Power Tool Trigger Mapping for Hysteresis and Dead Band Control
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Solution Overview
Problem
Existing power tool triggers face issues such as mechanical limitations, hysteresis effects, and difficulty in accurately judging the amount of pull required to achieve desired outputs due to non-standardized trigger position mapping, leading to overshooting and user discomfort.
Innovation Solution
Implementing a motor controller that detects trigger position changes, determines distance and direction, and applies hysteresis functions and trigger mapping adjustment techniques, including spline and reinforcement learning, to generate precise motor control signals based on user input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
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 initial operational dead band
Solution Approach 1:
The system performs preliminary mapping of trigger position to output values, establishing a relationship curve before operation. This pre-established mapping accounts for the mechanical dead band by designing the mapping function to compensate for the initial trigger depression required before output generation begins.
Solution Approach 2:
The patent changes the mapping parameters between trigger position and output values based on the direction of trigger movement. By using different mapping functions for trigger depression versus trigger release, the system compensates for the mechanical dead band and hysteresis effects, allowing output to be generated immediately when trigger movement is detected in either direction.
2Manufacturing precision
If a max limit for trigger position is set, then the output reaches a maximum value, but the trigger is not fully actuated to the mechanical limit, making it difficult for users to judge the amount of pull required
Solution Approach 1:
The system continuously monitors trigger position and provides feedback through the mapping function to adjust output accordingly. This feedback mechanism allows the output to reach maximum value at the appropriate trigger position while providing visual or tactile feedback to the user about the relationship between trigger pull and output level.
Solution Approach 2:
The patent implements dynamic trigger mapping where the relationship between trigger position and output value changes based on operational conditions. The mapping function can be adjusted in real-time to optimize the trigger curve, allowing users to achieve desired output levels with more intuitive trigger pull distances.
3Reliability
If hysteresis effects are present in the trigger, then the trigger position equivalent to a desired output differs depending on whether the trigger is being depressed or released, but this creates non-standardized mapping and difficulty in achieving desired output
Solution Approach 1:
The system dynamically adjusts the trigger mapping function based on the direction of trigger movement. When the trigger is being depressed, one mapping function is applied; when being released, a different mapping function is applied. This dynamic adaptation compensates for hysteresis effects and standardizes the mapping relationship.
Solution Approach 2:
The patent intentionally introduces asymmetry in the trigger mapping by using different functions for depression and release phases. This asymmetric mapping is designed to counterbalance the natural hysteresis asymmetry in the mechanical trigger, resulting in a standardized and predictable output response regardless of trigger movement direction.
4Reliability
If users actuate the trigger more than needed due to the initial operational dead band, then overshooting the desired output occurs, but this reduces control precision
Solution Approach 1:
The mapping function is preliminarily designed to account for the mechanical dead band by establishing a relationship where output begins immediately when trigger movement is detected, rather than after a threshold depression. This preliminary compensation prevents users from needing to pull the trigger beyond the desired position.
Solution Approach 2:
The system changes the mapping parameters to eliminate the dead band effect by using different sensitivity factors for trigger depression versus release. This parameter adjustment ensures that the output responds immediately to trigger movement in either direction, giving users precise control without overshooting.
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 accuracy by accounting for trigger direction and sensitivity, reducing overshooting and improving responsiveness and smoothness in power tool operations.
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
Implementation Method 2
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.