Electronic Pipette Backlash Compensation via Piston Position Feedback
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Mechanical wear in electronic pipettes leads to backlash and play between components, affecting the accuracy of liquid aspiration and dispensation volumes over time.
Innovation Solution
A system within the pipette measures the actual backlash affecting the piston's movement, using sensors to adjust the piston's movement based on measured backlash values, ensuring accurate liquid volumes by compensating for mechanical wear and hysteresis in both aspiration and dispensing directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the electronic pipette is used during its lifetime, then the piston components experience mechanical wear causing play and backlash, but the accuracy of liquid volumes aspired and dispensed deteriorates
Solution Approach 1:
The system performs preliminary measurement of backlash at the home position before actual pipetting operations. The control system stores this measured backlash value and uses it to pre-correct motor commands, compensating for mechanical wear effects before they affect dosing accuracy.
Solution Approach 2:
The system continuously measures the actual position of the piston using a sensor and compares it with the commanded position. The measured position feedback is used to calculate and correct backlash errors, which are then fed back to adjust subsequent motor commands for accurate liquid dispensing.
2Manufacturing precision
If a sensor system is added to measure piston position for backlash compensation, then the accuracy of liquid volumes is improved, but the device complexity increases
Solution Approach 1:
The sensor system serves multiple functions: it detects the home position for initialization, measures piston position during operation for backlash compensation, and provides feedback for control. This multi-functionality reduces the need for separate specialized sensors and simplifies the overall system architecture.
Solution Approach 2:
The system uses its own sensor measurements to automatically detect and compensate for its own mechanical wear and backlash. The control system self-calibrates by measuring the relationship between motor commands and actual piston positions, eliminating the need for external calibration equipment or manual adjustment.
3Manufacturing precision
If backlash measurement and compensation is implemented, then the accuracy throughout the pipette's lifespan is improved, but the ease of operation deteriorates due to automated calibration processes
Solution Approach 1:
The pipette automatically performs backlash measurement and compensation without user intervention. The system self-calibrates by moving the piston to the home position, measuring the actual position with the sensor, calculating the backlash value, and storing it for compensation. This automated process eliminates the need for manual calibration procedures.
Solution Approach 2:
The backlash measurement and compensation is performed automatically during the initialization phase or at predetermined intervals, preparing the system for accurate operation without requiring the user to perform calibration procedures before each use.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A method for controlling an electronic pipette (1), which pipette comprises a piston (11) actuated in a cylinder (10) by a motor (15), which motor is controlled with a control system, which control system is controlled through a user interface (6, 8, 9) for operating the pipette, wherein actual backlash affecting the movement of the piston (11) of the electronic pipette (1) is measured with a system (16) located in the pipette, the measured backlash value is forwarded to the control system of the electronic pipette, and the movement of the piston is adjusted by the control system based on the measured backlash value.