Semi-active guiding systems in surgery. A two-dof prototype of the passive arm with dynamic constraints (PADyC)

Abstract Guiding systems for surgical applications range from passive systems to active ones depending on the level of autonomy left to the surgeon. Passive systems provide the surgeon with suitable information to compare the executed strategy with a planned one whilst active systems autonomously perform a part of the surgical strategy. Depending on the selected technology, guiding systems may be more or less accurate, more or less safe, more or less user-friendly. Actuated robots are generally very accurate but raise safety and ergonomics issues; passive systems (optical localizers, motorless encoded arms, etc.) are well-suited to navigation but their use is difficult for executing complex surgical strategies. A new type of mechanical guiding system has been designed, based on the use of dynamic constraints; this passive arm is actuated by the surgeon who keeps, therefore, fully involved in the execution of the surgical strategy. At each instant, the motions proposed by the operator are “filtered” with respect to the task, before being transmitted to the arm. This system seems a good answer to the guided execution of potentially complex strategies in an accurate and ergonomical way. The principles of the PADyC arm are presented and experiments already done with a two-DOF prototype are described.