Power Tool Control System Angular Displacement Torque
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Solution Overview
Problem
Power tools, such as drills, face challenges in controlling high torque levels, which can lead to operator loss of control due to rapid or gradual torque increases, resulting in unpredictable reactions and potential tool mismanagement.
Innovation Solution
A control system incorporating a rotational rate sensor, current sensor, and microcontroller to detect torque conditions, adjusting torque levels and operation based on angular displacement to prevent operator loss of control, allowing for self-limiting operation and protective measures without terminating the tool's function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high torque levels are delivered to enable effective drilling, then drilling effectiveness is improved, but operator control is worsened due to rapid torque increases causing tool mismanagement
Solution Approach 1:
The control system continuously monitors motor current and calculates torque levels, comparing them against threshold values to detect twist conditions. This feedback mechanism allows the system to automatically adjust motor power output in real-time, reducing torque when twist conditions are detected and restoring it when conditions normalize, thereby maintaining both high power capability and operator control
Solution Approach 2:
The system dynamically adjusts motor power delivery based on real-time detection of twist conditions. By modulating the power output according to detected torque levels and angular displacement, the system transitions from static high-power delivery to adaptive power control, resolving the contradiction between maintaining high torque capability and preventing operator loss of control
2Ease of operation
If torque levels are reduced to improve operator control, then ease of operation is improved, but drilling effectiveness is worsened due to insufficient torque delivery
Solution Approach 1:
The control system implements periodic monitoring of motor current and angular displacement to detect twist conditions. When twist conditions are detected, the system periodically pulses power restoration at controlled intervals, allowing the operator to maintain control while periodically recovering drilling effectiveness as material is removed and twist conditions alleviate
3Reliability
If the tool shuts down completely to prevent operator loss of control, then safety is improved, but productivity is worsened due to operational termination and reset requirements
Solution Approach 1:
Instead of complete shutdown, the control system applies partial power reduction by modulating motor power output below maximum levels when twist conditions are detected. This partial action provides sufficient torque reduction to prevent operator loss of control while maintaining enough power to continue drilling operations, thereby improving safety without sacrificing productivity
Solution Approach 2:
The control system maintains continuous drilling operation by automatically detecting twist conditions and adjusting power delivery in real-time. Rather than terminating operation, the system continuously monitors and adjusts motor output, allowing the useful drilling action to continue uninterrupted while preventing harmful twist conditions, thus maintaining both safety and productivity
4Reliability
If sensors and control circuits are added to detect and prevent torque conditions, then operator safety is improved, but device complexity is worsened
Solution Approach 1:
The control system uses the existing motor current sensor, which serves dual purposes: monitoring overall motor operation and detecting twist conditions through analysis of current fluctuations. This multi-functional use of existing components provides safety functionality without adding separate dedicated sensors, thereby improving operator safety while minimizing increases in device complexity
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
Enables operators to regain control of power tools by dynamically adjusting torque in response to angular displacement, preventing tool mismanagement and reducing downtime by allowing continuous operation without complete shutdown.
Implementation Method 1
a rotational rate sensor configured to detect rotational motion of the tool about a longitudinal axis of the spindle
Data Source
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AI summary
A power tool is configured with a control system, the control system comprising a motor drivably coupled to a rotary shaft to impart rotary motion thereon, a rotational rate sensor disposed within the tool and operable to detect rotational motion of the tool generally about a longitudinal axis of the shaft; and a controller electrically connected to the rotational rate sensor. The controller is operable to detect a rotational condition of the tool based on the rotational motion detected by the sensor and control torque imparted to the rotary shaft upon detecting the rotational condition of the tool. The torque is inversely related to an angular displacement of the tool about the longitudinal axis.