JPH01183386A - Robot hand device - Google Patents

Abstract

PURPOSE:To hold an object stably and quickly, regardless of the spring constant of the object, even when the spring constant (hardness) is unknown, by providing a gain adjuster which adjusts the control gain according to the spring constant of the object. CONSTITUTION:A difference calculator 2 calculates the difference between the present holding force and the target-holding-force of a robot finger 11. On the other hand, the spring constant of an object O is determined from the degree of opening and holding force of the robot finger 11 in order to determine control gain G corresponding to the spring constant. Next, by using a gain adjuster 3, this control gain G is multiplied by the difference calculated by the difference calculator 2 in order to determined the opening/closing speed of the robot finger 11. Next, based on both control gain G and opening/closing speed, the robot finger 11 is opened/closed by a driving device 4. Thus, even when the spring constant is unknown, the object O can be held stably and quickly by the robot finger 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a robot hand device that can stably and quickly grip an object even when the spring constant of the object is unknown.

<Prior Art> In a robot hunt device that grasps an object by opening and closing robot fingers, conventionally, the control gain that determines the opening and closing speed of the robot finger is determined by the hardness of the object to be grasped, that is, the spring constant. The mainstream is a fixed gain method in which the gain is set to a constant value in advance.

Figures 5 and 6 are characteristic diagrams of the step response measured when an object is gripped by such a fixed gain robot hand device (the horizontal axis is time, and the vertical axis is the gripping force expressed in durams). ).

Figure 5(a) is a step response characteristic diagram when a sponge is gripped by a robot hand device whose control gain has been adjusted to suit a sponge with a small spring constant. It can be gripped with gripping force. However, when this same robot hand device grips a weight with a large spring constant, it will overshoot and vibrate significantly as shown in FIG. 5(b), and in the worst case, it will diverge.

On the other hand, when a robot hand device whose control gain is adjusted to suit a weight with a large spring constant grips one weight, it can quickly grip the object with a constant gripping force as shown in Figure 6 (a). However, when a sponge with a small spring constant is gripped, the convergence is slow, although stable, as shown in FIG. 6(b).

<Problems to be Solved by the Invention> As mentioned above, conventional fixed gain type robot hand devices cannot grasp various objects with different spring constants equally stably and quickly unless the control gain is adjusted each time. It is impossible to do so.

In order to solve the above-mentioned problems, the present invention automatically adjusts the control gain according to the spring constant of the object, so that the object can be gripped stably and quickly even when the spring constant is unknown. The purpose is to provide a robot hand device that can

Means for Solving Problems〉 The method is characterized by having the following components.

That is, a robot hand equipped with a robot finger that can detect the gripping force when gripping an object, a difference device that calculates the difference between the current gripping force of the robot finger and a target gripping force, and a robot hand that is equipped with a robot finger that can detect the gripping force when gripping an object; gain adjustment that determines a control gain by determining a spring constant of the object from the opening/closing degree and gripping force, and determines the opening/closing speed of the robot finger by multiplying the determined control gain by the difference calculated by the differentiator; and a drive device that opens and closes the robot finger based on the control gain and opening/closing speed determined by the gain adjustment device.

(Operation) In the robot hand device having the above configuration, by feeding back the current gripping force and degree of opening/closing of the robot fingers, the object to be gripped is gripped at an opening/closing speed corresponding to the spring constant of the object to be gripped.

(Example) Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a configuration diagram of a robot hunt device of the present invention.

As shown in the figure, this robot hand device includes a robot hunt l, a difference device 2, a gain adjustment device 3, and a drive bag g.
! 14.

The robot hand 1 is equipped with a robot finger 11 that can detect the gripping force when gripping the object O.

The difference device 2 calculates the difference between the current gripping force and the target gripping force of the robot finger 11.

Further, the gain adjustment device 3 is configured to control the robot finger 1.
The spring constant of the object O is determined from the opening/closing degree and the gripping force of 1, and the control gain G corresponding to the spring constant is determined.The control gain G is multiplied by the difference calculated by the differentiator 2. This determines the opening/closing speed of the robot finger 11.

Further, the drive device 4 controls the robot finger 1 based on the command from the gain adjustment device 213, that is, the control gain G and the opening/closing speed determined by the gain adjustment device a3.
1 opens and closes.

Therefore, the robot hand device having the above configuration can stably and quickly grip an object at an opening/closing speed corresponding to the object's spring constant by feeding back the degree of opening/closing of the robot fingers 11 and the current gripping force. Become.

FIG. 2 is a configuration diagram showing a specific example of the robot hand device.

As shown in the figure, the robot hand 1 is provided with a robot finger 11 that grips the target vRO. This robot finger 11 is opened and closed by rotating a pulse motor 43, which will be described later, and rotating a ball screw 6 via a coupling 5.

A strain gauge 7 is also attached to the robot finger 11 to detect the gripping force. This strain gauge 7
The amount of distortion is converted into a voltage by the distortion measuring device 8, and then converted into a digital signal by the A/D converter 9.

The differentiator 2 is composed of a computer, and the computer is shared with a computer 31 that constitutes a gain adjustment device 3, which will be described later.

The gain adjustment device (3) is composed of a computer 31 and an up/down counter 32. The computer 31 calculates the control gain G and the opening/closing speed of the robot finger 11 as described later, and controls the gripping operation of the robot hand device. The up/down counter 32 is connected to the robot finger 11 from a pulse generator 41 (described later).
When it receives a pulse that moves in the closing direction, it counts up, and when it receives a pulse that moves in the opening direction, it counts down. And by this up/down counter 32.

The opening/closing degree of the robot finger 11 is determined by the computer 3.
1 footback.

Further, the drive device 4 includes a pulse generator 41, a pulse motor driver 42, and a pulse motor 43. The pulse generator 41 receives instructions from the computer 31 and generates pulses according to the instructions,
The pulse motor driver 42 receives pulses from the pulse generator 41 and operates the pulse motor 43.

Next, the operation of the computer 31 for controlling the gripping operation of the robot hand device will be explained with reference to the flowchart shown in FIG.

First, the drive device 4 is started (S-1).

Next, from the A/D converter 9 to the robot finger 11
input the distortion amount ε(1) into the computer 31 (S-2
), and the movement amount χ(1) of the robot finger 11 is input from the up/down counter 32 (S-3).

Next, the spring constant K of the object O is calculated using the following formula (S-4).

K=A・ε(t)/(B・χ(1)−ε(t))(A,
(B is a constant) Next, the control gain G is determined using a table (stored in the computer 31) of the relationship between the spring constant and the control gain G created through experience (S-5).

Next, the difference E between the current gripping force R and the target gripping force F of the robot finger 11 is calculated (S-6).

Next, the difference E obtained in S-6 above is multiplied by the control gain G obtained in S-5 to obtain the speed MS of the pulse motor 43,
That is, the opening/closing speed of the robot finger 11 is determined and sent to the pulse generator 41 (S-7). The pulse generator 41 converts the speed MS into a pulse,
The signal is sent to the pulse motor driver 42. This activates the pulse motor 43 to drive the robot finger ll in the opening or closing direction.

Then, a new strain amount ε(1
) and the opening/closing degree to the gain adjustment device M3 and repeating the steps S-2 to S-7 above, the robot finger 11 can adjust the opening/closing speed and the optimal target gripping force F according to the spring constant of the object O. Therefore, the object 0 can be grasped stably and quickly.

FIG. 4 is a characteristic diagram of step responses measured when the robot hand device grips a sponge with a small spring constant (a) and when it grips a weight with a large spring constant (b).

This figure also shows that in the above robot hand device, the target object is 0.
It is confirmed that the control gain G is automatically adjusted regardless of the magnitude of the spring constant of , and that the object 0 can be gripped stably and quickly.

(Effects of the Invention) As described above, according to the robot hand device of the present invention,
Since the control gain is automatically adjusted according to the spring constant of the object, the object can be stabilized and quickly fixed regardless of the size of the spring constant, even if the spring constant or hardness is unknown. can be grasped.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a robot hand device of the present invention, and FIG. 2 is a block diagram showing a specific example of the present invention. FIG. 3 is a flowchart showing the operation of the computer. FIGS. 4(a) and (b) are characteristic diagrams of measured step responses of the robot hand device of the present invention, and FIGS. 5(a) and (b).
) is a characteristic diagram showing a step response in the conventional example, and FIGS. 6(a) and 6(b) are characteristic diagrams showing other step responses in the conventional example. l...Robot Hunt. 11-...Robot finger. 2...Differentiator. 3...Gain adjustment device. 4... Drive device. O...Object. Stone 3 figure (a) Gi I (b) 7#Me〃Defense~! I Figure 4 (a) V I (b) M

Claims (1)

[Scope of Claims] A robot hand device that grips an object by opening and closing robot fingers, comprising: a robot hand equipped with a robot finger capable of detecting a gripping force when gripping an object; a differentiator that calculates the difference between the gripping force and the target gripping force; a spring constant of the object is determined from the opening/closing degree of the robot finger and the gripping force to determine a control gain, and the determined control gain is a gain adjustment device that determines the opening/closing speed of the robot finger by multiplying the difference calculated by the differentiator; and a drive device that opens and closes the robot finger based on the control gain and opening/closing speed determined by the gain adjustment device. A robot hand device characterized by: