Capstan Haptic Controller for Human-Scale VR Grasp Forces
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Solution Overview
Problem
Current VR controllers lack the ability to render realistic haptic feedback, particularly in simulating human-scale forces during interactions with virtual objects, leading to inadequate grasping and manipulation experiences due to their reliance on large, power-hungry actuators and binary brake mechanisms.
Innovation Solution
The development of energy-storing resistive haptic controllers (ESR haptic controllers) that utilize capstan-based braking and twisted string actuators to provide variable resistive forces and energy storage, allowing for realistic rendering of both rigid and compliant object interactions without the need for large, high-force actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a strong servo motor is used to produce human-scale forces, then haptic feedback capability is improved, but device weight increases and power consumption increases
Solution Approach 1:
The patent introduces a capstan mechanism as an intermediary between the user's hand and the force-generating system. The capstan uses friction-based mechanics to amplify small forces from a lightweight actuator into large gripping forces, eliminating the need for heavy servo motors while maintaining human-scale haptic feedback capability.
Solution Approach 2:
The patent replaces traditional high-force electromagnetic actuators with a mechanical advantage system using capstans and friction. This substitution allows a lightweight actuator to generate substantial gripping forces through mechanical leverage, significantly reducing controller weight while maintaining haptic feedback performance.
2Force
If a brake mechanism is used to resist user force, then force sustainability is improved, but grasping release becomes manual and less flexible
Solution Approach 1:
The patent implements a dynamic braking system where the capstan's friction characteristics can be modulated in real-time. The brake force is not fixed but can be adjusted programmatically to allow automatic release when needed, providing both force sustainability during grasping and flexible release control for different object types.
Solution Approach 2:
The patent changes the friction parameter of the capstan brake dynamically based on the interaction state. By adjusting the normal force or friction coefficient of the capstan, the system can transition between high-force sustenance mode and easy-release mode, enabling automatic release for compliant objects while maintaining grip for rigid objects.
3Device complexity
If binary brake mechanism is used, then device complexity is reduced, but haptic rendering fidelity for compliant objects decreases
Solution Approach 1:
The patent transforms the static binary brake into a dynamic continuous-control brake. The capstan mechanism allows for variable friction levels through programmable actuation, enabling fine-grained control of gripping force that accurately renders compliant object properties while maintaining relatively simple mechanical structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These controllers enable safe, low-power, and cost-effective simulation of human-scale forces, providing a more natural and realistic haptic experience by resisting user input and storing energy from user movements, thus enhancing VR interaction fidelity.
Implementation Method 1
utilize capstan-based braking... to provide variable resistive forces
Implementation Method 2
energy-storing resistive haptic controllers (ESR haptic controllers) that utilize capstan-based braking and twisted string actuators to provide variable resistive forces and energy storage
Data Source
AI summary
The present concepts relate to haptic controllers. In one example the haptic controller can include first and second capstans rotationally secured to a base and an energy storage mechanism connected between the first and second capstans. The example haptic controller can also include a user engagement assembly secured to the first capstan and a controller configured to control rotational forces imparted on the user engagement assembly by controlling rotational friction experienced by the first and second capstans.