Rotary Input Control for Power Tool Torque Feedback
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Solution Overview
Problem
Conventional power tools require users to perform linear finger motion to control rotational output, making it difficult to directly correlate trigger travel with rotation speed and assess joint tightness, leading to inefficient control and potential reactionary torque.
Innovation Solution
A power screwdriver design that uses rotational user input to control the output member, incorporating a rotational rate sensor and controller to monitor angular velocity, displacement, and direction, allowing intuitive control similar to manual screwdrivers and providing haptic feedback for improved user experience.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If linear trigger switch control is used, then the tool can be activated and speed controlled, but the user cannot directly correlate trigger travel with rotation speed and assess joint tightness
Solution Approach 1:
The patent implements feedback by providing haptic resistance through the rotary control mechanism. As the output member encounters increased torque (such as when a joint becomes tight), the rotary control experiences corresponding resistance that the user can feel. This allows direct assessment of joint tightness and correlation between control input and output rotation without needing separate sensing systems.
Solution Approach 2:
The patent inverts the conventional control approach by making the control mechanism itself provide feedback through mechanical resistance rather than relying on separate sensors and electronic feedback systems. The rotary control's mechanical connection to the output member allows torque feedback to flow back to the user's hand, enabling intuitive assessment of joint tightness through tactile sensation.
2Power
If the motor attempts to continue spinning while the output member slows down, then power is maintained, but reactionary torque is felt in the user's wrist
Solution Approach 1:
The rotary control mechanism provides direct mechanical feedback from the output member to the user's hand. When the output member encounters resistance or slows down, the user feels this through the rotary control's resistance, allowing real-time assessment of joint tightness and immediate adjustment of input torque to maintain comfort and control.
3Productivity
If digital switch with full output is used, then the tool can be turned on, but the user lacks fine control over speed adjustments
Solution Approach 1:
The rotary control mechanism provides dynamic control where the user can easily adjust between full power and fine speed adjustments by varying the rotational input. The mechanical connection allows continuous modulation of motor speed through proportional torque application, enabling both rapid activation and precise speed control within a single unified control mechanism.
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
Enhances control precision and reduces reactionary torque by allowing direct correlation of rotational input with output speed, providing intuitive operation and improved user feedback.
Implementation Method 1
A rotational rate sensor and controller are provided in a power tool. The rotational rate sensor is disposed in the power tool and the controller is configured to receive a signal from the rotational rate sensor and control operation of the motor based on the signal from the rotational rate sensor.
Data Source
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AI summary
A power tool includes a housing, a motor, an output member driven by the motor, and a reaming attachment coupled to the output member. The reaming attachment has a front end portion selectively driven in rotation by the output member to drive a fastener into a workpiece, and a reaming portion selectively driven in rotation by the output member to remove material from an end surface of a conduit. A rotational motion sensor in the housing is operable to detect rotational motion of the housing about an axis. A controller receives a signal indicative of rotational motion from the sensor, determines a direction of the rotational motion of the housing, and drives the motor in a direction corresponding to the direction of rotational motion of the housing.