Capstan Haptic Controller for Human-Scale Force Feedback
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Solution Overview
Problem
Current VR controllers struggle to render realistic haptic feedback, especially in simulating human-scale forces during interactions like grasping and squeezing, due to limitations in design, power consumption, and safety.
Innovation Solution
The development of energy-storing resistive haptic controllers (ESR haptic controllers) that utilize a capstan-based brake and a clutchable spring to provide variable resistive forces and energy storage, enabling the simulation of both rigid and compliant objects without the need for large, power-hungry actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a strong servo motor is used to produce human-scale forces, then the haptic feedback capability is improved, but the device becomes heavy, expensive, and power-hungry
Solution Approach 1:
The system dynamically switches between brake-based force generation and spring-based energy storage depending on the interaction requirements. The brake is applied when high force is needed, then released to allow spring-driven compliant interaction, optimizing power consumption while maintaining force capability
Solution Approach 2:
The patent replaces the traditional continuous-power servo motor system with a hybrid passive-active mechanical system combining friction brakes and elastic springs. This substitution eliminates the need for continuous high-power motor operation while maintaining human-scale force output
2Force
If a brake is used to resist user applied force, then high forces can be sustained, but the grasp is locked at a certain point and requires manual release
Solution Approach 1:
The spring mechanism automatically releases the brake by reversing the winding direction when the user opens their grasp. The system serves itself by using the user's natural motion to trigger the release mechanism, eliminating the need for manual release operations
Solution Approach 2:
The system uses feedback from the user's grasp force and motion to automatically control the brake application and release. When detection indicates the user is opening their grasp, the system automatically reverses the brake action, providing adaptive control without manual intervention
3Reliability
If an active mechanism with servo motor is used, then haptic feedback is provided, but the device is non-robust and complex
Solution Approach 1:
The patent employs simple, robust mechanical components (brakes and springs) that can withstand high forces and repeated use without the fragility of electronic actuators. These passive mechanical elements are inherently more durable than active servo mechanisms in high-stress haptic applications
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 effectively render human-scale forces with lower power consumption, improved safety, and the ability to simulate a wide range of tactile experiences, including the sensation of squeezing both inelastic and elastic virtual objects.
Implementation Method 1
An alternative is resisting the user applied force with a brake
Implementation Method 2
The present device employs a brake, a spring, and a capstan
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.