Load Handling Shuttle Position Control Using IMU-Encoder Fusion
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Solution Overview
Problem
Existing automated storage and retrieval systems (ASRS) face challenges in precise positioning and operational efficiency due to inaccuracies in shuttle movement and item retrieval, necessitating improved control mechanisms for robotic shuttles.
Innovation Solution
A load handling shuttle equipped with inertial measurement units (IMUs) and motor encoders, coupled with processors, fuses linear acceleration data to predict and control the position of the shuttle and its load handling arms along the X and Y axes, using algorithms like Kalman filters for accurate state estimation and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If motor encoders alone are used for positioning feedback, then the system structure remains simple, but positioning precision deteriorates due to accumulation of positioning errors during shuttle movement
Solution Approach 1:
The patent introduces IMU sensors as an intermediary measurement system that independently monitors the shuttle's motion state (acceleration, angular velocity). This intermediary system provides real-time position and orientation data that supplements the motor encoder feedback, thereby improving positioning precision without requiring fundamental changes to the existing drive system structure.
Solution Approach 2:
The patent replaces pure mechanical positioning feedback (relying solely on motor encoders) with a hybrid approach that incorporates inertial measurement. The IMU sensors substitute for the insufficient mechanical feedback system by providing direct measurement of motion parameters, enabling more accurate position estimation through sensor fusion algorithms.
2Productivity
If traditional feedback control is used, then the control system remains simple, but operational efficiency deteriorates due to inability to compensate for positioning errors in real-time
Solution Approach 1:
The patent implements a dual-feedback control system that combines motor encoder position feedback with IMU-based motion state feedback. The controller continuously compares the desired position with the actual position (from encoders) and the measured acceleration/orientation (from IMU), using sensor fusion to generate corrected control commands. This enhanced feedback mechanism enables real-time compensation for positioning errors, thereby improving operational efficiency.
3Measurement precision
If high-precision positioning systems are implemented, then positioning accuracy improves, but the system becomes more complex and costly
Solution Approach 1:
The patent merges two existing systems (motor encoders and IMU sensors) into a unified positioning and control system. By combining the positional feedback from encoders with the motion state measurement from IMU, the system achieves higher positioning accuracy than either system could provide alone, while avoiding the need to implement a completely new high-precision positioning system from scratch.
Data Source
AI summary
A load handling shuttle adapted to move forward and backward along an X-axis and a Y-axis on a track is disclosed. The shuttle comprises a shuttle body, a load handling device (LHD) having a first LHD arm and a second LHD arm extendable back and forth in the Y-axis direction. The LHD comprising a first LHD motor and a second LHD motor configured to propel the first LHD arm and the second LHD arm in the Y-axis direction. Further, the LHD comprises a first LHD motor encoder and a second LHD motor encoder configured to determine one or more feedback parameters of the first LHD motor and the second LHD motor, respectively. Further, at least one inertial measurement unit (IMU) configured to determine linear acceleration of the LHD in the Y-axis direction. Further, at least one processor predicts a current state of the LHD.