Composition of industrial robots

Generally speaking, industrial robots are composed of three major parts and six subsystems. The three major parts are the mechanical part, sensing part, and control part. The six subsystems can be divided into mechanical structure system, driving system, perception system, robot environment interaction system, human-machine interaction system, and control system.

1. Mechanical structure system

From the perspective of mechanical structure, industrial robots are generally divided into series robots and parallel robots. The characteristic of a series robot is that the motion of one axis will change the coordinate origin of the other axis, while the motion of one axis of a parallel robot will not change the coordinate origin of the other axis. Early industrial robots used a series mechanism. Parallel mechanism is defined as a closed loop mechanism that the moving platform and the fixed platform are connected through at least two independent Kinematic chain, the mechanism has two or more degrees of freedom, and is driven in parallel. A parallel mechanism has two components, namely the wrist and arm. The arm movement area has a significant impact on the movement space, while the wrist is the connecting part between the tool and the body. Compared with series robots, parallel robots have the advantages of high stiffness, stable structure, large load-bearing capacity, high micro motion accuracy, and low motion load. In terms of position solving, the forward solution of the series robot is easy, but the reverse solution is very difficult; Parallel robots, on the other hand, have a difficult forward solution but a very easy reverse solution.

2. Drive system

A drive system is a device that provides power to a mechanical structural system. According to different power sources, the transmission methods of the drive system are divided into four types: hydraulic, pneumatic, electrical, and mechanical. Early industrial robots used hydraulic drive. Due to the problems of leakage, noise, and low speed instability in the hydraulic system, as well as the bulky and expensive power unit, currently only large heavy-duty robots, parallel machining robots, and some industrial robots driven by hydraulic pressure are used in special applications. Pneumatic drive has the advantages of fast speed, simple system structure, convenient maintenance, and low price. However, the working pressure of the pneumatic device is low, making it difficult to accurately locate, and it is generally only used for driving the end effector of industrial robots. Pneumatic grippers, rotating cylinders, and pneumatic suction cups can be used as end effectors for gripping and assembling workpieces with medium and small loads. Electric drive is currently one of the most commonly used driving methods in Zui, characterized by convenient access to power, fast response, large driving force, convenient signal detection, transmission, and processing, and multiple flexible control methods. The driving motor is generally a stepper motor or servo motor, and there are also direct driving motors, but the cost is high and the control is also complex. The reducer matched with the motor is usually a harmonic reducer Cycloidal gear reducer or planetary gear reducer. Due to the large demand for linear drive in parallel robots, linear motors have been widely used in the field of parallel robots.

3. Perception system

The robot perception system transforms various internal state and environmental information of the robot from signals to data and information that can be understood and applied by the robot itself or between robots. In addition to the need to perceive mechanical quantities related to its own working state, such as displacement, speed, and force, visual perception technology is an important aspect of industrial robot perception. The visual servo system uses visual information as feedback signals to control and adjust the position and posture of the robot. Machine vision systems have also been widely used in various aspects such as quality inspection, workpiece recognition, food sorting, and packaging. The perception system consists of internal sensor modules and external sensor modules, and the use of intelligent sensors improves the mobility, adaptability, and intelligence level of robots.

4. Robot environment interaction system

The robot environment interaction system is a system that enables the interaction and coordination between robots and devices in the external environment. The robot is integrated with external devices into a functional unit, such as processing and manufacturing units, welding units, assembly units, etc. Of course, it can also be the integration of multiple robots into a functional unit to perform complex tasks.

5. Human machine interaction system

The human-machine interaction system is a device that connects humans and robots and participates in robot control. For example, standard terminals of computers, command consoles, information display boards, danger signal alarms, etc.

6. Control system

The task of the control system is to control the execution mechanism of the robot to complete specified movements and functions based on the robot's operation instructions and signals feedback from sensors. If the robot does not have information feedback characteristics, it is an open-loop control system; have