Root-Finding Trajectory Control for Stable Load Handling Motion
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Solution Overview
Problem
Existing load handling devices in storage systems experience instability and oscillation during acceleration and deceleration on grid structures, leading to potential damage of items stored within the containers, due to uneven wheel rotation and sudden changes in movement.
Innovation Solution
A computer-implemented method and system for generating a motion control profile that includes trapezoidal and S-curve trajectory profiles to control the movement of load handling devices, ensuring smooth transitions between different speeds by synchronizing wheel movements and adjusting acceleration and deceleration phases to minimize jerk, thereby stabilizing the device and reducing item damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If load handling devices move quickly on grid structures, then productivity is improved, but stability deteriorates due to oscillation during acceleration and deceleration
Solution Approach 1:
The patent applies dynamics by implementing a motion control system that dynamically adjusts acceleration and deceleration profiles based on real-time device state. The controller modifies movement parameters during operation to maintain stability while achieving high productivity, using dynamic speed adjustment rather than fixed movement patterns
Solution Approach 2:
The patent implements feedback through sensors that continuously monitor the load handling device's position, speed, and acceleration. This feedback loop allows the controller to detect oscillations and adjust control signals accordingly, preventing instability while maintaining high movement speeds for improved productivity
2Productivity
If acceleration and deceleration are increased to improve operational efficiency, then productivity is improved, but harmful factors increase due to item damage from sudden movements
Solution Approach 1:
The patent applies preliminary action by pre-calculating optimal acceleration and deceleration profiles before movement begins. The motion control system plans trajectories in advance that balance speed requirements with item protection, preventing damage before it occurs while maintaining operational efficiency
Solution Approach 2:
The patent implements beforehand cushioning by incorporating gradual acceleration and deceleration phases into the motion profile. These cushioning phases absorb the shock of speed changes, protecting items from damage while still achieving high operational efficiency through optimized timing
3Speed
If wheel rotation speed is increased to improve movement speed, then productivity is improved, but stability deteriorates due to uneven wheel rotation causing oscillation
Solution Approach 1:
The patent uses feedback from encoders and sensors to monitor individual wheel rotation speeds in real-time. The controller compares actual wheel speeds with target speeds and adjusts motor commands to correct uneven rotation, maintaining high speed while preventing oscillation through continuous correction
Data Source
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AI summary
A method for generating a trajectory to control the movement of a motion device, the method comprising: i) receiving a specification of the trajectory, the specification comprising a commanded position, ii) receiving at least one jerk constraint; iii) using the at least one jerk constraint to generate a sequence of one or more trajectory segments, each of the one or more of trajectory segments being respective portions of the trajectory prescribing a jerk reference, an acceleration reference, a velocity reference and a position reference as a function of time; wherein the one or more trajectory segments of the sequence of trajectory segments are generated based on predicting a value of a parameter using a root finding algorithm to find a root of an objective function, the objective function being an amount of positional deviation of the magnitude of the position reference from the commanded position when the velocity reference and the acceleration reference is substantially zero and the root corresponding to the value of the parameter where the positional deviation from the commanded position being less than a predetermined threshold.