Rotational Motion Sensor Control for Power Tool Speed Feedback
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Solution Overview
Problem
Conventional power tools require users to actuate a switch with their fingers, making it difficult to directly control rotational speed and assess joint tightness due to the disconnect between trigger travel and output rotation, leading to inefficient operation.
Innovation Solution
A power tool design featuring a rotational motion sensor and controller that allows users to control the output member's rotation by rotating the tool itself, enabling intuitive control similar to manual screwdrivers and providing haptic feedback for improved operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a trigger switch assembly is used to control power tool operation, then the tool can be turned on and off, but the user cannot directly control rotational speed or assess joint tightness due to the disconnect between trigger travel and output rotation
Solution Approach 1:
The patent implements feedback by using a rotational motion sensor to detect the rotational speed of the housing and providing haptic feedback through the trigger switch assembly. The controller adjusts motor speed based on detected rotation, creating a closed-loop system that provides the user with tactile feedback proportional to output member speed and joint tightness, resolving the information disconnect between trigger position and actual tool output
Solution Approach 2:
The patent replaces the traditional mechanical trigger linkage system with an electronic control system using rotational motion sensors (gyroscopes or accelerometers) to detect housing rotation. This substitution allows the system to sense rotational input and translate it into proportional motor speed control, enabling direct correlation between user rotational input and output member speed
2Measurement precision
If the user grips the tool and actuates the trigger switch, then the tool operates, but the user must first sense tightness with the wrist before making control adjustments with the finger
Solution Approach 1:
The rotational motion sensor continuously monitors housing rotation and provides real-time feedback to the controller, which adjusts motor speed instantly. This eliminates the delay where users must manually assess joint tightness with their wrist before making trigger adjustments, as the system automatically detects and responds to changes in rotational speed caused by joint tightness
Solution Approach 2:
The system performs self-adjustment by using the rotational motion sensor to detect when the output member encounters resistance (joint tightness). The controller automatically reduces motor speed when deceleration is detected, eliminating the need for the user to manually sense and respond to tightness conditions, thus saving time and reducing cognitive load
3Productivity
If rotational motion sensors and controllers are added to enable intuitive control, then user control and efficiency are enhanced, but device complexity increases
Solution Approach 1:
The rotational motion sensor serves multiple functions: detecting housing rotation for speed control, providing haptic feedback through the trigger assembly, and enabling automatic adjustment for joint tightness. This multi-functionality reduces the need for separate control mechanisms, thereby limiting the increase in device complexity while achieving enhanced productivity
Solution Approach 2:
The patent changes the control parameter from linear trigger displacement to rotational motion of the housing. By using rotational motion sensors (gyroscopes or accelerometers) to detect angular velocity and integrate it to determine angular displacement, the system achieves intuitive proportional control where the degree of housing rotation directly correlates with output member speed, significantly improving task completion efficiency
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 user control and efficiency by allowing direct correlation of tool rotation with output speed and providing haptic feedback to assist in joint tightness assessment, reducing user effort and improving task completion.
Implementation Method 1
a rotational motion sensor arranged in the housing and operable to detect rotational motion of the housing, from a first reference orientation of the housing, about the longitudinal axis of the output member
Data Source
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AI summary
A power tool comprises: a housing; an output member at least partially contained in the housing and configured to rotate about a longitudinal axis; a motor contained in the housing and drivably connected to the output member to impart rotary motion thereto; and a rotational motion sensor arranged in the housing and operable to detect rotational motion of the housing, from a first reference orientation of the housing, about the longitudinal axis of the output member. A controller is also located in the housing, the controller configured to receive a signal indicative of the rotational motion from the rotational motion sensor and, in response to the signal, to drive the motor to rotate the output member. The power tool also includes a reset switch configured to reset the rotational motion sensor to a second reference orientation of the housing, which is different to the first reference orientation, upon actuation of the reset switch, the second reference orientation then being the reference orientation from which the rotational motion sensor is operable to detect the rotational motion of the housing.