CT Final Submission 2003 r.pdf
Creators: name: Darbyshire, Karl
Publisher: name: figshare
Year: 2016
Subjects: subject: 90602 Control Systems, Robotics and Automation
subject: FOS: Electrical engineering, electronic engineering, information engineering
subject: FOS: Electrical engineering, electronic engineering, information engineering

description: Controlled motion is a fundamental element in automation. Pneumatic cylinder rams and electric servo motors commonly provide this function in industry. Pneumatic systems generally consist of an array of rams and logic control valves arranged to perform repetitive, binary motion dedicated to a process. Electric servo systems are based on programmable digital control that enables motion instructions to be constantly reviewed and modified. Because pneumatic motion is based on linear actuation, resolving rotary solutions is restricted. Motors, on the other hand can generate rotary motion and (according to transmission arrangements) linear motion. Pneumatic systems continue to dominate the low cost automation market because of ease of application, their robust nature and intrinsic safety, despite their limited control capabilities. Similarly, electric servo-systems offer improved productivity and superior control features but are limited by their high cost and sensitivity to industrial environments. Responding to these challenges, Hydro-Drives have developed a novel hydraulic motor that is powered by common water at around 10-bar supply pressure. Operating at similar pressures enables the Hydro-Drives motor to share the positive features of ease of application, adaptability and safety with pneumatic systems. Low operating pressures allow the extensive use of plastics in motor design and system installation enabling Hydro-Drive systems to be price competitive in the target market. Hydro-Drives motors have been subject to field trials and have successfully completed over 8,000 hours continuous operation. The incompressibility and low viscosity of water make it highly responsive to control signals. These characteristics will enable high-level control to be applied that combines the adaptability and precision of digital servo control with the application flexibility and robust nature of pneumatics. An earlier feasibility study which aimed to examine the application of programmable control of motors, powered by compressed air has been undertaken. This concluded that given the inherently unstable nature of compressed air it was not commercially viable; however, an alternative fluid with low viscosity was possible. The project will aim to develop a system that will enable integrated control of water driven actuators. It looks to combine the robust nature and adaptability of pneumatics with the control flexibility and accuracy of servomotors but at a cost that is acceptable in the global market for low cost automation. In comparison with pneumatic systems, reduced operating costs can be expected from a Hydro-Drive system. A water hydraulics system is expected to be around 7 times more energy efficient than an equivalent pneumatic system with the ensuing reduction of CO2 levels at the electricity generating stage.