JPH0528523Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical slip detection device, and particularly to a device that optically detects the slip of a workpiece held by a hand.

[Prior Art] Today, with the spread of robots, work using robot hands is widely performed in various fields.

However, unlike a human hand, a robot hand itself does not have a sensor function, so when a robot hand is used to grip a workpiece and perform a desired task, it is necessary to check whether the workpiece is properly gripped by the hand or not. It is necessary to constantly detect whether

In particular, when a robot hand is used to grip a workpiece, the gripped workpiece may slip due to an unbalanced center of gravity caused by variations in the gripping parts of the workpiece. It is necessary to reliably detect slippage and prevent it from falling.

For this reason, slip detection devices of, for example, the Tokyo Institute of Technology type, the Nagoya Institute of Technology type, and the Belgrade University type have been proposed.

The Tokyo Institute of Technology type detection device has a disk provided with a measurement slit that is brought into contact with a workpiece held by a robot hand, and a light emitting diode and a phototransistor are formed to face each other through the slit of the disk. ing.

By doing this, when the workpiece gripped by the robot hand slips, the disk rotates due to this slippage, and the optical path between the light emitting diode and the phototransistor is intermittently interrupted.
By detecting the pulse signal output from the phototransistor at this time, slippage of the workpiece can be detected satisfactorily.

In addition, the Nagoya Institute of Technology type detection device uses the roughness of the workpiece surface to detect slippage, and uses a sapphire needle fixed to the surface of a piezoelectric element to be pressed against the surface of the workpiece held by the hand. It is formed as follows.

By doing this, the slippage of the workpiece is transmitted to the piezoelectric element via the sapphire needle, and the slippage of the workpiece gripped by the hand can be detected satisfactorily based on the pressure change generated at this time.

Further, in the Belgrade large type detection device, an insulating portion is formed in a checkered pattern on the surface of a ball made of a conductive material, and this ball is rotatably pressed into contact with a workpiece held by a robot hand.

By doing this, by providing electrical output contacts on the two support frames of the ball, the rotation of the ball caused by the slipping of the workpiece is detected as an electrical signal, and the ball is gripped by the hand. This makes it possible to effectively detect slippage of the workpiece.

[Problems to be solved by the invention] However, all of these conventional slip detection devices measure the amount of slip by mechanically contacting a pick-up such as a disk, a sapphire needle, or a ball with a workpiece held by a hand. It is formed to measure.

For this reason, the surface of the workpiece to be measured must be almost smooth, and especially with the Tokyo Institute of Technology type and Belgrade type equipment, it is difficult to measure the slippage of workpieces with complex shapes. I was faced with an extremely difficult problem.

In addition, in all of the conventional devices described above, the pick-up is formed to mechanically detect slippage, so it is not possible to sufficiently reduce the size and weight of the entire device, and there is a problem that the degree of freedom in its installation is small. It was hot.

Furthermore, since all of the above-mentioned conventional devices are formed so that the pick-up mechanically contacts the workpiece measuring section, the contact resistance between the pick-up and the workpiece surface has a large effect on detection accuracy, and in particular, the workpiece surface may slip. In cases where the slippage of the workpiece is easy to measure, there is a problem in that the slippage of the workpiece cannot be measured with sufficient accuracy.

[Purpose of the invention] The present invention was devised in view of the above-mentioned conventional problems, and its purpose is to effectively prevent the slippage of the workpiece held by the hand without affecting the shape of the workpiece and without contact. An object of the present invention is to provide an optical slip detection device that can perform measurements.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a light projecting means that projects a detection light onto a workpiece held by a hand, and a light projector that receives reflected light from the workpiece and generates an electrical signal. The present invention is characterized by comprising: a light-receiving means for converting the light into a light-receiving means; and a calculating means for calculating the slippage of the workpiece with respect to the hand based on the detection signal of the light-receiving means, and detects the slippage of the workpiece gripped by the hand in a non-contact manner.

Here, the calculation means includes an integration circuit that integrates the output of the light receiving means, and a sample hold circuit that samples and holds the output of the integration circuit at predetermined time intervals, and the output of the integration circuit and the sample and hold circuit. It is preferable to calculate the amount of slippage of the workpiece relative to the hand by calculating the difference between the output and the output.

[Function] The present invention has the above configuration, and its function will be explained next.

According to the present invention, detection light is emitted from the light projecting means toward the workpiece held by the hand, and the detection light reflected by the workpiece is received by the light receiving means.

At this time, if there is almost no slippage on the workpiece, there is almost no change in the amount of light received by the light receiving means, but if slippage occurs in the workpiece, the amount of light received by the light receiving means changes.

In the present invention, by calculating such a change in the amount of received light using a calculation means, it is possible to accurately detect and measure the slippage of a workpiece held by the hand without contact.

In particular, according to the present invention, this slippage can be measured in a non-contact manner without requiring any mechanical contact with the workpiece, so even if the workpiece has a complex shape, the slippage can be easily measured. In addition, the entire device can be made smaller and lighter,
The degree of freedom of attachment to the hand can be increased, and furthermore, slippage can be detected favorably without being affected by slip resistance on the workpiece surface.

[Example] Next, a preferred example of the present invention will be described based on the drawings.

FIG. 2 shows a preferred embodiment of the robot hand, and the robot hand 12 of the embodiment includes:
The workpiece 16 is configured to be gripped using a plurality of fingers 14.

Here, each finger 14 is connected by a pin 18.
The fingers 14 are rotatably fixed to the shaft, and each finger 14 has a plurality of claws 20 on the opposing inner surfaces thereof for gripping the workpiece 16.
is installed protrudingly.

Also, the cylinder 22 of this robot hand 12
A rod 24 is housed inside so as to be movable in the vertical direction in the figure, and the tip of the rod 24 is connected to the link 2.
6 to the upper end of each finger 14.

With the above configuration, by moving the rod 24 downward in the figure, each finger 14 opens in a V-shape via the pin 18, and the grip on the workpiece 16 is released.

Conversely, when the rod 24 is moved upward in the figure, each finger 14 is controlled to rotate in the opposite direction to the previous one, and the claw 20 is used to press the workpiece 16 with a predetermined pressing force. You will have to grasp it.

By the way, when gripping the workpiece 16 using the robot hand 12 in this way, the workpiece 16
Due to variations in the grasping part of the robot hand 1 or various other causes, the grasped workpiece 16 may be
There are cases where it slips from 2.

The characteristic feature of the present invention is that the work 16
The purpose of this technology is to optically detect slippage in a non-contact manner.

Therefore, in the present invention, a light emitting means for irradiating detection light onto the workpiece 16 held by the robot hand 12, and a light receiving means for receiving reflected light from the workpiece and converting it into an electrical signal are provided. The slippage of the workpiece 16 with respect to the hand 12 is detected based on the change in the amount of light received.

In the embodiment, an LED is used as the light emitting means.
A light-emitting element 30 such as the above is used, and a light-receiving element 32 such as a phototransistor is used as a light-receiving means.

These light receiving elements 30 and 32
is provided on the inner surface of the finger 14 between the nails 20, the light emitting element 30 emits detection light towards the workpiece 16, and the light receiving element 32 receives reflected light from the workpiece 16. It outputs an electrical signal according to the amount, and outputs the output signal to the arithmetic circuit 40.

In the present invention, the arithmetic circuit 40 operates the robot hand 12 based on the detection output of the light receiving element 32.
It is formed to calculate the slippage of the workpiece 16 relative to the workpiece 16.

FIG. 1 shows a specific configuration of this arithmetic circuit 40, and FIG. 3 shows output signal waveform diagrams at various parts of the circuit. Here, FIG. 3A shows a signal waveform when slippage occurs in the workpiece 16, and FIG. 3B shows a signal waveform when there is no slippage in the workpiece 16.

First, as shown in FIG. 3, the detection signal A output from the light-receiving element 32 contains noise components due to vibrations of the robot hand 12 and the workpiece 16. This may lead to incorrect calculations being performed. Therefore, the detection signal A of the light receiving element 32 is
After the noise component is removed via the integrating circuit 42, the signal is outputted via the amplifier 44 to a sample hold circuit 46 and a subtraction circuit 48, respectively.

The sample and hold circuit 46 samples and holds the output C of the amplifier 44 in synchronization with the clock pulse E output from the oscillation circuit 50, and the subtraction circuit 4
Output to 8.

That is, this sample hold circuit 46 is
When the clock pulse E output from the oscillation circuit 50 is at the H level, the output of the amplifier 44 is held and output to the subtraction circuit 48, and when the clock pulse E is at the L level, the output from the amplifier 44 is held and output to the subtraction circuit 48. 44's output C as it is as a subtraction circuit 48
Output to.

Therefore, if there is no slippage in the workpiece 16, the signal D output from the sample and hold circuit 46 matches the output C of the amplifier 44 as shown in FIG. is 0
becomes.

On the other hand, if slipping occurs in the workpiece 16, as shown in FIG. The signal F outputted has a value corresponding to the amount of slippage of the workpiece 16 per unit time.

The output signal F of the subtraction circuit 48 is input to a determination circuit 52 in which a reference value δV for slip detection is set in advance.
During the period in which the absolute value of the output signal F exceeds the absolute value of the reference value δV, the detection pulse signal G at H level is output.

Therefore, according to the apparatus of this embodiment, the workpiece 16
When there is no slippage in the workpiece 16, no pulse signal G is output from the determination circuit 52, and on the contrary, when there is slippage on the workpiece 16, a detection pulse having a pulse width corresponding to the amount of slippage is output. Signal G
will be output.

In this way, according to this embodiment, the determination circuit 52
Since the amount of slippage of the workpiece 16 can be detected based on the output G of the robot hand, it is possible to perform various controls based on this detection signal. , when the workpiece 16 slips, the gripping force of the robot hand section 12 is increased,
It becomes possible to control this so that it can be gripped reliably.

In this embodiment, the calculation circuit 40 is configured as shown in FIG. 1, but the present invention is not limited to this, and any circuit configuration can be adopted as long as it is possible to detect slippage of the workpiece based on the detection output of the light receiving element 32.

[Effects of the invention] As explained above, according to the invention, slippage of a workpiece held by the hand can be detected without contacting the workpiece, so that slippage can be detected even for workpieces with complex shapes. It is possible to perform the slip detection well, and also to perform this slip detection well without affecting the frictional resistance of the workpiece surface. Further, according to the present invention, since there is no mechanical contact portion with respect to the workpiece, it is possible to detect the slippage of the workpiece more accurately without being affected by the frictional resistance on the surface of the workpiece.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of the optical slip detection device according to the present invention, FIG. 2 is a schematic explanatory diagram of a robot hand equipped with the optical slip detection device of this embodiment, and FIG. 3 2 is a diagram of output signal waveforms at various parts of the circuit of the device shown in FIG. 1. FIG. 12... Robot hand, 16... Work, 3
0... Light emitting element, 32... Light receiving element, 40... Arithmetic circuit, 42... Integrating circuit, 46... Sample hold circuit, 48... Subtraction circuit, 50... Oscillation circuit, 52... Judgment circuit.

Claims (1)

[Claims for Utility Model Registration] Light projecting means for projecting detection light onto a workpiece held by a hand; light receiving means for receiving reflected light from the workpiece and converting it into an electrical signal; and an electrical signal from the light receiving means. calculation means for calculating the slippage of the workpiece relative to the hand based on the above, the light projecting means and the light receiving means are provided in a portion that does not contact the workpiece held by the hand, and the calculation means comprises: an integrating circuit that integrates the output of the light receiving means; a sample-hold circuit that samples and holds the output of the integrating circuit at predetermined time intervals; and a subtraction circuit that calculates the difference between the output of the integrating circuit and the output of the sample-hold circuit; The output of the subtraction circuit is compared with a preset reference value, and when the output of the subtraction circuit exceeds the absolute value of the reference value, it is determined that the workpiece is slipping, and during that period An optical slip detection device comprising: a determination circuit that outputs a detection pulse signal;