Homing Motion Axes Using Motor Electrical Parameters
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Solution Overview
Problem
Current homing methods in radiation systems lack precision and reliability, particularly in high-radiation environments, where single points of failure can occur due to inaccurate positioning and movement of sensors or switches, leading to safety concerns and the need for frequent recalibration.
Innovation Solution
A method involving a motor, load, and feedback device that uses hardstops to establish reference positions by monitoring electrical parameters or velocities, allowing for precise detection of contact with hardstops and automatic calibration, eliminating the need for home sensors and reducing the risk of single-point failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional homing methods using home sensors or switches are used, then the system can establish a reference position, but the positioning precision is poor and the system is vulnerable to single points of failure
Solution Approach 1:
The patent removes home sensors and switches from the homing system, extracting the vulnerable electronic detection components. Instead, it uses only the feedback device (encoder) and motor electrical parameters to detect hardstop contact and establish reference positions, eliminating single points of failure while maintaining precision through multiple measurement methods
Solution Approach 2:
The system uses feedback from the encoder (position feedback) and motor electrical parameters (current, voltage, speed) to detect when the axis contacts the hardstop. This multi-source feedback approach provides redundant information for reliable reference position establishment without needing separate home sensors
2Measurement precision
If multiple electronic components are used for homing, then measurement precision can be improved, but device complexity increases and reliability decreases in high-radiation environments
Solution Approach 1:
The feedback device and motor serve multiple functions: they provide both position feedback for normal operation and electrical parameter monitoring for hardstop detection during homing. This multi-functionality eliminates the need for dedicated homing components, reducing system complexity while maintaining precision
Solution Approach 2:
The system uses its own existing components (motor and feedback device) to perform the homing function. The motor's electrical parameters and the feedback device's position signals are already present for normal operation, so they are utilized self-servingly for homing without requiring additional external components
3Ease of operation
If home sensors are used for homing, then reference position can be established, but any movement of the sensor affects axis positioning accuracy
Solution Approach 1:
The patent extracts and removes the home sensor from the system entirely. Instead of relying on a physical sensor that can move or malfunction, it uses the feedback device and motor electrical parameters which are already integrated into the motion control system, eliminating the source of positioning errors
4Reliability
If conventional homing methods are used, then reference position can be established, but frequent recalibration is needed after component servicing or replacement
Solution Approach 1:
The system performs preliminary hardstop contact detection using electrical parameters and feedback signals before finalizing the reference position. This preliminary action ensures that even if components are replaced, the homing routine can re-establish accurate reference positions automatically without requiring manual recalibration
Solution Approach 2:
The continuous feedback from the encoder and motor electrical parameters during motion allows the system to detect hardstop contact and establish reference positions automatically. This feedback mechanism ensures that reference positions remain accurate even after component servicing, eliminating the need for frequent manual recalibration
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 provides a robust and reliable method for establishing precise and repeatable reference frames for motion axes in radiation systems, enhancing safety and reducing the need for system recalibration after component servicing or replacement.
Implementation Method 1
a motor, a load, a feedback device, and one or more hardstops. The load is driven by the motor to move toward a hardstop
Implementation Method 2
the value of the feedback device is captured when the monitored electrical parameter or motor velocity or load velocity reaches or exceeds the determined value
Data Source
AI summary
A method of homing motion axes in a radiation system uses a motor and one or more hardstops. A load is driven by a motor to move toward a hardstop during which an electrical parameter of the motor is monitored. A reference position for the motion axis is defined when the monitored electrical parameter reaches or exceeds a determined value. Alternative to monitoring the motor electrical parameter, the motor velocity may be monitored during the motion and a reference position for the motion axis is defined when the monitored motor velocity falls to or below a determined value. Alternatively, the load velocity may be monitored during the motion and a reference position for the motion axis is defined when the monitored load velocity falls to or below a determined value.