The Importance Of Actuator Synchronization

The importance of actuator synchronization
There are two methods of multiple actuator control – parallel and synchronous. Parallel control outputs a constant voltage to each actuator, while synchronous control outputs variable voltage to each actuator.

The process of synchronizing multiple actuators is necessary when implementing two or more actuators to move at the same speed. This can be achieved with two forms of positional feedback– Hall Effect sensors and multiple turn potentiometers.

Slight variance in actuator production results in a slight variance in actuator speed. This can be corrected by outputting a variable voltage to the actuator to match two actuator speeds. The positional feedback is necessary in order to determine how much voltage is required to output to each actuator.

Synchronization of actuators is important when controlling two or more actuators where precise control is needed. For example, applications that would require multiple actuators to move a load while maintaining equal load distribution across each actuator. If parallel control was used in this type of application, unequal load distribution may occur due to variable stroke speeds and ultimately cause excessive force on one of the actuators.

Hall effect sensor
To summarize the Hall Effect theory, Edwin Hall (who discovered the Hall Effect), stated that whenever a magnetic field is applied in a direction perpendicular to the flow of electric current in a conductor, a voltage difference is induced. This voltage can be used to detect whether the sensor is in the proximity of a magnet or not. By attaching a magnet to the shaft of the motor, the sensors can detect when the shaft is parallel to them. Using a small circuit board, this information can be output as a square wave, which can be counted as a string of pulses. By counting these pulses you can keep track of how many times the motor has spun and how the motor moves.

Some Hall Effect circuit boards have multiple sensors on them. It is common for them to have 2 sensors at 90 degrees which results in a quadrature output. By counting these pulses and seeing which comes first you can tell the direction that the motor is spinning. Or you can just monitor both sensors and get more counts for more precise control.