Racket String Tensioning System Using Force Sensor
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Solution Overview
Problem
Existing racket stringing machines face challenges in achieving accurate and consistent string tensions with minimal maintenance, requiring a strong current source, and high production costs, while also lacking quick adjustment options.
Innovation Solution
A hybrid string tensioning system combining a crank, a control module with a processor and memory, a force sensor, and a brake mechanism, along with an electric tensioning mechanism, which allows for accurate and consistent tensioning using a weak current source and smaller electric motors, enabling quick adjustment options and reduced maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If mechanical tensioning systems are used, then production cost is reduced, but manufacturing precision and reliability deteriorate due to spring compression changes over time
Solution Approach 1:
The patent replaces the mechanical spring-based tension measurement system with an electronic force sensor and digital control system. The force sensor (230) provides precise digital measurement of string tension, eliminating the degradation issues of mechanical springs while maintaining cost-effectiveness through the use of microcontroller-based control.
Solution Approach 2:
The patent implements a feedback control system where the force sensor continuously monitors string tension and provides real-time data to the microcontroller. The system compares actual tension against target tension values and automatically adjusts the motor-driven tensioning process to maintain precise tension accuracy throughout operation.
2Manufacturing precision
If electric tensioning systems are used, then manufacturing precision and reliability improve, but device complexity and power requirements increase
Solution Approach 1:
The patent integrates multiple functions into a single microcontroller-based control system that handles force sensor data acquisition, tension calculation, motor control, and user interface management. This consolidation reduces overall system complexity compared to separate dedicated circuits for each function while maintaining high precision tension control.
Solution Approach 2:
The system automatically performs tension measurements, calculations, and adjustments without requiring manual intervention. The microcontroller autonomously processes force sensor data, determines when target tension is reached, and controls the motor accordingly, reducing operational complexity while maintaining precision.
3Manufacturing precision
If electric tensioning systems are used, then manufacturing precision improves, but use of energy increases requiring strong current source
Solution Approach 1:
The patent employs periodic measurement and adjustment cycles rather than continuous operation. The force sensor takes discrete measurements at key points in the tensioning process, and the motor operates in intermittent bursts to achieve and maintain target tension, significantly reducing overall power consumption while preserving measurement precision.
Solution Approach 2:
The patent replaces power-intensive mechanical spring compression systems with a low-power electronic force sensor and microcontroller-based control system. The electronic system consumes minimal power compared to mechanical systems while providing superior tension measurement accuracy and consistency.
4Ease of operation
If mechanical tensioning systems are used, then ease of operation improves with simple crank mechanism, but productivity deteriorates due to manual operation requirements
Solution Approach 1:
The system automatically performs tension measurements, calculations, and motor control without requiring skilled manual operation. The microcontroller autonomously manages the entire tensioning process, making the system as easy to operate as manual cranking while achieving much higher productivity through automated rapid tensioning cycles.
Solution Approach 2:
The patent replaces manual crank-based mechanical tensioning with an automated motor-driven system controlled by a microcontroller. This substitution maintains operational simplicity through user-friendly interfaces while dramatically increasing productivity by eliminating manual cranking requirements and enabling rapid, consistent tensioning at higher speeds.
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 hybrid system achieves accurate and consistent string tensions with minimal maintenance, operates on a weak current source, and reduces production costs by using smaller electric motors, enhancing portability and lowering power consumption.
Implementation Method 1
a force sensor, which may sense a force of the tension transfer bar
Implementation Method 2
The brake mechanism may be a clamp configured to stop brake disc rotation
Data Source
AI summary
The present invention is directed at string tensioning system for use in racket stringing machines. The system produces accurate and consistent string tensions, requires minimum maintenance, works with a weak current source, such as a battery, and provides quick adjustment options, all achieved in a low-cost manner. The system may comprise a crank, a control module, a force sensor, and a brake mechanism. The system may further comprise an electric tensioning mechanism. The present invention is further directed at a string tensioning method. The method may comprise: fixing the first end of a racket string to a string holder of the string tensioning system, manually tensioning the racket string using a crank, and, in some embodiments, automatic tensioning of the racket string by an electric tensioning mechanism.