Bits and Bytes Boost Hydraulic System Capabilities
Software has become a mainstay for adding features and functions, with more to come as programming tools advance.
Off-highway vehicles are typically admired for their power, but the driving force behind a growing number of performance improvements are the invisible bits and bytes of control software. Many of the improvements touted by equipment makers are enabled by software that helps pumps, valves and other electrohydraulic parts operate more effectively. This shift follows a growing trend in which digital controls and software are taking a bigger role. This transition is expected to continue as rapid advances in semiconductors and software make it easier to add features and functions.
Caterpillar’s Next Generation Excavators highlight this transition to software. The machines use a new, advanced electrohydraulic system that combines electronic intelligence with efficient hydraulic components. Electronic joysticks in the cab control the electrohydraulic main control valve, directing hydraulic power to the different cylinders and motors on the excavator. The pumps and engine work in unison to provide efficient performance and fuel efficiency while meeting emissions regulations. Software is a critical element.
“The intelligence of this hydraulic system is applied through software,” said Brian Stellbrink, Caterpillar senior market professional, hydraulic excavators. “The software can be updated over-the-air via cellular signal. This ensures the most current software and latest features for the end user.”
Software’s importance grows
That focus on software should continue to grow. For years, electrohydraulic system development was strongly driven by mechanical, hydraulics and electrical experts. Many rapidly evolving technologies are helping empower software’s rising role in off-highway vehicles.
“The combination of several factors – using object-oriented design (OOD) in the design and implementation process, moving towards multithreaded applications via multi-core CPUs and embedded operating systems and a transition to agile project management models and tool chains – makes this sector a very palatable field also for many software engineers and computer scientists,” said Janosch Fauster, director, Application Development Center at TTControl.
Commercial-vehicle developers are rapidly establishing software partnerships so they can leverage the latest design tool advances. At the same time, the software revolution ripples out to end users, giving them more capabilities to operate more efficiently given the diverse needs of various industries. “Our tools offer increased integration with third-party tools and products, including simulation programs,” said Kevin Faulds, director of software product, marketing and sales at Danfoss Power Solutions. “This allows customers to add an entire platform to build their own IoT services and solutions.”
The focus on software is driving other changes in many companies’ design processes. Engineers and programmers can use a range of design tools to test out different strategies and techniques. Modular development strategies let design teams utilize proven software components for different projects. This approach also makes it easier to upgrade systems as knowledge bases and experience grow. Advanced digital tools are handling more of code creation and product development.
“We take a building-blocks approach, modeling a host of device performance characteristics – whether for a pump, valve or other devices – and building a virtual ‘digital mirror’ of a device composed of individual software building blocks,” said Terry Hershberger, director, sales product manager, Mobile Hydraulics at Bosch Rexroth. “In addition, we are expanding the use of simulation tools, such as MATLAB Simulink [by MathWorks], which generates code from simulations that can be put into a controller.”
Design for security
More powerful microcontrollers and soaring memory sizes are among the factors enabling the expanded power of software. These hardware enhancements are being matched by advances in software languages, standards and tools.
“New ECU generations have now enough computational resources and memory to handle the overhead introduced by OOD languages,” TTControl’s Fauster said. “MISRA C++ and Autosar guidelines combined with static analyzers provide a robust framework also for safety-related code. OOD combined with C++ allows for a more natural translation of software architectures and designs into code and enhance code abstraction, maintainability and reuse considerably.”
Developers are rapidly creating techniques for updating firmware over the air (FOTA). That makes it easy to get revisions and improvements out. That lets operators gain the benefits of improvements in security and other technologies without bringing vehicles into dealers or paying technicians to travel to sites to load in new software. Some companies are also using OTA techniques to let owners buy software upgrades. Design teams continue to improve communication techniques so critical upgrades can be downloaded quickly without issues.
“We can generate code that can be uploaded through our BODAS Connect platform to perform application software updates over the air or to fine tune a machine with parameter updates (POTA),” Hershberger said. “Additionally, being able to choose and change data to view remotely via BODAS Connect hardware expedites the development of the system solution. All these factors come together to improve the efficiency of software updates.”
Efficiency for OTA includes security, a factor that’s soared in importance as software and connectivity moved into the mainstream. Design teams are utilizing the latest standards and best practices to ensure that security and piracy aren’t compromised. “We use the latest wireless security standards and continuously update as these standards evolve,” Danfoss’ Faulds said. “This includes securing and controlling the endpoints for access and OTA updates, as well as building in safety mechanisms to ensure updates are managed from start to finish. OTA updates require a safe and secure channel to thwart intentional or unintentional hacking.”
The growing focus on software is changing the way companies operate. A hierarchy of programmers often team up to complete a project. “The increase of complexity of the software in electrohydraulic systems combined with the respective increase in the size of the software teams allow for more differentiated and specialized roles, also in many mid-sized companies: from dedicated software architects to controls engineers, framework software engineers and low-level software developers,” TTControl’s Fauster said. “This higher specialization can result in better design, better-performing solutions and higher implementation efficiency.”
Electrohydraulic advances optimize cabin experience
Microcontrollers and metal are being combined to improve the efficiency of off-highway vehicles. While software has become a primary driver for advanced electrohydraulics, mechanical components and computing hardware remain at the core of system designs.
Digital controls are making it possible to automate many tasks, allowing companies to hire less-skilled operators while also improving the effectiveness of veteran workers. Electronics are being paired with improved electrohydraulic components to enhance operational efficiency, improve fuel and emissions parameters and even streamline vehicle designs. Flex-Steer from Danfoss addresses streamlined design while also helping vehicle designers meet other goals.
“The Flex-Steer solution consists of an electrohydraulic steering valve, a steering input device such as a joystick or mini wheel, sensors and a complete software solution – reducing development time and streamlining implementation for OEMs,” explained Philipp Hermann, market segment director at Danfoss Power Solutions. “Flex-Steer can help optimize the cabin experience by getting rid of the need for a steering column, improving visibility or simplifying the overall rotating cabin design in roadbuilding or forestry applications.”
The actuation systems on various machines also are being improved to let operators work more efficiently. For example, advanced electrohydraulic systems on Caterpillar’s Next Generation Excavators provide key benefits for contractors. “The smart hydraulics combined with advanced sensors and software logic enable significant efficiency gains through the use of standard technologies such as Cat Grade, Cat Grade with Assist, Payload, and Lift Assist,” said Stellbrink. “For example, both 2D and 3D integrated machine grade control systems help contractors dig to grade more quickly and stay on grade with a high degree of accuracy, while eliminating or greatly minimizing traditional ground labor around the machine.”
Many different components make these advances possible. Pumps, valves, actuators and embedded sensors are all improving so complete systems can enhance operations. Powerful microcontrollers also help engineers increase efficiency. Danfoss recently started shipping digital displacement pumps (DDP) that sharply improve efficiency for excavators and other electrohydraulic system architectures.
“The DDP is a radial piston machine that enables and disables cylinders in real-time using ultra-fast mechatronic valves that are controlled by a dedicated computer,” said Christopher Williamson, senior systems engineer at Danfoss. “The primary advantages of DDP when compared to traditional swash-plate pumps are increased part-load efficiency, faster response (less than 30 milliseconds) and intelligent digital control.”