Co-Actuation: A Method for Achieving High Stiffness and Low Inertia for Haptic Devices

Area of Science:

• Robotics
• Human-Computer Interaction
• Virtual Reality

Background:

• Current haptic devices struggle to achieve both high stiffness and low inertia, limiting realistic simulation of virtual environments.
• Impedance-based devices excel at high stiffness but compromise on low inertia, while admittance-based devices face the opposite limitation.
• Simultaneously rendering hard contacts and low inertia is a significant challenge in virtual reality applications.

Purpose of the Study:

• To introduce and evaluate a novel co-actuation module designed to overcome the limitations of existing haptic devices.
• To enable haptic devices to simultaneously achieve high stiffness and low inertia for enhanced virtual environment interaction.
• To demonstrate the feasibility of co-actuation for rendering realistic haptic feedback, including hard surfaces.

Main Methods:

• A one degree-of-freedom (DOF) revolute joint co-actuation module was developed, incorporating a link and a physically constrained component with clearance.
• A motor was used to control the physical constraint, allowing it to move cooperatively with the link.
• The module's performance was evaluated on a two-DOF haptic device within a 100 mm × 100 mm workspace.

Main Results:

• The co-actuation module demonstrated effective inertia ranging from 64-142 g within the workspace.
• The haptic device successfully rendered a virtual wall with stiffness up to 65 N/mm.
• Minimal penetration (0.02-0.41 mm) was observed when interacting with the virtual wall at speeds of 80-320 mm/s, with a maximum back-driving force of 0.19 N.

Conclusions:

• The co-actuation module is a feasible concept for enhancing haptic devices.
• This approach effectively achieves a high range of stiffness and low inertia, crucial for realistic virtual interactions.
• The developed module significantly advances the capability of haptic devices in simulating complex physical properties.