Project 03 · 2026

MAGMA

A four-wheeled rover built for the German Aerospace Center's Vulcano challenge.

Role
Mechanical design — wheel mechanism and chassis
Team
Juan Rivera Chopinaud · Roman Daugavet
Brief
DLR Vulcano challenge — cross an active volcanic field, take measurements
Funding
Mouser Electronics · Stadtsparkasse München · Bayerischer Bildungsverband
Fig. 1Wheel — contract · expand
Scroll to run the mechanism

Loose ash and broken rock

Narrow wheels sink into ash, while large wheels can jam between broken rocks.

The wheel changes diameter while the rover moves

Curved segments on a gear ring slide outwards or inwards together, while the rover keeps moving.

How it works

Fig. 2Wheel — front elevation
Engineering drawing of the variable-diameter wheel, front elevation
Segments carried on a gear ring

Each wheel is built from overlapping curved segments carried on a gear ring. Rotating the ring relative to the hub slides every segment outwards or inwards at once, which changes the effective rolling diameter while keeping the contact surface continuous. The expansion drive is separate from the drive that turns the wheel, so diameter and speed are controlled independently and the rover doesn't have to stop to change configuration.

Each segment carries part of the vehicle's weight at every wheel diameter. The fully expanded position has the least overlap and the longest unsupported span, so it set the segment thickness, material and upper limit of the diameter range.

The starting point was a published variable-diameter wheel mechanism. I adapted it to a vehicle this size and to parts that could either be printed or bought from a normal distributor, because the version two bill of materials had to come in around €410. The budget determined the materials and mechanisms we could use.

Fig. 3Chassis sections, rev D
Engineering sections of the MAGMA chassis
Chassis sections used for fabrication

The rover carries an environmental sensor package and measures the air while it drives. The chassis was drawn to revision D before anything was cut.

Engineering drawings, rev D ↗
Fig. 4Vulcano sensor package
The open environmental sensor enclosure built for the MAGMA Vulcano rover
Gas sensor, fan and wiring inside the printed enclosure

This enclosure belongs to the MAGMA rover. It holds the environmental sensors and fan used during the DLR Vulcano challenge.

What I got wrong

Our demonstration video failed to show that the rover worked.

Our five-minute demonstration video was due while I was in Georgia visiting my grandparents, and the two days before the deadline were the Bavarian state round of a different competition. The rover was at my flat, nobody was there to film it, and what I had were isolated five-second clips of individual functions, filmed in a hurry the evening before my flight. I cut them together and submitted them, and the result was bad. We had spent months and about €450 on a machine that worked, and what the judges saw was a badly shot clip of something that could have been anything.

I now schedule documentation as part of the build and record each subsystem as soon as it works.

Where it stands

Fig. 5MAGMA V1 · rolling test
Four-wheel prototype, remote-operated

Version one drives, the wheel mechanism works, and the sensor package is integrated. Version two is designed and partly sourced.

The current vehicle is remote-operated. Autonomy is not implemented.

Repository ↗
Next projectTeaching
04 →