Force-Feedback Exoskeleton Actuator With Membrane-Controlled Braking
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Solution Overview
Problem
Existing force feedback exoskeletons face challenges in integrating miniaturized actuators that can be comfortably worn on the hand and function reliably over numerous actuation cycles, with passive actuators being compact but lacking the ability to perform work, and active actuators being large and potentially hazardous.
Innovation Solution
An actuator assembly comprising a rotating body coupled to a tendon and a spring, with a membrane-controlled braking mechanism using a pressurized fluid source to apply variable forces, allowing for compact design and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If passive force feedback actuators are used, then the device size and weight are reduced, but the ability to perform work on the user's body is lost
Solution Approach 1:
The system dynamically switches between passive brake mode (for size/weight benefits) and active motor mode (for work capability) based on operational requirements. The motor can actively drive the tendon when work is needed, while the brake provides passive resistance when compact size is prioritized.
Solution Approach 2:
The actuator assembly integrates both motor-driven active components and brake-driven passive components into a single multi-functional unit. This allows the same device to provide both active force generation and passive force resistance, eliminating the need for separate actuator systems.
2Power
If active force feedback actuators are used, then the ability to perform work is improved, but the device size and weight increase
Solution Approach 1:
The patent combines the motor and brake into a single integrated actuator assembly that shares common structural elements, such as the rotating body and tendon coupling mechanism. This merging reduces the total weight and size compared to having separate active and passive actuators.
Solution Approach 2:
The system dynamically switches between passive brake mode (for size/weight benefits) and active motor mode (for work capability) based on operational requirements. The motor can actively drive the tendon when work is needed, while the brake provides passive resistance when compact size is prioritized.
3Object-affected harmful factors
If passive force feedback actuators are used, then the device is inherently safer, but the ability to provide variable force feedback is limited
Solution Approach 1:
The actuator assembly integrates both motor-driven active components and brake-driven passive components into a single multi-functional unit. This allows the same device to provide both active force generation and passive force resistance, eliminating the need for separate actuator systems.
Solution Approach 2:
The control system can dynamically switch between passive brake-only mode (maximum safety) and active motor-driven mode (enhanced force feedback capability). The brake continues to provide inherent safety by dissipating energy, while the motor adds versatile force feedback when needed.
4Volume of moving object
If miniaturized actuators are integrated, then the wearable comfort is improved, but the reliability over numerous actuation cycles deteriorates
Solution Approach 1:
The patent combines the motor and brake into a single integrated actuator assembly that shares common structural elements, such as the rotating body and tendon coupling mechanism. This merging reduces the total volume while distributing mechanical stresses across robust shared components designed for high-cycle durability.
Solution Approach 2:
The brake mechanism provides inherent self-lubrication through friction surfaces and self-adjusting contact pressures that maintain reliable operation over hundreds of thousands of cycles. The passive dissipative nature of the brake reduces thermal buildup and wear compared to continuous active motor operation.
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
Enables a compact, safe, and reliable haptic feedback system that provides variable resistance to user motion, suitable for wearable applications.
Implementation Method 1
a spring, the spring configured to produce a torque on the rotating body
Implementation Method 2
a second body having a surface configured to apply a variable force to a surface of the rotating body by means of a membrane enclosing a volume fluidically coupled to at least one control valve and to a pressurized fluid source
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Improved actuator and retraction mechanisms for force feedback exoskeletons are described. An actuator assembly for a force-feedback exoskeleton comprising: a rotating body coupled to a tendon and to a spring, said spring configured to produce a torque on the rotating body; and a second body having a surface configured to apply a variable force to a surface of the rotating body by means of a membrane enclosing a volume fluidically coupled to at least one control valve and to a pressurized fluid source, wherein the volume enclosed by the membrane comprises: a first pressure state in which the rotating body contacts the second body; and a second pressure state in which the rotating body does not contact the second body.