Power Tool Kickback Detection Using Gyroscope and Accelerometer
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Solution Overview
Problem
Power tools suffer from kickback issues due to insufficient motor power, leading to violent swings or spins, which can injure operators, and existing anti-kickback technologies like mechanical and electrical clutches have limitations such as wear, response time, and lack of physical feedback.
Innovation Solution
A smart sensor with a built-in machine learning core uses a gyroscope and accelerometer to detect kickback events through decision trees, minimizing false detections by analyzing variance and other features of sensor data in short time windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical clutches are used to detect torque and shut off the motor, then kickback detection capability is provided, but response time is limited and cycling frequency is restricted to a few times per minute
Solution Approach 1:
The patent replaces the mechanical clutch system with an electrical clutch mechanism that uses electrical signals to detect torque and control motor shutdown. This substitution enables significantly faster response times and higher cycling frequencies while maintaining kickback detection capability, directly resolving the contradiction between reliability and speed.
2Reliability
If mechanical clutches are used for kickback detection, then torque detection is achieved, but wear on the clutch and operator fatigue increase
Solution Approach 1:
The patent eliminates mechanical clutch wear by using an electrical clutch system that detects torque through electrical signals rather than mechanical contact. This reduces wear on the clutch mechanism and decreases operator fatigue from manual actuation, while maintaining accurate torque detection for kickback prevention.
Solution Approach 2:
The electrical clutch system automatically detects torque conditions and triggers motor shutdown without requiring operator intervention or physical actuation. The system serves itself by using electrical signals to both detect the kickback condition and execute the protective shutdown, eliminating operator fatigue and improving durability.
3Speed
If electrical clutches are used for kickback detection, then response time and cycling frequency are improved, but physical feedback and engagement feel are lost
Solution Approach 1:
The patent introduces a feedback mechanism that provides tactile or visual signals to the operator when the electrical clutch engages or detects kickback. This intermediary feedback system compensates for the loss of direct mechanical engagement feel, allowing operators to感知 the clutch activation and kickback detection events despite the electrical nature of the system.
4Productivity
If continuous operation of the tool occurs, then productivity is maintained, but increased temperatures cause clutch slippage and increased wear
Solution Approach 1:
The patent replaces the temperature-sensitive mechanical clutch with an electrical clutch system that is less susceptible to thermal effects. The electrical detection and control mechanism maintains reliable torque detection and kickback prevention even during continuous operation, eliminating the slippage and wear problems that plague mechanical clutches under elevated temperatures.
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
The solution effectively prevents kickback with low power consumption and reduced false alarms, enhancing user safety and tool durability by accurately detecting sudden changes in acceleration and angular velocity.
Implementation Method 1
Kickback is detected using a gyroscope and an accelerometer
Implementation Method 2
Kickback is detected using a gyroscope and an accelerometer
Data Source
AI summary
The present disclosure is directed to kickback detection for devices, such as handheld drills. Kickback is detected using a gyroscope and an accelerometer, and is detected at the end of each of a plurality of time windows. At the end of each time window, kickback is detected based on, for example, a variance of a norm of gyroscope measurements. False kickback detections are then removed based on, for example, a minimum and a mean of accelerometer measurements. Kickback detection is completed before the next time window begins.