Electric axle vs wheel modules: new driveline concepts for farm robots
Direct electric drivelines could slash energy losses and unlock radical new designs for harvesters.
Researchers Timo Oksanen (TU Munich) and Karl Th. Renius have released a detailed comparison of electric driveline concepts for agricultural machinery, published as arXiv:2605.07657. The paper focuses on self-propelled equipment like combine harvesters, forage harvesters, root crop harvesters, equipment carriers, propelled trailers, and field robots. The core idea is to replace complex mechanical power-split drivelines with direct electric drives, offering new freedom in frame and suspension design while reducing energy losses.
The study defines two main approaches: axle modules and wheel modules. An axle module packages two electric motors, power electronics, steering, and controls into a single unit that replaces a traditional axle. A wheel module concentrates all those components into each wheel hub, enabling fully independent control. The wheel module excels in design freedom, redundancy, and controllability—critical for autonomous field robots. The axle module wins on cost, structural rigidity, and the ability to use existing vehicle structures with automatic load sharing via a differential. Both concepts require only a DC power bus and communication interface from the vehicle. The detailed engineering analysis covers loads, efficiency, steerability, braking, suspension, and manufacturing cost, providing a practical roadmap for electrifying heavy off-road agricultural vehicles.
- Wheel modules offer maximum design freedom and redundancy for field robots, while axle modules provide lower cost and structural rigidity.
- Both concepts integrate power electronics, distributed control, and steering into self-contained mechatronic units requiring only a DC bus and comms interface.
- Direct electric drivelines could significantly reduce energy losses compared to traditional mechanical power-split drivelines in heavy farm equipment.
Why It Matters
This electrification blueprint could slash energy use and unlock autonomous farming, reducing costs and environmental impact.