This is a simple PC based controller for the PneuStep motor, built for fMRI experiments at the K.U. Leuven in Belgium. The motor is connected to the PC case with 8m long hoses. Three of these carry the air for actuation and the forth one has a set of 4 optic fibers for the encoder. The motor is electricity free, does not contain any metals, and is entirely made of non-magnetic and dielectric materials.
In this implementation the PneuStep is configured for rotary output and fitted with a plastic belt drive gear. The motor and its hoses are MRI safe and fully compatible within the highest field strength. The controller box is not MRI compatible and is to be placed close by in the MRI controller room or other adjacent space. The hoses are passed through the waveguide access panel.
A small size industrial PC case houses the computer and the PneuStep controller. A motion control card gives the step and direction signals for the custom PneuStep driver. The driver commands three fast-acting solenoid valves mounted on a manifold feeding the three pneumatic hoses. An air supply (2-7 bar) port is fitted on the back side of the case. Their output is passed on the pneumatic hoses. Two fiber optic modules are used for the electro-optical interface of the built in PneuStep encoder. The feedback signals are passed to motion control card and used by the onboard DSP, which is configured for closed loop stepping. The DSP loop is customized from the motherboard for the special speed/torque characteristic of the PneuStep motor.