Electric Actuator End-Travel Calibration Using Current Sensing
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Solution Overview
Problem
Existing methods for defining the end travel limit of an electric actuator in crop harvesting implements are inaccurate due to variability in resistance and wear, leading to potential damage to the actuator and engaging components.
Innovation Solution
A method involving a current sensor and controller to measure and calibrate the electric actuator's current, setting a maximum calibration current, and defining the end travel limit based on a fault position with an offset, ensuring precise and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standardized current calibration level is used to define the end travel limit, then the calibration process is simple and fast, but the end travel limit is inaccurate due to variability in resistance and wear between different machines and over time
Solution Approach 1:
The patent changes the calibration approach from using a fixed standardized current level to dynamically determining a machine-specific maximum travel current by measuring the actual current at the mechanical end stop position. This parameter change accounts for variability in resistance and wear between different machines and over time, thereby improving end travel limit accuracy without requiring complex additional hardware
Solution Approach 2:
The calibration process utilizes the actuator's own current consumption characteristics to automatically determine its specific end travel limit. By measuring the current at the mechanical end stop position and using this information to set the end travel limit, the system performs self-calibration without requiring external reference standards or complex calibration equipment, thus improving accuracy while maintaining simplicity
2Productivity
If the electric actuator is allowed to move through its full range of motion, then the actuator utilizes its complete capability, but the crop engaging component may be damaged due to exceeding its allowable range of motion
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actuator's position and comparing it against the defined end travel limit. When the actuator approaches the end travel limit, the control system automatically stops movement, preventing the crop engaging component from exceeding its allowable range of motion and avoiding damage, while still allowing the actuator to operate through its full safe range
Solution Approach 2:
The end travel limit is predetermined through calibration before normal operation begins. By establishing the safe operating boundary in advance based on the crop engaging component's allowable range of motion, the system prevents harmful movements before they can occur, ensuring protection while maximizing productive range of motion
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
Accurately determines the end travel limit, preventing damage to the actuator and engaging components by accounting for variability in resistance and wear, enhancing operational safety and reliability.
Implementation Method 1
because the resistance between different components varies between different machines, wear on the components varies between different machines and on the same machine over time
Data Source
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AI summary
A method of defining an end travel limit of an electric actuator includes sensing an electric current of the electric actuator while moving the electric actuator from a first position to a second position. A maximum travel current of the electric current sensed during movement of the electric actuator between the first position to the second position is increased by a factor to define a maximum calibration current. The electric current is then sensed while moving from the second position toward an end travel position of the electric actuator. Movement of the electric actuator is stopped at a fault position when the electric current equals the maximum calibration current. The end travel limit of the electric actuator is then defined as a function of the fault position.