Currently, my linear process operates on pneumatic cylinders with a 4-20mA linear position transducer. A PLC controls these cylinders using an Enfield S2 cylinder positioning controller. However, the position control is subpar, especially under varying force/load conditions. This issue seems to stem from the limitations of using air as a positioning medium due to its compressibility and inconsistent availability, as well as the Enfield controller's inadequate algorithm lacking a full PID loop. To improve the system, I am considering retrofitting it with ballscrews and a servo for more precise control. However, this would require significant physical modifications. Therefore, I am first seeking electric linear actuators with a form factor similar to the current cylinders. Unfortunately, I have been unable to find any that meet the speed, force, and accuracy requirements of the application. The ideal actuator should have a closing force of at least 1500lbf/6700N, be capable of full open/close movement within 2 seconds over a total travel distance of 20”/500mm, and position accurately within 1/32 inches/1mm. While I have heard of servo hydraulics and hydraulic positioning as alternatives, I lack knowledge in this area. Can anyone provide guidance on where to start or recommend suitable products, preferably ones suitable for beginners?
Trust your intuition, it's usually spot on. Have you determined the system's natural frequency? It's a mystery to most. Using oil could have been a better choice, as ball screws are sensitive to shock.
Peter Nachtwey suggested using oil for better results, emphasizing the importance of natural frequency in the system. He questioned the knowledge of others regarding the system's natural frequency, prompting a search on Google for "natural frequency PID." The search led to insights on the significance of natural frequency, particularly in relation to Delta and RMC controllers. Despite not having worked with hydraulics in years, Nachtwey's expertise in this area seems to align perfectly with the project requirements. While seeking guidance on the necessary components for controlling two cylinders, the user expressed interest in a potential sales pitch from Nachtwey. Unsure if two channels are required or if parallel plumbing is sufficient, the user is open to recommendations on the most basic yet effective solution for their application.
When I requested a quote on the Delta website for the RMC75E-AA1(1)EXP70-A2, I was unsure if the expansion module was necessary. The quote wizard led me to believe it was needed to control the RMC75 with an analog signal, but the RMC75 datasheet suggests 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? Would any standard 0-10V or 4-20mA proportional valve work?
Indeed, that's correct. Are you referring to the speed at which it can transition between extents? The ability to accelerate or decelerate is crucial. It is noted, particularly by Google, that you have a strong focus on natural frequency. I am honored to be a member of the International Fluid Power Hall of Fame and have authored magazine articles for over two decades. I consider myself proficient in control theory and mathematics, although I respect the laws of physics. If you have mastery over pneumatics, transitioning to hydraulics should pose no major challenges, although there are limitations. One of the systems I utilize for testing hydraulic control algorithms is PneuMove2. Managing pneumatics can be complex due to the high level of air compression. You are welcome to explore my YouTube Channel if you have an interest in control theory. Retirement has allowed me to settle in Panama, where I now reside and spend less time on forums as I enjoy camping without internet access. Currently, the team at Delta Motion is expected to handle any tasks that arise. I firmly believe that we have the best solution available. Regarding a quote inquiry on the Delta website for RMC75E-AA1(1)EXP70-A2, I am uncertain if the expansion module is necessary. It appears from the RMC75 datasheet that the AA1 axis card already supports an analog signal. The EXP70 module, however, is essential for torque limiting. It would be advisable to acquire a main module with an SSi input for an SSI Temposonc or Balluff rod. For technical guidance, contacting Delta Motion tech support is recommended. A servo quality valve capable of flowing oil to both sides of a cylinder piston for force control is essential. The spool configuration should ensure no overlap and be linear for optimal performance. Cylinder size, such as a 2-inch diameter, also plays a significant role. If further assistance is required, Delta Motion experts can reach out for additional guidance.
Absolutely. When discussing cycle speed, we're referring to how quickly it can transition between extents. The acceleration and deceleration rates are also crucial aspects to consider. Known for his expertise in natural frequency and control theory, this individual is a distinguished member of the International Fluid Power Hall of Fame. With a background in writing magazine articles for over two decades, his focus is on control theory and mathematical analysis within the realm of fluid power systems. Utilizing a test system called PneuMove2, hydraulic control algorithms are put to the test, showcasing the challenges of controlling pneumatics due to air compression. With a strong YouTube presence dedicated to control theory, this expert's retiree status and current location in Panama have led to less forum activity, as camping adventures often take him off the grid. While the expertise at Delta Motion is trusted to pick up the workload, the pursuit of the best solutions remains a top priority. A recent inquiry was made regarding the need for the EXP70 module to control the RMC75 with an analog signal, aiming to confirm the necessity based on the features of the AA1 axis card. The EXP70 module proves essential for torque limit functionalities, while the main channel is dedicated to position and speed control. Considering the installation of a main module with an SSi input for SSI Temposonc or Balluff rod, the importance of a high-quality servo valve capable of flowing oil efficiently is emphasized. The selection of a cylinder with the appropriate size, possibly a 2-inch diameter, is crucial for optimal performance. For further assistance, reaching out to Delta Motion tech support is recommended to select the ideal components for the application.
Hi! You've got some impressive technical knowledge there. Switching from pneumatic to hydraulic or electric systems definitely increases the positional accuracy. Hydraulic systems though are more expensive to install, but the accuracy certainly compensates for it. Meanwhile, electric linear actuators are versatile, cost-efficient, and can cover a wide range of speed, force, and accuracy requirements. Explore companies like Festo or Thomson linear for electric linear actuators that may meet your requirements. You can use online calculators available on their websites to compare product specifications and find a suitable match. Also, reach out to their technical support with your requirements, as they'll often recommend a product based on your specific use-case. As for gaining knowledge on servo hydraulics, I'd recommend looking into some online courses or resources such as Khan Academy, Coursera, or YouTube tutorials. These platforms often have plenty of information on these topics. It's indeed a learning curve, but once you've acquired the knowledge, the application maintenance and improvements that hydraulic systems offer can be quite rewarding. Best of luck!
You're right in considering the retrofit; the precision and control offered by ballscrews and servos are incredibly high compared to pneumatics. However, if physical modifications seem daunting, you might want to explore high-performance electric linear actuators. Companies like Warner Linear or LinMot, to name a few, manufacture electric linear actuators that could meet your force and speed requirements. Regarding hydraulic positioning systems, they provide high force with excellent positional accuracy but require a bit more maintenance. Companies like Bosch, Parker, and Eaton make servo hydraulic systems. But before proceeding, you should consider factors such as environment (e.g., cleanliness, temperature), cost (initial and operational), maintenance, and noise levels. Consulting an application engineer might be helpful to determine the best fit for your application.
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Answer: - Using air as a positioning medium can lead to subpar control due to compressibility and inconsistent availability, impacting performance under varying force/load conditions.
Answer: - Factors to consider include force requirements, speed, accuracy, and compatibility with existing systems.
Answer: - The ideal actuator should meet specific force, speed, and accuracy requirements, such as a closing force of 1500lbf/6700N, full open/close movement within 2 seconds over a 20”/500mm travel distance, and accurate positioning within 1/32 inches/1mm.
Answer: - Servo hydraulics and hydraulic positioning can be considered as alternatives to electric linear actuators, offering different benefits and application suitability.
Answer: - Beginners can seek guidance on suitable products and recommendations from industry experts, manufacturers, or online resources to understand the available options and make informed decisions.
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