Servo System Offset Compensation via Time-Division Measurement
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Solution Overview
Problem
Existing servo control systems face challenges in maintaining accuracy due to offsets caused by component inaccuracies and environmental factors like ambient temperature and wear, which evolve over time, leading to degraded performance, particularly in applications like aircraft instrument panel backlighting where ambient light interference affects measurement accuracy.
Innovation Solution
A method for commanding a controlled system using time-division multi-level command, where two dissymmetrical measurements are taken to determine and compensate for the offset, allowing for a corrected response independent of ambient light, enabling the use of a single sensor for both control and ambient light measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a control sensor measures a characteristic variable to maintain system accuracy, then the system response accuracy is improved, but offset errors due to component inaccuracies and environmental factors degrade the measurement precision over time
Solution Approach 1:
The patent applies periodic action by implementing time-division multi-level command with alternating measurement phases. The control sensor periodically switches between measuring the characteristic variable during active phases and measuring reference values during reference phases. This periodic switching enables continuous offset compensation without interrupting system operation, thereby maintaining measurement precision while ensuring long-term reliability through adaptive correction of drift errors
Solution Approach 2:
The patent implements feedback by continuously comparing measured values against reference values obtained during reference phases. The controller calculates offset errors from these comparisons and feeds back corrected values to compensate for component inaccuracies and environmental effects. This closed-loop feedback mechanism dynamically maintains measurement accuracy over time, resolving the contradiction between initial precision and long-term stability
2Manufacturing precision
If optimization is performed to minimize offset values at a given time, then manufacturing precision is improved, but the offset evolution over time due to temperature and wear cannot be prevented
Solution Approach 1:
The patent applies preliminary action by establishing a reference measurement phase that occurs periodically before the system operates with degraded accuracy. During these reference phases, fresh reference values are captured under current environmental conditions, proactively preparing compensation data before offset errors significantly degrade measurement precision. This preliminary action prevents temporal drift rather than merely correcting it after occurrence
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the measurement approach based on system state. The controller alternates between measuring the characteristic variable and measuring reference values, and adapts the setpoint as a function of measured offset. This dynamic parameter adjustment enables the system to maintain reliability over time despite component wear and environmental variations, overcoming the limitations of static manufacturing precision
3Measurement precision
If ambient light interference is measured by the internal lighting sensor, then the sensor can detect lighting conditions, but the accuracy of brightness measurement is degraded by the interference
Solution Approach 1:
The patent applies taking out by separating the measurement of ambient light interference from the measurement of backlight brightness. During reference phases, the system measures only ambient light levels without backlight activation. During active phases, it measures the combined signal. By extracting and independently measuring the interference component, the system can subtract it from the total measurement to obtain accurate backlight brightness, thereby resolving the contradiction between detecting lighting conditions and maintaining measurement precision
Data Source
AI summary
The invention relates to a method for commanding a system controlled by means of a time-division multi-level command. The invention consists in acquiring two measurements by means of the sensor, each during a period, the two periods being dissymmetrical relative to the division of the command, determining an offset of the control subsystem and a corrected response without offset of the system to the command as a function of the measurements and of the measurement periods. With the aid of these two measurements, the invention makes it possible to eliminate the effect of the offset in the control subsystem of the system.