Robotic Lawnmower Wheel Camber Layout for Slope Stability
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Solution Overview
Problem
Self-propelled robotic lawnmowers face mobility issues on gardens with slopes and cavities, leading to instability and increased risk of rollover due to limited traction and ground clearance.
Innovation Solution
The robotic lawnmower features wheels arranged with a negative camber angle, widening the track gauge and lowering the center of gravity, enhancing stability and traction while allowing for a smaller, lighter design and larger cutting unit, which improves operational capabilities and reduces wear on grass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the track gauge is widened to improve stability, then the risk of rollover is reduced, but the dimensions and weight of the upper portion increase
Solution Approach 1:
The patent applies asymmetry by arranging the wheels with a negative camber angle, which creates an asymmetric wheel configuration relative to the chassis. This asymmetric arrangement widens the effective track gauge and lowers the center of gravity without requiring symmetric enlargement of the upper chassis portion, thereby improving stability without proportionally increasing weight
Solution Approach 2:
The patent transitions from considering only the horizontal track gauge dimension to incorporating the vertical dimension through negative camber angle. By tilting the wheels inward at the top, the solution exploits the vertical arrangement to achieve both widened effective track gauge and lowered center of gravity, resolving the contradiction between stability and weight
2Stability of the object's composition
If the track gauge is widened to improve stability, then lateral grip is improved, but the dimensions of the upper portion increase
Solution Approach 1:
The negative camber angle creates an asymmetric wheel configuration that effectively widens the track gauge for stability purposes without requiring proportional increases in the horizontal dimensions of the upper chassis. The asymmetric tilt allows the wheels to maintain better lateral contact with the ground while keeping the upper portion compact
3Stability of the object's composition
If the center of gravity is lowered to improve stability, then the risk of rollover is reduced, but the upper portion dimensions may increase
Solution Approach 1:
The patent lowers the center of gravity not by adding volume to the upper portion, but by utilizing the vertical dimension through negative camber angle wheel arrangement. This dimensional approach allows the center of gravity to be lowered while maintaining or even reducing the overall volume of the upper chassis portion
4Productivity
If a larger cutting unit is used to improve cutting efficiency, then the cutting result improves, but the overall dimensions and weight of the lawnmower increase
Solution Approach 1:
The patent inverts the conventional approach by not enlarging the upper portion to accommodate a larger cutting unit, but rather using the negative camber angle wheel arrangement to create sufficient space for an enlarged cutting unit without increasing upper portion dimensions. This inverted logic allows productivity improvement without the typical weight penalty
Data Source
Figure 1~2
Figure 3~4
AI summary
Herein a self-propelled robotic Iawnmower (1) Is disclosed comprising a Iawnmower chassis (3.1, 3.2) and wheels (5.1- 5.4) arranged at the Iawnmower chassis (3.1, 3.2). The wheels (5.1- 5.4) are arranged to support the Iawnmower chassis (3.1, 3.2) during operation of the Iawnmower (1). The wheels (5.1- 5.4) comprise at least a first wheel (5,1) and a second wheel (S.2), wherein the first and second wheels (5.1, S.2) are arranged at opposite lateral sides (6.1, 6.2) of the Iawnmower chassis (3.1, 3.2). At least the first and second wheels (5.1, 5.2) are arranged at the Iawnmower chassis (3.1, 3.2) with a negative camber angle (a).