By Leslie Langnau, Managing Editor
Design World

In mechatronic projects, the focus is often on the mechanical and electrical aspects of a system as engineers concentrate on throughput, speeds, accuracy, and so on.  How these system goals affect the desired control selection may not be addressed until too late to make changes. Mechanical engineers do their part, then electrical engineers do their part, then, the controls engineers must make it all work.

In addition to finding ways to improve the communication and interaction of the various engineering disciplines, there are other design aspects that affect controls to keep in mind. Robert Muehlfellner, Director Automation Technology, B&R Industrial Automation Corp., offers a few.

— Don’t overlook the fact that mechanical components have weight and inertia, which influence speed and throughput.  These properties can heavily influence the control choice.

— I/O, motion, and communication can be managed by one control or multiple controls. The choice will affect connectivity and communication decisions.  Increasingly controls vendors offer a “one-stop-shopping” approach to their products, so if you can choose one control for all these needs, you can save you or your customer time and headaches.

— Consider controls that are modular and with features that can be scaled up or down. Consider controls available in family style configurations too.

— Work with development software that combines or works with mechanical, electrical, and control design tools. A development package that also interfaces with E-cad packages, for example, helps move control system hardware configuration data into electrical packages for faster creation of electrical drawings.

— Test the desired control with a machine model. Mechanical engineers can develop machine models in packages like Simulink, which lets controls engineers run models of their control design in conjunction with the application. Such programs allow virtual development and verification of expected machine throughput prior to testing the controls application on a real prototype machine.

— Consider power needs. It may be desirable to configure independent supply voltages for some drive systems, so as to, for example, eliminate the need for isolation transformers.

— Consider the need for diagnostic features in the control system. Quick and accurate diagnosis of machine problems improves machine uptime. Choose controls that automatically collect data or run diagnostic routines. A seamless integration of subsystems like drive controls combined with smart features can also allow for predictive rather then preventive maintenance.

— Choose controls and components that conserve energy without compromising function. For example, the efficiency of hydraulic systems can be improved with variable speed control of the pump to maintain constant system pressure instead of the conventional way of running the pump at constant speed and bleeding excess pressure through the pressure relief valve.

— To save time and costs for engineering changes throughout the lifecycle of the machine, choose equipment that will be available for many years to come.

— And keep in mind that while maintaining your current technology, plan to leverage new technology while reusing the intellectual investment. Focus on making your next generation application better instead of dealing with migration issues.