Aalto University Works with Industry Partners to Develop Energy-Efficient Designs for Construction Equipment
“With MATLAB, Simulink, and Simscape we were able to create and validate designs spanning multiple domains—mechanical, electrical, and hydraulic—that are now being used by our commercial partners to improve energy efficiency on their machines.”
Challenge
Work with manufacturers to develop more energy-efficient excavators, loaders, and other construction and off-road machinery
Solution
Use MATLAB, Simulink, and Simscape to model and simulate designs that incorporate hybrid technologies and decentralized hydraulic systems
Results
- Energy efficiency doubled
- Industry-academia collaboration established
- In-demand skills developed
The one-tonne micro excavator modeled by Aalto University and Tampere University researchers in the EL-Zon and EZE projects.
Faced with stricter limits on CO2 emissions and increased demand for more fuel-efficient equipment, construction machinery manufacturers are exploring new designs for excavators, loaders, and other non-road mobile machinery (NRMM). In conventional NRMM designs, an internal combustion engine drives a centralized hydraulic pump, continuously supplying enough hydraulic power for a maximum workload. This amount of power is needed only when a heavy load is being lifted or lowered, and any excess power is dissipated as heat. As a result, traditional construction machinery often operates at as little as 10% efficiency.
Researchers and students at Aalto University are working with Finnish heavy machinery manufacturers on NRMM designs that incorporate hybrid technologies and decentralized or zonal hydraulic systems powered by electric motors. The goal is to demonstrate the ability of modern electric drives to complement conventional hydraulics and increase the efficiency of working hydraulics in mobile machinery. Both projects are tightly connected to industry and supported by funding from Business Finland.
These direct-driven hydraulic designs are modeled and simulated using MATLAB®, Simulink®, and Simscape™ before they are built and validated in real-world tests.
“By running accurate simulations with Simulink and Simscape, we can make significant advances much faster,” says Tatiana Minav, a postdoctoral researcher at Aalto who is currently working as an assistant professor at Tampere University. “Modeling and simulation provide an affordable way to rapidly validate new design concepts for large machinery.”
Challenge
Decentralized hydraulic systems powered by electric motors can significantly reduce energy losses and consumption. To make this approach viable for industry, the Aalto research group wanted to use commercially available motors and hydraulic components, but they needed to find the best sizes and configurations for these components.
The researchers sought a modeling and simulation environment that supported multiple physical domains, including electronics and hydraulics. They wanted this environment to be one that most Aalto students either already knew or could learn quickly. In addition, they wanted to use the same tools as their industry partners, both to facilitate collaboration and to enable students to develop marketable skills.
Measured (orange) and calculated (blue) positions of the boom and bucket with 1040 kg payload. (Image credit: T. Sourander master’s thesis, Aalto University, 2017)
Solution
Aalto researchers used Simulink and Simscape to design hydraulic systems for stationary and mobile machines, including a one-tonne micro excavator and a 14-ton serial hybrid mining loader.
They used Simscape Multibody™ to develop mechanical models of their systems. On the excavator project, for example, the team exported a CAD assembly from PTC® Creo™ to create a 3D mechanical model of the boom, arm, and bucket for simulation.
The team modeled the electric and hydraulic components of their design, including the PMSM motors, cylinders, pumps, and pipelines, in Simscape.
After completing a physical model, the group performed simulations to evaluate various configurations and component dimensions. They visualized and analyzed simulation results in MATLAB.
They created a closed-loop PI control model to position the excavator cylinder. They also developed a controller model for the mining loader and deployed it to dSPACE® MicroAutoBox® hardware for real-time testing.
The group is currently developing a configurable model that will enable companies to simulate a wide variety of equipment for lifting and lowering loads.
The upcoming EZE project (Aalto University) and EMMA project (Tampere University) will provide additional research into decentralized hydraulic system development using MATLAB and Simulink.
Simscape Multibody visualization of the excavator developed by EL-Zon researchers.
Results
- Energy efficiency doubled. “The decentralized hydraulic systems we designed in Simscape were significantly more efficient than similar machines that have traditional hydraulic systems,” says Minav. “On the excavator, for example, direct-driven hydraulics and energy regeneration enabled us to achieve an overall efficiency of 71%, compared with just 18% on a traditional excavator, based on our simulation study.”
- Industry-academia collaboration established. “We have close relationships with off-road machinery manufacturers in Finland, with whom we share our results, and in some cases, Simulink models,” says Minav. “The companies use the models to run detailed simulations and continue their own development projects.”
- In-demand skills developed. “The students who work with us gain a number of valuable skills, including how to work on a team and how to model and simulate real systems with MATLAB and Simulink,” notes Minav. “These are the same tools used by many of the companies we work with, making it easy for our students to be hired directly from our project once they graduate.”
