Haptic Device Control System for Patient Safety
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Solution Overview
Problem
Haptic devices used in patient assistance during recovery from surgery face instability issues due to actuator saturation, leading to potential system failure and risk of injury to the patient, as they struggle to generate the required forces or torques, especially during sudden movements or falls.
Innovation Solution
A control system that determines stability boundaries based on the device's current position and velocity, adjusts the reaction course of action to prevent instability by selectively damping projected actions and implementing alternative courses of action that do not exceed these boundaries, ensuring safe operation and preventing oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control system generates high force or torque to address sudden patient movements or falls, then the patient safety and support capability are improved, but the actuator saturation and system instability occur
Solution Approach 1:
The control system applies preliminary damping forces to counteract potential instability before it occurs. By detecting conditions that may lead to actuator saturation or instability, the system proactively applies opposing damping forces to prevent erratic motion, thereby maintaining both patient safety and system stability simultaneously
Solution Approach 2:
The system continuously monitors actuator saturation conditions and system stability parameters, using this feedback to dynamically adjust control forces. When instability is detected, the feedback loop triggers damping actions to restore stability, resolving the contradiction between maintaining high support forces and preventing system instability
2Speed
If the control system allows full reaction forces to address patient motion, then the responsiveness and support capability are improved, but oscillations and erratic device motion occur
Solution Approach 1:
The control system dynamically adjusts damping parameters based on real-time system conditions and patient motion characteristics. By varying damping levels adaptively, the system maintains responsiveness to necessary patient movements while suppressing oscillations and erratic motion, resolving the contradiction between speed and harmful oscillations
Solution Approach 2:
The system changes control parameters (damping coefficients, force limits) based on detected motion patterns and stability conditions. When oscillations are detected, parameters are adjusted to increase damping and reduce erratic motion, while maintaining high responsiveness for legitimate patient movement needs
Data Source
AI summary
Systems and methods for use with haptic devices. A control system for haptic devices determines a first course of action based on a user's motion. Prior to implementing the first course of action, the control system determines if the first course of action would lead to instability in the haptic device which could cause an unsafe situation such as failure of its components. If the first course of action would lead to instability, the control device determines a second course of action that would not lead to instability and implements this second course of action. To assist in this second course of action and to prevent potential oscillation in the haptic device, the control system also selectively dampens a projected action of the haptic device. A haptic device using such a control system is also disclosed.