Task based kinematic design of a serial robot for the treatment of vestibular lithiasis

Benign Paroxymal Positional Vertigo and variants, collectively called "vestibular lithiasis", designate a common disorder caused by a malfunction of the inner ear. These pathologies are connected with the presence of dense particles within the semicircular canals which interfere with the sensing capabilities of angular velocity in the patient, causing nystagmus and vertigo. Some of these conditions can be treated by repositioning maneuvers physically done by the doctor that moves the head of the patient along different poses in space. Despite the fact that the treatment shows a success rate up to 80-90%, the failure rate remains highly significant and it is proven that precision repeatability and unlimited 360 degrees manoeuvrability can improve diagnostic and treatment potential for overcoming this kind of vertigo. In this paper the kinematic design of a serial robot that will execute repositioning maneuvers automatically is performed through a simplified task based kinematic design technique. The aim of the method is to find the minimum number of degrees of freedom to carry out a set of given tasks as well as the manipulator's topology and the Denavit-Hartenberg parameters. The proposed procedure firstly minimizes the number of degrees of freedom only and then a cost function connected to the total link length.