EROS

A Rover Built From First Principles

EROS — Extreme Research and Observation System — is FRoST’s most ambitious platform to date. Where every previous rover iterated on an existing design, EROS started from a blank page. The goal: build the most capable, reliable, and autonomous rover the team has ever fielded, incorporating everything learned across four competition seasons with ARES. The result moves and operates differently from any rover the team has built before.

A Completely New Way to Move

The most fundamental departure from ARES is how EROS gets around. ARES used a proven track-based drive system — reliable and battle-tested. EROS abandons that entirely in favour of four independently driven, steered, and height-adjustable wheel assemblies.

Each wheel is its own self-contained unit with three degrees of freedom: drive, steer, and height. The height adjustment — driven by a precision spindle mechanism — lets EROS actively level its chassis over uneven terrain, maintain contact on loose or rocky surfaces, and lower its centre of gravity when stability matters most. This kind of active adaptability is simply not possible with a track or fixed-suspension design.

From the driver’s perspective, EROS can move in ways ARES never could. Ackermann steering for tight turns. Synchronised steering for precise lateral translation. Crab steering to hold a heading while moving sideways. The control software emulates all three seamlessly — while underneath, each wheel is doing its own independent thing, responding to force sensors and chassis tilt data at every moment.

The Arm Returns

The 6-degree-of-freedom robotic arm that earned FRoST the maintenance award at ERC 2025 carries over to EROS. At 1.3 metres in reach and capable of lifting 5 kg, the arm handles everything the ERC demands: turning valves, actuating switches, plugging and unplugging connectors, collecting rock samples, and positioning scientific instruments with millimetre precision.

Every joint uses strain wave gearboxes — compact, backlash-free, and high-torque — paired with slip rings on all rotational axes so the joints can turn indefinitely without winding up cable bundles. The gripper operates in both position mode and force-controlled mode, allowing it to grip delicate objects without damaging them.

At the end of the arm, a stereo camera generates a dense point cloud of the immediate workspace, enabling semi-autonomous manipulation: the operator selects a target, and the arm plans a collision-free approach and executes it without joint-level input.

Science Payload

For the ERC science tasks, EROS carries a dedicated modular payload. A Deep Drill Unit penetrates up to 35 cm below the surface to extract soil samples. An accelerometer monitors vibration signatures during drilling, and a machine learning classifier determines in real time when sufficient material has been collected — eliminating the guesswork. Surface regolith and rock samples go into two separate sealed storage containers, each fitted with a precision load cell accurate to within one gram.

The entire science payload mounts modularly, so EROS can be configured with or without it depending on the mission — dropping the total weight from 69 kg to roughly 59 kg.

Eyes, Ears, and a Sense of Place

Finding your way on a simulated Martian landscape requires more than a map. EROS carries two 3D-LiDAR sensors — one at ground level for close-range terrain scanning, one elevated on the Multi-Purpose Tower for broader situational awareness. Together, they feed a real-time 3D-SLAM pipeline running on a GPU-accelerated onboard computer, giving EROS a continuously updated three-dimensional model of its surroundings and the ability to close loops and correct accumulated drift.

For absolute positioning, an RTK-GNSS receiver achieves 1–2 cm horizontal accuracy by receiving correction signals from a reference station at the competition site. LiDAR odometry and RTK data are fused through a Kalman filter, producing estimates that degrade gracefully if one source becomes temporarily unavailable.

The Multi-Purpose Tower sits at the rear of the rover and acts as a communication and sensor hub. It carries the WiFi antenna, a LiDAR for wide-area scanning, a gimbal camera system for close-up views, a 360-degree camera for panoramic views, an LED status ring that tells the operations team at a glance what mode the rover is in, and the digital emergency switch.

Autonomous by Design

EROS is the most autonomous rover FRoST has built. An operator can mark waypoints on a live map at the ground station, and EROS will plan and execute a collision-free route without further input — navigating around obstacles, adapting to terrain conditions, and feeding back telemetry throughout.

Beyond navigation, cameras distributed across the chassis and science payload feed into semantic segmentation and object classification pipelines that identify scientifically relevant targets: suitable drilling sites, surface probes, and rock samples of interest. The arm’s stereo camera generates a dense point cloud of the immediate working volume, enabling the semi-autonomous manipulation described above.

A mission planning framework ties all of this together. Operators can define high-level task sequences — a complete science run from approach to sample delivery — and execute them with real-time oversight and the ability to intervene at any point. The system exposes a unified interface for every autonomous subsystem, so operators always have a clear picture of what EROS is doing and why.

Powering the Mission

EROS draws power from up to two custom-built lithium-ion battery packs, each running at 48 V nominal and storing 403 Wh. The high bus voltage keeps cable cross-sections small and current losses low. A network of Energy Monitoring and Distribution Modules (EMDMs) connected via CAN bus controls every subsystem individually, monitoring voltage and current in real time and switching components on or off from the ground station.

Safety is hardwired in. A physical emergency stop at the rear of the rover — plus a software-triggered remote equivalent — can cut power to all motors within 100 ms. The system fails open: if the CAN bus or the emergency switch stops responding, the motors shut down automatically.