Dozer Blade Height Control Using Gyroscopic Feedback
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Solution Overview
Problem
Current dozer blade control systems face limitations due to delays and noise in absolute height sensors and unknown non-linearity in hydraulic systems, restricting operating speed and surface smoothness.
Innovation Solution
A closed-loop control system combining a single-axis inertial sensor, such as a gyroscope, with an absolute height sensor to reduce noise and delay, using the gyroscope's output to calculate angular displacement and combine with absolute height measurements for improved control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absolute height sensors are used for blade control, then measurement capability is provided, but delays and noise in sensor output restrict operating speed and surface smoothness
Solution Approach 1:
The patent introduces an intermediary calculation unit that processes both the absolute height sensor output and inertial sensor output. This unit acts as a mediator that combines information from both sensors through mathematical operations (integration of angular velocity to get angular position, then combining with absolute height to derive blade position), thereby resolving the contradiction by using the inertial sensor to bridge the time delay gap while maintaining the accuracy benefits of the absolute height sensor.
Solution Approach 2:
The patent applies preliminary action by using the inertial sensor to continuously track and predict blade position changes before the absolute height sensor can provide updated measurements. The inertial measurement unit continuously integrates angular velocity to obtain angular position, which is then combined with the absolute height measurement to calculate current blade position, effectively anticipating position changes and eliminating the delay effect.
2Reliability
If PID controllers are used to counteract feedback loop problems, then system stability is improved, but the system becomes too slow for optimal earth-moving speed
Solution Approach 1:
The patent replaces the traditional mechanical feedback control system (PID controller) with a predictive control approach based on inertial sensing and mathematical calculation. Instead of relying on slow feedback loops that measure and react to errors, the system uses the inertial measurement unit to continuously track blade position and predict future positions, allowing for much faster response times while maintaining stability through the mathematical model of the system dynamics.
Solution Approach 2:
The system performs preliminary action by continuously calculating the expected blade position based on inertial sensor data and system geometry, rather than waiting for feedback from absolute height measurements. The control unit uses the relationship between supporting arm angle and blade position to proactively determine the correct blade position, enabling high-speed operation without sacrificing stability.
3Ease of operation
If hydraulic cylinders are used to move supporting arms, then blade positioning capability is achieved, but unknown non-linearity in the hydraulic system complicates control
Solution Approach 1:
The patent applies feedback by using the inertial measurement unit to continuously monitor the actual supporting arm angle and comparing it with the desired angle calculated from the blade position requirements. This feedback is then used by the control unit to adjust hydraulic valve commands in real-time, compensating for the non-linearities in the hydraulic system. The system also uses feedback from the absolute height sensor to verify and correct position accuracy.
Solution Approach 2:
The patent replaces direct mechanical control of the hydraulic system with an intelligent control approach that uses inertial sensing and mathematical calculation. Instead of relying on complex mechanical linkages or empirical tuning of hydraulic systems, the control unit uses the known geometric relationship between supporting arm angle and blade position, combined with real-time inertial measurement, to calculate the precise hydraulic valve commands needed, thereby simplifying the overall control strategy despite the hydraulic non-linearities.
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 approach enables more aggressive control, reducing noise and delay, allowing for higher speed and smoother surface creation by compensating for the limitations of absolute height sensors and hydraulic systems.
Implementation Method 1
one inertial sensor with one degree of freedom, the output of which is angular velocity in a plane perpendicular to the connecting line between said pivot points
Data Source
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AI summary
Known systems for automatic height control of a dozer blade (302), which rotates about a line through pivot points (304) for supporting arms (303) when it changes its height use feedback and a reference from an absolute blade height measuring system (306). This only permits a slow operation. According to the invention the input from the slow absolute height sensor (306) is combined with an input from a fast gyroscope (307 or 308) that measures the instant rotation and recalculates it into a vertical height change using the length (309) of the supporting arms as the basis. The combination obtains the accuracy of the infrequent absolute height information and an increased speed of measurement resulting in a compensated height estimate that is input to a hydraulic control system of the feedback type. This improved height feedback enables much more aggressive control even though the hydraulic system has an unknown linearity and delay associated with it. The gyroscopic sensor forms an IMU (307 or 308) with one degree of freedom to compensate for the inevitable drawbacks of the absolute height sensor (306) in use with regard to delay, noise and update rate to obtain a frequent, time-correct height position with a reduced level of noise by means of a calculation based on both types of sensor output.