Mechatronics, Industrial Control & Instrumentation

The General Principle of using a Servo Motor for Position Control

Servo motors are typically employed in closed-loop position control; for example let us consider the following application, where the angular position of the output shaft is intended to follow the reference voltage (ϴref).

Closed loop angular position control using a DC motor and angle feedback from a servo-type potentiometer
Figure 1.0 Closed loop angular position control using a DC motor and angle feedback from a servo-type potentiometer

The potentiometer mounted on the output shaft provides a feedback voltage proportional to the actual position of the output shaft. The voltage from this potentiometer must be a linear function of angle, and must not vary with temperature; else the accuracy of the system will be affected.

The feedback voltage – representing the actual angle of the shaft, is subtracted from the reference voltage – representing the desired position and the resulting position error signal is amplified and used to drive the motor so as to rotate the output shaft in the desired direction. When the output shaft reaches the target position, the position error becomes zero, no voltage is applied to the motor, and the output shaft remains at rest. Any effort to physically move the output shaft from its target position immediately creates a position error and a restoring torque is applied by the motor.

Related: How Servo Motors are used in Process Control

The tachometer feedback is used in addition to the main position feedback to help improve the dynamic performance of the system.

John Mulindi

John Mulindi is an Industrial Instrumentation and Control Professional with a wide range of experience in electrical and electronics, process measurement, control systems and automation. In free time he spends time reading, taking adventure walks and watching football.

Recent Posts

The Problems Associated with Embedded Power Generation

Image source Pixabay The rate of the development of energy sources that are alternatives to…

1 day ago

The Power of Automation in Construction: How It Transforms Efficiency and Safety

Image by Pixabay Automation is transforming industries worldwide, and construction is no exception. Companies are…

2 days ago

LED Beacon Lights: What Does Each Colour Lens Mean?

A closeup shot of a warning lamp in the street at night, image by Freepik…

3 days ago

Impeller Flowmeters: Features, Installation Considerations & Uses

Impeller flowmeters at times referred to as paddlewheel meters are one of the frequently utilized…

1 week ago

Sell Old Electronics: Turn Your Used Devices into Cash

Photo by Héctor Martínez on Unsplash Introduction Yes! If you have old electronic devices that you…

1 week ago

The Effects of Low Power Factor on Electrical Equipment

The cosine of the angle between voltage and current in an AC circuit is referred…

1 week ago