System Design and Strategy
Industrial controls design is the key to manufacturing flexibility as it encompasses logic, motion, operator interface and data handling functions. The task can be daunting for manufacturers considering the current range of architectures, hardware and software solutions available, but good design can result in systems that have shorter lead times and greater flexibility without compromising quality or safety.
The discipline of controls design encompasses a wide range of programming skills, from simple ladder logic to factory wide information systems and data archiving, and from clear intuitive MMIs to advanced motion control.
The strategy that is used through the design process of a control system can deeply affect the outcome of the system. The design of a new control system encompasses more than just the obvious steps of deciding on the desired equipment functions, cost, and types of technology to be used. Considering the safety requirements up front and alongside the desired functionality of the system results in savings of cost and time, with an increase in system functionality.
Working through details of equipment functionality naturally leads to talk of system architecture components and standards, but end users are cautioned not to choose the exact components too early in the design process. Using the proper strategy for design of control systems is critical to the outcome. Take a higher-level approach and consider required safety and functionality initially, choosing specific components in later stages of the process. It is important to have deep-level discussions about functionality, driving down to what the end user is actually trying to achieve with the system. The outcome of these discussions is the functional specification document, which details the blueprint for the operation and functionality of an automation project.
Use these strategic questions during the initial stage of the design:
- What level of safety is required?
- What safety specifications or requirements are in play?
- Is the system being designed from scratch?
- Have any components already been selected?
- Will this system function alongside other equipment?
- Is this part of an equipment retrofit plan?
- How does the system need to function?
- What is the most efficient use of the budget in terms of functionality?
- What are the given specifications?
- What are the requirements for the control of information?
- What level of automation does the customer currently have? (are they a new user or experienced)
- Who will be the primary users of the automation and what level of training do they have and what are the expectations for them (simply an operator, basic troubleshooting, etc..)
- What is the end user trying to produce?
How often will it be produced (cycle time)?
- How much control is required in the process?
- How much variability is there in the process?
Too often in initial discussions, the manufacturer reveals that they have already selected the components for the proposed system. When the project kicks off and system functionality is addressed, the controls team has the tough job of informing the customer that the completed system will not be able to meet the goals if the previously-specified components are used. It’s important to have strategic conversations such as these in the beginning of the process, resulting in a better system that functions as the customer wants it to, and usually has a lower cost.
Although end users can fall into the trap of considering safety after the primary functions of the controls have been decided, there are strong advantages to bringing equipment safety considerations into initial discussions. In the preliminary phases of design, decisions should be made as to what level of safety is required, and which safety specifications or requirements are in play. Failing to take safety considerations into account until the end of the design process can result in a higher priced, fragmented, or less functional system.
Once the safety parameters have been mapped out, designers work with end users to take an in-depth look at the desired functionality of the system. Conversations revolve around what the automation is expected to do and what tasks any human operator will be responsible for, and safety is always a big part of these discussions.
With the recent major advances in automation technology, factory modernization has become a vehicle for increasing productivity, lowering costs, and filling gaps created by labor shortages. Factory modernization encompasses many types of systems, including controls upgrades and legacy systems upgrades.
There are many aspects to modernization opportunities that should be considered. Quantifying the benefit of modernization opportunities is essential including its effect on quality and production. Existing equipment and the ability for new components to properly work within the constraints of current technology and infrastructure is a major influence on these types of decisions. Understanding limitations of currently employed technology is critical to deciding the scope of potential upgrade plans. There is also a greater probability of affecting current production processes during a replacement installation that must be fully understood in order to properly mitigate its impact to suppliers, facilities, and other stakeholders.
Collection and Sharing of Data Integrating with Business Systems
Another aspect of the design of industrial control systems is understanding what information needs to be collected and shared, and with which departments in the end user’s organization in order to integrate with existing business systems. Understanding the information sharing requirements will assist in determining hardware and software needs for the control system.
Use these strategic questions during discussions about collecting and sharing system data:
- What information needs to be collected from the automation process?
- Who needs access to the information?
- Are there cybersecurity concerns that must be addressed with the control system?
Efficient Field Installation
Creating the best installation impact for customers requires creating a robust strategy and doing careful planning to mitigate risk. Busy customers often have strict requirements that need to be taken into account when planning for field installations. Often there is a customized strategy and highly detailed plan to work around production and downtime requirements to reduce economic impact on the customer. Factory acceptance testing and runoff criteria need to be defined early in the design process to prevent possible rework. Plans for pull-ahead design and review may include offline programming and virtual commissioning activities to reduce risk and lessen installation time on the floor.
Use these questions to guide discussions for planning installation strategy:
- What are the end user’s downtime windows for installation?
- Can the installation be comfortably completed in one downtime window, or will a phased approach be necessary?
- If installation will occur in phases, are there interim accommodations that must be made, such as temporarily connecting new equipment to existing equipment?
- What are the criteria for a successful factory acceptance test (FAT) and runoff?
- What are the runoff standards that will be used?
- Can any tasks be pulled forward and be vetted at a production level before installation?
- Will the system require remote support?
Material transport is a wide category of automation solutions, encompassing the movement of products and materials of all sizes and shapes. Transport can be handled through a hardware-based system such as a conveyor and can range from the relatively straightforward movement of like items in case sortation, to much more difficult applications with potentially problematic materials like polystyrene.
Transport can also be through a free-ranging system like a flexible (“smart”) robot or vehicle, such as with automated storage and retrieval systems (ASRS) for the warehousing industry and material transport systems for the automated guided robot (AMR) industry. There are many types of robots and vehicles used in material transport, and the terminology can become confusing. Early systems in the material transport industry included automatic guided vehicles (AGVs), and in recent years AGVs have been replaced by more sophisticated AMRs.
A hybrid solution also exists, where “smart” carriers such as an automated guided cart (AGC) tow materials throughout the manufacturing space, and can leave and come back as needed.
Today’s material transport systems mainly use global positioning satellites (GPS) to track location. A newer technology known as SLAM, simultaneous localization and mapping, is also emerging as a cost-effective solution. SLAM uses a combination of vision and LiDAR to map the environment and identify the robot or cart’s location.
Material transport systems commonly perform the tasks of adding and removing materials from storage systems; this encompasses case handling, palletizing, depalletizing, mixed load depalletizing, decanting, and repacking for order fulfillment.
These systems often involve peripherals such as weighing, x-ray or vision inspection, and traceable RFID asset tracking or other technologies unique to the customer’s particular industry. Material transport systems are found in nearly every sector of manufacturing, including:
- Consumer products
- Food (human or pet)
- E-Commerce/Order Fulfillment
- 3rd Party Warehousing and Logistics (3PL)
The material transport design is based on how flexible (“smart”) the system needs to be, and whether to plan for future modifications or rerouting. If the system has hardware-based movement such as conveyors or rails, the movement can be difficult and costly to alter. If it is free-ranging as with a GPS system, it can easily be modified to program additional routes without infrastructure changes. As part of the design process, controls engineers will help find the most appropriate transfer system, from traditional conveyance to flexible control AMR systems.
There are varying levels of advanced control for material handling systems. On large physical-based transport systems, discrete event modeling is often required to analyze traffic control logic and downtime impact to throughput especially when merging different sections of conveyors. With free-ranging systems such as the AMR, throughput modeling for fleet size becomes important to prevent over- or underestimating the system requirements in such a flexible environment.
When designing a material transport system, there are many questions to be answered, such as:
- How much flexibility does the system need to have?
- Is a “smart” system required?
- Is GPS involved in any transport function?
- Are hard-routed conveyors required?
- Is the system hardware-based?
- Are there custom fabricated components such as carriers to move this product?
- Will the system work with or replace human operators?
- Is material sorting or order fulfillment involved?
- Is data reading or tracking required?
Controls design for factory automation involves integrating a wide range of hardware peripherals to work together in one system, and components can include advanced robotics, motion control, motors, drives, mechatronics, control valves, sensors, machine vision, transmitters, positioners, and more. Controls design also encompasses choosing and integrating various software platforms to coordinate the peripherals and capture the needed system and production data. Compiling products from myriad hardware and software manufacturers into an efficiently-functioning system is best accomplished by a team of experienced controls engineers with complementary competencies.
Early on in the design process for turnkey factory automation systems, controls engineers work closely with customers to determine hardware and software logic design requirements for the new system. Often machine data tracking is incorporated, along with embedded controls.
For the design of PLCs, controls engineers will determine the required processor size, whether a safety PLC is required, and many other design criteria described above.
Choosing hardware and peripherals for factory automation requires knowledge, experience, and careful consideration to ensure compatibility and full functionality. On the power supply side, panels should incorporate energy efficiency and power protection into the power distribution, panels, and related components. The latest HMI designs on the market are moving toward hardware with data collection capabilities and improved visualization of the process.
Before starting a controls design, there are many hardware questions to be answered, such as:
- Are there concerns about retrofits and obsolescence?
- Do the hardware and peripheral brands need to match existing equipment?
- Does the end user have existing knowledge or more familiarity with certain brands?
- Is the desired hardware available for an on-time build schedule?
- Is potential OEM support a consideration?
- Are the hardware components within budget?
- What is the desired level of quality of components?
- What are the maintenance requirements for the components?
- Are panel designs and fabrication required? If so, where will they be completed?
- Are there advanced robotics in the system? Does the end user have a preferred manufacturer?
These are typical hardware and peripherals that may be present in the factory automation control system:
- Advanced robotics
- Control valves
- Machine vision
- Power supplies
- Power protection
- CNC machines
There are several choices for factory automation software platforms, and they all have a best use. A full-service independent controls engineering team will have brand-neutral expertise with many different manufacturers, providing the best possible solution to the end user.
Ideal software solutions incorporate logic designed to enable plantwide networking and communication with user-friendly HMIs and GUIs, with the optional functionality of testing, error proofing, diagnostics, data tracking and archiving. Additionally, the control system will utilize motion control, pneumatic and hydraulic software to assist in achieving production goals.
Before starting a control system design, there are many software questions to be answered, such as:
- Is machine data tracking required?
- Are embedded controls required?
- Is motion control required?
- Are there conveyors in the system?
Networking & Information
Modern automation systems allow for the merging of operations technology (OT) with Information technology (IT) with the secure transfer of information via Ethernet or wireless, and recording of manufacturing data (via historians) using a variety of technology and device infrastructure. Often network and information subtasks are part of PLC and HMI programming in later stages of factory automation systems.
Plantwide networking and communication protocols must meet stringent requirements for cybersecurity, especially those tying into plant information systems. The specific network protocol used on a given project may be determined by the end user’s IT department or chosen to have functionality to communicate with existing equipment. Just as with safety considerations of hardware based automation components, the security of a network is a part of upfront design consideration that is continuously evaluated during the system design.
To achieve corporate goals, a variety of devices such as I/O modules can be added to the system for data acquisition and asset management. The latest trends for enterprise-level functions are the addition of Industrial Internet of Things (IIoT)/Industry 4.0 apps to collect large amounts of data, using artificial intelligence (AI) to process it into a useful format.
The sky and the budget are the limits on what can be implemented with the technologies available in today’s control systems, especially when using Overall Equipment Effectiveness (OEE) concepts to measure productivity. Advanced systems can monitor production and communicate with upstream or downstream equipment to control process flow where interruptions or slowdowns are taking place so those issues can be addressed.
Control systems can add new layers of safety to factory automation with the addition of sensors, alarms, and other components, automatically stopping or slowing machinery or closing interlocks if a human operator is in the area.
Well-programmed HMIs can assist in achieving safety goals with notification and alarm management, and bring productivity gains with more diagnostics and faster error recovery.
Here are some questions to consider when making decisions about networking and information:
- What networking protocols are required for this project?
- What level of cybersecurity protection is required, i.e. does this equipment run critical public infrastructure?
- What is the goal the end user is trying to achieve with the collected manufacturing information?
- Do the end user’s goals indicate potential use of IIoT/Industry 4.0 technology?
- Is part tracking part of the factory automation system?
For more information on our controls design capabilities or to discuss a project, please contact us.