Design and Control of a Cable-Driven Sectorial Rotary Actuator for Open-Loop Force Control

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Virginia Tech

This thesis focuses on the detailed design, implementation, and testing of a unique high performance rotary actuator for use in a custom haptic force feedback device. This six degree of freedom (DoF) position input and three DoF force output haptic device is specifically designed to recreate force sensations with the goal of improving operator performance in remote or simulated environments. By upholding the strict design principles of an ideal force-source actuator, the developed actuator and consequently the haptic controller can successfully replicate forces accurately and realistically. In the comprehensive presentation of this design, numerous analytical tools are also developed and presented with the intention of them being resourceful in the design or improvement of other haptic actuators, specifically cable-driven force feedback designs. These tools which include a linear system model can be valuable not only in the development but in the control of cable-driven actuators.

Due to the imposed design criteria, the developed 1.045 Nm (1.359 Nm peak) cable-driven sectorial rotary actuator exhibits numerous properties that are desired in an open-loop force controlled actuator. These properties include low inertia (6.53e-04 kgm^2), low perceived mass (0.102 kg), small torque resolution (3.84e-04 Nm), small position resolution (21.5 arcsec), and high bandwidth (300 Hz). Due to the efficient cable transmission the design is also backdrivable, isotropic, low friction, and zero backlash. As a result of these numerous intrinsic properties, a high fidelity force feedback haptic actuator was conceived and is presented in this thesis.

Cable Drive, Delta, Force Control, Haptic, Impedance, Open-Loop, Rotary Actuator