JPH11198077A - Power-assisted assistant arm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smooth the transfer of workpieces depending on the force applied to them or on their transfer rate. SOLUTION: On the basis of the magnitude of operating force F that a force sensor 18 detects, a decision part 30 decides which mechanical-characteristic compensator means 40, 42 or 44 should be used and switches over changeover switches 35A and 35B accordingly. Upon detecting that an extremely small force moves workpieces, for example, the decision part 30 switches over the changeover switches 35A and 35B to select the mechanical-characteristic compensator means 40 such that the control system has characteristics in which workpieces are positioned easily. Upon detecting that an extremely large force is applied to workpieces, on the other hand, the decision part 30 selects the mechanical-characteristic compensator means 44 such that the control system has characteristics in which workpieces are moved rapidly.

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 a power assist which can carry a work of transferring a work according to a force applied to the work or a transfer speed of the 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.

That is, the position θ of each arm (axis) is calculated by a control system as shown in FIG. 8 based on the magnitude F of the force detected by the sensor for detecting the acting force.

If the transfer of the work is controlled by such a control system, the operability during the transfer is certainly improved. However, if such a control system is used, the control characteristics will be unique regardless of the force applied to the work or the speed at which the work is moved. The work must be handled with the same operating force when the work is moved in small increments (for example, when the work is moved to a nearby position) or when the engine is moved into the engine room and positioned.

For example, if the control system is configured so that the work can be moved with a very light operating force, the positioning work and the like performed while moving the work delicately can be easily performed, but the work can be easily performed. When is moved largely, it can be operated with a light operating force, but cannot be moved at a high speed, which poses a problem in terms of work efficiency. On the other hand, if the control system is configured to have the opposite characteristic, the work efficiency can be ensured, but there is a contradictory problem that the positioning work becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has been made in consideration of the above circumstances. A power assist apparatus capable of performing a work transfer operation of a work according to a force applied to the work or a transfer speed of the work without discomfort. The purpose is to provide an assisting arm.

[0010]

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 the 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 for driving each of the plurality of arms; A response characteristic changing means for changing a response characteristic from the acting force detection sensor to the driving means based on the magnitude of the force in each direction detected by the detection sensor. It is.

According to a second aspect of the present invention, in the assisting arm with power assist according to the first aspect, the response characteristic changing means includes a plurality of mechanical devices prepared so that the assisting arm exhibits a preferable response operation. Characteristic compensating means, selecting means for selecting any one of the mechanical characteristic compensating means from the plurality of mechanical characteristic compensating means, and selecting the mechanical characteristic compensating means according to the range of the magnitude of the force detected by the acting force detecting sensor. Operating means for operating the selecting means.

According to a third aspect of the present invention, there are provided 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 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 that drives each of the plurality of arms. A plurality of mechanical property compensating means prepared so that the assisting arm exhibits a preferable response operation; a selecting means for selecting any one of the plurality of mechanical property compensating means; According to the range of the magnitude of the speed of the work calculated based on the magnitude of the force detected by the acting force detection sensor by the selected mechanical characteristic compensating means. A power-assisted aid arm and having an operation means for operating said selection means.

According to a fourth aspect of the present invention, in the assisting arm with power assist according to any one of the first to third aspects, the acting force detecting sensor is a force sensor. .

According to a fifth aspect of the present invention, in the assisting arm with power assist according to any one of the first to third aspects, the driving means is a servomotor.

[0015]

According to the first, second, fourth and fifth aspects of the present invention, the power assist is performed based on the magnitude of the force in each direction detected by the acting force detection sensor. The response characteristics (mechanical characteristics) of the assisting arm are changed, so that the work can be transported without discomfort. Operability can be simultaneously realized when is moved small (the acting force is small).

According to the present invention, the power assist is performed based on the speed of the work indirectly obtained from the magnitude of the force in each direction detected by the acting force detection sensor. By changing the response characteristics (mechanical characteristics) of the assisting arm, the work transfer operation can be performed without discomfort, and work efficiency can be secured when moving the work largely (work transfer speed is fast). In addition, when the work is moved small (the transfer speed of the work is slow), operability can be ensured.

[0017]

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 drawing, 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 force sensor 18, which is an acting force detection sensor for detecting a force applied by an operator to a work, is attached to the hand 15.
8, the external force in the three-dimensional (X, Y, Z) direction and the force in the torsion direction in each of these dimensions are detected. The arm 10
It is designed to be able to turn around the 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 receives a detection signal (operating force) from the force sensor 18 and motors 13, 17, and 20. A pulse signal from a rotation angle detection encoder (not shown) is input to the
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 direction of the force applied to the work are detected by the force sensor 18, and the controller 25 detects the force sensor 1.
The control characteristics are changed based on the detection signal from the control unit 8. For example, when a workpiece is to be transported far away, the operator normally applies a large force to the workpiece, so the control is changed to a mechanical property that allows the workpiece to move at a relatively high speed, while positioning the workpiece. In such a case, since the worker applies only a small force to the work, the control is changed to a mechanical property that allows the work to be moved with a very light force at the expense of speed. When the operator releases his / her hand from the work, the force acting on the force sensor 18 disappears, and the work stops naturally.

As described above, if the mechanical characteristics of the control system are changed according to the magnitude of the force applied to the workpiece, the operator can move as desired and the workability of transport and positioning is improved. .

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 calculator 50, and the motor 1
It is used as a feedback signal for rotating 3, 17, 20 at a designated speed, and as a signal for determining whether or not the motor of each axis exceeds the maximum speed.

The force sensor 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 twisting directions in each dimension, and each axis is converted into an electric signal to generate an electric signal. This is output to the motor speed calculation unit 50. Specifically, the external force F in the X, Y, and Z directions is output.
And the torsional forces N in the X, Y, and Z directions are output.

Each axis motor speed calculating section 50 controls the motors 13, 1 of each axis according to the operating force detected by the force sensor 18.
Based on the pulse signals q1 to q3 output from the encoder 1 to the encoder 3, respectively, the torque to be output from each of the motors 13, 17, and 20 is determined so that the optimum torque is output from the encoders 7 and 20 by the Jacobian matrix J ( g) and 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 relating to Coriolis force, centrifugal force, viscous friction force h (q, q dot) Inertia matrix R (g) Using external force F in X, Y, Z directions and torsional force N in X, Y, Z directions The torque is calculated by performing the following calculation.

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.

[0028] Where J^T(Θ) is the Jacobian matrix of the arm, F
Is the external force applied to the work, N is the torsional force, and θ is the indirect
Angle, and therefore the assist force
What is necessary is just to generate torque in the motor so as to cancel out.

At this time, the motor torque τ is Becomes

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

Although 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 + T At this time, if it is desired to reduce the load on the worker,
It is assumed that K = D = T = 0, and M is selected to be a value smaller than the actual mass of the work (the smaller the value, the greater the load reduction rate). When the time constant D / M is reduced and K = 0, the operability in a case where the work is largely moved can be improved. When the time constant D / M is increased and K = 0, the work alignment can be performed. The operability in such a case can be improved, and if K ≠ 0, the displacement can be absorbed.
The operability of the work for fitting the work is improved.

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

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

[0035] 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) is a term 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, and in the case of the assisting arm, gravity is offset by a cylinder or the like.
^-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 section 50 (not shown) J ^-1 (g).
The calculation unit, J ^T (g) calculation unit, differential calculation unit, h (q, q dot) calculation unit, R (g) calculation unit, and force sensor 18 output the weight M of the work. Thus, the torque to be generated in each of the motors 13, 17, 20 can be calculated.

The optimum torque to be applied to the work is calculated as described above. In the assisting arm with power assist of the present invention, depending on the force applied to the work by the operator,
A configuration is added in which the magnitude of the generated torque can be changed.

That is, in order to reduce the operating force required to operate the assisting arm, each axis of the assisting arm is adjusted to follow the ideal mechanical characteristics (light inertia weight, low friction) of the assisting arm. By controlling the operation of the motor
The configuration is such that the apparent mechanical characteristics of the assisting arm can be changed.

By adopting such a configuration, the response characteristics of the control are different between when the assisting arm is largely moved when the work is conveyed or when the assisting arm is slightly moved when the work is positioned or the like. The assist arm can be operated with characteristics more suitable for the contents.

FIG. 3 is a diagram showing the concept of this control. The force acting on the work of the worker is detected by the force sensor 18 as an operation force. The detected operating force is converted into a digital value by an A / D conversion board, and a target speed (an arm tip speed command) is calculated based on the digital value.
The speed for each arm is calculated from this target speed (joint conversion), the speed for each arm is converted to an analog value by a D / A conversion board, and the motor 1
3, 17, and 20 are driven. The content of the calculation is changed according to the magnitude of this operation force or the magnitude of the calculated target speed, and the assist arm is operated with a response characteristic more suitable for the work content. Also, pulse signals from the encoder generated by the rotation of these motors are fed back for speed calculation. The reason why the pulse signal from the encoder is fed back is to detect the motor that has reached the maximum speed. Parts other than the force sensor 18, the servo driver, the motor and the encoder are functions provided in each axis motor speed calculating section 50, and the servo drivers are provided by the current amplifying sections 13 A and 17.
A, 20A.

Specifically, the processing according to the flowchart shown in FIG. 4 is performed. The operation of this flowchart is shown in FIG.
This will be described with reference to FIG. First, when a detected value is detected by the force sensor 18, each axis motor speed calculating section 50 calculates an operating force F from the detected value (S1, S2). If the operation force F is smaller than a threshold value H1 stored in a storage device (not shown) provided in each axis motor speed calculation unit 50, the operator performs a positioning operation such as a positioning operation. And the determination unit 30 (provided in each axis motor speed calculation unit 50) determines to switch the control compensation to the fine operation impedance. Specifically, the determination unit 30 determines whether the changeover switch 3
5A and 35B are switched to the mechanical characteristic compensation means 40 side. As a result, the arm tip speed changes (in this case, the arm tip speed decreases), and the work can be easily moved with a small operation force (S3, S4).

On the other hand, the operating force F is applied to each axis motor speed calculating section 5.
If the operating force F is larger than a threshold value H2 stored in a storage device (not shown) provided at 0, the operation force F is compared with a threshold value H2 stored in the storage device.
If it is smaller than 2, the determination unit 30 determines that the worker is performing a normal general work, and switches the control compensation to the normal impedance. Specifically, the judgment unit 3
0 switches the changeover switches 35A and 35B to the mechanical characteristic compensation means 42 side. As a result, the arm tip speed changes (in this case, the arm tip speed becomes slightly higher), and the work can be moved slightly faster (S5, S5).
6).

If the operation force F is larger than the threshold value H2, the judgment section 30 judges that the worker is about to move the work largely, and switches the control compensation to a larger operation impedance. Specifically, the determining unit 30 sets the changeover switches 35A and 35B to the mechanical characteristic compensating means 4
Switch to side 4. As a result, the arm tip speed changes (in this case, the arm tip speed increases), and the work can be moved quickly (S5, S7).

When the arm tip speed is calculated according to the range of the magnitude of the detected operating force in this way, the target speed for each axis is calculated by multiplying the Jacobian matrix. Speed command θv of motors 13, 17, 20 for each axis
(Θ1, θ2, θ3) are calculated. Then, the speed command θv is output to the current amplifiers 13A, 17A, and 20A for the motors 13, 17, and 20, respectively.
3, 17, 20 are the speeds based on this command (θ1, θ2,
θ3). Therefore, a worker can carry a work having a large inertial force as if it were a light work by a light operation. Note that the response characteristic changing means of the present invention includes a determination unit 30, a changeover switch 35A,
35B, and is constituted by mechanical characteristic compensating means 40, 42, and 44, and is provided in each axis motor speed calculating section 50.

In the above embodiment, the control characteristics are changed by detecting the operation force of the operator. FIG. 6 shows the mechanical characteristic compensation means (FIG. In this configuration, the switching to any one of the mechanical compensating means is performed according to the arm tip speed calculated by the mechanical characteristic compensating means 40).

In the above two embodiments, the mechanical characteristic compensating means for changing the mechanical characteristic of the assist arm is provided by three.
However, the present invention is not limited to this, and an extremely large number of mechanical characteristic compensating means may be provided. When many mechanical characteristic compensating means are provided, the mechanical characteristics can be changed almost steplessly, so that the ideal operation of the assisting arm can be realized. However, even in such a case, it is needless to say that the arithmetic expression of the mechanical characteristic compensating means must match the magnitude of the force detected by the force sensor.

In the above embodiment, the mechanical characteristic compensating means is automatically selected according to the detected operating force or the calculated magnitude of the arm tip speed. A selection button may be provided on the arm so that the operator can manually switch the mechanical characteristic compensation means.

Further, the automatic mode in which the switching is automatically performed as described above and the manual mode in which the operator manually switches the mode are provided, and when any one of the modes is selected, the mechanical mode in each mode is selected. The selection of the characteristic compensation means may be performed.

[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 diagram for explaining the operation of the assisting arm with power assist according to the present invention.

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.

FIG. 8 is a diagram for explaining the operation of a conventional assisting arm with power assist.

[Explanation of symbols]

 10, 16 ... arm, 14 ... spindle, 13, 17, 20 ... motor, 18 ... force sensor, 30 ... judgment unit, 40, 42, 44 ... mechanical characteristic compensation means, 50 ... motor speed calculation unit for each axis.

Claims (5)

[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, driving means for driving each of the plurality of arms, and detection by the acting force detection sensor A response characteristic changing unit that changes a response characteristic from the acting force detection sensor to the driving unit based on the magnitude of the force in each direction. 2. The response characteristic changing unit includes: a plurality of mechanical characteristic compensation units prepared so that the assisting arm exhibits a preferable response operation; and any one of the plurality of mechanical characteristic compensation units. The selecting means for selecting a dynamic characteristic compensating means, and an operating means for operating the selecting means in accordance with a range of the magnitude of the force detected by the acting force detection sensor. A helping arm with power assist. 3. 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 that is applied to the workpiece by a user, a driving unit that drives each of the plurality of arms, and a preferable response operation in which the assisting arm is preferable A plurality of mechanical property compensating means prepared so as to exhibit; a selecting means for selecting any one of the plurality of mechanical property compensating means; and a mechanical property currently selected The selection means is operated according to the range of the magnitude of the speed of the work calculated based on the magnitude of the force detected by the acting force detection sensor by the compensation means. The power-assisted aid arm and having an operation means that. 4. The assisting arm with power assist according to claim 1, wherein the acting force detection sensor is a force sensor. 5. The assisting arm with power assist according to claim 1, wherein said driving means is a servomotor.