Harvester Drive System Acceleration Control
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Solution Overview
Problem
Existing harvester drive systems face challenges in controlling propulsion speed to maintain desired crop throughput, leading to limitations in acceleration and driver comfort, especially when dealing with varying crop densities and requiring predictive sensors and complex speed curve rescheduling.
Innovation Solution
A harvester with a controller that calculates an acceleration signal based on setpoint and actual values related to crop throughput, determining a control signal to adjust the transmission ratio and minimize differences, while limiting acceleration within operator-defined limits to improve comfort and avoid integral control errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PID controllers with integral values are used to control propulsion speed, then the control signal is determined based on the difference between setpoint and actual values, but the integral values integrate too high when setpoint values cannot be reached due to population densities, leading to incorrect control signals
Solution Approach 1:
The patent extracts the problematic integral control component from the PID controller and replaces it with acceleration-based control. By removing the integral term that causes windup, the system avoids generating incorrect control signals when setpoint values cannot be reached, eliminating the need for anti-windup strategies while maintaining control accuracy.
Solution Approach 2:
The patent changes the control parameter from speed (with integral accumulation) to acceleration. This parameter transformation prevents the integration error that occurs in traditional PID controllers, as acceleration control directly responds to the difference between setpoint and actual values without accumulating error over time.
2Ease of operation
If predictive throughput sensors and speed curve rescheduling are used to limit acceleration, then driver comfort is improved, but the control system becomes more complex and difficult to implement
Solution Approach 1:
The patent replaces the complex mechanical control approach (predictive sensors and speed curve rescheduling) with a simpler electronic control system based on acceleration signals. The controller directly generates acceleration-based control signals that inherently limit rate of change, providing driver comfort without requiring predictive sensors or complex speed curve management.
3Productivity
If the harvester speed is controlled to maintain desired throughput, then crop processing efficiency is improved, but the acceleration is limited which reduces productivity during high throughput conditions
Solution Approach 1:
The patent implements dynamic control by using acceleration-based signals that allow the system to respond flexibly to changing conditions. The controller can apply maximum acceleration when throughput increases, enabling the harvester to quickly adapt to high productivity conditions while maintaining desired throughput, thus resolving the contradiction between speed control and acceleration capability.
Data Source
AI summary
A harvester comprising: a drive engine connected via a first drive train to ground engagement equipment of the harvester and via a second drive train to crop processing equipment of the harvester; an actuator configured to adjust the transmission ratio of the first drive train to control the propulsion speed of the harvester; and a controller configured to receive setpoint and actual values dependent on the crop throughput of the harvester, the controller configured to calculate an acceleration signal based on the setpoint and actual values, the acceleration signal representing an acceleration of the harvester suitable for minimizing the difference between the setpoint and actual values, and to determine a control signal for controlling the actuator based on the acceleration signal.