Digitalization of Product Engineering
ESI proposes “sustainable” product development via virtual prototyping to ensure operational safety and comfort for off-highway machines.
Today’s off-highway machines must be safe, clean and productive – in a word: “sustainable,” an adjective that also should apply to product development. How can engineers know they are on the right track without producing a bunch of physical prototypes? How can they avoid costly design changes late in the process? And how can the useful life of machines be extended? The digitalization of product engineering is here to answer these challenges by enabling the evaluation of product performance at every stage of product development, as well as during manufacturing and operations.
The goal at ESI is to help customers move towards “zero tests,” “zero prototypes” and “zero downtime” – referring to physical tests/prototypes, of course. Traditional methods for testing and evaluating products virtually using sporadic simulations, usually only of the nominal machine, are useful but only reflect specific conditions. They occasionally fall short of what can be learned when those products are rolled out to actual construction sites, farms, forests or mines. To avoid such shortcomings, leading enterprises in the heavy-machinery sector, including Liebherr and Siemens Minerals, employ virtual prototyping solutions to get a realistic account of how multiple subsystems behave and interact in real life under varying conditions.
Virtually operating products from a “virtual proving ground” helps manufacturers gain insights on their products not only as designed but also as used. They connect the evaluation of operational safety and comfort to how the machine behaves in planned use, misuse or abuse, including how this affects the people operating/driving the machines.
Virtual prototyping lets OEMs evaluate machine dynamics and stability in rough terrain, assess machine behavior in emergency situations, ensure interior and exterior noise regulations are met, and even verify operator visibility, reachability and accessibility at all times. As a result, design engineers consider trade-offs and balance out competing requirements to reach an optimum. For instance, they can create safe and stable designs with low risk of tipping and increase comfort by minimizing the noise and vibrations the operator is exposed to during machine use.
Improving acoustic performance
Powertrain radiation, muffler noise, rattle and the acoustic behavior of seals, grommets and instrumentation panels can affect both the overall acoustic performance of construction equipment and the end user’s perception. Virtual prototyping helps understand noise contributors faster than physical tests, enabling engineers to assess alternative designs, to reduce design iterations to meet regulations or to propose efficient countermeasures – even if the product is already in the field.
When looking at exterior noise for construction equipment, virtual prototyping enables the prediction of sound power levels according to regulations including ISO 6395. Using different modeling techniques such as boundary element method (BEM), ray tracing or statistical energy analysis (SEA), different noise control treatments can be virtually tested to reach the desired acoustic performance, while saving time and cutting additional costs.
In addition, interior noise is closely connected to operator safety and comfort, and it’s an important brand differentiator for heavy machinery OEMs. Interior noise can be addressed by statistical simulation methods like SEA to efficiently achieve high-frequency comfort goals, or by deterministic methods such as finite elements to take into account the precise shape of the interior and the detailed composition of the sound package. With the advent of hands-free devices and the need for the operator to communicate with the construction cab, speech clarity analyses become crucial to ensure that infotainment systems are designed correctly.
Finally, tool noise can be an important contributor to both interior and exterior noise performance. Being able to predict the noise that will be emitted during heavy machinery operations is instrumental to reach acoustic targets. Oftentimes, engineers will use component-level simulation using BEM that can then be leveraged in system simulation.
Virtually testing vehicle dynamics
Another important aspect of operator comfort is the vibrations that the driver feels in the cabin while operating equipment. Using a physics-based model of the machine to consider vehicle dynamics, it is possible to calculate the propagation of forces, the torques and the pressures and other physical quantities that are occurring in the machine from their source through the vehicle frame to the seat rail. In so doing, performance indicators can be generated to predict how comfortable the operator would be during typical operation cycles.
From early design stages, placing a virtual prototype of a machine into a virtual proving ground enables engineers to test out different design concepts and evaluate their effect on operator comfort. Going further through the development and test cycle, our customers use these same models for additional analyses such as stability or tipping safety as well as energy efficiency.
Wheel loaders are subject to various vibration and shock excitations during their work cycles. The integration of suspension systems ensures high levels of operator comfort and safety. Liebherr has been using ESI’s system modeling software SimulationX for several years to improve the dynamics of their machines, avoiding disturbances such as the “jumping man” effect.
“Using SimulationX, we can analyze and optimize the vibrational behavior of our wheel loaders with virtual prototypes, all in a very efficient development environment, which helps reduce our test efforts,” said Dr. Manuel Boes from Liebherr-Werk Bischofshofen GmbH, Austria.
As heavy equipment becomes fitted with more and more sensors, the possibilities for developing advanced safety functionalities also increase. For example, a virtual test platform for an emergency braking function can use a system model to represent the machine dynamics of the mechanical and hydraulic systems. Mounted on the machine are virtual sensors, in particular a radar sensor that will simulate the distance and angle between the machine and a vehicle. In addition to the virtual machine and sensors, there is an emergency braking algorithm, reading in the sensor data and sending an emergency brake signal to the machine model.
All these examples show how virtual prototyping brings together the various engineering tasks and groups to collaborate on one virtual test platform for developing advanced functionalities for ultimate comfort and safety.
Validating ergonomics via VR
To produce products without checking that human operators fit well in the new product would be reckless; ergonomics and human factors for operators, technicians and assembly workers need to be evaluated. Designs should be checked for accessibility, reachability, visibility and whether they are well suited for the intended purpose. Simulating a brief 30-second interaction using common Digital Mock-Up (DMU) or ergonomics solutions can take hours for experts and possibly days for others. Conducting reviews using real people with physical products postpones critical lessons learned, delaying improvements or making changes too expensive to implement.
Digital on-screen evaluation of ergonomics conventionally requires hours of effort to evaluate “ease/difficulty” to reach machine controls, access service areas or install subassemblies. Each movement or “pose” requires positioning a digital human model, or manikin, limb-by-limb. Each new population increases the required investment in effort and time. Real-world testing with physically constructed mock-ups requires investment in materials, time, space and human resources to achieve improved testing fidelity. With immersive virtual reality (VR), it is possible to bring the benefits of these two different approaches while minimizing the downsides of either approach.
Visibility and reachability can be validated in VR without waiting for construction of physical mock-ups or requiring access to prototype parts and production environments. CAD models can be placed within a virtual reality scene where users can enter VR and experience for themselves what is easy/difficult to reach or see. Once the scene exists, it takes little time to put on VR glasses to validate many procedures and processes with physically realistic handling of collisions between parts and obstructed installation/removal paths.
VR validation of operator interactions in and around proposed products accelerates product-development timelines by effectively enabling engineers and other stakeholders to perform human-factors studies on 100% digital inputs. People can sit in a virtual cockpit or driver’s seat of a future product, and ergonomists could then cycle a wide range of individuals through cockpit validations for driver reach, view and comfort. All of this is achievable without a physical testing environment.
Recording and measuring interactions between all the different possibilities of operators and engineering design variants is another seemingly insurmountable task. To address this challenge, recording the movements of people and virtual objects and playing back those interactions is possible, but with digital human models representing a wider range of anthropometries than one may have available to them. With this capability, it is possible to combine the very fast first-person experience for reach, view and comfort with third-person analytics across a diverse population and complete range of design variants.
Enabling engineers and stakeholder teams to experience operator processes within the proposed products virtually can reduce latent risk to operator safety and user comfort. Whether considering the driver-operator, assembly worker or service technician, experience-based human-centric validation of the product within an intended process and performed early in the product-development timeline greatly improves the overall product and assures sustainable operations.
Alex Magdanz, domain leader systems engineering, and Eric Kam, industry marketing manager, ESI Group, wrote this article for SAE Media. ESI is hosting a free digital event in November dedicated to virtual prototyping and customer applications in heavy machinery and other industries.