The robot system is composed of the robot and the operation object and environment together, which includes four major parts: mechanical system, drive system, control system and sensing system.
Mechanical system
The mechanical system of an industrial robot includes parts such as the body, arm, wrist, end manipulator and walking mechanism, each of which has several degrees of freedom, thus constituting a multi-degree-of-freedom mechanical system. In addition, some robots also have a travel mechanism. If the robot has a walking mechanism, it is a walking robot; if the robot does not have a walking and waist rotation mechanism, it is a single robot arm. The end manipulator is an important component mounted directly on the wrist, which can be a two-finger or multi-finger hand claw, or an operating tool such as a spray paint gun or welding gun. The role of the industrial robot mechanical system is equivalent to that of the human body (e.g. bone marrow, hands, arms and legs).
Drive system
The drive system is mainly the driving device that drives the action of the mechanical system. Depending on the drive source, the drive system can be divided into three types: electrical, hydraulic and pneumatic, as well as a comprehensive system that combines them for application. The role of this part is equivalent to the human muscle.
Electrical drive systems are more commonly used in industrial robots and can be divided into three types of drives: stepper motors, DC servo motors and AC servo motors. In the early days, stepper motors were mostly used, and later DC servo motors were developed, and AC servo motor drives were gradually applied. Some of the above drive units are used to directly drive the movement of the mechanism: some drive the movement of the mechanism after deceleration through the harmonic reducer, and its structure is simple and compact.
The hydraulic drive system has smooth motion and large load capacity, so it is reasonable to use hydraulic drive for robots with heavy load handling and parts processing. However, hydraulic drive has disadvantages such as complicated piping and difficult cleaning, thus limiting its application in assembly operations.
Both electrically and hydraulically driven robots use pneumatic forms for the opening and closing of their hand claws. Pneumatic-driven robots are simple in structure, fast in action and inexpensive, but because air is compressible, its working speed is less stable. However, the compressibility of air can make the hand claw in grasping or clamping objects to improve the compliance, to prevent excessive force caused by the grasped object or the damage of the hand claw itself. The pressure of the pneumatic system is generally 0.7 MPa, and thus the gripping force is small, only a few dozen to a few hundred cows size.
Control system
The task of the control system is to control the robot's actuator according to the robot's operation instruction program and the signals returned from the sensors, so that it can complete the prescribed movement and function.
If the robot does not have information feedback characteristics, the control system is called an open-loop control system; if the robot has information feedback characteristics, the control system is called a closed-loop control system. This part mainly consists of computer hardware and control software. The software is mainly composed of the human-robot interaction system and control algorithms that link the human and the robot. The role of this part is equivalent to that of the human brain.
Sensory system
The sensing system consists of internal sensors and external sensors, which are used to obtain information about the internal and external environment of the robot and feed this information to the control system. Internal state sensors are used to detect the position, speed and other variables of each joint and provide feedback to the closed-loop servo control system. External state sensors are used to detect some state variables between the robot and its surroundings, such as distance, proximity, and contact, and are used to guide the robot so that it can easily identify objects and process them accordingly. External sensors allow the robot to respond to the environment it is in in a flexible way, giving it a certain level of intelligence. The role of this part is equivalent to that of the five human senses.
A robot is an automated machine that has some intelligent capabilities similar to those of a human or a living creature, such as perception, planning, movement and collaboration, and is an automated machine with a high degree of flexibility.
