I currently have a single-axis linear process powered by pneumatic cylinders with a 4-20mA linear position transducer. The cylinders are controlled by an Enfield S2 cylinder positioning controller, which is connected to a PLC. However, the position control is not optimal, especially under varying force/load conditions. I believe the issue lies in the limitations of using air as a medium for precise and consistent positioning, as well as the Enfield controller lacking a comprehensive PID loop algorithm. Despite these challenges, I am reluctant to completely retrofit the system with ballscrews and a servo due to the extensive physical modifications required. I am therefore in search of an alternative solution that maintains a similar form factor as the current cylinders. Electric linear actuators meeting the speed, force, and accuracy criteria needed for the application have proven elusive. The ideal replacement should deliver at least 1500lbf/6700N closing force, operate within a 20”/500mm total travel distance in approximately 2 seconds, and ensure positioning accuracy within 1/32 inches/1mm. Although I am aware of servo hydraulics and hydraulic positioning as possible alternatives, I lack expertise in this area. Where should I begin my search for suitable products or recommendations? Any suggestions for user-friendly options for someone with limited experience in this field would be greatly appreciated.
Trust your intuition - it's often spot on. Have you determined the natural frequency of the system yet? It's a factor that many overlook. Consider using oil to avoid damaging the ball screws, as they are sensitive to shock.
Peter Nachtwey mentioned the importance of using oil for optimal performance, stating that it's better late than never. He also questioned the natural frequency of the system, emphasizing its crucial role in the cycling between extents. Wondering about the specifics, he turned to Google and discovered valuable information on natural frequency and PID control. This led him to delve deeper into the world of Delta, RMC controllers, and hydraulics. Despite not having been in the hydraulic field for some time, Peter realized that he needed the right equipment for controlling two cylinders. He pondered whether he required two channels or if the cylinders could be connected in parallel. Wanting to make the best purchase decision, he sought guidance on the most basic yet effective solution available. Curious why he hadn't been pitched a sales offer, he expressed interest in learning more about the product specifications. If unable to provide details in the current conversation, he requested to be contacted via email for further discussion.
I recently requested a quote on the Delta website for the RMC75E-AA1 (1)EXP70-A2 and I'm unsure if the expansion module is necessary. While the quote wizard suggested it was needed to control the RMC75 with an analog signal, the RMC75 datasheet states that the AA1 axis card already accepts an analog signal. I couldn't find any valves on the Delta site - what type of valves do you suggest? Should I go for any 0-10V or 4-20mA proportional valve?
Absolutely. So, does that mean how quickly it can switch between different levels of performance? The speed at which it can speed up or slow down. It appears that Google recognizes you for your focus on natural frequency, among other things. I am honored to be a member of the International Fluid Power Hall of Fame. Over the span of 20 years, I have written articles for magazines and consider myself a specialist in control theory. While I am skilled in mathematics, I understand that I cannot defy the laws of physics, especially if the mass is too large. If you can master pneumatics, then hydraulics becomes manageable, but there are still constraints. I utilize the PneuMove2 test system to evaluate hydraulic control algorithms, which can be challenging due to the significant compressibility of air in pneumatics. My YouTube Channel is a valuable resource for those interested in control theory. Despite my retirement and current location in Panama, where I now reside, I am less active on forums as I am often camping without internet access. Others at Delta Motion are expected to pick up where I left off. Rest assured, I am confident that we have the optimal solution. Inquiring about the RMC75E-AA1(1)EXP70-A2 on the Delta website, I am uncertain if the expansion module is necessary as the RMC75 datasheet suggests the AA1 axis card already accepts an analog signal. The EXP70 module, however, is vital for torque limitation, with the main channel dedicated to position and speed control. While I am not up to date on all the available options, I would recommend obtaining a main module equipped with an SSi input for an SSI Temposonc or Balluff rod. If in doubt, contacting Delta Motion tech support is advisable, ensuring a servo quality valve capable of providing oil flow to both sides of a cylinder piston for force adjustments. It's essential that the spool has no overlap and offers a linear performance. Cylinder size does matter, with a 2-inch diameter possibly sufficient, but further details would be needed for accurate sizing. If the Delta team encounters challenges, they can always reach out to me for support.
Of course. How quickly it can switch between different states? The speed at which it can accelerate or decelerate. It seems like Google recognizes you for your expertise in natural frequency. I am a member of the International Fluid Power Hall of Fame and have been writing magazine articles for over 20 years. I consider myself a specialist in control theory. While I can work wonders with math, I can't defy the laws of physics. If you have a grasp on pneumatics, then hydraulics should be straightforward, although there are limitations. One of my test systems, PneuMove2, is used for testing hydraulic control algorithms. Managing pneumatic control can be challenging due to the high compression of air. If you're interested in control theory, my YouTube channel offers valuable content. I'm currently retired and residing in Panama, contemplating a permanent move. I'm not as active on forums as before, often spending my time camping without internet access. Other team members at Delta Motion are expected to pick up where I left off. I firmly believe we have the best solution. On the Delta website, I inquired about a quote for the RMC75E-AA1(1)EXP70-A2. Although I initially thought the expansion module was necessary, the RMC75 datasheet indicates that the AA1 axis card can accept an analog signal without it. The EXP70 module is essential for torque limitations, with the main channel focused on position/speed control. I recommend considering a main module with an SSi input for a SSI Temposonc or Balluff rod. For specific needs, I would suggest consulting Delta Motion tech support for a servo valve capable of flowing oil on both sides of a cylinder piston. The spool should be non-overlapping and linear in design, with size playing a crucial role. A 2-inch diameter cylinder might suffice, but more information would be necessary.
I completely understand the difficulties you're facing with the current setup. Considering the parameters you’ve mentioned - speed, force, and accuracy - in addition to the requirement for a comprehensive feedback system, I'd wager to say that electric rod actuators could be a viable solution. Though slightly more expensive, companies like Exlar, Bosch Rexroth, or Tolomatic offer high precision, robust build quality, and better overall control over their operation, which could overcome your issues with load variance. They function similar to your current pneumatic cylinders, thus requiring minimal alterations to your current setup. As far as a starting point goes, I'd recommend looking into their catalogs, speaking with their sales/engineering teams (they’re usually quite willing to help given your specific needs), or even reaching out to local distributors. Good luck with your search!
You're definitely on the right track by considering a move away from pneumatics for precision positioning. Electric actuators could fit your requirements but the challenge usually arises when you seek both speed and force within a small form factor. While you’ve already ruled out ballscrews and servos, don't completely dismiss them yet - there are compact models available that can deliver your required force within a small footprint. As for hydraulic systems, they can indeed provide excellent force and speed, but suffer from lower accuracy due to the compressibility of hydraulic fluid, so they might not be the best choice for you. I suggest diving further into electric actuator alternatives, perhaps specifically exploring the miniature linear actuator offerings from companies like LinMot or Exlar. These manufacturers design their products for such niche requirements and might just have what you need. Regardless, it seems a bit more research and perhaps some professional consulting could be helpful for your specific application. It's a complex problem, but there's surely an optimal solution out there!
It seems like you've really narrowed down your problem, and that you're looking at the right alternatives. A servo-hydraulic system could indeed be a great solution considering the high force and accuracy requirements. You might want to look into brands like Parker or Bosch Rexroth, which provide top-tier industrial hydraulic systems with suitable software interfaces for beginners. I recommend also considering a detailed consultation with their tech support or sales engineering team to ensure all your requirements are met. As for the inexperience in the field, don't worry too much. Most good suppliers provide excellent support for new customers to help them understand and implement their products, so it's more about getting the right product rather than having prior expertise.
It sounds like you have a solid understanding of your current system's limitations, and it’s great that you're exploring alternatives without heading into a full retrofit. For your requirements, you might want to check out electric linear actuators from brands like THK, Guden, or Actuonix—they often provide options that can deliver the force and speed you need with good accuracy and are designed to fit into tight spaces. Another avenue to consider is collaborating with a specialist in motion control who has experience with both electric and hydraulic systems; they can offer tailored advice and potentially recommend products that you wouldn't necessarily find through general research. Lastly, don’t overlook possibly integrating more advanced control algorithms into your current setup; sometimes, even a minor tweak in the control strategy can yield significant improvements. Good luck with your hunt!
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Answer: - Air can have limitations in achieving precise and consistent positioning due to factors such as compressibility, varying force/load conditions, and lack of comprehensive control algorithms like PID loops for fine-tuning positioning.
Answer: - Retrofitting a pneumatic system with ballscrews and servos for precise linear motion control can be challenging due to the extensive physical modifications required, such as changing the form factor and integrating new components into the existing setup.
Answer: - When searching for alternative solutions to pneumatic cylinders, factors to consider include speed, force, accuracy requirements, total travel distance, closing force, and positioning accuracy specifications to ensure compatibility with the application's needs.
Answer: - One can start their search for suitable hydraulic solutions for linear motion control by exploring manufacturers, suppliers, and distributors specializing in servo hydraulics and hydraulic positioning systems. Additionally, consulting with experts in the field or attending industry-specific trade shows can provide valuable insights and recommendations.
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