The Chair of Agrimechatronics at the Technical University of Munich (TUM) is the leading teaching and research centre in agrimechatronics. They use a suite of Kvaser products and software to teach undergraduates and PhD students, as well as support research and development of practical applications for cutting-edge technology.

What is agrimechatronics?
If you have not already heard of this, you are not alone since agrimechatronics is a relatively new term. It is the combined technology of electronics and mechanical engineering for use in agricultural applications.

Based just north of Munich in southern Germany, The Chair of Agrimechatronics at TUM is a pioneer in the field, with research projects involving tractors and other agricultural vehicles, tractor-implement automation, communication technologies for vehicles (such as ISOBUS), autonomous agricultural vehicles and robots, guidance and planning, model-based control of mechatronic systems, drives and power systems, and robotic implements.

Kvaser interfaces in the classroom
TUM uses Kvaser Leaf Lights CAN (controller area network) to USB interfaces, Kvaser Memorator data loggers and the Kvaser Air Bridge wireless CAN link, plus Kvaser’s free software and Canlib API, which works across the entire product portfolio. Recounts Prof. Dr.-Ing. Timo Oksanen, who heads up the chair:

“An easy-to-start-with approach is important when working with students so they can quickly learn the basics of CAN bus. Kvaser’s CanKing CAN bus monitor and general-purpose diagnostic tool also offers quick learning for the basics and for trying out simple things.”

Prof Oksanen sees value in standardising tool use across the entire institute. He notes: “Kvaser’s tools have an economic price-tag for classroom use. We use Kvaser products in several classes so that each student has their own to get connected to the same bus.”

Field testing, literally
DigiMilch (digital milk) is one of Germany’s experimental field projects, and TUM’s contribution is aimed at improving slurry spreading accuracy. The Kvaser Memorator Light HS v2 captures all CAN traffic in order to test the performance of the ISOBUS task controller at the protocol level.

Samuel Brodie, a PhD student on the team, explains: “We use a Kvaser Memorator Light HS v2 to collect time-synchronous data from one or two CAN bus segments (one of which is always ISO 11783) to analyse agricultural machine performance in the field. Everything is easily collected to one file for later analysis, which is then imported into MATLAB thanks to the different export formats available.” MATLAB integration, along with integration to other software tools, was one of TUM’s many motivations behind using Kvaser products, confirms Brodie.

The research team used the Kvaser Memorator API to program the data logger so that the data could be read and uploaded over the internet. Notes Brodie: “I have created a GUI that allows the farmer to do this once the tractor is turned off, as the Memorator must be disconnected from CAN to do the upload.” As the research team relies on input from the farmer, who may forget to upload the data, they appreciate the Memorator’s ability to store recorded data for a long time before it is overwritten.

The Digimilch data flow:
Kvaser Memorator > read by tablet > uploads .kme50 files via internet > converted to .asc files > MATLAB > processed into sensor data /GNSS position etc.

Capturing CAN data, over-the-air
The TUM researchers have made their own versions of the ISOBUS functionality, such as diagnostics, object pool capturing etc. Mr Brodie says: “This creates the perfect environment for fast-prototyping with closed-loop control and agile data logging online.”

With the goal of further optimising their prototyping environment, the TUM researchers have used a Kvaser Air Bridge Light HS to solve some of the ergonomic issues with tractor and implement data gathering. Mr Brodie recounts: “The ISOBUS connector is in the tractor cabin and there is no connection at the rear of the implement, so when working there, the Kvaser Air Bridge Light HS saves time running backwards and forwards. It also allows for software development outside of the cabin. For teaching purposes, we have one unit of an Air Bridge pair inside, communicating with the other unit which is connected to the machinery outside.”

What does the future of agrimechatronics look like?
Professor Oksanen explains that CAN bus has been the workhorse of agricultural vehicle mechatronics for two decades – used in tractors to make them run, providing communications in harsh environments, and enabling and standardising the ISO 11783 tractor-implement plug-and-play network, known as ISOBUS.

“Standardised interfaces in machines with lifetimes of decades are hard to replace in the short term, so CAN bus will still be the workhorse for at least the next two decades. Single-pair Ethernet-based communication technology is now playing an important role in high-performance automation in vehicle engineering, and the same trend is also seen in agricultural vehicle engineering, including autonomy.”

Are there similarities between agricultural engineering and high-performance vehicle engineering? In Europe, tractor engineering has several similarities to truck engineering as speeds of up to 60 km/h are possible. Reaching stable driving conditions at such speeds with large inflation volume tyres and limited suspension capabilities has challenged and driven tractor transmission and suspension engineering remarkably in the past few decades. However, as standard tractors are optimised for field work with a speed range of 4-12 km/h, tractor design is a compromise between off-road capability with high traction torque and high-speed on-road conditions. In other regions where tractors are not used so much on-road (or are limited to 30 km/h), tractor design can be optimised differently.