Tremor compensation by use of a mechatronic cup holder

In this paper a new assistive device for persons suffering tremor disease is presented. It should help those people to get along with the everyday life situation of consuming beverages and replace the feeding cups currently used. The cup holder is built up as a mechatronic system. It consists of a kinematic structure sustaining a standard cup as well as electronic and software components. The cup is moved by the device in order to compensate linear and rotational accelerations as well as tilt induced by a person´s tremor. For this purpose the characteristics of the fast and large scaled tremor movements of the patient´s hand are measured first. By use of the inverse kinematics calculated for the system and a method for the modelling of the liquid´s movement, necessary reactions of the cup holder are deduced. Using this information the device´s motors are actuated to avoid spillage of the liquid. The underlying calculations are run on a micro controller integrated in the system. An experiment was conducted to validate the function of the system. For this purpose an industrial robot was used to apply common tremor frequencies and amplitudes to the cup holder. It was shown that by use of the compensatory cup holder the spillage of the beverage can be eliminated at a wide range of different tremors.