The assembly robot is the core equipment of the flexible automated assembly system and consists of robotic manipulator, controller, end effector and sensing system.
Among them, the structural types of the operating machine are horizontal joint type, rectangular coordinate type, multi-joint type and cylindrical coordinate type;
The controller generally adopts a multi-CPU or multi-level computer system to realize motion control and motion programming;
The end effector is designed to adapt to different assembly objects and is designed into various claws and wrists;
The sensing system again acquires information about the interaction between the assembly robot and the environment and assembly objects.
The basic type and structure
The PUMA developed by Unimation in the United States in 1977 is a computer-controlled multi-joint assembly robot.
There are typically 5 or 6 degrees of freedom, namely the rotation of the waist, shoulders, and elbow, as well as the bending, rotation, and twisting of the wrist (Figure 1).
Its control system consists of microcomputer, servo system, input and output system, and external device.
Using VALII as the programming language, for example the statement “APPRO PART, 50” means that the hand moves to 50 mm above the PART.
The location of the PART can be typed or taught.
VAL has the function of continuous trajectory motion and matrix transformation.
A large number of assembly operations are vertically downwards, requiring greater flexibility of the horizontal (X, Y) movement of the fingers to compensate for positional errors.
Vertical (Z) movement and rotation about the horizontal axis are more rigid for accurate and powerful assembly.
It is also required to have greater flexibility around the Z-axis for key or spline engagement.
The Yamanashi University of Japan developed the SCARA robot, and its structural characteristics meet the above requirements (Figure 2).
The control system is also relatively simple. For example, the SR-3000 robot uses a microprocessor to implement semi-closed loop control for θ1, θ2, and Z three-axis (DC servo motors), and open-loop control of the s-axis (stepper motor).
The programming language uses a SERF similar to BASIC.
The latest version of Level4 has functions such as coordinate transformation, linear and circular interpolation, arbitrary speed setting, subroutine named after text, and error detection.
SCARA robots are one of the most widely used types.
Assembly robots are mainly used in the manufacture of various electrical appliances (including household appliances such as televisions, tape recorders, washing machines, refrigerators, vacuum cleaners), small motors, automobiles and their components, computers, toys, mechanical and electrical products and their assembly.