Swivel Caster Control for Robotic Mower Direction Changes
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Solution Overview
Problem
Self-propelled robotic lawnmowers face issues with wheel slip and traction on slopes, leading to uneven wear and reduced coverage due to uncontrolled swivel caster wheel rotation during direction changes, which increases the risk of wheel slip and impairs slope performance.
Innovation Solution
A propulsion control arrangement that turns the robotic lawnmower a predetermined angle before initiating propulsion in a new direction, ensuring the swivel caster wheel pivots transversally, reducing resistance and the risk of unexpected travel direction changes, thereby improving traction and coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the robotic lawnmower initiates propulsion in the opposite direction without turning the swivel caster wheel, then the direction change is faster, but wheel slip and unexpected travel direction changes occur
Solution Approach 1:
The control unit performs a preliminary action by detecting when the robotic lawnmower is traveling in a first direction and actively controlling the swivel caster wheel to pivot transversally before initiating propulsion in the opposite second direction. This preliminary positioning of the swivel caster wheel prevents wheel slip and unexpected direction changes during the subsequent reverse propulsion, thereby resolving the contradiction between fast direction change and travel stability.
2Area of stationary object
If the robotic lawnmower operates on slopes, then coverage area is increased, but traction and navigability deteriorate due to wheel slip
Solution Approach 1:
Before initiating propulsion on slope terrain, the control unit detects the slope condition and actively controls the swivel caster wheel to pivot transversally to the propulsion direction. This preliminary action optimizes the wheel's contact angle with the ground, maximizing traction and preventing wheel slip during operation on slopes, thereby enabling reliable coverage of inclined areas.
Solution Approach 2:
The control unit dynamically adjusts the orientation parameter of the swivel caster wheel based on terrain conditions. By changing the wheel's pivot angle to be transversal to the propulsion direction, especially on slopes, the system optimizes ground contact and friction characteristics, improving traction and preventing wheel slip while maintaining coverage capability.
3Ease of operation
If the swivel caster wheel rotates uncontrolled during direction changes, then maneuverability is improved, but wear and tear on the ground surface increases
Solution Approach 1:
The control unit implements feedback control by continuously monitoring the position and orientation of the swivel caster wheel during direction changes. When the wheel begins to rotate uncontrolled, the control unit detects this and actively counteracts by controlling the wheel to pivot transversally, preventing unwanted ground contact patterns that cause wear. This feedback mechanism maintains maneuverability while eliminating harmful wear effects.
Solution Approach 2:
The control unit dynamically adjusts the swivel caster wheel's orientation parameter during operation. By changing the wheel's pivot angle to be transversal to the propulsion direction during direction changes, the system maintains controlled maneuverability while preventing the uncontrolled rotation that causes ground surface wear and tear.
Data Source
Figure 1~3
Figure 4a~4d
Figure 5~7
AI summary
A propulsion control arrangement (1) for a self-propelled robotic tool (3) is disclosed, wherein the robotic tool (3) comprises at least one swivel caster wheel (5, 5') configured to abut against a ground surface (7) during operation of the robotic tool (3). The control arrangement (1) is configured to, upon detection of a stop event of the robotic tool (3) after travel in a first longitudinal direction (Id1) of the robotic tool (3), turn the robotic tool (3) a predetermined angle (a1), and then initiate propulsion in a second longitudinal direction (Id2) of the robotic tool (3) being opposite to the first longitudinal direction (Id1). The present disclosure further relates to a self-propelled robotic tool (3), a method (100) of propelling a self-propelled robotic tool (3), a computer program, and a computer-readable medium (200).