Steerable Caster Wheel Assembly With Encoder-Based Angle Alignment
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Solution Overview
Problem
Existing lawnmowers face challenges in ensuring consistent and reliable steering due to difficulties in accurately adjusting the directional angle of steerable wheels, which can lead to misalignment over time and require complex or expensive systems that are prone to damage.
Innovation Solution
A steerable-wheel assembly with a motor that pivots a caster wheel about a pivot axis, using a gear system to set the directional angle, and an encoder to detect and adjust the position, ensuring accurate steering input is maintained through a controller that receives input from a user interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional linkages or motors are used to adjust the directional angle of steering wheels, then steering adjustment capability is provided, but the system becomes complex, expensive, and prone to damage
Solution Approach 1:
The patent replaces traditional mechanical linkages with an electric motor-driven system. The motor (324) is mechanically coupled to the caster connector (312) to pivot it about the pivot axis (XP), eliminating complex mechanical linkages while providing reliable steering adjustment capability through electrical control.
Solution Approach 2:
The patent introduces a gear system as an intermediary between the motor and the caster connector. The gear system (including primary drive gear 332, primary driven gear 334, and secondary driven gear 338) transmits and transforms the motor's rotational motion into the appropriate pivoting motion of the caster connector, enabling precise control while protecting the motor from direct mechanical stress.
2Ease of operation
If traditional exposed linkages or motors are used for steering adjustment, then steering control is achieved, but the components are susceptible to damage or interference during use
Solution Approach 1:
The patent nests the motor (324) and gear system within the support arm (310) structure. The motor is positioned within a motor cavity (344) defined by the support arm, and the gear system is integrated into the same structural envelope, protecting these vulnerable components from external damage and interference while maintaining their functional integrity.
Solution Approach 2:
The gear system acts as a protective intermediary, placing the motor at a radial offset from the caster connector. This arrangement shields the motor from direct exposure to external forces and debris while still enabling effective transmission of rotational force to pivot the caster connector for steering control.
3Adaptability or versatility
If existing steering systems are used, then directional angle adjustment is possible, but accurate alignment between desired angle and steering input becomes difficult over time
Solution Approach 1:
The patent implements a feedback mechanism using an encoder (360) with a magnetic sensor that detects the pivotable position of a detectable magnet (364) fixed to the caster connector. This feedback is sent to the controller (302), which compares the actual position with the desired steering input and automatically adjusts the motor to correct any misalignment, ensuring accurate steering control is maintained over time.
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 provides a robust, durable, and cost-effective steerable-wheel assembly that accurately adjusts directional angles, enhancing the reliability and consistency of steering in lawnmowers, reducing the risk of damage and maintenance costs.
Implementation Method 1
an encoder (360) disposed coaxially with the detectable magnet (364) and including a magnetic sensor (362) to detect a pivotable position of the detectable magnet (364)
Data Source
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AI summary
A tool device, such as a lawnmower, or a steerable-wheel assembly therefor may include a frame, a walking element, a drive motor, a steerable-wheel assembly (SWA), and one or more controllers attached to the frame. The walking element may be coupled to the frame. The drive motor may selectively power the walking element. The SWA may be attached to the frame apart from the walking element. The SWA may include a caster connector pivotably mounted to the frame to rotate about a pivot axis, a steerable wheel rotatably coupled to the caster connector, a first sensor configured to detect a pivotable position of the caster connector, and a second sensor configured to detect the set reference point.