Introduction and Debugging of Servo Motors
Apr 29, 2023
A servo motor is a type of electric motor used in precise motion control systems that require high accuracy and positioning. It uses a feedback control system to monitor and adjust its position and speed, allowing it to move precisely to specific angles or distances. Servo motors are commonly used in robotics, CNC machines, and automation systems. They can provide high torque and speed while maintaining high accuracy and reliability.
The servo motor can control speed with very accurate position accuracy, and can convert voltage signals into torque and speed to drive the control object. The rotor speed of the servo motor is controlled by input signals and can react quickly. In automatic control systems, it is used as an executing element and has characteristics such as small electromechanical time constant and high linearity. It can convert the received electrical signal into angular displacement or angular velocity output on the motor shaft. It is divided into two categories: DC and AC servo motors, and its main feature is that there is no self rotation phenomenon when the signal voltage is zero, and the speed decreases uniformly with the increase of torque.
Our company sells various brands of servo motors, such as
1.Allen-Bradley: 1326AB-B740C-S2L, 2004-RZ02BA1AN3, H-4050-P-H00AA, HPK-B1307C-MB44AA, MPL-A420P-SJ72AA,
MPL-A430H-HJ24AA, MPL-B420P-MJ22AA, MPL-B430P-MJ24AA, RSMZ-04BH6ANK3, RSMZ-08BH6ABK3, TL-A2530P-HJ32AN
2.ABB: 3HAC17327-1/01、LC440TGR0002, PS-130/6-50-2P-PMB-4056, PS-130/6-60-P-LSS-4057, PS-90/6-57-P-LSS-4280,
PS-90/6-79-P-PMB-3773, SDM251-000N5-055/40-2000, SDM251-000N5-055/60-2000, T4F2BR0511
3.SIEMENS: 1FK6042-6AF71-1TA0, 1FK7063-5AF71-1KH5,A5E03326159, 6SN2132-1CU11-1BA0,6SL3000-0CE15-0AA0,
6SL3562-6DF71-0RG1,1FK6042-6AF71-1TH2-Z,1FK6060-6AF71-1TA0,1FK6063-6AF71-1TG0
4.CT/Emerson: 107U2B200VBFCA13014X, 75DSA600C, 95DSC600C, R142DSC450C, XVM-402-TONS-D001,
95EZA300CACAA-UL,142U2D150CACAB165240
5.SANYO: 103-546-0241, P20B13500HXSH6E, P50B07040DXSG2, R2AA08040FCHCW, V404T-012,
V506BT-412, 103H8222-5111,R2AA08075FXPF6,P50B04010DCL9W
6.Lenze: CFM71M/BR/HR/TF/RH1L/SB50, MDSKABS080-22, MDSKSBS056-33, SSN40-1GVAR-063C22,MDSKSRS036-13
So, how is the servo motor debugged before use?
1. Initialization parameters
Before wiring, initialize the parameters first.
On the control card: select the control method; Clear the PID parameters to zero; When the control card is powered on, the default enable signal is turned off; Save this state to ensure that the control card is in this state when powered on again.
On the servo motor: set the control mode; Set to enable external control; The gear ratio output by the encoder signal; Set the proportional relationship between the control signal and the motor speed. It is recommended to set the maximum design speed during servo
2. Wiring
Power off the control card and connect the signal wire between the control card and the servo. The following lines must be connected: the analog output line of the control card, the enable signal line, and the encoder signal line of the servo output. After reviewing the wiring without any errors, power on the servo motor and control card (as well as PC). At this point, the motor should not move and can easily rotate with external force. If this is not the case, check the setting and wiring of the enable signal. Rotate the motor with external force and check if the control card can correctly detect changes in motor position. Otherwise, check the wiring and settings of the encoder signal.
3. Test direction
For a closed-loop control system, if the direction of the feedback signal is not correct, the consequences will definitely be catastrophic. Turn on the enable signal of the servo through the control card. This is when the servo should rotate at a lower speed, which is known as "zero drift" in legend.
Generally, there are instructions or parameters on the control card to suppress zero drift. Use this command or parameter to see if the speed and direction of the motor can be controlled through this command (parameter).
If it cannot be controlled, check the parameter settings of the analog wiring and control method. Confirm that a positive number is given, the motor rotates forward, and the encoder count increases; Given a negative number, the motor rotates in reverse and the encoder count decreases.
If the motor carries a load and has limited travel, do not use this method. Do not apply excessive voltage during testing, it is recommended to keep it below 1V. If the directions are inconsistent, the parameters on the control card or motor can be modified to make them consistent.
4. Suppress zero drift
In the closed-loop control process, the presence of zero drift will have a certain impact on the control effect, and it is best to suppress it. Use the control card or servo to suppress zero drift parameters and carefully adjust them to make the motor speed approach zero. Due to the randomness of zero drift itself, it is not necessary to require the motor speed to be absolutely zero.
5. Establish closed-loop control
Once again, release the servo enable signal through the control card and input a small proportional gain on the control card. As for how large it is, it can only be considered small based on feelings. If you are really not confident, enter the minimum value allowed by the control card. Turn on the enable signal of the control card and servo. At this point, the motor should be able to roughly follow the motion instructions.
6. Adjusting closed-loop parameters
Fine tuning of control parameters to ensure that the motor moves according to the instructions of the control card is a necessary task, and this part of the work is more about experience, which depends on daily accumulation.
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