Prosthetic Simulator Virtual Soft Tissue Control
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Solution Overview
Problem
Current prosthetic simulator machines fail to accurately replicate the complex motion and soft tissue constraints of human joints, leading to inadequate testing of prosthetic devices and increased risk of implant failure due to polyethylene wear and other failure mechanisms.
Innovation Solution
A virtual soft tissue control system is integrated into prosthetic simulator machines, utilizing a digital proportional integral derivative (PID) controller and an iterative learning control system to algorithmically model soft tissue constraints, enhancing motion control and simulating the natural forces encountered by prosthetics within the human body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical springs are used to simulate soft tissue constraints, then some soft tissue simulation capability is provided, but the system becomes cumbersome and has limited capability to simulate complex soft tissue characteristics
Solution Approach 1:
The patent replaces the mechanical spring system with a computer-controlled actuation system that uses sensors, controllers, and algorithms to simulate soft tissue constraints. This substitution eliminates the physical mechanical springs while achieving more accurate and programmable soft tissue behavior simulation through digital control mechanisms.
Solution Approach 2:
The patent implements a programmable control system that can dynamically adjust parameters such as force, displacement, and stiffness to simulate various soft tissue characteristics. This allows the system to adapt to different soft tissue behaviors by changing control parameters rather than requiring different physical mechanical components for each tissue type.
2Productivity
If displacement controlled machines use a priori kinematic descriptions, then the prosthetic device is subjected to prescribed motions, but the system makes no allowance for variations in prosthetic design and provides only rough approximation of human joint motion
Solution Approach 1:
The patent transitions from static, pre-programmed displacement control to a dynamic control system that adapts to the specific prosthetic device being tested. The system uses sensors to monitor actual device behavior and adjusts motion parameters in real-time, allowing the simulation to evolve during testing rather than following fixed predetermined paths.
Solution Approach 2:
The patent implements feedback control mechanisms where sensors monitor the prosthetic device's response during testing, and this information is fed back to the control system. The controller uses this feedback to adjust actuation parameters, ensuring the simulation accurately reflects the interaction between the prosthetic and soft tissues throughout the testing process.
Data Source
AI summary
A virtual soft tissue control system that provides enhanced motion control to a prosthetic simulator machine. The control system advantageously adds a “virtual soft tissue” control scheme to a conventional control system, such as a digital proportional integral derivative (PID) controller, to algorithmically model the soft tissue constraints that would be encountered by the prosthesis within the human body, and account for these forces in driving the simulator. In another aspect, a prosthetic simulator comprises a prosthetic drive mechanism; a feedback control system that drives the prosthetic drive mechanism; and an iterative learning control system that determines an error from a previous iteration of motion of the drive mechanism and uses the error to determine a drive signal for a subsequent iteration of motion. In certain embodiments, the prosthetic simulator uses both a soft tissue model and an iterative learning control system.