Some of the following content is original, and some are excerpts. Right as a colleague in the industry to throw a brick to attract jade[/color]
[color=#0000FF]1. about the application of servo. [/color]There are many aspects, even a small electromagnetic regulator, can be considered a servo system. Other servo applications such as artillery or radar, used as a follower, requiring good real-time, fast dynamic response, small overshoot, precision in the next. If it is a machine tool, it is often used as a constant speed, positional high precision, real-time requirements are not high.
First of all, you have to determine what you are applying to. If used in the machine tool, the control part of the hardware can be designed relatively simple, the cost is correspondingly low. If used in the military, the internal firmware design control algorithms should be more flexible, such as providing position loop filtering, speed loop filtering, nonlinear, optimization or intelligent algorithms. Of course, it does not need to be realized on a hardware part. Can be object-oriented made into several types of products.
AC servo in the machining center, automatic lathe, electric injection molding machine, robot, printing machine, packaging machine, spring machine, coordinate measuring machine, EDM machine and so on in the aspect of the equipment has a broad application.
[color=#0000FF]2. There is a big difference between the performance about stepper motor and AC servo motor. [/color]Stepping motor is a discrete motion device, it and modern digital control technology has an essential link. In the current domestic digital control system, the stepper motor is widely used. With the emergence of all-digital AC servo systems, AC servo motors are also increasingly used in digital control systems. In order to adapt to the development trend of digital control, most of the motion control systems use stepper motors or all-digital AC servo motors as execution motors.
Although the two in the control mode is similar (pulse string and direction signal), but in the use of performance and application occasions there are large differences. Such as: 1, the system precision is different; 2, low-frequency characteristics are different 3, moment frequency characteristics are different 4, overload capacity is different 5, different operating performance 6, speed response performance is different.
AC servo systems are superior to stepper motors in many performance aspects. But in some of the less demanding occasions also often use stepper motors to do the implementation of the motor. Therefore, in the control system design process to consider the control requirements, cost and other factors, the selection of appropriate control motor.
[color=#808000]3. The problem of servo zero switch. [/color]There are many ways to find the zero, according to the required precision and practical requirements to choose. Can be completed by the servo motor itself (some brands of servo motors have a complete return to the origin function), can also be completed through the upper computer with the servo, but the principle of return to the origin is basically common as follows.
When the servo motor is looking for the origin, when it touches the origin switch, it will decelerate and stop immediately, and this point is the origin.
When returning to the origin, it directly searches for the Z signal of the encoder, and decelerates and stops immediately when there is a Z signal. This return to the original method is generally only used in the rotary axis, and the return to the original speed is not high, the accuracy is not high.
[color=#0000FF]4. Synchronous belt installation on the servo positioning also has a great impact. [/color]
In this case, you have to know if the servo is tuned soft? Common servo is controlled by pulse, so what is the proportional gain of the position loop, the proportional gain of the velocity loop, and the integral time constant?
Position loop proportional gain: 21rad/s
Velocity loop proportional gain: 105rad/s
Velocity loop integral time constant: 84ms
[color=#0000FF]5. On the servo's three kinds of control mode, general servo have three kinds of control mode: speed control mode, torque control mode, position control mode. Position control mode. I want to know is that these three control methods based on what to choose? [/color]
Speed control and torque control are controlled by analog. Position control is controlled by sending pulses. The specific control method should be chosen according to the customer's requirement and what kind of motion function is satisfied.
If you don't have any requirement on the speed and position of the motor, as long as it outputs a constant torque, of course, you should use the torque mode.
If you have some precision requirements for position and speed, and are not very concerned about the real-time torque, it is not convenient to use the torque mode, and it is better to use the speed or position mode. If the upper controller has a better closed-loop control function, the effect of using speed control will be better. If the requirements themselves are not very high, or, basically, there is no real-time requirements, with the position control mode on the upper controller does not have high requirements.
In terms of the response speed of the servo drive, the torque mode has the smallest amount of arithmetic, the drive's response to the control signal is the fastest; the position mode has the largest amount of arithmetic, the drive's response to the control signal is the slowest.
When there is a high demand for dynamic performance in motion, the motor needs to be adjusted in real time. Then if the controller itself is very slow (such as PLC, or low-end motion controllers), the position mode control. If the controller computing speed is faster, you can use the speed method, the position loop from the drive to the controller, reduce the workload of the drive to improve efficiency; if there is a better upper controller, you can also use the torque method of control, the speed loop is also removed from the drive, which is generally only the high-end dedicated controller to do so, and, at this time, there is no need to use servo motors.