Comprehensive interpretation of the basic components of industrial robots

It is widely used in industrial manufacturing, such as automobile manufacturing, electrical appliances, and food. It can replace repetitive machine-operated work and is a machine that relies on its own power and control capabilities to achieve various functions. It can accept human command and can also operate according to pre-programmed programs. Today we will talk about the basic main components.

1. Subject

The main body is the base and the actuator, including the upper arm, lower arm, wrist and hand, forming a multi-degree-of-freedom mechanical system. Some robots also have walking mechanisms. Industrial robots have 6 degrees of freedom or more, and the wrist generally has 1 to 3 degrees of freedom.

2. Drive system

The drive system of industrial robots is divided into three categories according to the power source: hydraulic, pneumatic and electric. According to the needs, these three types of examples can also be combined into a composite drive system. Or it can be driven indirectly through mechanical transmission mechanisms such as synchronous belts, wheel trains, and gears. The drive system has a power device and a transmission mechanism to implement the corresponding actions of the mechanism. These three basic drive systems have their own characteristics. The mainstream is the electric drive system. Due to the widespread acceptance of low inertia, large torque AC, DC and their supporting servos (AC, DC pulse width modulators). This type of system does not require energy conversion, is easy to use, and is sensitive to control. Most of them need to be installed with a sophisticated transmission mechanism: a reducer. Its teeth use the speed of the gear to reduce the number of reverse rotations of the motor to the desired number of reverse rotations, and obtain a device with a larger torque, thereby reducing the speed and increasing the torque. When the load is large, it is not cost-effective to simply increase the power of the servo motor. The output torque can be improved through a reducer within an appropriate speed range. The servo motor is prone to heat and low-frequency vibration under low-frequency operation. Long-term and repetitive work is not conducive to ensuring its accurate and reliable operation. The existence of precision reduction motor enables the servo motor to run at a suitable speed, strengthen the rigidity of the machine body and output greater torque. There are two mainstream reducers nowadays: harmonic reducer and RV reducer

3.

The robot control system is the brain of the robot and the main factor that determines the function and performance of the robot. The control system issues instructions to the drive system and the actuator according to the input program and controls it. The main task of industrial robot control technology is to control the range of activities, postures and trajectories, and the time of actions of industrial robots in the workspace. It has the characteristics of simplicity, software menu operation, friendly human-computer interaction interface, online operation prompts and easy use. The system is a robot, and foreign countries are closely closed to my country's experiments. In recent years, with the development of micro technology, the performance of microprocessors has become higher and higher, while the price has become cheaper and cheaper. Now there are 32-bit microprocessors with a price of 1-2 US dollars on the market.

Cost-effective microprocessors have brought new development opportunities for robot controllers, making it possible to develop low-cost, high-performance robot controllers. In order to make the system have sufficient computing and storage capabilities, robot controllers are now mostly composed of strong series, series, POWERPC series, series, etc. Since the existing general-purpose chip functions and functions cannot fully meet the requirements of some robot systems in terms of price, function, integration and so on, this has given rise to the demand for SoC (System on Chip) technology in robot systems. Integrating a specific processor with the required interface can simplify the design of system peripheral circuits, reduce system size, and reduce costs. For example, the company integrates the processor core of NEOS or ARM7 on it to form a complete SoC system. In terms of robot technology controllers, its research is mainly concentrated in the United States and Japan, and there are mature products, such as the American DELTATAU company and the Japanese Pengli Co., Ltd. Its motion controller is based on DSP technology and adopts an open structure based on PC.

4. Perception system

It is composed of internal modules and external sensor modules, which obtain meaningful information from internal and external environmental states. Internal sensors: sensors used to detect the state of the robot itself (such as the angle between the arms), mostly sensors that detect position and angle. Specifically: position sensors, position sensors, angle sensors, etc. External sensors: sensors used to detect the robot's environment (such as detecting objects, the distance from objects) and conditions (such as detecting whether the grasped object slips). Specifically, there are distance sensors, visual sensors, force sensors, etc. The use of sensing systems improves the maneuverability, practicality and intelligence of robots. The human perception system is less intelligent than robots for information about the external world. However, for some special information, sensors are more effective than human systems.

5. End effector

The end effector is a component connected to the last joint of the manipulator. It is generally used to grab objects, connect with other mechanisms and perform the required tasks. Robot manufacturers generally do not design or sell end effectors. In most cases, they only provide a simple gripper. Usually the end effector is installed on the flange of the robot's 6 axes to complete tasks in a given environment, such as welding, painting, gluing, and parts loading and unloading, which are tasks that require robots to complete.

Overview of Servo Motors

Servo drive, also known as "servo controller" or "servo", is a controller used to control servo motors. Its function is similar to that of frequency converters on ordinary AC motors and is part of the servo system. Generally, the servo motor is controlled by position, speed and torque to achieve the positioning of the transmission system.

1. Classification of servo motors

It is divided into two categories: DC and AC servo motors. AC servo motors are further divided into asynchronous servo motors and synchronous servo motors. At present, AC systems are gradually replacing DC systems. Compared with DC systems, AC servo motors have the advantages of high reliability, good heat dissipation, small rotational inertia, and can work in a state. Because there are no brushes and steering gears, the AC servo system is also called a brushless servo system. The motors used in it are brushless cage asynchronous motors and permanent magnet synchronous motors. 1) DC servo motors are divided into brushed and brushed motors. ① Brushed motors have low cost, simple structure, large starting torque, wide speed regulation range, easy control, and require maintenance, but convenient maintenance (replace carbon brushes), generate electromagnetic interference, and have requirements for the use environment. They are usually used in ordinary industrial and civil occasions that are sensitive to cost; ② Brushless motors are small in size and light in weight, have high output and fast response, high speed and small inertia, stable torque and smooth rotation, complex control, intelligent, flexible electronic commutation, square wave or sine wave commutation, maintenance-free motors, high efficiency and energy saving, small electromagnetic radiation, low temperature rise and long life, suitable for various environments.

2. Characteristics of different types of servo motors

1) Advantages and Disadvantages of DC Servo Motors Advantages: Accurate speed control, very hard torque-speed characteristics, simple control principle, easy to use, cheap. Disadvantages: Brush commutation, speed limitation, additional resistance, generation of wear particles (not suitable for dust-free and explosive environments) 2) Advantages and Disadvantages of AC Servo Motors Advantages: Good speed control characteristics, smooth control can be achieved in the entire speed range, almost no oscillation, high efficiency of more than 90%, less heat, high-speed control, high-precision position control (depending on accuracy), constant torque can be achieved within the rated operating area, low inertia, low noise, no brush wear, maintenance-free (suitable for dust-free and explosive environments).

Disadvantages: The control is more complicated, the driver needs to adjust the D parameters on site, and more wiring is required. At present, the mainstream servo drivers all use (DSP) as the control core, which can realize relatively complex control algorithms, realize digitalization, optimization and intelligence. Power devices are generally designed with intelligent power modules (IPM) as the core. The IPM integrates the drive circuit internally, and has overvoltage, over, overheating, undervoltage and other fault detection. A soft start circuit is also added to the main circuit to reduce the impact of the start-up process on the driver. The power drive unit first rectifies the input three-phase electricity or mains through a three-phase full-bridge rectifier circuit to obtain the corresponding direct current. After the rectified three-phase electricity or mains, the three-phase permanent magnet synchronous AC servo motor is driven by a three-phase sinusoidal PWM voltage-type frequency conversion. The whole process of the power drive unit can be simply described as an AC process. The main topology circuit of the rectifier unit (AC-DC) is a three-phase full-bridge uncontrolled rectifier circuit.