Walk-Behind Mower Yaw Control for Straight Travel and Turning
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Solution Overview
Problem
Existing walk-behind power equipment, such as lawn mowers, struggles with straight-line stability and efficient turning, requiring skilled operators to maintain path alignment and overlap, leading to reduced aesthetics and work efficiency.
Innovation Solution
Incorporating a control unit with tilt angle and yaw rate detection, along with lateral load sensing, to differentiate between straight-line and turning operations by adjusting the rotational speeds of rear wheels, facilitating easy operation by reducing the need for manual handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If manual handle pushing and pulling is used to maintain straight-line stability, then straight-line stability is improved, but ease of operation deteriorates
Solution Approach 1:
The lawn mower performs self-correction of straight-line travel through automatic control of the rear wheels. The control unit detects yaw rate and tilt angle, then automatically adjusts the rotational speeds of the left and right rear wheels to counteract deviations from straight-line path, eliminating the need for manual handle adjustments by the operator.
Solution Approach 2:
The system continuously monitors the actual travel direction through yaw rate and tilt angle sensors, compares it with the desired straight-line path, and automatically adjusts the rear wheel speeds to correct any deviations. This closed-loop feedback control maintains straight-line stability without requiring operator intervention.
2Manufacturing precision
If manual control is used for accurate turning, then turning precision is improved, but ease of operation deteriorates
Solution Approach 1:
The lawn mower performs self-correction during turning operations through automatic control. The control unit detects the operator's turning intent via tilt angle changes, then automatically adjusts the rotational speeds of the left and right rear wheels to achieve precise turning while maintaining parallel travel paths and proper swath overlap, eliminating the need for skilled manual control.
Solution Approach 2:
The system continuously monitors tilt angle to detect turning operations and automatically adjusts rear wheel speeds to achieve the desired turning radius and path alignment. This feedback control ensures accurate turning performance without requiring operator skill.
3Reliability
If increased overlap of travel paths is used to prevent unmowed lawn, then reliability of mowing coverage is improved, but productivity deteriorates
Solution Approach 1:
The system uses tilt angle and yaw rate sensors to detect the operator's turning actions and automatically controls the rear wheel speeds to achieve precise path alignment. This ensures that the edges of adjacent swaths overlap correctly without excessive overlap, maintaining complete mowing coverage while minimizing redundant passes and maximizing productivity.
Data Source
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AI summary
To provide walk-behind power equipment that is easy to operate, walk-behind power equipment (1) includes: a main body (2) provided with at least one front wheel (4) and a pair of left and right rear wheels (5) as well as a work unit (3); a pair of left and right travel motors (9L, 9R) provided for the respective rear wheels; a handle (6) extending from the main body rearward and upward; at least one of a tilt angle detection means (41) that detects a tilt angle of the main body and a downward load detection means (38) that detects a downward load applied to the handle; a yaw rate detection means (37) that detects a yaw rate; and a control unit (10) that drive-controls the travel motors, wherein the control unit determines whether the main body is in a rearward tilted state based on the tilt angle or the downward load, and if it is determined that the main body is not in the rearward tilted state, the control unit performs straight-line travel control to set a rotational speed difference between the left and right travel motors to reduce the yaw rate, and if it is determined that the main body is in the rearward tilted state, the control unit does not perform the straight-line travel control.