JPS5932276B2 - industrial robot hand - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an industrial robot hand.

More specifically, a pressure-sensitive resistor made of conductive metal particles and an elastic polymer material is attached to the entire finger of the robot, and
This relates to a robot hand with contact points arranged at regular intervals. General industrial robots are not only an extremely important technology for automating production and saving labor, but are also essential equipment for handling radioactive and toxic substances.

However, since conventional industrial robots do not have sensory abilities, they have the disadvantage that, although they are effective in welding and other tasks, they cannot be operated properly when it comes to complex tasks such as assembly. In other words, the scope of work was limited due to a lack of ability to cope with the work, and for example, they were clumsy and unable to perform basic tasks such as fitting, which would be trivial for a human. Recently, there has been an increasing amount of research into giving machines their own senses, such as vision and touch. That is, there is a desire for the emergence of intelligent robots that can respond to changes in the external world according to perceived recognition results. For intelligent robots, information from the outside world comes first.
The problem is whether the process can be accurately grasped, and how quickly the work can be corrected in response.

To do this, it is necessary to accurately grasp the condition of the parts while performing the work, and it is necessary to provide the robot with senses such as sight, touch, and hearing. As a visual recognition method, a method has been developed that uses a television camera as a visual.

That is, by introducing the television image to a computer and having it recognize its shape and positional relationship, it is possible to correspond to the work procedure. Additionally, systems have been developed that allow quality checks to be performed by recognizing dirt, scratches, etc. that exist on work objects. As a means of tactile recognition,
Various strain gauges, pressure-sensitive transistors, piezo elements, microswitches, etc. have been proposed to be used as tactile elements, and to confirm whether the robot has grasped a part, it can be accompanied by turning the microswitch ON10FF. There is.

However, none of them has been able to satisfy the essential characteristic of the sense of touch, which is that pressure is recognized as a sensation only after receiving external deformation. When working with a robot, the first step is to grasp the parts in order to supply them, and in conventional technology, as mentioned above, a microswitch attached to the robot's palm is turned ON10F.
It was normal to get an F rating.

However, the microswitch is ON10F at one point.
Although it exerts enough power to confirm F, it was necessary to install multiple microswitches in order to determine how the fingers of the robot's hand as a whole were grasping the parts. However, increasing the packaging density of microswitches would complicate the specifications of the robot's palm, creating a major problem in practical use. Furthermore, even if the part is grasped accurately, the part to be grasped is covered with a hard surface such as metal, so while this is not a problem when grasping hard metal parts, it is difficult to grasp soft or easily broken parts. When grasping parts, special processing was required, such as attaching a diaphragm to the microswitch and covering the palm with a soft material. In order to eliminate such drawbacks, Japanese Patent Application Laid-Open No. 49-92757 has been proposed, and this invention uses a gripping surface of at least one of a pair of movable members as a common electrode made of a conductive elastic material. This hand part for a robot is formed by arranging a large number of linear or dotted electrodes facing a common electrode and filling the space between the two electrodes with a resistive powder, for example, Si powder. However, in the robot arm of the present invention, one of the electrodes is used as a common electrode, and a powdered resistor is filled between the two electrodes, so the sensitivity is low and hysteresis is likely to occur during repeated deformation. However, in order to prevent this, a method was required to pressurize the resistor powder in advance. In order to solve the above-mentioned drawbacks of the prior art, the present invention disposes a pressure sensitive resistor in which conductive fine particles are dispersed and mixed in silicone rubber on the gripping surface of the robot's fingers.
Where do both sides of the pressure-sensitive resistor correspond to each other? Multiple contacts are arranged for each. Therefore, it is an object of the present invention to provide an industrial robot hand that can recognize the shape of an object to be grasped, prevent destruction of the object, and control the grasping force.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 1 shows an outline of the structure of a robot hand in an industrial robot.

1 indicates an arm, a base 2 is attached to one end of the arm, and fingers 3, 4, and 5 are attached to this base.

The fingers 3, 4, and 5 are each driven in the direction of the arrow by a connected drive device, and perform the work of grasping parts and the like. FIG. 2 is an enlarged view of the finger 4.

Fingers 3 and 5 also have a similar structure, so a description thereof will be omitted here. The structure of the finger 4 includes a base 6, a printed circuit board 7 bonded to the base, a pressure sensitive resistor 8, a flexible printed circuit board 9,
It consists of a flexible insulating sheet 10. Metal contacts (A-1) are arranged on the printed circuit board 7 as shown in the figure. Similarly, metal contacts NV are arranged on the flexible printed circuit board 9 at positions facing the contacts A-1. The pressure sensitive resistor 8 exhibits a decrease in resistance value as shown in FIG. 3 depending on pressure. The pressure sensitive resistor 8 used in the present invention is made of silicone rubber, SB
Fe, Ni, Cr, Ag, Au. It can be easily obtained by dispersing and mixing conductive metal fine particles such as Cu at a volume fraction of about 10 to 40%. The pressure-sensitive resistor 8 is made of a material that is elastically deformed by applied pressure and has a characteristic that electrical resistance changes. As a tactile element for robots, it is desirable to have good durability against repeated deformation, low compression set, etc., and excellent properties in terms of heat resistance, chemical resistance, etc.
From these points of view, it is desirable to use silicone rubber as the polymeric elastic material.

According to the industrial robot hand of the present invention, FIG. 4 shows the current pattern when gripping a certain part (not shown). A current flows through F/ as shown by the dotted line (in this case, the lower limit recognition current is set to 10 mA).

) indicates that the part position is accurate. Furthermore, if the part is held in the wrong position, if current flows through a contact other than the contact FF', such as a contact DD' or GG', this indicates that the part is in a wrong position. Furthermore, as fingers 3, 4, and 5 firmly grasp the part, the contacts AA', BB', EE'
, FF'GG' indicates that the parts are securely grasped. For example, contact CC other than this pattern
If a current flows through ′, the shapes of the parts are different. For example, if no current flows through contact BB', there is a defect in the component. As the pressure on the fingers 3, 4, and 5 gradually increases, the resistance value of the pressure-sensitive resistor 8 gradually decreases as shown in Figure 3, so the current value becomes extremely large at the contact point FF'. . The current value is within a certain limit (in this case 40
Set to mA. ), the fingers 3, 4, and 5 stop driving, and no further pressure is applied to the gripped parts. Therefore, the parts can be supplied to the next process in a completely protected form. As described above, according to the present invention, since it is possible to increase the density of the switch portion, 0N/0F of each point
F allows the shape of the item to be accurately grasped.

Also, by detecting the upper limit current for the grasped object,
Appropriate pressure can be detected, thereby preventing material destruction. Furthermore, by utilizing the property that the resistance value decreases with pressure, the application of excessive pressure to the parts can be prevented by stopping the finger drive when a current exceeding a certain value flows. Furthermore, new functions that could not be considered with robot hands using conventional microswitches can be added to the robot, making it possible to automate and improve the precision of assembly work. In particular, the present invention uses a pressure-sensitive resistor in which conductive fine particles are dispersed and mixed between the movable contact and the fixed contact, so it has high durability against repeated deformation, low compression set, and high heat resistance and chemical resistance. Combined with the fact that a plurality of contacts are arranged at mutually corresponding positions on both sides of the pressure-sensitive resistor, it is possible to precisely and highly sensitively recognize the shape of the object to be grasped, prevent destruction, and control the grasping force. It can be performed.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an industrial robot hand according to an embodiment of the present invention, FIG. 2 is an enlarged view of a part of the finger in FIG. 1, and FIG. FIG. 4 is a characteristic diagram showing resistance value characteristics, and is a diagram showing current values at various parts of the fingers when gripping a component. 1... Arm, 2, 6... Base, 3, 4, 5...
- Finger, 7, 9... Printed circuit board, 8... Pressure sensitive resistor, 10... Insulating sheet, A-1, A' to F... Metal contact.

Claims (1)

[Claims] 1 A pressure-sensitive resistor made of conductive particles dispersed in silicone rubber is placed on the gripping surface of the robot's fingers, and
An industrial robot hand characterized in that a plurality of contacts are arranged at mutually corresponding positions on both sides of the pressure-sensitive resistor.