Linear Motor Biopsy Control for Penetration Overshoot Prevention
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Solution Overview
Problem
Existing biopsy devices often result in overshoots during procedures, causing excessive damage to surrounding tissues and prolonging recovery times, particularly when penetrating tougher layers like bone cortex or softer tissues near organs.
Innovation Solution
A biopsy device equipped with a linear motor and feedback control system that includes a controller circuit, linear motor shaft feedback, and housing position detector, allowing precise control of the penetrating member's advancement to maintain a constant axial position and compensate for user movement, thereby reducing overshoots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a user applies large force to penetrate tougher bone cortex layers, then penetration capability is improved, but penetration depth accuracy deteriorates causing overshoot into softer bone and marrow layers
Solution Approach 1:
The system employs a feedback control mechanism where a position sensor detects the actual position of the linear motor shaft, and a controller adjusts the drive signals based on the difference between target and actual positions. This closed-loop feedback enables precise control of penetration depth even when large forces are applied to penetrate bone cortex, preventing overshoot into softer layers.
Solution Approach 2:
The patent replaces manual mechanical control with an automated linear motor system that uses electromagnetic forces instead of purely mechanical force application. This substitution allows for programmable, precise control of penetration depth and rate, eliminating the need for users to manually apply large forces that lead to overshooting.
2Productivity
If penetration rate is increased to improve productivity, then biopsy procedure time is reduced, but penetration depth control accuracy deteriorates leading to overshoots and tissue damage
Solution Approach 1:
The system dynamically adjusts the linear motor shaft's advancement rate based on real-time feedback from the position sensor. The controller can modify acceleration, velocity, and deceleration profiles during the biopsy procedure, enabling high-speed penetration when appropriate while automatically slowing down near the target depth to maintain precision and prevent overshoot.
Solution Approach 2:
The feedback control system continuously monitors the linear motor shaft position and adjusts drive signals to maintain accurate depth control regardless of penetration speed. This enables the system to achieve both high productivity through faster overall penetration and high precision through real-time position correction.
3Device complexity
If manual control is used to adjust penetration depth, then device simplicity is maintained, but penetration depth precision deteriorates due to user movement and timing errors
Solution Approach 1:
The system performs self-correction of penetration depth through automated feedback control. The position sensor continuously monitors the linear motor shaft position, and the controller automatically adjusts positioning without requiring manual intervention. This self-service capability eliminates user movement and timing errors that plague manual control systems.
Solution Approach 2:
The patent replaces manual mechanical depth adjustment with an automated electromechanical control system. The linear motor, position sensor, and controller work together to automatically achieve precise penetration depth, substituting human operator control with an automated system that eliminates timing errors and movement inconsistencies.
4Manufacturing precision
If overshoot prevention measures are added to improve accuracy, then penetration depth precision is improved, but device complexity increases
Solution Approach 1:
The system uses a straightforward feedback control architecture with a position sensor and controller that adjusts the linear motor based on position feedback. This relatively simple feedback mechanism effectively prevents overshoot by continuously comparing target and actual positions and making real-time corrections, achieving high precision without excessive complexity.
Solution Approach 2:
The controller acts as an intermediary between the user's depth command and the linear motor's actual movement. It processes position feedback from the sensor and generates appropriate drive signals, mediating the control process to achieve precise depth control while keeping the overall system architecture relatively simple and modular.
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 device achieves greater accuracy in biopsy procedures by maintaining consistent penetration depth and rate, minimizing damage to surrounding tissues and reducing procedural complications.
Implementation Method 1
The linear motor has a motor housing and a linear motor shaft. The motor housing is coupled to the device housing. The linear motor shaft is movable in the motor housing along a longitudinal axis.
Implementation Method 2
A controller circuit is operatively coupled to the linear motor. The controller circuit has a processor circuit, a first feedback circuit, and a second feedback circuit. The first feedback circuit has at least one drive characteristic sensor associated with the linear motor shaft.
Data Source
AI summary
A biopsy device includes a device housing, a linear motor, and a controller circuit. The controller circuit has a processor circuit, a first feedback circuit, and a second feedback circuit. The first feedback circuit and the second feedback circuit operate simultaneously. The processor circuit executes program instructions to control an axial advancement of the distal end of the linear motor shaft in accordance with a linear motor shaft advancement profile based on first control signals received from at least one drive characteristic sensor of the first feedback circuit, and executes program instructions to keep the distal end of the linear motor shaft at a constant axial position, as offset by the position indicated by the linear motor shaft advancement profile, based on second control signals received from the housing position detector of the second feedback circuit so as to compensate for user movement of the device housing.