Machine Design Concepts Get Real with Automation and Controls Simulation
Virtual design tools and automation software intersect to save time and costs in machine commissioning
Fast-moving product development efforts demand continual improvements in controls engineering and manufacturing processes. Corporate initiatives frequently place responsibility on controls engineers to accelerate time to market, complicating this dynamic. Of course, an expanding array of design tools is available to help speed engineering efforts. These include a few well-known technology milestones, such as the introduction of Computer Aided Drafting (CAD) on the mechanical side and Programmable Logic Controllers (PLCs) on the control side. While these greatly increased the speed and performance of machine designs, they are still individual systems that must ultimately come together with many other technologies to realize a new manufactured product or a functioning machine.
Systems and tools used in engineering and design also need methods to test new projects in a digital space. Fortunately, there are numerous options available to accomplish this today. The next great improvement to engineering and design is automation and controls simulation. This provides the ability to start the testing and commissioning of machines very early in the process, such as before or during the delivery or fabrication of the initial mechanical components.
When taking the first step in simulation, look to modern control system development software, such as TwinCAT 3 automation software. This engineering environment permits the simulation of scalable control code on the engineering PC without the need for a real hardware controller in the design phase. TwinCAT code runs in real-time, meaning if the PLC code has a 1-ms update cycle, then it should be simulated at 1 ms. Running a simulated PLC with a different update rate might prevent the programmer from identifying potential timing or ‘race’ conditions of multiple tasks. Simulation capabilities extend beyond the PLC to incorporate motion system design as well. Programmers of advanced motion functionality, such as kinematics, precise gearing and advanced cam tables can write, test and debug code before purchasing any motors or drives.
CAD considerations for effective simulation
Once the PLC and motion control simulations are in place within the engineering and programming environment, the next integration test is to run them with plant/facility models and CAD tools that allow 3D simulation of machines and systems. This is done by creating a digital link that connects the controls engineering environment, simulation software and a 3D CAD or emulation system. The aim of this connection is a software-in-the-loop (SIL) simulation of the intended sequence on a machine or system to support virtual commissioning.
The 3D simulation of machine and system components is a key element when implementing virtual commissioning. In the simulation, the movements and interactions of all individually installed components are represented in combination in order to predict collisions and critical system states in advance. In addition, simulations can be used before completion of the machine to train operators and maintenance personnel for regular operation and to learn troubleshooting instructions based on simulated critical machine states. This can also extend to sales representative use to demonstrate the real-world use of machines or machine components using detailed 3D simulations.
Modern simulation tools, such as those incorporated into TwinCAT, feature convenient drag-and-drop functions for use in configuring and parameterizing links. Complex relationships can be mapped between software tools, meaning that SIL simulation of machines, systems and installed components is easy and convenient, even in the event of future system expansions.
Factor in fieldbuses and networking
The goal of any simulation used in virtual commissioning is to represent the machine or process with a completely accurate model. To this end, many virtual commissioning systems do not take into account the fieldbus or networking technology in the application. Testing and commissioning of the real system would never be complete without checking for a fully functional fieldbus, so the simulation or virtual commissioning should be included as well.
With EtherCAT industrial Ethernet technology, complete virtual machine commissioning becomes possible by simply connecting the machine controller to a computer running the simulation via an Ethernet cable, without requiring reconfiguration of the machine controller. With EtherCAT Simulation functions available in PC-based control software and a standard network adapter, the simulation computer can simulate all connected EtherCAT slaves. For configuration purposes, the architecture of the EtherCAT slaves from the original machine configuration is inverted. All EtherCAT features necessary for machine simulation are modelled – including distributed clocks for highly precise synchronization of devices. Since CAN Application Protocol over EtherCAT (CoE) and Servo Drive Profile over EtherCAT (SoE) are implemented, acyclic commands can also be processed in the simulation environment.
During machine design, it is also possible to simulate the full fieldbus network in real-time. This approach provides the actual network update rates to accurately size the controller CPU needed for the application. This ensures engineers will not experience the unwelcome surprise of needing to switch to a bigger processor when physically commissioning the machine. In addition, this maintains the appropriate machine control performance level and keeps overall equipment costs under control.
Real-time HIL and SIL simulation with MATLAB®/Simulink®
Engineers can create advanced algorithms using the tools available within the powerful MATLAB®/Simulink® environments and run them in real-time with PC-based control software. As the machine control projects can be simulated in PC-based control platforms, they can be used for SIL real-time simulation. Using a software connector to Simulink, it is possible to read and write real-world sensor and actuator data. This allows the Simulink model to operate on real information and enables HIL simulation of the software model.
Virtual commissioning, real engineering efficiency
As a part of a standardized engineering process, control system simulation and virtual commissioning can yield significant savings in all stages of machine and plant design, additionally increasing overall time to market. By using software to identify and resolve every flaw in mechanics, controls and programming, engineers are working smarter, not harder in every sense of the phrase.
Are you interested in leveraging simulation technologies to optimize your machine performance? Contact your local Beckhoff sales engineer today.
Daymon Thompson is the Automation Product Manager for Beckhoff Automation LLC.
A version of this article previously appeared in Control Engineering.