Virtual design may facilitate powertrain electrification for agricultural machinery

So far, electric powertrains are rarely used for agricultural machinery due to higher costs and technical challenges, even though the electric systems increasingly used in smaller machinery are also suitable for more powerful machines. Virtual design and modelling provide opportunities for advancing new technologies without the need to manufacture expensive prototypes from the get-go.

Antti Lajunen, assistant professor of agricultural engineering, was born on a farm. He does not look particularly fondly back on the tractor stock of the 1970s and 1980s, which, in comparison to their predecessors, were at least equipped with a synchronised transmission, padded seats and safety cabs. However, other comforts were relatively scarce. It was only in the 1990s that farmers got power shift transmissions, closed cabs and air conditioning for their mobile offices.

Lajunen, who assumed his position at the Faculty of Agriculture and Forestry, University of Helsinki in June 2018, has previously focused on investigating the technology of urban buses and commercial machinery, concentrating in recent years on the electrification of their transmissions. His doctoral dissertation, defended at Aalto University in 2014, was written on the same topic.

Differences in the performance requirements of buses and machinery may vary greatly, depending on the operating situation. Whereas the primary goal for electric urban buses mainly running on relatively level roads is a long operating range, electric tractors turning over fields in the autumn need raw power.

“Problems in making the powertrain of machinery electric don’t usually revolve around extending the operating range, but increasing performance. What’s more, today’s technology of electrification is more complicated compared to using a traditional lead-acid battery. Now we need high voltages, plenty of diagnostics, temperature controls, power electronics and, to top it off, system control.”

Low demand, low supply

Designers and manufacturers have not been as interested in electrifying the powertrains of machinery as that of, say, passenger cars. As regards the industry, it boils down to sales numbers – cars are sold in greater numbers than tractors and other machinery. Even customers who buy machinery have not been particularly active in asking for electronic alternatives for machinery powered by combustion technology. Commercial vehicles larger than passenger cars have already been electrified, but in Finland they are far and few between.

“In Paris, for example, electric garbage trucks have already been used for more than a decade. They are so quiet that waste can be collected even in the middle of the night. Our roads are not too congested for waste management to be conducted in the broad daylight also in cities. This may be the reason that the possibilities of electrification have not been given serious consideration,” says Lajunen, who has lived in France for several years.

Biggest benefits currently in the electrification of small machinery

Even if the extensive electrification of heavy machinery may not be quite on the horizon yet, advancements in small machinery are several steps further. This will be taken further yet by an EU directive coming into force in the beginning of 2019, applying to all performance categories of machinery. Previously, no emission regulations have governed the use of engines in machinery with an output of less than 19 kilowatts, such as miniloaders.

“In practice, lawnmowers powered by flathead engines were among the worst polluters in the world. Due to absent regulations, there was no need to advance technology developed in the 1950s until the 2000s, when the introduction of increasingly strict emission regulations resulted in a drastic decrease in the use of lawnmowers based on this outdated technology. It will be interesting to see what fate awaits machinery powered by internal combustion – whether they will be equipped with catalytic converters and other exhaust gas treatment technology or whether some other technical solutions will be employed to cut emissions to the required level.”

Virtual tools and modelling open new opportunities

The key to technological development is design, whether in terms of electrifying powertrains or other advances. Challenges in the design of machinery include smaller production series compared to passenger cars and often individually manufactured components, which makes the production of prototypes for each individual machine financially unfeasible.

Virtual design would cut many corners and guarantee that individual parts need not be finished products before the machine under development has passed the virtual design stage.


“In the car business, the trend towards this is already in full swing. Within the next five to ten years, new passenger cars will in practice be designed and manufactured completely virtually, introduced for testing as actual cars only after that process.”

According to Lajunen, another great benefit of virtual design and related modelling and simulations is that they help in observing the functioning of machinery in situations where machines could not in reality be reliably tested. Such special circumstances include driving off the road and machinery getting stuck in a mire.

Lajunen admits that simulation has its own weaknesses.

“The most challenging thing is to perceive the possibilities of new technology. It is natural not to be able to yearn for something that we don’t yet know anything about. The proverb about all computer models being wrong, but some being useful, is pretty accurate.”

In his own research, Lajunen would like to focus on the effective utilisation of modelling and simulations in virtual environments.

“If you wanted to study the effect of tractor tyres on traction during soil cultivation, how accurate should modelling be to be able to assess traction without massive field experiments? There is a selection of software available, but how reliable are they? How could the assessment of accuracy be made less burdensome? How could existing extensive masses of data, or big data, be utilised in the future?” ponders Lajunen.