SU1269995A1 - Method of monitoring presence of work in robot grips - Google Patents

Abstract

The invention relates to robotics, in particular, to controlling the presence of a part in robotic manipulators using capture mechanisms with energy accumulation by an elastic element of the part ejection mechanism, and can be used to create flexible automated productions. The aim of the invention is to increase the reliability of control of the part in the gripping mechanism in difficult process conditions and to simplify the device for controlling the presence of the part in the gripping of the robot. The method of controlling the presence of a part is based on the difference between the transient movement of the gripping mechanism with the part and without the detail by changing the structure of the differential equation of the transient movement caused by the absence or presence of a torque component from the elastic element of the gripping mechanism of the robot, 2 or less.

Description

Yu

O5 CO

CO co

The invention relates to robotic systems and may find application in the construction of flexible automated modules.

The aim of the invention is to improve the reliability of control of the presence of parts in the capture of the robot in difficult technological conditions and simplify the control device.

The proposed method of controlling the presence of a part is based on the change in the speed increment of the gripping mechanism in a transient process when the compressed elastic element of the ejection mechanism is fixed (the gripping mechanism has clamped the part) and in the absence of its fixation by changing the structure of the differential equation of the transient motion caused by the absence or presence of the components of the moment of force from the action of the elastic element of the mechanism for pushing the gripper of the robot.

During normal operation of the gripping mechanism (the part is clamped), the motion equation of the motor shaft when moving with the part has the form

AljsB-Ms G7sb, where M in - the moment developed on the shaft

electric motor; MS - the moment of external and internal

forces acting on the drive, 3 — total moment of inertia of moving parts, reduced to the motor shaft;

and - angular acceleration of the electric drive. In case of failure of the gripping mechanism of the part (x etal is not clamped), the movement equation of the motor shaft when moving without part has the form

Mln - Ms4- a ,, 3a,

de a „is the moment developed by the elastic element and reduced and reduced to the shaft of the electric motor; I-reduced stiffness coefficient of the elastic element; - the angle of rotation of the shaft of the electrolyte when the working stroke of the elastic element.

Thus, in case of failure of the gripping mechanism, the moment developed by the compressed elastic element acts according to the torque of the electric motor and changes the acceleration of the movement of the gripping mechanism in the transient process towards its increase. The magnitude of the movement acceleration is recorded based on internal information sensor data. As a reference value, the comparison takes the value of the acceleration of the movement of the locking mechanism during its movement without detail, i.e. The proposed method of controlling the availability of parts does not depend on its weight.

FIG. 1 is a functional diagram of a possible technical implementation.

the way to control the availability of parts in the gripping mechanism; in fig. 2 shows transient curves of the speed of movement of the locking mechanism.

The proposed method can be implemented, for example, using the capture mechanism 1. The gripping mechanism consists of two tongs 2 and 3, located at an angle of 90 ° in the movable body 4. Each tong is equipped with three movable cams 5, springs 6 and a pusher 7, which serves to install the part 8 into the machine chuck.

The movement mechanism 9 provides the forward movement of the capture mechanism 1 and is connected to the electric motor 10, on whose shaft the movement sensor 11 is fixed (a photo-pulse sensor). A movement sensor 11 is connected by an electric circuit to a speed measuring unit 12, the output of which is mated to a differentiation unit 13. The output of the unit 13 is connected to the first input of the comparator unit 14 by an electrical circuit, the second input of which is connected to the unit 15 of the reference setpoint. The output of the block 14 by an electric circuit connected to the block

 16, which contains a command board, a power amplifier and a digital display board.

The device for controlling the presence of parts in the gripping mechanism works as follows.

0 From the control device 16, a command is sent to move by a given amount of the capture mechanism 1 to the pick-up area of the part 8. The signal goes through the power amplifier to the electric motor 10, which causes the displacement mechanism 9 to move and the part capture mechanism 1 attached to its shaft. When the pick-up mechanism 1 moves, the displacement sensors 11 produce electrical impulses, which are fed to the velocity measuring unit 12. When working out

0 of the predetermined movement, the block 16 generates a command to stop the engine 10. In this position, the part 8 presses the springs 6 of the gripper 2 by means of the stroke of the stroke 8 via the pusher 7. After the shutdown phase of the part gripping mechanism 1, the control device 16 generates a command for clamping the part 8 by cams 5, which is detached using a pneumatic system integrated into the gripping mechanism. After the clamping phase of the part is completed, the control device 16 outputs a signal to move the locking mechanism 1. The motor 10 drives the movement mechanism 9 and the part locking mechanism. From the movement sensor 11, pulses corresponding to the magnitude of the movement of the capture mechanism I,

5 enters speed measurement unit 12. The magnitude of the speed from the block 12 enters the block 13 of the speed differentiation. From block 3, the magnitude of the derivative of speed

the movement of the capture mechanism enters the comparison block 14, where it is compared with the reference setpoint coming from block 15. The difference signal of the measured value of the derivative of the speed of the capture mechanism and the reference value from block 14 enters the control block 16, which, when the sign of the signal changes from block 14, produces signal to stop the motor 10 due to the lack of details in the mechanism of capture.

It is possible to more simply implement the proposed method of controlling the presence of a part in the gripping mechanism. It is associated with the formation of a transient curve of the speed of movement of the locking mechanism upon its failure, i.e. a process of the kind in which the aperiodic process of the speed of movement of the locking mechanism can be modified to oscillatory (Fig. 2, curve a). In this case, the reference setpoint block and the comparison block are not required. A conclusion on the malfunctioning of the trapping mechanism can be obtained by changing the sign of the derivative of the velocity (i.e., acceleration) of the movement of the trapping mechanism.

The formation of the transition speed curve of the movement can be made by selecting parameters such as the magnitude of the force developed by the springs of the gripping mechanism, the electromechanical constant of the time of the moving mechanism, the mode of movement of the electric drive.

During normal operation of the part gripping mechanism (cams squeezed part), the curve of the transition process of the speed of the part gripping mechanism corresponds to the view b. FIG. 2

Thus, the proposed control method uses an indirect method of controlling the presence of a part, in which there is no contact of the sensitive element with the part in the working area of the locking mechanism, which allows the method of control to be applied in severe environmental conditions and any visibility. The technical implementation of the method uses the same functional and structural elements of the robot that are necessary for its normal operation (engine, gripping mechanism, etc.).

The most promising object of practical application of this method of controlling the presence of parts in the gripping mechanisms is the first-generation software-controlled robots. They are usually

They have no means of sensing and are often used to perform the following technological operations: "grab a part from the container," install it in the machine chuck, "press the part tightly to the chuck end of the cartridge with an elastic mechanical gripper, and after machining the part, perform the reverse sequence . Using the proposed method, it is possible to “sense the robot by the operation of controlling the part in the gripping mechanism without constructive modifications of the gripping mechanism.

Claims (1)

Invention Formula The method of controlling the presence of a part in the gripping mechanisms of a robot, predominantly with the accumulation of energy by an elastic element of the part ejection mechanism, consisting in receiving a signal from a sensitive element and analyzing it, characterized in that, in order to simplify the device controlling the presence of the part in the gripper and increase the reliability of control in complex technological conditions, measured with the help of a sensitive element, the acceleration of the movement of the gripper at the beginning of its movement after the operation of clamping the part, and from the comparison measured acceleration of a reference value determined, for example, in the absence of items, determining the presence of a moment of force against the elastic element ejecting mechanism by which signal is formed in the absence of items PICKUP e.