Sewing Machine Speed Control for Consistent Pitch Limits
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Solution Overview
Problem
Existing sewing machines lack flexibility in controlling rotational speed based on various input information, limiting their ability to adapt to different sewing conditions.
Innovation Solution
A sewing machine with a rotational speed determination unit, upper limit rotational speed setting unit, and rotational speed control unit that adjusts the sewing machine motor speed based on inputs from a movement detection sensor, a speed controller, and a foot controller, ensuring consistent sewing pitch and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rotational speed is controlled only based on workpiece movement amount, then the sewing pitch can be kept constant, but the control flexibility based on various input information is insufficient
Solution Approach 1:
The rotational speed control system is designed to accept multiple types of input information (workpiece movement amount, operator instructions, sensor data) and process them through a unified control algorithm. The control unit integrates signals from different sources to determine the final rotational speed instruction value, making the system versatile and adaptable to various sewing conditions while maintaining a relatively simple overall structure
Solution Approach 2:
The control unit acts as an intermediary that receives and processes multiple input signals before generating the rotational speed instruction. It mediates between the raw sensor data/movement information and the motor control, applying upper limit constraints and integration logic to produce a balanced control output that considers all input factors
2Manufacturing precision
If the rotational speed instruction value is increased to maintain sewing pitch at high workpiece speeds, then the sewing pitch consistency is improved, but the risk of excessive speed and safety issues increases
Solution Approach 1:
The control system proactively prevents excessive rotational speed by implementing an upper limit value constraint before the speed can become dangerous. The control unit compares the calculated rotational speed instruction against a predetermined upper limit and clamps the output to this safe maximum value, thereby preventing harmful high-speed conditions while still maintaining sewing pitch consistency within safe operating parameters
Solution Approach 2:
The system continuously monitors workpiece movement and adjusts the rotational speed instruction in real-time to maintain consistent sewing pitch. By using feedback from movement detection and dynamically adjusting speed within safe limits, the system achieves precision without requiring excessively high speeds that would create safety risks
Data Source
AI summary
A sewing machine includes a rotational speed determination unit configured to determine a rotational speed instruction value on the basis of information from a movement detection sensor that detects movement of a workpiece and a predetermined sewing pitch amount, an upper limit rotational speed setting unit configured to set an upper limit rotational speed value, a rotational speed control unit configured to control a rotational speed to the rotational speed instruction value and control the rotational speed to the upper limit rotational speed value when the rotational speed instruction value reaches the upper limit rotational speed value, and a sewing machine motor driven at the controlled rotational speed to operate a needle. Rotational speed control of the sewing machine motor according to a movement amount of the workpiece is executed, but the rotational speed is controlled so as not to exceed the upper limit rotational speed.