Medical Robot Arm Anchor Point Stiffness Model
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Solution Overview
Problem
Medical robotic arms often experience deviations from their target positions due to limited rigidity, affecting positioning accuracy, which is critical in medical applications.
Innovation Solution
A method to determine the optimal anchor point and joint positions of a robotic arm by calculating and maintaining a specified rigidity throughout its workspace using a stiffness model, incorporating mechanical and control stiffness, and accounting for forces and dead weight, ensuring high positioning accuracy and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the robot arm is designed with limited rigidity to reduce weight and complexity, then the device complexity and weight are reduced, but the positioning accuracy deteriorates due to deviations from target positions
Solution Approach 1:
The system performs preliminary calculation of the stiffness model and predicts position deviations before the robot arm executes movement. By pre-calculating the anchor point and compensating for expected deviations, the system maintains positioning accuracy without requiring physically rigid (and thus complex and heavy) arm structures.
Solution Approach 2:
The system continuously monitors the actual position of the robot arm and compares it with the theoretical position based on joint angles. Using the stiffness model, it calculates deviations and applies real-time compensation to maintain accurate positioning despite the arm's limited physical rigidity.
2Weight of moving object
If the robot arm uses flexible materials and designs to reduce weight, then the weight is reduced, but the rigidity and positioning stability worsen
Solution Approach 1:
The system replaces physical mechanical rigidity with computational compensation. Instead of relying on heavy, rigid materials to maintain stability, it uses a stiffness model and control algorithms to calculate and compensate for position deviations, achieving stability through information processing rather than physical mass.
Solution Approach 2:
The system dynamically adjusts operational parameters based on the calculated stiffness model. By changing joint positions and calculating corresponding position deviations in real-time, it compensates for the effects of reduced physical rigidity, maintaining positioning accuracy despite using lighter, more flexible arm constructions.
3Manufacturing precision
If the robot arm is made more rigid to improve positioning accuracy, then the positioning accuracy is improved, but the weight and energy consumption increase
Solution Approach 1:
The invention substitutes mechanical rigidity with a computational stiffness model. Rather than increasing physical weight to achieve rigidity, the system uses software-based prediction and compensation of position deviations, maintaining high positioning accuracy with lighter arm construction.
4Ease of manufacture
If the robot arm structure is simplified to reduce complexity, then the ease of manufacture is improved, but the positioning accuracy deteriorates due to unaccounted rigidity variations
Solution Approach 1:
The system performs preliminary characterization of the robot arm's stiffness properties during manufacturing or setup. By pre-calculating the stiffness model based on the actual simplified structure, it compensates for rigidity variations in subsequent operations, allowing simple, easy-to-manufacture arm designs to achieve high positioning accuracy through computational correction.
Data Source
Figure 1
AI summary
Method for assessing the positioning accuracy of a medical robot arm with at least one joint, wherein the stiffness of the robot arm in a joint position is calculated and assessed using a stiffness model.