06CV-145 Multi-Domain Modeling and Simulation of an Electro-Hydraulic Implement System Sameer M. Prabhu, Jeff Wendlandt, John Glass, and Tom Egel The MathWorks, Inc. ABSTRACT The need to meet new regulatory requirements as well as customer expectations in terms of machine productivity, safety, maintenance and uptime, is driving a significant transformation from conventional hydraulic and mechanical systems to electro-hydraulic systems in the earth-moving and agricultural equipment industry. The ability to model and simulate such systems plays a key role in this transformation by allowing manufacturers to test whether the system meets requirements using virtual prototypes rather than physical prototypes. Modeling the electrical, electronic, mechanical, and hydraulic domains in the same modeling environment can significantly improve the product development process of such machines. This paper illustrates those benefits using the example of an electro-hydraulic implement system. INTRODUCTION The earthmoving and agricultural equipment industry is undergoing a significant transformation from conventional hydraulic and mechanical systems to electro-hydraulic systems. The market drivers for this transformation can be broadly classified into two categories. The first category deals with regulatory requirements on engine emissions, machine noise levels, etc. As an example, engine emissions regulations are getting more and more restrictive which in turn necessitates the adoption of electronics to precisely control engine combustion and after-treatment. The second category deals with the need to meet customer demands in terms of improved machine productivity, safety, maintenance and uptime. As an example, in an electro-hydraulic implement system the lift and tilt modulation characteristics can be adapted based on the work tool connected to the implement linkage (e.g., bucket vs. forks), thereby lessening the burden on the operator and improving productivity. THE CHALLENGE OF ELECTRO-HYDRAULICS However, it is not enough to just take individual systems such as implements and transmission and transform them to their electro-hydraulic equivalents. In order to fully realize the benefits of electronics, both from a customer and a machine manufacturer point of view, it is imperative that these systems “talk” to each other and thereby can be fully integrated with each other into an overall machine system. As an example, in a typical off- highway machine such as a wheel loader, if the powertrain and the electro-hydraulic implement controller can talk to each other then the transmission “knows” the position of the implements. This means that if the bucket is high up in the air then the transmission shifts can be made smoother so as to increase load retention in the bucket. On the other hand, when the bucket is near the ground level, the transmission shifts can be more aggressive and thereby help in reducing the overall cycle time. This customer benefit in terms of reduced cycle times can only be achieved when the individual systems talk to each other and we can implement features that we couldn’t when only individual systems were electronically controlled. The key then is to integrate the various systems such that the overall machine performance is optimized. We are, in effect, designing a “system of systems” The design of these complex machines is already a difficult challenge due to the complex interaction of various individual systems. We complicate it further by introducing electronics and the accompanying system behavior adaptability. To better understand why this is the case, let’s consider the example of a wheel loader. One of the most common applications for a wheel loader is the V-cycle where the loader penetrates into a pile, picks up gravel, backs up from the pile, reverses direction, approaches a truck, while raising the implement linkage, such that the linkage is in a position to dump when it approaches the truck. Once the loader has dumped the gravel in the truck, the loader backs up from the truck, lowers the linkage, reverses direction again, and approaches the pile, at which point the cycle repeats. This operation involves the complex interaction of the loader powertrain, hydraulics, implement linkage, and steering system. The net performance of the machine is a function of these systems and their interactions. Furthermore, the problem is essentially a multi-domain problem since there are different physical phenomena such as hydraulics and mechanics that interact with each other during this operation. These