Actuator Velocity Calibration via Current Adjustment
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Solution Overview
Problem
Existing actuator calibration methods for construction machines, such as milling machines, are less than optimal due to variations in control valve performance caused by wear and tear and frictional differences, leading to inconsistent fluid flow rates for the same input current, and require impractical sensor placements for accurate calibration.
Innovation Solution
A distance-based actuator velocity calibration system that uses a controller to determine the current required for nominal actuator velocity, adjusts based on measured velocity, and applies the adjusted current to control valves to maintain consistent height adjustments, reducing the need for precise sensor placement and accounting for variations in valve performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cracking current calibration is used to account for control valve variations, then reliability of actuator velocity control is improved, but device complexity increases due to requiring pressure sensors in specific locations
Solution Approach 1:
The patent replaces the mechanical sensor-based calibration system with an electronic solution. Instead of using pressure sensors to detect fluid flow and determine cracking current, the system uses the actuator's position sensor to measure actual velocity and iteratively adjusts control valve current until the desired velocity is achieved. This substitution eliminates the need for complex sensor placement while maintaining calibration accuracy.
Solution Approach 2:
The calibration system uses the actuator's own position feedback mechanism to perform self-calibration. The position sensor on the actuator provides velocity information that is used to adjust the control valve current, allowing the system to calibrate itself without requiring external pressure sensors or complex installation procedures.
2Measurement precision
If multiple sensors are placed to accurately measure actuator velocity, then measurement precision is improved, but ease of operation deteriorates due to complex installation and maintenance
Solution Approach 1:
The patent makes the existing position sensor serve multiple functions: it is used for normal actuator position feedback during operation and also for velocity measurement during calibration. By reusing the same sensor for both positioning and velocity measurement, the system eliminates the need for separate velocity sensors, simplifying installation and maintenance while maintaining measurement precision.
3Ease of manufacture
If traditional cracking current calibration is used, then ease of manufacture is improved by using simple pressure sensors, but manufacturing precision deteriorates due to inability to account for valve variations
Solution Approach 1:
The patent changes the calibration parameter from static cracking current detection to dynamic velocity-based current adjustment. Instead of finding a fixed cracking current value, the system continuously adjusts the control valve current based on actual actuator velocity feedback, accounting for manufacturing variations in each control valve while maintaining simple implementation using existing sensors.
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
This system ensures accurate and reliable actuator velocity calibration, improving the consistency and precision of height adjustments in construction machines by directly addressing variations in control valve performance and eliminating the need for complex sensor placements.
Implementation Method 1
a control valve configured to selectively control a flow of fluid into or out of the actuator based on an amount of current supplied to the control valve
Implementation Method 2
an actuator connecting the frame to a track from the plurality of ground engaging tracks. The actuator may be configured to adjust a height of the frame relative to a ground surface
Data Source
AI summary
A milling machine may have a frame, ground engaging tracks that support the frame, and an actuator that adjusts a height of the frame relative to the track. The milling machine may have a control valve that selectively controls a flow of fluid into or out of the actuator based on the current supplied to the control valve. The milling machine may have a controller that determines the amount of current required to operate the actuator at a nominal actuator velocity and supplies that current to the control valve. The controller determines a measured actuator velocity based on a time required to extend or retract the actuator by a predetermined length, and adjusts the amount of current based on the measured and nominal actuator velocities. The controller also supplies the adjusted amount of current to the control valve to adjust the height of the frame relative to the track.