Rotary Input Control for Power Screwdriver Torque Management
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Solution Overview
Problem
Current power tool control methods require linear finger motion to control rotational output, making it difficult to directly compare trigger travel to output rotation and adjust speed finely, and also struggle with assessing joint tightness, leading to reactionary torque and reduced control precision.
Innovation Solution
A power tool design that uses rotational user input to control the output shaft, incorporating a rotational rate sensor and controller to monitor angular velocity, displacement, and direction, allowing for intuitive control similar to manual screwdrivers, with features like a switch for initiating work, haptic feedback, and self-locking planetary gear sets to prevent oscillatory states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a linear trigger switch is used to control power tool output, then the tool can be turned on and off with full control, but the user cannot directly compare trigger travel to output rotation and make quick speed adjustments
Solution Approach 1:
The patent implements a feedback mechanism where the rotational position of the output shaft is sensed and fed back to the control system. This allows the system to understand the relationship between trigger input and output rotation, enabling the user to make precise speed adjustments by providing visual or tactile feedback on the actual rotational output corresponding to the trigger position.
Solution Approach 2:
The patent introduces an intermediary computational layer that translates the linear trigger movement into rotational control commands. This intermediary system processes the trigger position signal and converts it into appropriate motor control signals, creating a mapping relationship that allows the user to intuitively control rotation speed through linear motion while maintaining awareness of the actual rotational output.
2Power
If the tool motor continues spinning while the output shaft slows down, then the motor maintains power, but reactionary torque is felt in the user's wrist reducing control
Solution Approach 1:
The patent uses feedback from rotational sensors to detect when the output shaft slows down due to joint tightness. This feedback signal is sent to the control system, which then adjusts motor power accordingly. This prevents the motor from continuing to spin at full power when the output shaft encounters resistance, thereby eliminating the reactionary torque that would otherwise be felt by the user.
Solution Approach 2:
The patent implements dynamic power adjustment where the motor power is not fixed but continuously adapted based on real-time operational conditions. When the sensor detects reduced output shaft speed indicating joint tightness, the system dynamically reduces motor power to match the actual work being performed, maintaining control stability while preserving sufficient power when needed.
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
This configuration provides intuitive control over power tool rotation, enhances speed adjustment precision, and reduces reactionary torque by aligning control input and output on the same axis, improving user experience and operational stability.
Implementation Method 1
A rotational rate sensor and controller are provided in the power tool. The controller has a control module that receives a signal from the rotational rate sensor and drives the motor based upon the signal.
Implementation Method 2
self-locking planetary gear sets to prevent oscillatory states
Data Source
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AI summary
A power tool includes an output shaft configured to rotate about a longitudinal axis, a motor drivably connected to the output shaft to impart rotary motions thereto, and a rotational motion sensor spatially separated from the output shaft and operable to determine the user-imparted rotational motion of the power tool with respect to the longitudinal axis. A controller is electrically connected to the rotational motion sensor and the motor. The controller determines angular velocity of the power tool about the axis, rotational displacement of the power tool about the axis, and/or a direction of the rotational displacement using input from the rotational motion sensor. The controller then controls the motor according to the angular velocity, the rotational displacement, and/or the direction of the rotational displacement.