Accurate Position Tracking Control of a Lung Tumor Mimic Model Using a Low-Cost Pneumatic Robot

This paper presents a new approach for the control of a pneumatic robot dedicated to precisely reproduce the breathing-induced motion of a human lung tumor. In medical research and tumor scanner experiments, a tumor mimic model should perform the identical smooth motion as it occurs in a real human body during exhalation and inhalation. For this purpose, a serial robot with three pneumatically driven axes has been developed and built up. Aiming at a low-cost solution, only three pneumatic valves are used. Given the small chamber volumes of the pneumatic cylinders, a precise modeling and identification of the pneumatic components proves important. The proposed control approach involves a cascaded tracking control structure with fast inner control loops for the cylinder force, whereas the corresponding outer control loop handles the position control of the corresponding cylinder. Furthermore, a lumped disturbance force is counteracted by a simplified disturbance observer. The performance of this low-cost solution is validated and compared with results from a previous, more expensive design.