Force-Position Hybrid Control for Robot Assisted Thoracic-Abdominal Puncture With Respiratory Movement

Percutaneous puncture is a widely used procedure in the diagnosis and therapy of cancer such as biopsy and ablation operations, while the organs in the thoracic and abdominal cavities are significantly affected by patients' respiratory movement. In this letter, a robotic puncture system with respiratory movement is firstly developed, which can simulate the different motions of body surface and internal organ during respiratory cycle. Then a force-position hybrid control framework is proposed, which includes needle insertion along the planned path at the end of inspiration and respiratory motion following according to interaction force sensing at the other phases. Since it requires only one CT scan at the end of inspiration, which complies with clinical routine procedures. Furthurmore, to avoid tearing damage of tissue, the robotic needle takes a virtual RCM constraint at the needle insertion point when following the respiratory motion. And for better respiratory motion compensation, an admittance control optimization method is proposed based on the maximal needle-tissue interaction force, the respiratory following displacement percentage and the overshoot dis-placement/force. Experiments have been conducted, and results show that compared with position control only, our proposed force-position control can reduce the needle-tissue interaction force by 74% and the target puncure error by 56%, indicating better safety and accuracy of robotic puncture with respiratory movement.