Greetings everyone, I am currently engaged in a project that entails managing a set of nozzles in a CNC environment. These nozzles move along a linear trajectory at a consistent speed and angle. The main goal is to activate all nozzles simultaneously along a line perpendicular to their path (refer to the image). This control is executed through G-code for motion commands and M functions for toggling the nozzles on/off. The main challenge I am encountering is achieving precise synchronization between the motion of the nozzles and their activation/deactivation, particularly considering the inherent delay in the hardware's response time. At present, the nozzles are moving at a speed of 500 mm/s, with the PLC system functioning at a cycle time of 1 ms. This configuration limits the system's accuracy to about 0.5 mm, directly related to the PLC's cycle time. Given these limitations, I am considering whether switching to a dedicated controller with a faster cycle time could be a viable solution. I would greatly appreciate your input on the following queries: - Viability: Is adopting a dedicated controller with a faster cycle time a feasible method to improve accuracy in this context? Have you implemented a similar solution in your own practice? - Recommendations: If a dedicated controller is recommended, are there specific models or brands that suit these criteria well? Keep in mind there are 24 individual nozzles in the array. - Alternatives: Alternatively, are there other methods or technologies you would propose exploring to tackle the synchronization and accuracy issues without necessitating a switch to a different controller? I am eager to hear your opinions, experiences, and any guidance you can offer on enhancing the efficiency of such a system. Thank you in advance for your assistance and insights!
What is the optimal resolution needed for achieving the best response times when activating a nozzle? Additionally, what is the noise level associated with these response times? It is worth noting that cos(Îą) can be substituted with â(nP2- 1S2) / nP to streamline function calls.
Drbitboy inquired about the necessary or preferred resolution and the noise level associated with response times when activating a nozzle. He also asked about the best achievable resolution. Additionally, he mentioned that cos(Îą) could potentially be substituted with â(nP2- 1S2) / nP to streamline calculations.
Thank you for your response. The response time of the nozzles is 6 milliseconds to activate and 8 milliseconds to deactivate. The CNC controller has the capability to pre-call M-functions, allowing for effective management of delays. However, the challenge arises when increasing nozzle density (or reducing niD in the diagram), as this may result in multiple calls within the same cycle. With the current dimensions of the effectors and motion profile taken into consideration, the ideal cycle time to avoid this issue would fall within the range of 10-100 microseconds.
Determining whether the equipment is a standard product or a customized machine is crucial in determining the level of investment needed. Coordinating the movement of 24 or more nozzles is a manageable task, but the challenge lies in achieving precise timing for turning them on and off. It seems that specialized hardware is necessary to achieve the level of accuracy desired in controlling the nozzles based on their location. How consistent is this process? Can the timing for the nozzles be programmed into a Field-Programmable Gate Array (FPGA)?
We have a unique prototype that is a one-of-a-kind creation, with both budget and time allocated for its development. I understand the challenge lies in efficiently managing the nozzles. Currently, I am utilizing M-functions within the CNC controller to handle this task. This approach minimizes the computational load during operation, yet I foresee difficulties when expanding the system to control more densely packed nozzle arrays. Exploring the use of FPGAs seems promising and worth investigating. When it comes to correlating the nozzle status with the current TCP location, the crucial aspect will be determining the tolerance level for identifying whether the nozzle is ON or OFF. In this case, would you consider storing the "bitmap" in the internal memory of the FPGA card and using the position vector (x,y,a) as input?
Hi there, it sounds like you are wrestling with a tricky system there! Based on your explanation, adopting a controller with quicker cycle time does seem like a plausible solution - faster response time should definitely contribute to increased accuracy. We had a similar challenge in one of our projects and indeed moving to a dedicated controller with a smaller cycle time helped us improve accuracy. You might want to check out Beckhoff's TwinCAT controllers - they have a better cycle time range (down to 50Ξs). Alternatively, you might also want to reconsider the overall system design and see if there are possibilities to adjust the nozzle movement speed or simplify physical processes - these changes can generate considerable improvements in synchronization without necessarily needing a controller switch. Good luck with your project!
From my experience, a dedicated controller with a faster cycle time could indeed make a difference when it comes to upgrading the precision of your nozzle system. However, you should also consider other elements such as communication speeds and programming capacity, as they could contribute to the total response time. As for the brand or model, it really depends on your specific applications and budget but I've seen success with Siemens' S7-1500 PLC series in similar setups. As an alternative, have you considered exploring real-time kinematic (RTK) positioning? It's typically used in GPS applications, but the precision it offers might just reduce the synchronization and accuracy issues you're facing, though this would entail a different kind of implementation complexity.
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Answer: - Transitioning to a dedicated controller with a faster cycle time can indeed be a feasible method to improve accuracy in CNC nozzle array systems. The reduced cycle time can help minimize delays in activating/deactivating the nozzles, thereby enhancing synchronization and precision. However, it is essential to ensure compatibility with existing hardware and consider the specific requirements of the system.
Answer: - While specific recommendations may vary based on individual needs and system specifications, when selecting a dedicated controller for managing 24 individual nozzles in a CNC environment, it is crucial to look for controllers known for their fast cycle times, reliable performance, and compatibility with the existing setup. Brands that specialize in CNC control systems or have a proven track record in precision control applications may be worth exploring.
Answer: - There are alternative methods and technologies that can be explored to tackle synchronization and accuracy challenges in CNC nozzle array systems without necessarily switching to a different controller. For instance, optimizing motion planning algorithms, implementing sensor feedback mechanisms for real-time adjustments, or fine-tuning the G-code instructions for smoother operation could potentially enhance system efficiency and precision.
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