Design av styrsystem till rotationsstol och utveckling av numerisk modell av otolitmembran

Sammanfattning

This master thesis is made of two parts. The first part concerns the method and results of

designing a motion control system for a piece of research-equipment called BIRGIT. The

equipment is made to be used for research on eyemovements. In the second part, a computer

model of a part of the balance organ in the inner-ear is developed. The work has been done at

the Bernadotte laboratory at S:t Erik Eye Hospital.

The equipment the control system is made for is a so-called rotationchair. A rotationchair is a

piece of eqiupment with wich it is possible to physically translate and/or rotate a person.

Doing this will stimulate the balance-senses of the person and thus causing eye movement

responses. These responses are measured by an advanced video system.

The control system consists of a user interface on a PC, a motion control unit, servo motors

and sensors. The first part of creating the control system was to find out how to control the

motors to create the desired stimuli to the test-person. This was then done by programming

the PC interface and a motion control program on the motion control unit. A large part of the

work has been spent on making sure that the different parts of the system works together in a

correct and well controlled way.

The computer model shall simulate the dynamics of the so-called otoliths that are part of the

balance organs located in the inner ears. The otoliths resembles tiny gel membranes. In the

membranes there are motion sensitive receptors, detecting linear accelerations of the head. A

requirement of the model was to make it so that it could be implemented in the user interface.

The work started by examining previous articles concerning this field of study and data was

collected. A model was made by using numerical methods. Unfortunatelly the simulations

made with this model takes to long time to execute. The model is not practically usable. No

way has been found to work around this problem.