Swivel Assembly for Actively Limiting Cable Torsion in TTFields Testing
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Solution Overview
Problem
Current systems for testing Tumor Treating Fields (TTFields) in animal test subjects face challenges such as cable twisting, animal damage to electrical components, and restricted movement due to inadequate slack or excessive restriction, leading to incorrect positioning and potential damage.
Innovation Solution
A swivel assembly that securely engages cables, allowing for rotational movement while maintaining electrical communication, equipped with a motor and sensor system to detect torsion and adjust the cable position, and a controller to manage motor rotation and detect abnormal rotation, ensuring consistent and safe TTFields delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cable is allowed to rotate freely to enable animal movement, then the animal's mobility is improved, but cable twisting and winding occur leading to potential damage and positioning errors
Solution Approach 1:
A swivel assembly is introduced as an intermediary device between the cable and the treatment assembly. The swivel includes a rotor that can rotate relative to a stator, allowing the cable to follow the animal's movements without twisting. The rotor connects to the cable via a connector while the stator remains fixed to the cage, serving as a mediator that decouples the cable from rotational forces.
Solution Approach 2:
The swivel assembly transitions from a static cable connection to a dynamic rotating connection. The rotor is configured to rotate freely in response to torques applied by the moving animal, while a spring mechanism provides a restoring force to return the rotor to its neutral position when torque is removed, enabling continuous adaptive movement without cable damage.
2Reliability
If the cable is restricted to prevent twisting, then cable damage is reduced, but animal movement becomes restricted leading to incorrect positioning
Solution Approach 1:
The swivel assembly acts as a mediator that allows rotational movement of the treatment assembly while keeping the cable connection point fixed to the cage. The rotor can rotate independently within the swivel housing, permitting the animal to move freely without transmitting twisting forces to the cable.
Solution Approach 2:
The swivel assembly divides the cable connection system into two independent parts: the stator fixed to the cage and the rotor that rotates with the animal's movements. This segmentation allows the cable to remain stationary while the treatment assembly moves, preventing cable twisting while maintaining animal mobility.
3Reliability
If a swivel assembly is added to prevent cable twisting, then cable integrity is improved, but device complexity increases
Solution Approach 1:
The swivel assembly is designed to automatically respond to the animal's movements without external control. The rotor rotates freely in response to applied torques, and the spring automatically provides a restoring force, eliminating the need for motors, sensors, or complex control systems that would further increase device complexity.
Solution Approach 2:
The swivel assembly uses a spring mechanism to provide a variable restoring torque that depends on the rotation angle. The spring constant and pre-load can be adjusted to control the rotational characteristics, allowing optimization of the balance between allowing movement and preventing excessive twisting without adding complex active control systems.
4Ease of operation
If the swivel allows free rotation to maintain electrical communication, then animal movement is improved, but abnormal rotation may damage components
Solution Approach 1:
The spring mechanism in the swivel assembly provides a restoring force that acts before excessive rotation can occur. The spring continuously exerts a torque to return the rotor to its neutral position, cushioning against abnormal rotations and preventing the cable and electrical connectors from being damaged by extreme twisting.
Solution Approach 2:
The spring mechanism converts the harmful effect of uncontrolled rotation into a beneficial restoring force. Instead of allowing free rotation that could lead to damage, the spring uses the rotational displacement itself to generate a counter-torque that actively returns the system to its safe neutral position, turning the potential harm of movement into a protective mechanism.
Data Source
AI summary
A swivel assembly can have a longitudinal axis. The swivel assembly can have an upper portion and a lower portion that is rotationally coupled to the upper portion. The lower portion can have a connector configured to securely engage a cable. The lower portion can be configured to remain in electrical communication with the upper portion as the lower portion rotates with respect to the upper portion. A motor can be disposed between the upper portion and the lower portion and configured to selectively rotate the lower portion. A sensor can be configured to detect torsion in the cable. A controller can be in communication with the sensor and the motor. Upon receiving a signal from the sensor indicating a threshold torsion in the cable, the controller can be configured to cause the motor to rotate in a direction corresponding to a direction of the torsion in the cable.