title: Modelling and control of a five-degrees-of-freedom pneumatically actuated magnetic resonance-compatible robot.
abstract: BACKGROUND
  Magnetic resonance imaging (MRI) combined with robotic assistance has the potential to improve on clinical outcomes of biopsy and local treatment of prostate cancer. This paper introduces a pneumatically actuated surgical robotic system for prostatic interventions under MRI guidance.
  
  
  METHODS
  A mechanical dynamics model was established using the Lagrange method and simulated using MATLAB software. A pneumatic actuator model was built through the use of system identification, and stability analysis was proposed based on the Nyquist criterion. In addition, a proportional-integral-derivative controller was implemented on the robot for accurate position control.
  
  
  RESULTS
  Simulation results showed that the steady-state error of a step response was 0.3 mm and the tracking error of a 1.0 Hz sinusoidal response was 1.5 mm. Experimental results showed that the insertion precision was 0.72 mm in the general laboratory environment.
  
  
  CONCLUSIONS
  The results demonstrated that the robotic system with the designed controller was effective in both position control and trajectory tracking.
authors.affiliation: Key Laboratory of Mechanism and Equipment Design of the Ministry of Education, Tianjin University, People's Republic of China.
authors.forename: Shan
authors.initials: S
authors.lastname: Jiang
authors.forename: Wenhao
authors.initials: W
authors.lastname: Feng
authors.forename: Jinlong
authors.initials: J
authors.lastname: Lou
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
mesh_terms: D001696:Biomechanical Phenomena; D001707:Biopsy, Needle / Q000295:instrumentation; D001918:Brachytherapy / Q000295:instrumentation; D003198:Computer Simulation; D004867:Equipment Design; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D019047:Phantoms, Imaging; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000532:radiotherapy; D011880:Radiotherapy Planning, Computer-Assisted; D065287:Robotic Surgical Procedures / Q000295:instrumentation*; D012984:Software
keywords: MRI guidance; PID controller; actuator model; dynamics model; prostatic interventions; surgical robotics