As one of the most crucial components of an industrial robot, the robot controller plays a decisive role in the robot's performance and influences its development to a certain extent. It generally consists of four parts: input, output, control elements, and algorithms. In a simple robot system, the corresponding components are:
1. Input: Sensors, including sonar, infrared, camera, gyroscope, accelerometer, compass, etc.;
2. Output: Control element, usually a motor;
3. Control Algorithm: The control board is implemented from small microcontrollers to large microcomputers;
4. Control objectives: such as robot path tracking.
Definition of robot control system
The function of a robot control system is to receive detection signals from sensors and drive the various motors in the robotic arm according to the requirements of the operational task. Just as human movement relies on its joints, robot motion control is inseparable from sensors. Robots need sensors to detect various states. Internal sensor signals are used to reflect the actual movement state of the robotic arm joints, while external sensor signals are used to detect changes in the working environment. Therefore, the robot's neural network and brain work together to form a complete robot control system.
The four main components of a robot motion control system
Actuator: Servo motor or stepper motor;
Drive mechanism: servo or stepper driver;
Control mechanism: Motion controller, which performs algorithmic calculations and controls the path and motor linkage;
Control method: If there is a fixed action mode, then program the motion controller with fixed parameters; if a vision system or other sensors are added, program the motion controller with variable parameters based on the sensor signals.
Introduction to Industrial Robot Control Systems
(1) Hardware structure of industrial robot control system
The controller is the core of the robot system. Foreign companies have imposed strict technology blockade on my country, which has restricted the development of domestic technology. In recent years, with the development of microelectronics technology, the performance of microprocessors has become higher and higher, while the price has become cheaper and cheaper. Currently, 32-bit microprocessors with a price of 1-2 US dollars have appeared on the market.
High-performance, cost-effective microprocessors have brought new development opportunities to robot controllers, making it possible to develop low-cost, high-performance robot controllers. To ensure that the system has sufficient computing and storage capabilities, current robot controllers mostly use chips with strong computing power, such as the Arm series, DSP series, POWER PC series, and Intel series chips.
(2) Industrial robot control system architecture
In terms of controller architecture, the research focus is on functional partitioning and the standardization of information exchange between functions. In the research of open controller architectures, there are two basic structures: one is a hardware-layer-based structure, which is relatively simple. In Japan, the architecture is partitioned based on hardware; for example, Mitsubishi Heavy Industries divides its PA210 portable general-purpose intelligent arm robot into a five-layer structure. The other is a function-based structure, which considers both hardware and software, and is the direction of research and development in robot controller architecture.
Basic functions of robot control system
(1) Memory function: Stores work sequence, movement path, movement mode, movement speed, and information related to production process;
(2) Teaching functions: offline programming, online teaching, and indirect teaching. Online teaching includes two types: teach pendant and guided teaching;
(3) Communication with peripheral devices: input and output interfaces, communication interface, network interface, synchronization interface;
(4) Coordinate setting function: There are four types of coordinate systems: joint, absolute, tool, and user-defined;
(5) Human-machine interface: teach pendant, operation panel, display screen;
(6) Sensor interfaces: position detection, vision, touch, force, etc.;
(7) Position servo function: multi-axis linkage of robot, motion control, speed and acceleration control, dynamic compensation, etc.;
(8) Fault diagnosis and safety protection functions: system status monitoring during operation, safety protection under fault conditions, and fault self-diagnosis.
