Prosthetic Arm Segmentation and Dynamic Support for Range of Motion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing prosthetic arms have limited movement and functionality, particularly for users who have lost their entire arm from shoulder to hand, with limited degrees of freedom and inability to perform finer tasks effectively.
Innovation Solution
A prosthetic arm apparatus with a shoulder unit, humeral rotator, elbow flexion joint, wrist rotation site, and hand assembly featuring harmonic drive gearing systems, compliance sensors, and non-backdriving clutches to provide increased range of motion, tactile capabilities, and comfort, along with a dynamic support apparatus that adjusts geometry and temperature for secure fit and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing prosthetic arm designs are used, then the device structure is simple, but the range of motion and degrees of freedom are limited
Solution Approach 1:
The prosthetic arm is divided into multiple independent joint modules (shoulder flexion/abduction, elbow flexion/extension, wrist rotation, hand assembly), each with its own actuation system. This segmentation allows each joint to provide specific degrees of freedom while maintaining overall system manageability and adaptability.
Solution Approach 2:
The prosthetic arm employs dynamic actuation systems with motors and gear trains that can adjust movement parameters in real-time. The compliant elements and sensors enable the system to adapt its stiffness and motion characteristics dynamically, providing realistic movement patterns while maintaining structural integrity.
2Measurement precision
If existing prosthetic hand designs are used, then the device is simple to manufacture, but the tactile capabilities and fine task performance are limited
Solution Approach 1:
The hand assembly incorporates specialized tactile sensors and compliant elements at specific locations (fingertips, palm) where tactile feedback is most needed. This localized enhancement of sensing capability provides fine task performance without requiring complex structures throughout the entire hand assembly.
Solution Approach 2:
Tactile sensors in the hand assembly provide real-time feedback about contact forces and object properties. This feedback is transmitted to the control system, which adjusts actuator commands to enable precise manipulation and fine task performance, creating a closed-loop control system.
3Reliability
If a secure fit is prioritized, then the support apparatus provides stability, but the comfort and adaptability to user movement are reduced
Solution Approach 1:
The support apparatus uses compliant elements and adjustable support forces that can dynamically adapt to user movements and residual limb shape changes. This dynamic adaptation maintains a secure fit during various activities while preventing discomfort from excessive or misplaced forces.
Solution Approach 2:
The support apparatus can adjust key parameters such as support force magnitude, contact pressure distribution, and geometric configuration to optimize both security and comfort. These parameter changes allow the system to adapt to different user needs, activities, and residual limb conditions.
4Adaptability or versatility
If multiple sensors and actuators are added to improve functionality, then the range of motion and tactile capabilities increase, but the weight of the device increases
Solution Approach 1:
Sensors and actuators are distributed across separate modular joint assemblies rather than concentrated in one location. This segmentation allows each module to be optimized for its specific function and enables selective actuation, reducing the effective moving mass during different tasks.
Solution Approach 2:
Compliant elements and passive mechanical structures provide support and movement assistance without requiring active actuation. This self-service capability reduces the number of motors and sensors needed, thereby reducing overall device weight while maintaining functionality.
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
The prosthetic arm apparatus offers improved range of motion, tactile feedback, and comfort, enabling users to perform complex tasks with increased degrees of freedom and secure fit, while the dynamic support apparatus ensures a comfortable and secure interface with the user's body.
Implementation Method 1
The harmonic drive gearing system has an interior wave generator that corresponds with the flexible spline. The spline in turn engages the exterior circular spline, resulting in drastic reduction rates and driving the shoulder output flange
Implementation Method 2
The circular spline, series elastic elements and reactor elements are circumferentially disposed around the interior of a clamp. Together, the clamp and a compliance reactor substantially enclose the circular spline, series elastic elements, and reactor elements. Upon application of force, the position of the circular spline alters causing the series elastic elements to compress against the reactor elements
Implementation Method 3
Additionally, a magnet is disposed on the exterior rim of the circular spline for measuring compliance. Upon application of force, the position of the circular spline alters causing the series elastic elements to compress against the reactor elements. The movement of the reactor elements transmits the rotational displacement of the circular spline via the reactor movement in relation to the stationary magnet
Implementation Method 4
The clutch has an input cage, an output hex, and a clutch race, or ground. When the shoulder flexion joint is acted upon by an output force, the output hex is engaged in a friction lock with the clutch race and bearings lining the exterior of the output hex, preventing backward transfer of power through the clutch
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A prosthetic arm apparatus including a plurality of segments that provide a user of the prosthetic arm apparatus with substantially the same movement capability and function as a human arm. The segments are connectable to one another and connectable to a prosthetic support apparatus that may be adorned by the user. Each segment of the plurality of segments provides a portion of the movement capability, enabling the plurality of connected segments connected to the harness mount to provide substantially the same movement capability as that lacking in the user. A dynamic support apparatus for supporting the prosthetic arm apparatus has a frame, a dynamic interface, a temperature control mechanism, and a control system. The dynamic support apparatus has a control system that is operably connected to the dynamic interface and controls the dynamic interface to change its geometry.