Elevator Position Calibration Using IMU and Encoder Fusion
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Solution Overview
Problem
Elevator systems often experience deviations between actual and commanded landing locations, leading to operational inefficiencies and user safety issues, such as the formation of lips between the elevator car and the floor, which can cause injuries and difficulties in loading/unloading heavy objects.
Innovation Solution
The implementation of an inertial measurement unit (IMU) to compute the position of the elevator car, combined with a correcting vane and encoder data, using Kalman filtering to estimate and minimize the position error, thereby ensuring accurate landing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional encoder-based positioning is used, then the system structure is simple, but the landing position accuracy deteriorates due to dynamic errors
Solution Approach 1:
The patent combines multiple positioning systems (encoder, IMU, correcting vane) into a unified hybrid positioning system. The encoder provides baseline position data, the IMU compensates for dynamic errors during motion, and the correcting vane provides reference corrections, together achieving high accuracy landing positioning that none of the individual systems could achieve alone.
Solution Approach 2:
The IMU acts as an intermediary between the encoder and the final position calculation. It measures dynamic errors (accelerations, vibrations) that occur during elevator motion and provides correction data to the controller, which then adjusts the encoder-based position to achieve accurate landing positioning.
2Measurement precision
If high-precision positioning systems are implemented, then landing accuracy improves, but the device complexity increases
Solution Approach 1:
The system uses the elevator's own motion-induced dynamic errors (which cause positioning inaccuracies) as the measurement target for the IMU. By measuring these self-generated errors and compensating for them, the system achieves high accuracy without requiring external reference systems or additional complex infrastructure.
Solution Approach 2:
The patent changes the measurement parameters by introducing temporal and frequency dimensions. Instead of only measuring static position, the system measures position over time and analyzes frequency characteristics of dynamic errors, enabling differentiation between intentional motion and erroneous deviations for more accurate compensation.
3Measurement precision
If dynamic error compensation is added, then positioning accuracy improves, but the control complexity increases
Solution Approach 1:
The system implements multi-loop feedback: the encoder provides continuous position feedback, the IMU provides dynamic error feedback during motion, and the correcting vane provides reference feedback. The controller integrates all feedback signals to continuously adjust and refine the position estimate, achieving accurate landing positioning through layered feedback mechanisms.
Solution Approach 2:
The system performs preliminary calibration by establishing the relationship between IMU measurements and actual positioning errors before operation. This pre-characterization of dynamic error patterns allows the controller to apply pre-computed compensation strategies, reducing the complexity of real-time control calculations during actual elevator operation.
Data Source
AI summary
Embodiments are directed to reducing at least one dynamically generated error in terms of an actual position of an elevator car, comprising: triggering an inertial measurement unit (IMU) to compute a position of an elevator car of an elevator system, obtaining a position of a correcting vane in a hoist-way of the elevator system, obtaining a position of the elevator car as determined by an encoder of the elevator system, and estimating the position of the elevator car based on the computation of the position by the IMU, the position of the correcting vane, and the position of the elevator car as determined by the encoder.