Grip-Sensor Kickback Control in Brushless Power Tools
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Solution Overview
Problem
Power tools often experience kickback due to binding in workpieces, leading to loss of user control and potential injury, as existing technologies lack effective mechanisms to detect and mitigate this issue in real-time.
Innovation Solution
A power tool design incorporating a motor with a rotor and stator, equipped with grip sensors and an electronic processor that monitors angular velocity and grip parameters to determine kickback thresholds, allowing the processor to control the switching network to cease motor drive in case of kickback, thereby reducing user exposure to kickback events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time kickback detection is implemented using sensors and processors, then user safety is improved, but device complexity increases
Solution Approach 1:
The system performs preliminary actions by detecting kickback conditions before they result in injury. The force sensor continuously monitors for abnormal forces, and the processor is pre-programmed with kickback detection algorithms that trigger motor cessation immediately when kickback is detected, preventing harm before it occurs.
Solution Approach 2:
The system implements feedback by using the force sensor to continuously monitor operational conditions and provide real-time data to the processor. When the sensor detects forces characteristic of kickback, the processor receives this feedback and automatically responds by ceasing motor drive, creating a closed-loop safety system.
2Object-affected harmful factors
If kickback detection mechanisms are added to power tools, then kickback mitigation is improved, but manufacturing cost increases
Solution Approach 1:
The invention replaces complex mechanical kickback mitigation mechanisms with an electronic sensing and control system. Instead of using mechanical devices to physically prevent or reduce kickback, the system uses a force sensor and processor to detect kickback conditions and electronically control motor cessation, simplifying the overall system architecture.
Solution Approach 2:
The power tool performs self-service by automatically detecting its own kickback conditions through the integrated force sensor and processor, and autonomously responding by ceasing motor drive. The system monitors itself and takes corrective action without requiring external intervention or complex external safety mechanisms.
3Measurement precision
If continuous monitoring of power tool characteristics is performed, then kickback detection accuracy is improved, but energy consumption increases
Solution Approach 1:
The system uses skipping by continuously monitoring force characteristics rather than all possible power tool parameters. The force sensor specifically targets the critical force parameter related to kickback, allowing the system to achieve accurate kickback detection while minimizing energy consumption by not continuously monitoring unnecessary parameters.
Data Source
AI summary
A power tool including a housing, a motor having a rotor and a stator, at least one grip sensor configured to generate a grip parameter, and a switching network electrically coupled to the brushless DC motor. An electronic processor is connected to the switching network and the at least one grip sensor and configured to implement kickback control of the power tool. The electronic processor is configured to determine a kickback threshold based on the grip parameter, control the switching network to drive the motor, receive a signal related to a power tool characteristic, determine, based on the power tool characteristic being greater than or equal to the kickback threshold, that a kickback event of the power tool is occurring, and control, in response to determining that the kickback event is occurring, the switching network to cease driving of the motor.