A Large Force Haptic Interface with Modular Linear Actuators

This paper presents a haptic interface with modular linear actuators which can address limitations of conventional devices based on rotatory joints. The proposed haptic interface is composed of parallel linear actuators that provide high backdrivability and small inertia. The performance of the haptic interface is compared with the conventional mechanisms in terms of force capability, reflected inertia, and structural stiffness. High stiffness, large range of motion with high force capability are achieved with the proposed mechanism, which are in trade-off relationships in traditional haptic interfaces. The device can apply up to 83 N continuously, which is three times larger than most haptic devices. The theoretical minimum haptic force density and the stiffness of the proposed mechanism were 1.3 to 1.9 times and 37 times of conventional mechanisms in a similar condition, respectively. The system is also scalable because its structural stiffness only depends on the timing belt stiffness, while that of conventional haptic interfaces is inversely proportional to the cube of structural lengths. The modular actuator design enables change of degrees freedom (DOFs) for different applications. The proposed haptic interface was tested by the interaction experiment with a virtual environment with rigid walls.