title: Design, implementation and evaluation of an independent real-time safety layer for medical robotic systems using a force-torque-acceleration (FTA) sensor.
abstract: OBJECTIVE
  Most medical robotic systems require direct interaction or contact with the robot. Force-Torque (FT) sensors can easily be mounted to the robot to control the contact pressure. However, evaluation is often done in software, which leads to latencies.
  
  
  METHODS
  To overcome that, we developed an independent safety system, named FTA sensor, which is based on an FT sensor and an accelerometer. An embedded system (ES) runs a real-time monitoring system for continuously checking of the readings. In case of a collision or error, it instantaneously stops the robot via the robot's external emergency stop.
  
  
  RESULTS
  We found that the ES implementing the FTA sensor has a maximum latency of [Formula: see text] ms to trigger the robot's emergency stop. For the standard settings in the application of robotized transcranial magnetic stimulation, the robot will stop after at most 4 mm.
  
  
  CONCLUSIONS
  Therefore, it works as an independent safety layer preventing patient and/or operator from serious harm.
authors.affiliation: Institute for Robotics and Cognitive Systems, University of Lübeck, Ratzeburger Allee 160, 23562 , Lüebeck, Germany. richter@rob.uni-luebeck.de
authors.forename: Lars
authors.initials: L
authors.lastname: Richter
authors.forename: Ralf
authors.initials: R
authors.lastname: Bruder
mesh_terms: D000054:Acceleration; D000465:Algorithms; D004867:Equipment Design; D006801:Humans; D019300:Medical Errors / Q000517:prevention & control*; D008954:Models, Biological; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D012371:Robotics; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D019415:Torque; D014160:Transducers, Pressure; D014584:User-Computer Interface