4 control methods of industrial robots

2021-01-05 10:22:02
1. Point control mode (PTP)

The point control system is actually a kind of position servo system. Their basic structure and composition are basically the same, but the focus is different and the control complexity is different. The point control system generally includes the final mechanical actuator, mechanical transmission mechanism, power element, controller, position measuring device, etc. The mechanical actuator is an active component that completes functional requirements, such as the manipulator of a welding robot, and the workbench of a CNC machining machine tool. Wait. Broadly speaking, the actuator also includes motion support components such as guide rails, which play a key role in positioning accuracy.

This control method only controls the position and posture of certain designated discrete points in the workspace of the industrial robot terminal actuator. In the control, the industrial robot is only required to move quickly and accurately between adjacent points, and the trajectory of the target point is not required to reach the target point. Positioning accuracy and movement time are the two main technical indicators of this control method. The control method has the characteristics of simple implementation and low positioning accuracy. Therefore, it is often used for the loading and unloading, loading and unloading, spot welding, and placement of components on the circuit board, and only requires the position and posture of the terminal actuator to be accurate at the target point. This method is relatively simple, but it is difficult to achieve a positioning accuracy of 2 to 3 μm.

2. Continuous trajectory control method

This control method is to continuously control the position and posture of the end effector of the industrial robot in the working space. It is required to strictly follow the predetermined trajectory and speed to move within a certain accuracy range, and the speed is controllable, the trajectory is smooth, and the movement is stable. Complete operational tasks. Among them, trajectory accuracy and motion stability are the two most important indicators.

The joints of the industrial robot move continuously and synchronously, and the end effector of the industrial robot can form a continuous trajectory. The main technical index of this control method is the trajectory tracking accuracy and stability of the industrial robot end effector, which is usually used for arc welding, painting, hair removal, and inspection robots.

3. Force control mode

When the robot completes some tasks related to the environment, such as grinding and assembling, simple position control will cause excessive position errors and cause damage to the parts or the robot. When robots move in this kind of environment restricted by movement, they often need to be combined with ability control before they can be used. At this time, they must use (torque) servo mode. The principle of this control method is basically the same as that of position servo control, except that the input and feedback are not positioned signals, but force (torque) signals, so the system must have a powerful torque sensor. Sometimes, adaptive control is also carried out using sensor functions such as proximity and sliding.

4. Intelligent control method

The intelligent control of the robot is to acquire the knowledge of the surrounding environment through sensors and make corresponding decisions based on its own internal knowledge base. Using intelligent control technology, the robot has strong environmental adaptability and self-learning ability. The development of intelligent control technology depends on the rapid development of artificial intelligence, such as artificial neural networks, genetic algorithms, genetic algorithms, expert systems, etc. Perhaps this kind of control method, industrial robots really have the flavor of "artificial intelligence" landing, and it is also the most difficult to control. In addition to algorithms, it also relies heavily on the accuracy of components.