JPH04354690A - Robot hand - Google Patents

Abstract

PURPOSE:To detect each operating force in response to each operating action with a single voltage detecting circuit by constituting a composite bridge circuit with distortion-sensitive resistive elements for detecting each operating force of holding force, pressing force and rotating force. CONSTITUTION:Distortion-sensitive resistive elements G1, G2, P1, P2, T1-T4 stuck on a robot hand for detecting the holding force, pressing force and rotating force respectively, a composite bridge circuit 10 including the distortion- sensitive resistive elements for detecting the holding force, pressing force and rotating force, and a voltage detecting means 12 detecting the output voltage of the composite bridge circuit 12 are provided. The holding force, pressing force and rotating force are detected respectively from the change quantity of the output voltage of the voltage detecting means 12 at the time of holding, pressing and rotating actions.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot hand, and more particularly to a robot hand that can detect gripping, pressing, and rotating forces with a simple configuration.

0002

2. Description of the Related Art FIG. 7A is a diagram showing an example of a two-fingered robot hand having a gripping force detection function. Strain-sensitive resistive elements 3 and 4, such as strain gauges, are attached approximately to the center of the fingers 1 and 2. When a workpiece is gripped by such a robot hand, the elements 3 and 4 are deformed in proportion to the gripping force, and the resistance values of these strain sensitive resistance elements also change in accordance with the amount of deformation. Using these strain sensitive resistive elements 3 and 4 and known resistors 5 and 6, (
If a bridge circuit is configured as shown in b), the resistance values of elements 3 and 4 will change according to the gripping force of the robot hand, so changes in the potential difference between two points a and b of this bridge circuit can be detected. By doing so, it is possible to detect the gripping force.

[0003] In addition, by attaching another strain-sensitive element to the tip of the finger to detect the pressing force by the finger, or by attaching another strain-sensitive element to an appropriate position on the robot hand, rotational force ( torque force).

0004

[Problem to be Solved by the Invention] As mentioned above, when trying to detect various acting forces such as gripping force, pressing force, and rotational force with one robot hand, the circuit for detecting each acting force is need to be provided separately, which complicates the circuit configuration, and since detection voltages are obtained for each detection circuit, microprocessor software that controls various movements of the robot hand according to these detection voltages is also required. It will be necessary to completely rewrite it. Furthermore, when interaction occurs between the strain-sensitive resistance elements for detecting each acting force, for example, strain occurs in the resistance element for detecting pressing force or rotational force due to a gripping operation, making it difficult to accurately measure each acting force. becomes difficult.

[0005] Accordingly, an object of the present invention is to provide a robot hand that can detect various acting forces such as gripping force, pressing force, and rotational force with a simple configuration.

Another object of the present invention is to provide a robot hand that can independently and accurately detect only specific acting forces such as gripping force and pressing force.

[0007]

[Means for Solving the Problems] The robot hand of the present invention improves the gripping force by simply adding a simple configuration to the conventional robot hand that can perform operations such as gripping, pressing, and rotating a workpiece. It has an added function to effectively detect acting forces such as pressing force and rotational force. That is, the configuration of the present invention includes a strain-sensitive resistance element for detecting gripping force, pressing force, and rotational force that is attached to a robot hand and detecting gripping force, pressing force, and rotational force, respectively; and a composite bridge circuit including a strain-sensitive resistance element for detecting rotational force, and voltage detection means for detecting the output voltage of this composite bridge circuit, and the output voltage of the voltage detection means during each operation of gripping, pressing, and rotating. This is a robot hand that detects gripping force, pressing force, and rotational force from the amount of change in .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of a preferred embodiment of the present invention. The composite bridge circuit 10 is composed of a strain-sensitive resistive element attached to a two-fingered robot hand. These strain sensitive resistance elements are G1 and G2 for detecting gripping force, P1 and P2 for detecting pressing force, and rotational force (torque force).
These are T1, T2, T3 and T4 for detection. In this way, two strain-sensitive resistance elements are used to detect the gripping force and the pressing force, and four strain-sensitive resistance elements are used to detect the rotational force, but it is clear that the present invention is not limited to this embodiment. Yes, and in the minimum configuration, one strain-sensitive resistive element may be used for each applied force. A pair of output voltages of the composite bridge circuit 10 are respectively supplied to differential input terminals of a differential amplifier 12, and the output voltage of the differential amplifier 12 is applied to an analog-to-digital converter (ADC).
) 14 into corresponding digital data. This digital data is supplied to the control device 16 including a microprocessor, and based on this data, the control device 1
6 controls the drive device 18 of the robot hand.

The arrangement of each strain sensitive resistance element in this composite bridge circuit 10 should be determined depending on how it is attached to the robot hand. For example, if we consider a bridge circuit made up of only T1, T2, T3, and T4 for detecting rotational force, T1 is placed in an opposing relationship with T4, and placed in an adjacent relationship with T2 and T3. has been done. In this case, when a rotational force is applied to the hand, the resistance values of T1 and T4 at opposite positions change in the same direction, and the resistance values of T1 and T2 at adjacent positions change.
The resistance values of 3 should be attached to the hand so that they change in opposite directions. By arranging the strain sensitive resistive elements in this manner, the output voltage (V1-V2) of the bridge circuit changes most sensitively in proportion to changes in rotational force, and measurement accuracy can be improved. Similarly, G1 for grip force detection
and G2, and P1 and P2 for detecting the pressing force are arranged at mutually opposing positions because the resistance values of these G1 and G2 and P1 and P2 change in the same direction according to changes in the gripping force and the pressing force, respectively. This is because it is affixed so that it does. In addition, in the bridge circuit 10 of FIG. 1, P1 and T
1, P2 and T4, G1 and T2, and G2 and T3
Although these elements are connected in parallel with each other, it should be noted that it is also possible to detect each acting force by connecting these elements in series to form a composite bridge circuit.

FIG. 2 shows an example of a procedure for the microprocessor in the control device 16 of FIG. 1 to detect and control each acting force in response to the gripping, pressing, and rotating movements of the robot hand. This is a flowchart. First, in step 20, the control device 16 controls the operation of the robot hand based on a control program. In the next step 22, the ADC
The data of the acting force from 14 is measured, and in the next judgment step 24 it is judged whether or not a gripping operation is being executed. If a gripping operation is in progress, in step 26 the gripping force is increased or decreased to be adjusted to a desired value. If it is determined in step 22 that the gripping operation is not in progress, it is determined in step 28 whether or not the pressing operation is in progress, and if YES, the pressing force is adjusted in step 30, and if NO, it is determined in step 32 whether or not the rotation is in progress. be judged. If YES in step 32, the rotational force is appropriately controlled in step 34. After executing each of the controls in steps 26, 30, and 34, the process returns to step 20 to control the motion of the robot hand again. If no in step 32, it is determined in step 36 whether or not the predetermined motion of the robot hand has been completed, and the above-described motion is repeated until the determination is YES.

FIG. 3 is a diagram showing the configuration of a two-fingered robot hand with a gripping force detection function according to the present invention. The two fingers 40 and 40' are connected to rotation axes 41 and 4.
1', it is rotatably connected to the hand body 42. Pulleys 44 and 44' are provided at the ends of these two fingers, respectively, and these two pulleys abut with appropriate pressure against a tapered surface 47 at the tip of a drive rod 46 that is reciprocated by a drive device. A spring 48 is engaged between the fingers. As the drive rod 46 reciprocates, the pulleys 44 and 44' rotate on the tapered surface 47, thereby controlling the gripping motion of the fingers 40 and 40'. The fingers 40 and 40' are further formed with thinner portions 50 and 50', respectively, approximately at the center thereof. Both ends of the flexible thin plates 52 and 52' are connected to the fingers 40 and 4 so as to be spaced apart substantially parallel to the inner surfaces 51 and 51' of these thin parts.
They are each fixed at 0'. These thin plates 52 and 52'
Strain sensitive resistive elements 54 and 54' are pasted thereon. When the workpiece 55 is gripped by the tips of the fingers 40 and 40', the thin part 50 of the fingers is proportional to the gripping force.
and 50' are elastically deformed, with the inner surfaces 51 and 51' being the principal strain surfaces that deform most, especially in the thinner parts. A thin plate 52 spaced apart approximately parallel to these principal strain planes 51 and 51'
and 52' are deformed more greatly, so the strain-sensitive resistors 54 and 54' attached to the thin plates are deformed in proportion to the gripping force, and the output voltage of the bridge circuit composed of these strain-sensitive resistors is proportional to the gripping force. changes extremely sensitively in proportion to These strain sensitive resistive elements 54 and 54' correspond to G1 and G2 in the bridge circuit 10 of FIG. It is. In addition, fingers 40 and 4
It is desirable that the central axes of the fingers 40 and 40' and the central axes of the thin parts 50 and 50' coincide so that the thin parts are not deformed when the workpiece is pressed with the tip of the fingers 40 and 40'. With the above configuration, the robot hand shown in FIG. 3 can sensitively detect only the gripping force.

By improving the finger portion of the robot hand shown in FIG. 3, a robot hand that can easily detect pressing force can be realized. FIG. 4 shows an example of a finger structure suitable for effectively detecting pressing force. Figure 4
(a), (b) and (c) respectively show a side view, a top view and a bottom view of one finger. Three shafts 63, 64 and 65 connect the finger tip 60 and the finger main body 62. The central shaft 63 has one end fixed to the finger tip 60, the other end slidable with the finger body 62, and the other end protruding into a hollow 66 formed at the center of the finger body. A stopper 68 is provided at the end to prevent the finger tip 60 from falling off. Shafts 64 and 6
5 has one end fixed to the finger main body 62 and the other end slidably connected to the finger tip 60. Further, one end of the flexible thin plate 70 is fixed to the bottom surface of the finger body 62, and the other end is fixed to the finger tip 60.
is in contact with the end face of A strain sensitive resistance element 72 for detecting pressing force is pasted on this flexible thin plate 70. The finger in FIG. 4 is shown in a state in which the finger tip 60 presses the workpiece and the tip is slightly retracted toward the finger body. The flexible thin plate 70 is elastically deformed in proportion to this pressing force, and the pressing force can be detected by the strain sensitive resistance element 72 according to the amount of deformation. When the pressing operation of the finger is completed, the finger tip 60 slides to a position where it stops at the stopper 68 due to the elastic restoring force of the flexible thin plate 70. When a robot hand is constructed using two such fingers, the two strain-sensitive resistive elements deform in the same direction according to the pressing force, so that the two strain-sensitive resistive elements deform in the same direction according to the pressing force. By placing it in a certain position, the pressing force can be detected sensitively. Furthermore, with this structure, there is almost no influence from gripping force or rotational force, and only the pressing force can be accurately detected.

FIG. 5 is a side view of another embodiment of the finger portion with a pressing force detection function. In the finger shown in FIG. 5A, a cavity 82 is formed in the finger main body, and a shaft 84 passes through the interior of this cavity 82.
The distal end portion of 4 is formed to be slidable with the finger distal end portion. One end of the flexible thin plate 87 is the finger tip 8
The other end of the thin plate 87 is formed to be slidable on the shaft 84 in the cavity. Furthermore, a spring 88 is provided in a compressed state around the shaft 84 in the cavity 82, and the other end of the flexible thin plate 87 is connected between one end of the spring 88 and the inner wall surface of the cavity 82. It is being pinched. Further, a strain sensitive resistance element 89 for detecting pressing force is attached on the thin plate 87. When the tip 86 of this finger presses the workpiece, the other end of the flexible thin plate 87 is held between the inner wall surface of the cavity and the spring 88, so the pressing force Fp is applied from the spring 88 to the thin plate 87. Until the received force Fs is reached, the thin plate 87 is elastically deformed in proportion to the pressing force, and the strain sensitive resistance element 89 can detect the pressing force. When the pressing force Fp of the finger exceeds Fs, not only the flexible thin plate 87 but also the spring 88 is compressed, so the finger tip 86 retreats according to the pressing force Fp, and a pressing force detection finger with a compliance function for the pressing operation is formed. becomes.

FIG. 5(b) is similar to the embodiment of FIG. 5(a), except that the cavity 82' is formed in the finger tip 86' and the spring 88 disposed around the shaft 84'. ′
One end of the thin flexible plate 87' is held between the inner wall surface of the gap 82' and the other end of the thin plate 87' is fixed to the bottom of the finger main body 80'. One end of the shaft 84' passes through the gap 82' at the tip of the finger and is fixed to the tip 86' of the finger, and the other end of the shaft is formed to be slidable with the body of the finger 80'. The operation of the finger in (b) is exactly the same as the operation of the finger in (a). In the embodiments shown in FIGS. 5(a) and 5(b), parts of the flexible thin plates 87 and 87' are held between the inner wall surface of the cavity and the spring, so there is no fear that the tips of the fingers may fall off. There is no need for a stopper.

FIG. 6 shows an embodiment of a robot hand with a rotational force (torque force) detection function, in which (a) is a side view and (b) is a view cut along the line segment X-Y. FIG. The hand section 90 and the drive section 92 are connected by four cylindrical support shafts 93, and both ends of flexible thin plates 94 and 95 are fixed respectively. Strain sensitive resistive elements 96 and 9 are disposed on these flexible thin plates 94.
7 is pasted crosswise in a letter X shape. Similarly, strain-sensitive resistive elements 98 and 99 are cross-attached on the flexible thin plate 95 as well. These strain-sensitive resistance elements 96, 97, 98, and 99 correspond to T1, T2, T3, and T4, respectively, of the bridge circuit 10 in FIG. It is attached so that when T1 and T4 expand, T2 and T3 contract. As a result, a robot hand having a measurement function that is extremely sensitive to rotational force can be easily realized. Furthermore, the detection mechanism shown in FIG. 6 hardly reacts to gripping force and pressing force, and can accurately detect only rotational force.

By combining the embodiments shown in FIGS. 3 to 6, it is possible to easily realize a robot hand having a function of detecting each of the gripping force, pressing force, and rotational force. Then, by configuring the strain sensitive resistance elements for detecting each acting force as in the composite bridge circuit 10 shown in FIG. 1, and controlling them according to the procedure shown in the flowchart shown in FIG. 2, it is possible to easily and accurately use a single voltage detection circuit. It becomes possible to detect each acting force.

[0017]

[Effects of the Invention] The robot hand of the present invention has a gripping force,
A composite bridge circuit is constructed with strain-sensitive resistance elements for detecting each acting force of pressing force and rotational force, and each acting force can be detected in response to each acting operation with a single voltage detection circuit.
Configuration becomes easier. Further, the above-described mechanisms for detecting the gripping force, pressing force, and rotational force can accurately detect only the corresponding acting force, and can be easily combined into one hand for use.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a flow chart showing an example of the operation of the control device in FIG. 1;

FIG. 3 is a diagram illustrating an embodiment of a robot hand with a gripping force detection function.

FIG. 4 is a diagram of an embodiment of a robot hand finger suitable for detecting pressing force.

FIG. 5 is a diagram of another embodiment of a robot hand finger suitable for detecting pressing force.

FIG. 6 is a diagram showing the configuration of an embodiment of a robot hand suitable for detecting rotational force.

FIG. 7 is a diagram showing an example of a conventional robot hand with a gripping force detection function.

[Explanation of symbols]

10 Composite bridge circuit 12 Differential amplifier 14 Analog-to-digital converter 16 Control device 18 Robot hand drive device

Claims (5)

[Claims] Claim 1: In a robot hand that can perform operations such as gripping, pressing, and rotating a workpiece, a gripping force and a pressing force are attached to the robot hand to detect the gripping force, pressing force, and rotational force, respectively. and a composite bridge circuit including a strain-sensitive resistance element for detecting rotational force, a strain-sensitive resistance element for detecting the gripping force, pressing force, and rotational force, respectively, and voltage detection means for detecting an output voltage of the composite bridge circuit. A robot hand comprising: a gripping force, a pressing force, and a rotational force, each of which is detected from the amount of change in the output voltage of the voltage detection means during each of gripping, pressing, and rotating operations. 2. A thin part formed in a part of a finger that grips a workpiece, the center axis of which is substantially common to the finger, and a thin part that is separated approximately parallel to a principal strain plane of the thin part during a gripping operation,
A gripping force-sensitive robot hand comprising: a flexible thin plate whose both ends are fixed to the fingers; and a strain-sensitive resistance element pasted onto the thin plate. 3. A shaft fixed to either one of a finger tip that presses a workpiece and a finger main body mechanically connected to a drive mechanism and slidable with the other; and the finger tip and the finger main body. 1. A pressing force-sensitive robot hand comprising: a flexible thin plate member fixed and abutted to one and the other of the parts; and a strain-sensitive resistance element affixed to the thin plate member. 4. A shaft fixed to either one of the tip of the finger that presses the workpiece and the main body of the finger mechanically connected to the drive mechanism, and formed to be slidable with respect to the other; and the shaft is fixed. A gap is formed in one of the finger tip and the main body, and elastic means for applying a predetermined force to a pair of opposing inner wall surfaces perpendicular to the axis of the finger of the gap; One end is held between the elastic means and an inner wall surface near the other of the finger tip and the main body within the inner wall surface of the finger, and the other end is fixed to the other of the finger tip and the main body. A pressing force sensitive robot hand comprising a flexible thin plate body and a strain sensitive resistance element affixed on the thin plate body. 5. A robot hand comprising: a hand portion capable of gripping a workpiece; and a drive mechanism portion transmitting rotational force for rotating the workpiece gripped by the hand portion around a central axis of the hand portion. A support means connected between the hand part and the drive mechanism part, a flexible thin plate body connected between the hand part and the drive mechanism part, and a flexible thin plate body attached to the thin plate body. A rotational force sensitive robot hand characterized by comprising a strain sensitive resistance element.