Martin Bräutigam; Mikael Gustafsson , pp. 50. TEK/avd. för signalbehandling, 2006.
Researchers in neurophysiology in Lund have undertaken measurements of the spinal cord in rats where the movement of the spinal cord due to blood flow and breathing has proved to be a major obstacle in their research. Except from manufacturing electrodes specialized for the task, an idea has been to reduce the effect of the motion by moving a table on which the object is placed, in a compensating manner. To further explore this idea, cooperation with an engineer at the department of Neurophysiology, Lund University, has been the subject of this thesis.
A table movable in three directions was constructed. DC-motors controlling an eccentric were chosen as actuators for the motion control. A circuit for direct analogue control of DC-motors implementing proportional, integrating and differentiating stages aimed for standard PID control was built. The circuit allows current control to avoid overload of the motor as well as balancing of DC-noise from the amplifier stages.
Recordings of the spinal cord motion as well as heart and breathing signals was done with a laser-vibrometer. Signal analysis was performed to investigate the suitability of reference-based feed forward control with the filtered-x LMS algorithm. The analysis showed poor result for this method.