Power Tool Trigger Mapping for Hysteresis and Overshoot Control
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Solution Overview
Problem
Traditional power tool triggers exhibit hysteresis effects and mechanical limitations, leading to difficulty in accurately judging the amount of pull required for desired output and potential overshooting due to non-standardized position mapping based on actuation direction.
Innovation Solution
Implementing a motor controller that detects trigger position changes, determines distance and direction, and applies hysteresis functions to generate precise motor control signals, using techniques such as linear, polynomial, and lookup table functions, with optional adjustment via communication interfaces and reinforcement learning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional trigger control mechanisms are used, then the device can detect trigger movement, but the trigger must be depressed a certain amount before any output is generated, creating an operational dead band
Solution Approach 1:
The patent applies parameter changes by implementing non-linear mapping functions that transform the trigger position parameters dynamically. The mapping function adjusts the relationship between trigger position and output based on the direction of movement, allowing the system to be more responsive during activation while maintaining precision during deactivation. This resolves the dead band issue by changing how the trigger position parameter is interpreted rather than requiring a larger physical depression.
2Productivity
If traditional trigger mapping is used, then the output reaches a maximum value before the trigger is fully actuated, but users have difficulty judging the amount of pull required to achieve the desired result
Solution Approach 1:
The patent implements feedback by continuously monitoring trigger position and using hysteresis functions to adjust the mapping based on the current state. The system provides visual or tactile feedback to the user about the current output level relative to the trigger position, allowing users to better judge the amount of pull required. The adaptive mapping function learns from user behavior and adjusts to provide optimal control precision while maintaining productivity.
3Ease of operation
If traditional trigger mapping is used, then overshooting the desired output is possible due to the initial operational dead band
Solution Approach 1:
The patent applies preliminary action by implementing a ramp-up function that gradually increases the output before the trigger reaches its full depression. The system anticipates the user's intent and begins increasing output earlier in the trigger stroke, then slows the rate of increase as the desired output is approached. This preliminary adjustment prevents overshooting while maintaining ease of operation, as the user doesn't need to precisely judge the exact trigger position for maximum output.
4Adaptability or versatility
If traditional trigger mapping is used, then hysteresis effects differ depending on the type of actuation, resulting in non-standardized trigger position mapping
Solution Approach 1:
The patent implements dynamics by making the trigger mapping function adaptive rather than static. The system dynamically adjusts the mapping parameters based on the direction of trigger movement (activation vs. deactivation) and the current operational state. This dynamic adaptation allows the system to account for hysteresis effects while maintaining consistent and predictable output for equivalent operational needs, regardless of whether the trigger is being pressed or released.
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 by accounting for trigger direction and sensitivity variations, providing accurate and responsive motor output adjustments, reducing overshooting and improving user experience.
Implementation Method 1
the motor controller is configured to detect a position change of the trigger, determine a distance and direction of the position change, generate an output using one or more hysteresis functions based on the determined distance and the determine direction
Data Source
AI summary
A power tool including a housing, a trigger, a motor coupled to an output member, and a motor drive circuit coupled to the motor. The power tool further includes a motor controller coupled to the motor drive circuit. The motor control circuit is configured to detect a position change of the trigger, determine one or more parameters associated with the position change, and generate an output based on the one or more determined parameters and a variable trigger mapping function. The output is then output to the motor drive circuit.