force in a three-dimensional direction and a torsion direction in each dimension that an operator acts on the work, and a driving unit provided in each of the plurality of arms. Based on the magnitude and direction of the force detected by the acting force detection sensor, each drive unit is controlled so that the work moves at a speed desired by the operator in a desired direction. When the operating speed of any one of the driving means reaches the limit, the moving of the other driving means is performed so that the workpiece moves in the direction coinciding with the direction in which the worker intends to carry. A power-assisted aid arm, characterized in that a control means for reducing the speed.

According to a third aspect of the present invention, in the assisting arm with power assist according to the first or second aspect, the control of the operating speed of each of the driving means is performed by controlling a gain of a signal given to each of the driving means. Is performed by changing

According to a fourth aspect of the present invention, in the assisting arm with the power assist according to the first or second aspect, the change of the gain of the signal applied to each of the driving means is limited to an operating speed. It is characterized in that it is performed based on the driving means.

[0012]

According to the first to fourth aspects of the present invention, the workpiece always moves in the direction desired by the worker based on the magnitude and direction of the force detected by the acting force detection sensor. As a result, it is possible to perform a transport operation without a sense of incongruity.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an assisting arm with power assist according to the present invention will be described below.
FIG. 1 is an external view of an assisting arm with power assist of the present invention.

As shown in the figure, a cylinder 12 for gravity balance is attached to the arm 10. The arm 10 is vertically rotated by a motor 13 with respect to a main shaft 14. An arm 16 for moving the hand 15 is provided at the tip of the arm 10.
6 is moved by the motor 17. A load cell 18 for detecting a force applied by an operator to a work is attached to the hand 15, and the three-dimensional (X, X,
The external force in the (Y, Z) direction and the force in the torsional direction in each of these dimensions are detected. The arm 10 can be turned around a main shaft 14, and this turning is performed by a motor 20.

The controller 25 controls the operation of the assisting arm with power assist. The controller 25 includes a detection signal (operating force) from the load cell 18 and the rotation of each of the motors 13, 17, and 20. A pulse signal is input from an angle detection encoder (not shown), and the motors 13 and 1 are sent from the controller 25.
The current and the voltage to be supplied to 7, 20 are output. Further, it has an adjusting function for freely adjusting the assist force.
Incidentally, low-power servo motors of about 80 W are used for these motors 13, 17, and 20 from the viewpoint of safety.

The assisting arm with power assist according to the present invention operates as follows. When the worker grips the work with the hand 15 and tries to move the work, the magnitude and the direction of the force applied to the work are detected by the load cell 18, and the controller 25 sends the load cell 1.
The work is moved in the direction in which the worker is going to move at the speed at which the worker is going to move, based on the detection signal from 8.
If the operator releases his / her hand from the work, there is no longer any force acting on the load cell 18, and the work naturally stops.

On the other hand, when the worker attempts to move the work at a relatively high speed, the maximum speed of any one of the motors may be exceeded. In such a case, the intention of the worker is intended. The workpiece will move in a direction different from the direction. This not only makes the work uncomfortable, but also poses a problem in terms of work safety.Therefore, when moving the work at a speed exceeding the maximum speed of the motor of one arm is required. In this method, the moving speed of the work is reduced so that only the moving direction is in line with the worker's request, so that the work does not feel uncomfortable.

FIG. 2 is a schematic block diagram of a control system of the assisting arm with power assist according to the present invention. The encoders 1 to 3 are provided in each of the motors 13, 17, and 20 for driving each arm shown in FIG. 1, and are configured to output a pulse signal at every fixed rotation angle. Is what it is.

The pulse signals q1 to q3 output from the encoder 1 to the encoder 3 are input to each axis motor speed calculation unit 50 as control means, and designate motors 13, 17, and 20 of each axis as drive means. And a signal for judging whether or not the motor of each axis exceeds the maximum speed.

The load cell 18 functions as an acting force detecting sensor. As described above, the force (operating force) applied to the work by the operator is divided into three-dimensional directions and torsional directions in each dimension, and is converted into an electric signal as an electric signal. The external force F in the X, Y, and Z directions is output to the arithmetic unit 50.
And the torsional forces N in the X, Y, and Z directions are output.

Although not directly related to the present invention, each axis motor speed calculating section 50 outputs the signals from the encoder 1 to the encoder 3 so that the optimum torque is output from the motors 13, 17, 20 of each axis. Pulse signals q1 to q
3, the torque to be output from each of the motors 13, 17, 20 is calculated using a Jacobian matrix J (g) or the like.

More specifically, the inverse matrix J ⁻¹ (g) of the Jacobian matrix J (g) and the transposed matrix J of the Jacobian matrix J (g)
^T (g), differential value q1 dot of pulse signals q1 to q3
q3 dot Terms h (q, q) related to Coriolis force, centrifugal force, viscous friction force
(Dot) Inertia matrix R (g) Torque is calculated by performing the following calculation using the external force F in the X, Y, and Z directions and the torsional force N in the X, Y, and Z directions.

Generally, assuming that the torque of the motor corresponding to the force applied to the work is τ, the torque of each motor can be represented by the following equation.

[0024] Where J ^T (θ) is the Jacobian matrix of the arm, F
Is an external force applied to the work, N is a torsional force, and θ is an indirect angle. Therefore, the assist force may be generated by causing the motor to cancel the torque τ.

At this time, the motor torque τ is Becomes

The external force F and the torsional force N are obtained from the load cell 18, and the indirect angle θ is obtained from a pulse signal output from the encoder.

The general formula is as described above. Further, considering a specific equation of motion for the work, if the external force applied to the work by the operator is F, the desired motion of the work is given by the following formula.

F = M · d ² x / dt ² + D · dx / dt + Kx At this time, if it is desirable to reduce the load on the worker,
It is assumed that K = 0 and D = 0, and M is selected to be smaller than the actual mass of the work (the smaller the smaller, the larger the load reduction rate).

When the above equation is rewritten based on the above condition, F = M · d ² x / dt ² (1)

On the other hand, the equation of motion of the assisting arm is generally represented by the following equation.

[0031] τ = (J0 + R (g )) d 2 q / dt 2 +
h (q, q dot) + g (q) where J0 is the moment of inertia of each arm and R (g)
Is an inertia matrix, h (q, q dots) are terms relating to Coriolis force, centrifugal force, viscous friction force, g (q) is a term relating to gravity, and τ is a torque of each motor.

Therefore, the torque of the motor giving the desired motion characteristics is given by τ = h (q, q dot) + g (q)-(J0 + R
(G)) · J ^-1 (g) · J dot (g) · q dot +
｛(J0 + R (g)) · J ^-1 (g) · M ^-1 -J
^T (g)｝ · F In the case of the assisting arm, gravity is canceled by a cylinder or the like, so that τ = h (q, q dot) − (J0 + R (g)) · J
^-1 (g) · J dot (g) · q dot + ｛(J0 + R
(G)) · J ⁻¹ (g) · M ⁻¹ −J ^T (g)｝ · F

Various quantities required for this calculation are provided in each axis motor speed calculation unit 50 (not shown) J ^-1 (g).
The calculation unit, the J ^T (g) calculation unit, the differentiation calculation unit, the h (q, q dot) calculation unit, the R (g) calculation unit, and the load cell 18 respectively output the weight M of the work. The torque to be generated in each of the motors 13, 17, 20 can be calculated.

As described above, the optimum torque to be applied to the work is calculated. In addition, the assist arm with power assist of the present invention moves the work in the intended direction at the speed intended by the operator. Control.

FIG. 3 is a diagram showing the concept of this control. The force acting on the workpiece by the worker is calculated by the load
Is detected as The detected force F is multiplied by a gain K to calculate a speed command V, and this speed is multiplied by a Jacobian matrix to calculate a speed command θ for each axis. The speed command θ of each axis is applied to the motor control system, and the motor M of each axis, specifically, the motors 13, 17, 20 are driven.

The pulse signals from the encoder E generated by the rotation of these motors are fed back to the motor control system and the Jacobian matrix operation unit. The reason why the pulse signal from the encoder E is fed back is to detect the motor that has reached the maximum speed and to recalculate the gain of another motor. The parts other than the load cell 18, the motor M, and the encoder E are functions provided in each axis motor speed calculation unit 50.

Specifically, the processing according to the flowchart shown in FIG. 4 is performed. First, when the operation force F is detected by the load cell 18, the operation force F is transmitted to each axis motor speed calculation unit 5.
The speed command V is calculated by multiplying the operating force F by a gain K. The speed command V is calculated as a three-dimensional speed (Vx, Vy, Vz) (S1,
S2). Next, the speed command V is multiplied by the Jacobian matrix shown in FIG. 5 to calculate the speed command θ (θ1, θ2, θ3) of the motors 13, 17, 20 for each axis (S3).

The calculated speed commands θ1, θ2, θ3
Are determined not to exceed the maximum speeds θ1max, θ2max, θ3max set for the respective motors. If all of the motors do not exceed their respective maximum speeds, it is possible to convey the work at the speed requested by the operator in the required direction. 17,2
The current is output to the current amplifying units 13A, 17A, and 20A for 0, and the motors 13, 17, and 20 rotate at the speeds (θ1, θ2, θ3) based on this command (S4 to S6).

On the other hand, if the speed of any of the motors exceeds the set maximum speed, the speed command θ is output to the current amplifying units 13A, 17A, and 20A, but is not required by the operator. Work cannot be transported at the required speed in the required direction.

For example, as shown in FIG. 6, when the speed and direction required by the operator to transfer the work are expressed as a vector θ (thick line) in FIG. 6, the maximum speed θ 2max of the motor 2
Therefore, the actual transport speed and the transport direction of the work are vectors represented by θ ′ (thin line) in FIG. In this case, since the workpiece is not transported as intended by the operator, the operator feels uncomfortable.

In such a case, while the rotation speed of the motor exceeding the maximum speed (motor 2 in FIG. 6) is maintained at the maximum speed, the speed of the other motor (motor 1 in FIG. 6) is changed to θ1 in FIG. ′, The transport speed is no longer the intended speed, but only the direction is the intended direction, and the sense of discomfort of the operator can be reduced and safety can be ensured.

This is specifically solved by recalculating the gain K of the Jacobian matrix shown in FIG. In other words, the motor is subjected to a calculation of multiplying the Jacobian matrix Jsin ^-1 (θ) by the speed command V, dividing the speed command θ by the calculation result, and obtaining the gain. For example, in the case of FIG. 6, a gain k is obtained assuming that a speed command of .theta.2max is output as the speed of the motor 2, and the speed command .theta.1 of the motor 1 is recalculated using this gain (S7 to S9). ).

As described above, when there is a motor whose command speed exceeds the maximum speed, if the motor moves at the maximum speed, the speed at which the other motor should move is calculated again. The work can be moved in the direction intended by the operator.

In this embodiment, the mode in which the gain is recalculated based on a motor exceeding the maximum speed (one motor is used as a reference) is exemplified. However, the present invention is not limited to this, and the direction intended by the operator is not limited to this. Change all motor speed commands so that the workpiece can be transported to any position (not based on any motor)
The gain may be recalculated as follows.

[Brief description of the drawings]

FIG. 1 is an external view of an assisting arm with power assist of the present invention.

FIG. 2 is a schematic configuration diagram of a control system of an assist arm with power assist according to the present invention.

FIG. 3 is a conceptual diagram of control of an assist arm with power assist according to the present invention.

FIG. 4 is an operation flowchart of the assisting arm with power assist according to the present invention.

FIG. 5 is a Jacobian matrix used for calculating each axis speed command.

FIG. 6 is a diagram for explaining the operation of the assisting arm with power assist according to the present invention.

FIG. 7 is an external view of a general assisting arm.

[Explanation of symbols]

 10, 16: arm, 14: spindle, 13, 17, 20: motor, 18: load cell, 50: motor speed calculation unit for each axis.

Claims (4)

[Claims] An assisting arm comprising: a plurality of arms for transporting a work to a desired position; and a gravitational balance mechanism acting on one of the arms to balance the weight of the work with gravity. Force detecting sensor for detecting the magnitude of a force in a three-dimensional direction and a torsion direction in each dimension to be applied to the workpiece by a person, a driving unit provided on each of the plurality of arms, and the working force detecting sensor. The magnitude of the detected force,
On the basis of the direction, while controlling the respective driving means so that the work moves in a desired direction at a speed desired by the worker, when the operation speed of any of the driving means reaches a limit during the control. A control means for controlling the operating speed of each drive means so that the moving direction is in the direction desired by the operator. 2. An assisting arm comprising a plurality of arms for transporting a work to a desired position, and a gravitational balance mechanism acting on one of the arms to balance the weight of the work with gravity. Force detecting sensor for detecting the magnitude of a force in a three-dimensional direction and a torsion direction in each dimension to be applied to the workpiece by a person, a driving unit provided on each of the plurality of arms, and the working force detecting sensor. The magnitude of the detected force,
On the basis of the direction, while controlling the respective driving means so that the work moves in a desired direction at a speed desired by the worker, when the operation speed of any of the driving means reaches a limit during the control. A control means for lowering the operation speed of another driving means so that the work moves in a direction coinciding with a direction in which the worker intends to carry the assisting arm with power assist. . 3. The apparatus according to claim 1, wherein the control of the operating speed of each of the driving units is performed by changing a gain of a signal applied to each of the driving units. Helping arm with power assist. 4. The apparatus according to claim 1, wherein the gain of the signal applied to each of the driving units is changed based on the driving unit whose operation speed has reached a limit. Helping arm.