The industrial robot has four parts, which are body, servo, reducer and controller.

The general structure of industrial robot electric servo system is three closed-loop control, namely, current loop, speed loop and position loop. In general, the position control, speed control, torque control and other functions of AC servo drive can be achieved by manually setting its internal functional parameters.

So what do you need to know about servomotors? Here is a summary of 19 servo motor problems you may not know, let's take a look.

1. How to choose servo motor and stepper motor correctly?

A: mainly depends on the specific application situation, simply say to determine: the nature of the load (such as horizontal or vertical load, etc.), torque, inertia, speed, precision, acceleration and deceleration requirements, upper control requirements (such as port interface and communication requirements), the main control mode is the position, torque or speed mode. Whether the power supply is DC or AC, or battery powered, voltage range. This is used to determine the type of motor and associated driver or controller.

2. How to use the stepper motor driver?

A: According to the current of the motor, with a driver greater than or equal to this current. If low vibration or high precision is required, subdivision drivers can be used. For large torque motor, high voltage driver is used as far as possible to obtain good high speed performance.

What is the difference between 3.2 phase and 3 phase stepper motor and how to choose?

A: The 2-phase motor has low cost, but the vibration is large at low speed, and the torque drops quickly at high speed. The 3-phase motor has small vibration, good high-speed performance, 30~50% higher speed than the 2-phase motor, and can replace the servo motor in some occasions.

4. When to choose DC servo system and what is the difference between it and AC servo system?

A: DC servo motors are divided into brushless and brushless motors.

Brush motor has the advantages of low cost, simple structure, large starting torque, wide speed regulating range, easy control, need maintenance, but convenient maintenance (carbon brush), electromagnetic interference and environmental requirements. Therefore, it can be used in cost sensitive common industrial and civil applications.

Brushless motor small size, light weight, large output, fast response, high speed, small inertia, smooth rotation, torque stability. The control is complex, easy to realize intelligent, its electronic commutation mode is flexible, can be square wave or sine wave commutation. Motor maintenance-free, high efficiency, low operating temperature, small electromagnetic radiation, long life, can be used in a variety of environments.

Ac servo motor is also brushless motor, which can be divided into synchronous and asynchronous motors. At present, synchronous motors are generally used in motion control. It has a large power range and can achieve great power. Large inertia, low maximum rotational speed, and with the increase of power rapidly decreased. Therefore, it is suitable for the application of low speed and smooth operation.

5. What should we pay attention to when using the motor?

A: Check the following before powering on:

1) Whether the power supply voltage is appropriate (overvoltage is likely to cause damage to the drive module); The +/- polarity of the DC input must not be connected incorrectly, and whether the motor model or current setting value on the drive controller is appropriate (not too large at the beginning);

2) The control signal line is firmly connected, and it is best to consider the shielding problem on the industrial site (such as the use of twisted pair);

3) Do not connect all the lines that need to be connected at the beginning, only connect into the most basic system, after good operation, and then gradually connect.

4) We must figure out the grounding method, or use floating air not connected.

5) Within half an hour of starting operation, the state of the motor should be closely observed, such as whether the movement is normal, sound and temperature rise. If any problem is found, the motor should be shut down and adjusted immediately.

6. When the stepper motor starts and runs, sometimes it stops moving or moves back and forth in place, and sometimes loses its step when running. What is the problem?

Generally, the following aspects should be considered for inspection:

1) Whether the motor torque is large enough to drive the load, so we generally recommend that the user choose the motor with torque 50% ~ 100% larger than the actual need when selecting the type, because the stepper motor can not run over the load, even if it is instantaneous, will cause misstep, serious stop or irregular repeated movement in place.

2) Whether the current of the input step pulse from the upper controller is large enough (generally >10mA) to make the optical coupler stable conduction, whether the input frequency is too high, resulting in the reception of the driver, if the output circuit of the upper controller is a CMOS circuit, then the CMOS input driver should also be selected.

3) Whether the starting frequency is too high and whether the acceleration process is set in the starting procedure. It is better to accelerate from the specified starting frequency of the motor to the set frequency, even if the acceleration time is very short, otherwise it may be unstable or even in the idle state.

4) When the motor is not fixed, this situation sometimes occurs, which is normal. Because, in fact, this caused a strong resonance of the motor and led to the out-of-step state. The motor must be secured.

5) For a 3-phase motor, the phase connection is wrong and the motor cannot work.

7. I want to control the servo motor directly by means of communication, is that OK?

Yes, it's also convenient, but it's a matter of speed. It's used for applications that don't require high response speed. If you need fast response control parameters, it is better to use servo motion control card, which generally has DSP and high speed logic processing circuit, in order to achieve high speed and high precision motion control. Such as S acceleration, multi - axis interpolation, etc.

8. There is a servo motor with encoder feedback, can it be controlled by a servo driver only with a speed measuring machine port?

Yes, we need an encoder to velocimeter signal module.

9. Can the code plate of the servo motor be disassembled?

Do not disassemble, because the quartz sheet in the code plate is easy to break, and after entering the dust, the life and accuracy will not be guaranteed, the need for professional maintenance.

10. Can stepper and servo motors be disassembled for maintenance or modification?

No, it is better to let the manufacturer do it. After disassembling, it is difficult to install the original without professional equipment, and the clearance between the stator of the motor cannot be guaranteed. The properties of magnetic steel materials are damaged, and even the magnetic loss is caused, and the motor torque is greatly reduced.