PLC CAM Table Phase Adjustment for Motion Control
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Solution Overview
Problem
Existing electronic cam systems in motion control applications face challenges in fine-tuning device machine differences and altering dependent shaft operations during electronic cam operations, as conventional methods rely on pre-created CAM tables that do not allow for easy adjustments or real-time modifications.
Innovation Solution
A programmable logic controller (PLC) computation unit that can alter CAM table phases or displacements based on user commands, allowing for real-time adjustments and fine-tuning of dependent shaft operations by storing and modifying CAM data in both volatile and non-volatile memory, and executing these changes using a post-alteration CAM table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pre-created CAM table is used in conventional electronic cam systems, then the system structure is simple and stable, but the system cannot be easily adjusted or modified during operation, reducing adaptability
Solution Approach 1:
The patent applies the dynamics principle by enabling the CAM table to be modified during operation rather than being fixed. The microprocessor updates CAM data in the CAM table based on update commands received during electronic cam operation, allowing the system to adapt to changing requirements while maintaining a relatively simple overall structure. This dynamic modification capability resolves the contradiction between adaptability and structural simplicity.
2Adaptability or versatility
If the CAM table is modified during electronic cam operation, then the adaptability and fine-tuning capability are improved, but the computation and processing time increase
Solution Approach 1:
The patent applies preliminary action by pre-organizing the CAM table data structure and having the microprocessor ready to receive and process update commands. The system maintains a ready-state configuration where CAM data can be quickly updated without requiring extensive recomputation or system reconfiguration. This preparation reduces the time penalty associated with real-time modifications.
3Speed
If the CAM table data is stored only in volatile memory, then the modification speed is fast, but the data is lost when power is turned off, reducing reliability
Solution Approach 1:
The patent applies preliminary action by pre-establishing a dual-memory storage architecture where CAM data is maintained in volatile memory for fast access and modification, while also being stored in non-volatile memory for persistence. This preliminary configuration ensures that modifications made during operation are quickly reflected (using volatile memory) while also being preserved across power cycles (using non-volatile memory), thus resolving the contradiction between speed and reliability.
Data Source
AI summary
A CPU unit of a PLC executes a motion control and a sequence control. The CPU unit stores a CAM table and a control program for performing the motion control using the CAM table. When a microprocessor receives a command for altering one of a plurality of phases and/or a displacement associated with the phase, the microprocessor alters the phase and/or the displacement in the CAM table to a value that is on the basis of the command. When the microprocessor performs the alteration, the microprocessor executes a control program using a post-alteration CAM table, and outputs the execution results to an apparatus to be controlled.