Long-Stroke Rolling Diaphragm Actuators For Haptic Display of Forces in Teleoperation

We present a new rolling diaphragm actuator for transmitting forces in a teleoperated system. The initial application is for MR-guided biopsy procedures, providing accurate transmission of motions and forces between the fingertips of a physician and a biopsy needle being inserted into tissue. Desirable actuator qualities include low hysteresis, high axial stiffness, and long travel. The actuator uses an anisotropic laser-patterned fabric embedded in a soft silicone sleeve for a combination of low stretch in the axial direction and sufficient stretch in the radial direction so that a taper is not required; hence the actuator can have almost any length. We present results for a prototype input/output system with 6 cm stroke, 1 cm diameter, and a minimum force of 0.3 N to initiate motion. We compare its performance to a system using commercial rolling diaphragm actuators and show that the new system provides an improved combination of long stroke, high stiffness, and accurate transmission of fingertip forces.