What should we do if we find that the position of stepping motor is not correct?

There are generally the following reasons:

1. When changing direction, the pulse is lost, which shows that it is accurate in any direction, but when changing direction, it will accumulate deviation, and the more the number of deviations is, the more the deviation is.

2. The initial velocity is too high and the acceleration is too high, which sometimes leads to step loss.

3. Software compensation is too much or too little when synchronous belt is used.

4. Insufficient motor power;

5. Misoperation caused by disturbance of the controller;

6. The driver is disturbed.

7. Software Defects; Analysis of the above problems is as follows:

1) General stepping drivers have certain requirements for direction and pulse signal, such as: direction signal is determined several microseconds before the first pulse rising or falling edge (different drivers require different) arrives, otherwise there will be a pulse running angle opposite to the actual required steering, and the final failure phenomenon is that the more deviated, the smaller the subdivision, the more obvious the solution. The method mainly uses software to change the logic or delay of the pulse.

2) Because of the characteristics of stepper motors, the initial speed should not be too high, especially when the load inertia is large, it is suggested that the initial speed should be below 1r/s, so that the impact is smaller, the same acceleration is too big, and the impact on the system is also large, and it is easy to overshoot, resulting in inaccurate positioning; there should be a certain pause time between the forward and reverse of the motor, if not, it will cause overshoot due to too large reverse acceleration.

3) Adjust the compensated parameters according to the actual situation. (Because the elastic deformation of the synchronous belt is large, it needs to be compensated when changing the direction.)

4) Increase the motor current appropriately, increase the driver voltage (pay attention to the choice of driver) and select the motor with larger torque.

5) The disturbance of the system causes the wrong action of the controller or driver. We can only find out the disturbance source, reduce its disturbance ability (such as shielding, increasing the interval distance, etc.), cut off the transmission path, and improve its anti-interference ability. Common measures are as follows:

(1) Using double-striped shielding wire instead of common conductor, the signal line in the system is separated from the conductor with large current or large voltage variation, so as to reduce the electromagnetic interference ability.

(2) Power filter is used to filter the interference wave from the power grid, and power filter is added to the input of the major electrical equipment under the permissible conditions to reduce the interference between the various equipment in the system.

(3) It is better to use photoelectric isolation devices to transmit signals between devices. Under the permissible conditions, the pulse and direction signals should be transmitted by differential mode and photoelectric isolation. In the inductive load (such as electromagnetic relay, solenoid valve) with resistance capacitance absorption or fast discharge circuit at both ends, the inductive load can generate 10-100 times peak voltage at the beginning, if the operating frequency is above 20 KHZ.

6) The software does some fault-tolerant processing to eliminate the interference.

Shenzhen East Servo  Technology Co., Ltd.