Reel Cutting Unit Speed Control for Uniform Clip Frequency
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Solution Overview
Problem
Existing grass mowing machines with multiple reel cutting units face challenges in maintaining consistent frequency of clip during straight-line and turning operations, leading to issues like marcelling, over-stressing grass, and accelerated component wear due to varying reel rotational speeds.
Innovation Solution
A radial frequency of clip control system that adjusts the rotational speed of each reel cutting unit based on the distance to an instantaneous turn center, using sensor inputs and a controller to ensure consistent clip frequency during turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the same reel rotational speed is commanded to all reel cutting units based on vehicle mow speed, then the control system is simple, but the frequency of clip varies during turns causing marcelling and poor cutting quality
Solution Approach 1:
The patent applies local quality by providing different rotational speed commands to different reel cutting units based on their specific radial distance from the turn center. Each reel receives a customized speed command tailored to its local position, ensuring uniform frequency of clip across all reels while accounting for their different travel paths during turns.
Solution Approach 2:
The system dynamically adjusts reel rotational speeds based on real-time operating conditions including turn radius, vehicle speed, and reel position. The controller continuously calculates and updates speed commands to maintain optimal frequency of clip as the machine transitions between straight-line mowing and turning operations.
2Manufacturing precision
If reel cutting units operate at different rotational speeds during turns, then the frequency of clip can be maintained uniformly, but the control system becomes more complex requiring sensor inputs and calculations
Solution Approach 1:
The control system uses feedback from sensor inputs regarding vehicle speed and turn angle to continuously adjust reel rotational speeds. The controller processes this feedback information to calculate the appropriate speed commands for each reel, ensuring uniform frequency of clip while adapting to changing operating conditions.
Solution Approach 2:
The system performs preliminary calculations of the instantaneous turn center and radial distances for each reel before executing speed adjustments. This preliminary action allows the controller to pre-determine the appropriate rotational speed commands based on the current turning geometry, ensuring smooth and accurate frequency of clip maintenance.
3Productivity
If frequency of clip is too fast to maintain uniform cutting, then cutting speed increases, but the grass becomes over-stressed developing stripes and brown tips with accelerated component wear
Solution Approach 1:
The system dynamically changes the rotational speed parameter for each reel based on its radial position during turns. Reels at larger radii that would otherwise operate too fast are commanded to reduce speed, while reels at smaller radii maintain higher speeds. This parameter adjustment ensures all reels operate within the optimal frequency of clip range, preventing grass over-stress and reducing component wear while maintaining productivity.
Data Source
AI summary
A radial frequency of clip control system includes a steering angle sensor for a steerable rear wheel of a grass mowing machine, a pedal sensor for sensing an operator input for a desired ground speed at a reference point adjacent an operator seat on the grass mowing machine; and an electronic controller that uses the desired ground speed and location of each of a plurality of reel cutting units to calculate a rotational speed for each of the plurality of reel cutting units.