Screw Tightening Device with Sensor Offset Correction
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Solution Overview
Problem
Hand-held motor-driven screwing tools cannot ensure accurate angle of rotation in screw tightening, which is critical for safety and durability in dynamic screw connections, especially in safety-relevant applications like automotive engineering, due to user influence and potential sensor errors from temperature fluctuations or defects.
Innovation Solution
A motor-driven screwing device with a detection unit that identifies faulty sensor data by comparing measured angles with predefined threshold values during an idle state, preventing further use if errors are detected, and incorporating redundant angle measurement and correction mechanisms to ensure accurate screw tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hand-held motor-driven screwing tools are used, then flexibility and ease of operation are improved, but measurement precision and reliability of angle of rotation deteriorate due to user influence and sensor errors
Solution Approach 1:
The system performs preliminary actions by detecting the idle state before actual screwing operation and correcting sensor offsets in advance. The offset detection unit measures the angle sensor output when the housing is stationary, calculates the offset from the expected zero position, and stores this offset value for subsequent compensation during operation, ensuring accurate angle measurements from the start of each operation.
Solution Approach 2:
The system implements feedback by continuously monitoring the angle sensor output, comparing it with corrected values that account for detected offsets, and using this information to compensate for measurement errors. The correction unit adjusts the measured angle based on the stored offset, creating a closed-loop system that maintains measurement accuracy despite hand-held operation variations.
2Measurement precision
If angle measuring devices are added to correct housing movement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system applies self-service by using the existing angle sensor to detect both the housing movement and the screw head rotation. Instead of adding separate measurement devices, the system enables the single angle sensor to serve dual purposes: monitoring housing orientation changes and measuring screw rotation relative to the housing, thereby maintaining measurement precision while minimizing device complexity.
Solution Approach 2:
The angle sensor is designed with multi-functionality, serving both to detect housing movement relative to the environment and to measure the rotation angle of the screw head relative to the housing. This universal application of a single sensor eliminates the need for multiple specialized measurement devices, reducing system complexity while maintaining comprehensive measurement capability.
3Reliability
If redundant control and self-test of measuring sensors are implemented, then reliability is improved, but device complexity and loss of time increase
Solution Approach 1:
The system performs preliminary self-testing by automatically detecting the idle state and measuring sensor offsets before actual screwing operations begin. This preliminary action ensures that the measurement system is calibrated and functional before critical operations, improving reliability without requiring complex continuous monitoring during operation.
Solution Approach 2:
The detection unit performs self-service by automatically monitoring its own operational state, detecting when the housing is in idle position, and self-calibrating by measuring and correcting sensor offsets. This self-monitoring and self-correction capability provides redundant control and reliability assurance without requiring external monitoring systems or complex control logic.
Data Source
Figure 1
Figure 2~5b
Figure 3
AI summary
The invention relates to an assembly device (100) and method having a screw device (101) for tightening and loosening screws, having a screw head (102) and a housing (103), wherein measurement errors of an angle measuring device (104) are corrected by means of a detecting unit (105) for detecting erroneous sensor data in the rest state, and more precise and secure tightening of screws or nuts is thereby enabled.