Magnetic Counterbalance Technology

Gravity compensation for vertical loads provides a critical role in preventing the sudden fall of that load during power loss.  It also minimizes the required force to hold or make small moves, reducing current requirement to the motor.  It also may help reduce the size to the actuator, reduce heating, and improve positioning accuracy.

There are a number of methods, both mechanical  and active control-based used to compensate for gravity.

Counterweights: A simple approach using an equivalent mass to the load, connected via a pully, providing an opposing force.  This is common on many elevator systems.

Springs: Another simple approach to use a constant force spring to provide a counterforce, although this can introduce compliance e into mechanics causing issues with servo tuning, reducing overall system bandwidth.

Pneumatics or hydraulics: These can be effective solutions for significant loads but are more complex to implement and add additional maintenance and environmental issues into the application.

Magnetic Counterbalances:  Utilize magnetic principles to provide an offset force based on the expected load force of the system.

Active Techniques: Control based techniques can use feedback elements and model-based feedforward algorithms to offset the gravitational forces. Inverse dynamics and virtual displacement systems used complex calculations to provide gravity offsets as needed based on feedback elements.

The gLess magnetic counterbalance is a non-contact passive device adopting a unique magnet arrangement in the outer shell with a bi-metallic rod which provides a constant counterforce throughout its range of motion.  This simple device is maintenance free and is simple to install and tune.  The magnetic design also has virtually no magnetic flux leakage on the outside case or rod allowing for mounting in close proximity to linear shaft motors and magnetic encoders.