Stacker Crane Control Device Using Encoder and Mark Sensor
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Solution Overview
Problem
Existing stop control systems for movable objects like stacker cranes and robot hands struggle to accurately and swiftly stop at designated positions due to changes over time, such as abrasion or deformation, which affects the reliability and accuracy of stop data.
Innovation Solution
A control device utilizing an encoder for movement distance detection, a linear sensor for absolute distance output, and a mark sensor for precise positioning, allowing for error correction and maintenance scheduling, enabling the movable object to stop correctly and swiftly even with changes in the transportation apparatus or stop position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stop data is stored in memory for stopping the movable object at each shelf, then the stopping process is simplified and speed is improved, but the accuracy of stopping position deteriorates over time due to wear and deformation
Solution Approach 1:
The patent implements feedback by using sensors (mark sensor, linear sensor) to detect the actual position of the movable object and comparing it with the target stop position. The detected position information is fed back to the control unit, which calculates the deviation and generates correction commands to adjust the stopping position, thereby maintaining accuracy despite wear and deformation over time.
Solution Approach 2:
The patent replaces reliance on mechanical wear-resistant components with optical/electronic sensing systems. Instead of depending solely on mechanically stored stop data that degrades with wheel abrasion, the system uses mark sensors and linear sensors to optically detect position, substituting mechanical measurement with non-contact sensing that does not degrade with mechanical wear.
2Measurement precision
If multiple sensors are used for position detection, then the stopping accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent segments the position detection function into two distinct sensing stages: a mark sensor for coarse position detection at larger distances, and a linear sensor for fine position detection near the stop position. This segmentation allows each sensor to operate in its optimal range, achieving high overall accuracy while managing complexity by dividing the detection task rather than using a single complex sensor system.
Solution Approach 2:
The patent implements dynamic sensor switching where the control unit automatically selects which sensor to use based on the current position of the movable object. The system transitions from mark sensor to linear sensor as the object approaches the stop position, creating a dynamic sensing system that adapts to changing conditions rather than using a static, always-on complex sensor array.
3Measurement precision
If the movable object moves slowly to ensure precise stopping, then the stopping accuracy is improved, but the productivity decreases
Solution Approach 1:
The patent implements dynamic speed control where the movable object travels at high speed during most of the journey and automatically reduces speed only in the final approach to the stop position. The control unit monitors position via sensors and commands speed reduction only when the object enters the detection range of the linear sensor, maintaining high productivity while ensuring accuracy during the critical stopping phase.
Solution Approach 2:
The patent performs preliminary position detection using the mark sensor at a distance before the actual stop point. This allows the system to prepare for deceleration in advance, transitioning smoothly from high-speed travel to controlled stopping without abrupt speed changes, thereby maintaining efficiency while ensuring precision in the final positioning phase.
Data Source
AI summary
An encoder 13 determines the remaining travel distance of a stacker crane to perform deceleration control. When a linear sensor 8 determines an absolute distance from the stop position, the linear sensor 8 performs deceleration control, and when a mark sensor 26 detects a mark 36, the mark sensor 26 performs stop control. Likewise, deceleration control is performed based on the remaining elevation distance determined by an encoder 19. When a linear sensor 9 determines an absolute distance from the stop position, the linear sensor 9 performs deceleration control, and when the mark sensor 26 detects the mark 36, the mark sensor 26 performs stop control.