DC Servo

System

The equipment includes student experiments in the laboratory with non-hazardous low voltage. Experimental procedures are carried out using a manual in printed or electronic form.

Experimental procedures are carried out with experimental panels in a profile frame.

Learning objectives

• Test setup and wiring according to circuit diagram
• Dealing with closed control loops
• Optimisation of servo systems
• Use of computer-controlled measuring interfaces

Function

Servos are adjustment drives for transmitting position or angular positions. The current position is measured at the target location and compared with the target value in the sense of an approximation. Servos are therefore an application of classic control technology. Servos have a (small) driving machine and a follower potentiometer. Servos are evaluated by analysing the step response. However, optimisation using the known methods (ZN or CHR) is not possible as these only provide rules for PTn paths. A DC servo has a controlled system with mainly integral behaviour. Servos are therefore typically operated with P-controllers.

Target group

Vocational training in industry and students specialising in energy technology and mechatronics. The course offers intermediate-level experiments for vocational schools.

Topics

• Simulation of the stability limit
• Commissioning the DC servo
• Manual recording of the servo characteristic curve
• Automatic recording of the servo characteristic curve
• Step responses of an integral controlled system
• Step responses of the DC servo
• Step response with fitting function
• Determination of the 3 dB cut-off frequency of the servo
• Guidance control of the DC servo
• Guiding behaviour with mounted mass washer (high moment of inertia)
• Control with rise limitation of the reference variable
• Computer-based simulation of the DC servo