Autonomous Mower Cutting Frame Height Control With Lead Screw
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Solution Overview
Problem
Autonomous lawn mowers lack efficient mechanisms for adjusting the height of their cutting blades, which is essential for adapting to varying lawn conditions and user preferences, and manual adjustments are often undesirable.
Innovation Solution
The implementation of a height adjustment system that includes parallel guide rods, a rotatable drive screw with a helical thread, and biased bearings, allowing for automatic or manual adjustment of the cutting blade's height relative to the ground surface, controlled by a motor or manual turn screw, and incorporating sensors for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If manual adjustment mechanism is used, then device complexity is reduced, but ease of operation deteriorates because manual interaction is undesirable for autonomous mowers
Solution Approach 1:
The patent replaces manual mechanical adjustment with an automated motor-driven lead screw mechanism. The motor rotates the lead screw, which converts rotational motion into linear motion to adjust the cutting blade height automatically, eliminating the need for manual intervention while maintaining mechanical simplicity.
Solution Approach 2:
The system enables self-adjustment through the autonomous mower's own motor and control system. The motor-driven lead screw mechanism allows the mower to automatically adjust its cutting height without external manual operation, making the system self-sufficient in adapting to different cutting requirements.
2Ease of operation
If automated motor-driven adjustment is used, then ease of operation improves, but device complexity increases
Solution Approach 1:
The patent employs a motor-driven lead screw mechanism that substitutes complex manual adjustment operations with a simple automated system. The lead screw converts motor rotation into precise linear displacement, providing easy height adjustment while keeping the mechanical structure relatively simple through the use of standard mechanical components.
3Device complexity
If simple adjustment mechanism is used, then device complexity is reduced, but manufacturing precision deteriorates due to binding and chatter
Solution Approach 1:
The lead screw mechanism provides precise conversion of rotational motion to linear motion, enabling accurate cutting height adjustment. The threaded geometry of the lead screw ensures controlled, precise movement while maintaining mechanical simplicity, avoiding the binding and chatter issues associated with simpler adjustment mechanisms.
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
Enables cost-effective, smooth, and precise adjustment of the cutting height with minimal binding or chatter, allowing the mower to adapt to different grass heights and conditions autonomously or via remote control, enhancing cutting efficiency and user convenience.
Implementation Method 1
a rotatable drive screw operatively connected to the chassis and defining a screw axis extending parallel to the first direction, the drive screw comprising a helical external thread; a driven member operatively connected to the frame and including a helical internal thread adapted to threadably receive the external thread of the drive screw
Implementation Method 2
a biasing member associated with the frame and adapted to bias a bearing associated with the frame directly against the first guide rod
Implementation Method 3
the biasing member may include a first spring
Data Source
AI summary
An autonomous vehicle (e.g., mower) includes two or more wheels supporting a chassis upon a ground surface. A cutting motor powers at least one cutting blade, and a cutting frame supports the cutting motor relative to the chassis. The cutting frame is movable, relative to the chassis, to allow adjustment of a height-of-cut of the cutting blade relative to the ground surface. First and second guide rods are operatively attached to the chassis and are received within corresponding first and second apertures of the cutting frame to guide movement of the cutting frame. Biased bearings associated with the cutting frame may bias associated bearing members against the guide rods.