Agricultural Implement Positioning Control via Periodic Actuation
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Solution Overview
Problem
Agricultural control systems often fail to accurately control the position of implements like harvesting headers due to inadequate consideration of positioning response time, leading to overshooting and 'hunting' issues, as they do not frequently enough sense the implement's position or account for ground changes.
Innovation Solution
A method involving a controller that receives position signals from sensors and produces output signals with alternating active and inactive times based on the positioning system's response time, allowing the implement to settle into a non-transient position, using a vehicle communications bus to transmit these signals and adjust actuator movements accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the positioning system continuously moves the implement towards the desired position, then the response speed is improved, but the implement overshoots the setpoint and causes constant hunting
Solution Approach 1:
The control signal is applied periodically with active and inactive periods. During active periods, the positioning system moves the implement towards the desired position. During inactive periods, the system allows the implement to settle. This periodic application of control signals prevents continuous movement that causes overshooting while maintaining adequate response speed.
Solution Approach 2:
The controller predicts the implement position at a future time based on current position, desired position, and known positioning response time. Control signals are generated in advance accounting for the system's response characteristics, preventing overshoot before it occurs by preparing the appropriate control action ahead of time.
2Measurement precision
If the control system senses position frequently, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The controller uses known positioning response time to predict future implement positions without requiring continuous high-frequency sensing. By calculating where the implement will be based on current position and system characteristics, the system achieves accurate control with reduced sensing frequency, lowering complexity while maintaining precision.
3Manufacturing precision
If the control system accounts for positioning response time, then the positioning precision is improved, but the control delay increases
Solution Approach 1:
The controller proactively generates control signals based on predicted future positions that account for the positioning response time. By preparing control actions in advance based on system characteristics, the controller achieves precise positioning without reactive delays, as the control signal is already optimized for the system's response characteristics.
Solution Approach 2:
The control system uses periodic active and inactive periods that are timed according to the positioning response time. This rhythmic control pattern synchronizes with the system's natural response characteristics, achieving precise positioning while maintaining efficient timing that minimizes overall control delay.
Data Source
AI summary
A method, apparatus and system for controlling positioning of an agricultural implement is disclosed. The agricultural implement is mounted on a propulsion unit having a positioning system. A position signal is received from a position sensor representing a position of the agricultural implement relative to the ground, and while a difference between the position and a desired position is greater than a threshold difference, a controller produces and transmits an output signal having a control state that alternates successively between an active time during which the output signal causes the positioning system to move the agricultural implement towards the desired position, and an inactive time during which the output signal causes the positioning system to discontinue movement. The respective times are based on a positioning response time and are operable to permit the agricultural implement to settle in a non-transient position during the inactive time while receiving the position signal.