Construction should be sustainable. Contractors, authorities, as well as contracting entities are aware of this. But does sustainability not already start during the excavation phase? Clearly not, since topics such as electrification and sustainability are still on the backburner when it comes to construction machinery. This is certainly the impression gained by eight aspiring mechanical engineers at ETH Zürich. Reason enough to take the matter into their own hands. As part of a focus project, the students have made it their mission to fully electrify an excavator. But that's not all. The ambitious team, which goes by the name of eXact, is taking this a step further and is also fitting the electric excavator with augmented reality features. This will improve the human-machine interface and open up new opportunities in terms of accuracy and efficiency – both factors that contribute to sustainability in the construction phase as a result of a more targeted approach. Jonas Rogge, who heads the team and is also responsible for the mechanics, says: "We want to make the most efficient use of renewables." Rogge adds that this way, eXact aims to contributesignificantly to electrification on construction sites.
The eight undergraduate mechanical engineering students have been working on the project since September 2022. They are guided by supervisors Professor Andreas Kunz from the Innovation Center Virtual Reality at ETH and Stefan Schneider, whose successful company Suncar HK AG is also the result of an ETH focus project. The eXact team has moved to premises at Technopark Zurich, made available to them by ETH. eXact depends on sponsors for financing the project. These include construction equipment manufacturer Volvo, who is providing an ECR25 excavator, as well as Syslogic, the experts in embedded computers, who are contributing hardware components including an AI-enabled control computer.
The project is divided into two sections: work on the excavator and work on the human-machine interface. The Volvo ECR25 is one of the first electric excavators on the market. So eXact is not actually starting from scratch, but is going one step further and significantly improving the efficiency of the electric excavator. It has become evident that the hydraulics of the excavator are extremely power-hungry, which affects its energy efficiency. eXact has therefore decided to replace the hydraulic linear actuators with appropriate electric linear actuators, which offer a much higher level of efficiency compared to hydraulics. This will make operation of the modified excavator much more environmentally friendly than the series product. Plus, it is possible to achieve considerably more working hours with a single battery charge – a convincing argument on construction sites.
Some hurdles must still be overcome, though, before this concept can be used in tough everyday construction life on sites –starting with the resistance factor. Compared to hydraulics, electric components are a lot more susceptible to vibrations and jolts. eXact is therefore developing a damper system to ensure that linear actuators are suitable for use on construction sites. Another challenge so far has been actuator control. Aaron Häusler, who is responsible for software at eXact, explains that great progress has however been made as regards development in this area, not least thanks to the advent of AI and machine learning. As a result, the team is using the latest innovative methods, says Häusler.
All components required for the conversion are currently being acquired. The plan is to replace the hydraulic components with the new electric linear actuators by May 2023. This will then be followed by a testing phase. At the same time, the team is working hard on the augmented reality technology.
To this end, eXact uses a HoloLens 2, an augmented reality headset developed and manufactured by Microsoft. The headset runs on software developed by eXact, which enables a variety of visualizations to be generated. For instance, the HoloLens can be used to show underground lines or pipes. And areas that are to be dug up by the excavator can be incorporated in the image and displayed directly to the excavator operator. This makes for efficient and precise operation. Because GPS has been proven to be too inaccurate, eXact is working with an RTK system (Real Time Kinematic). This surveying system calculates the position and rotation angle of the excavator and the person wearing the HoloLens with centimeter precision by means of multiple signals. eXact uses positioning services provided by private GNSS reference network RefNet.
The data from the positioning system is transferred to the Syslogic industrial computer, which in turn transfers the data to the HoloLens. The computer thus takes on a central role. The device used is an AI-enabled rugged computer RPC RS A3N. This computer meets protection class IP67 and is suitable for use on construction sites. Technology-wise, Syslogic's rugged computer is based on the Jetson Xavier NX by NVIDIA. It allows data from different high-resolution sensors to be processed almost in real time. Aaron Häusler explains: "Syslogic's AI computer gives us power reserves that make it possible to automate work steps or implement remote-controlled operation at a later stage."
The eight students used the occasion of a milestone presentation on December 20, 2022 at the Innovation Park in Dübendorf to provide an update on the project progress. In the next step, the eXact team will install the rugged computer in the excavator and implement the RTK system. The next milestone presentation is scheduled for March 2023. The aim is to complete the converted excavator in June 2023. We will follow the progress of the project in this blog.
We at Syslogic are happy to be able to contribute to this pioneering focus project and consequently to the use of renewables in the construction sector by way of sponsoring equipment.