A 3D-printed low-cost 6-DOF human interaction force sensor for a haptic interface

A haptic interface typically only senses the motion of the interface and provides a force for haptic feedback. It does not sense the force/torque applied by the human operator on the interface. The applied human force can be useful for controlling the haptic interface as a manipulator (as in bilateral teleoperation) and for interpreting operator intent. This paper describes a custom 3D-printed 6-DOF human interaction force sensor designed for the Novint Falcon haptic interface which costs two orders magnitude less than commercial 6-DOF force sensors. The sensor design uses a Maltese cross configuration with integrated electronics and features for attachment to the Falcon. Finite element analysis of the 6-DOF sensor was used to optimize strain gauge placements and for evaluating design changes. The sensor was 3D printed in PLA using a low-cost hobbyist printer. Calibration and testing results of the sensor prototype indicate that the sensor has good linearity and sensitivity, minimal cross-coupling between axes and a force range and responsiveness that are suited for the haptic interface application.