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Volvo's vehicle co-simulation cuts virtual prototyping time in half [Mining Engineering]
[October 20, 2011]

Volvo's vehicle co-simulation cuts virtual prototyping time in half [Mining Engineering]


(Mining Engineering Via Acquire Media NewsEdge) To maintain its brand position in the competitive market of mining equipment, the Volvo Construction Equipment (Volvo CE) engineers were challenged to develop topperforming wheel loaders and articulated haulers even faster than before. To start, this meant reducing prototype test cycles by two-thirds.



The final goal? Chopping in half the virtual prototyping time in early design phases.

Creating a unified co-simulation solution In this ground-breaking project, the Volvo Construction Equipment design team in Eskilstuna, Sweden, replaced its piecemeal department-by-department process with a single solution based on LMS Imagine.Lab AMESim. With one unified model, they could simulate the behavior of four major vehicle subsystems in wheel loaders and articulated haulers: hydraulics, powertrain, thermal management and the actual driver. Subsystem models exchanged data seamlessly.


The team could refer to the master LMS Imagine.Lab AMESim co-simulation model, including MATLAB for electronic control subsystems, to review subsystem interaction and full vehicle performance under real-world operating conditions. Rather than using many separate tools, engineers collaborated using LMS Imagine.Lab AMESim for all physics-based models, which serves as a common language to compare various design alternatives, predict fuel consumption and equipment operability and optimize design concepts early on.

In a sense, the development process was turned upside down. The easy-to-use, click-and-go graphical user interface let the team work together quickly to refine the design from the start. All the engineers had to do was drag, drop and interconnect simple icons - predefined and validated one-dimensional units selected from libraries - to create a unified physicsbased model. The resulting block diagram looks simple enough, but underlying it is a sophisticated representation of exactly how all the different vehicle parts will operate together in the real world.

Why LMS lmagine.Lab AMESim? Not surprisingly, the primary reason Volvo CE opted for the LMS Imagine.Lab solution is that it is one of the few products on the market today that can accurately predict vehicle fuel consumption and operability - both makeor-break brand criteria for Volvo CE. On the nuts-and-bolts side, the project, code-named SamSim, aimed to streamline and accelerate the overall development process by building a collaborative simulation platform using a reduced number of consolidated software tools.

Previously, Volvo CE had five separate software packages that were mostly incompatible. Upon hearing that there was a single, unique solution on the market made the choice pretty easy.

"After a six-month evaluation period and six months of further model synthesis and validation, the impressive results led us to massively invest and widely deploy the LMS Imagine. Lab AMESim solution. It is a critical component of our global simulation platform," explained Jonas Larsson, simulation coordinator for hauler and loader development at Volvo CE.

Not only could LMS Imagine.Lab AMESim exchange data efficiently among the various modules, it was also compatible with other inhouse SamSim software - specifically, thirdparty packages for multi-body, engine design and electronic control simulation as well as special in-house Volvo CE codes. In a sense, LMS Imagine.Lab AMESim became the one common language that all the engineers on the design team could speak.

Value of LMS Engineering Services As part of the primary evaluation, LMS Engineering Services performed a process audit that thoroughly examined Volvo CE's simulation structure. The goal was to optimally implement the LMS software and yield a maximum benefit quickly within a defined budget and time frame. This audit showed that by replacing legacy code with LMS Imagine.Lab AMESim, Volvo CE could cut the number of simulation tools they were using to two: an impressive return on investment, considering that all maintenance and renewal contracts for the old software could be eliminated, as well as training and time spent working out incompatibility issues.

"This audit gave us valuable information regarding the 10 models we wanted to create to start. The idea was to jumpstart the implementation of LMS Imagine.Lab AMESim with a set of basic models created by LMS - models that our engineers could then use as templates in representing different new vehicle designs," said Larsson.

One model for all major subsystems (and hybrids, too) To model the loaders and haulers to accurately predict fuel consumption and operability, LMS engineers had to take many complicating factors, transients and boundary conditions into consideration - not only for each subsystem, but how each subsystem interacted within the entire vehicle as well. There was also the electrical vs. engine power of hybrid models to consider.

With the powertrain, for example, LMS Imagine.Lab AMESim proved to be an extremely flexible tool. The Volvo CE engineers could select the number of gears as well as multidisc brakes, various types of differentials and engine models, merely by pointing and clicking on the appropriate icons. Likewise, fuel consumption was readily calculated for hybrid wheel loaders in which the internal combustion engine, complemented with an electric motor, was used to power the vehicle around the worksite while performing scooping, lifting and dumping operations.

"LMS Imagine.Lab AMESim played a key role in the hybridization of the Volvo CE wheel loader and proved to be an effective flexible tool in evaluating the many options and optimizing the final design," Larsson said.

Simulating the driver from the start A success factor for the machine model was a representation of expected driver actions during typical vehicle operation. Vehicle measurements were taken on the Eskilstuna test tracks and used to create operating profiles in the LMS ImagineXab AMESim simulation. Profiles included speed and acceleration to fit various weather and terrain conditions and road grades in the hauler case. Operating profiles for loaders included bucket scooping, lifting and dumping for varìous gravel types and operator driving styles.

The hydraulic system modeling was done in close conjunction with the driveline, since components from these two subsystems had to be sized together with respect to operational transients. These models included hydraulic pumps connected directly to the engine, as well as the loader bucket and hauler dump bed. Another major consideration was the power for the hydraulically driven cooling fan pumps. LMS Imagine.Lab AMESim balanced these and other critical requirements to maintain hydraulic oil pressure for the major components with optimal efficiency and minimal drag on engine power.

Optimizing fuel consumption with thermal management One area of critical importance in predicting and optimizing fuel consumption and machine operability was thermal management, that is, the sizing and control of the cooling system regulating the engine temperature, transmission and hydraulic oil for brakes and axles. Simply stated: oil temperature determines its viscosity and, therefore, friction. And the more friction, the more fuel consumption.

The basic idea was to find the right balance. The oil temperature could not be too high, because that causes rapid oil deterioration and damage to mechanical parts. Other factors that the LMS Imagine.Lab AMESim model could simulate included warm-up times and the effect of weather conditions and operating cycles - all vital aspects to deterriiine a thermal management control strategy for the hydraulically driven radiator fan (which consumes a considerable part of vehicle power) and other parts of the cooling circuits heat exchangers.

Impressive ROI: Virtual prototype in half "Manually tracking and balancing these multiple requirements is not practical given our time and resource constraints," said Larsson. "To maintain the high fidelity of the co-simulation, the common platform provided by LMS Imagine.Lab AMESim was absolutely essential. Moreover, with all members of the design team using the same tool in their work, they now 'speak the same language' and can collaborate more closely in development. The team can study moré alternative concepts early in development and better optimize designs throughout the entire process." The return on investment for Volvo CE is huge. According to Larsson, engineers can now optimize the design of a single new vehicle using simulation, verify the design with a physical mockup and then develop multiple derivatives of the same design using simulation alone. This allows the company to develop a range of vehicles with down to a third of the physical testing ordinarily required.

Engineers can readily adapt vehicles to specific customer requirements using different electronic control strategies in optimizing fuel consumption and vehicle performance for particular load/unload cycles. Customized design is a huge selling point in the competitive global construction equipment market.

"This project is a quantum leap in engineering productivity in the construction equipment market. With process improvements in collaboration and co-simulation - plus improvements in developing simulation models, control strategies and derivative models - Volvo CE has cut overall vehicle virtual prototyping time in early design phases in haltThis yields a valuable reduction in overall product development time. It shows what LMS engineering innovation can do for a company willing to make a commitment to fully leveraging cutting-edge LMS technology in their design processes," concluded Larsson.

Volvo decreased its prototype test cycle time with a single solution to simulate vehicle subsytems.

For powertrain design and thermal management, LMS Imagine. Lab AMESim modeled the engine, gearbox, transmission, power steering, hydraulic actuation, cooling circuits, fans and mechanical devices - all in a single unified intelligent solution.

(c) 2011 Society for Mining, Metallurgy, and Exploration, Inc.

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