Glossary
This glossary covers the vocabulary used across the reference. It mixes terms that belong to URC, such as the missions, the reviews and the field, with the standard robotics and engineering terms the analysis applies to them. Entries are short and aim at the sense the term carries in this book, not at a textbook definition.
Definitions follow the usage in the chapters and the rules. Where a term has a number attached, such as a deadline, a point value or a dimension, the number is the 2027 value and the rulebook or the chapter that owns the term carries the citation.
A
Ackermann steering: Steering geometry where the front wheels turn at different angles so all wheels share a turn centre. It avoids skid scrub but adds actuation and complexity.
ArUco: Open-source square fiducial marker family, for example the 4x4_50 dictionary, used by URC for the keyboard, key, lock and autonomy-post targets. Detection gives pose from a single camera.
ATP: Adenosine triphosphate, the universal biological energy carrier. Its presence is a life-detection target (Q&A Astrobiology Q9).
Autonomy: Rover driving and task execution without operator input. In 2027 the Autonomy Mission has an Astronaut Assistance and a Route-Finding sub-mission, and the LED must show red while autonomous and blue while teleoperated.
B
Backlash: Lost motion between a gearbox input and output. It is the dominant error source for precise arm tasks such as keyboard typing.
Behaviour tree: A hierarchical task structure of sequences, selectors and decorators for robot missions. It is easier to inspect and recover than a flat state machine.
Bentonite: The expansive clay mineral that makes MDRS soil slippery when dry, sticky when wet and extremely dusty.
BMS: Battery Management System. It monitors cell voltages and temperature, balances cells and disconnects on fault. A BMS trip can shut the rover down mid-mission.
C
C2 station: Command and Control station, the trailer or Hab room where operators sit with no direct view of the course.
Cam-lock: A push-on hose coupling with two cam arms. The 2027 Equipment Servicing hose task uses a 1.5 inch cam-lock with a half-thickness gasket.
CAN bus: A robust differential two-wire fieldbus used between motor controllers and the rover computer. It is deterministic and noise-tolerant.
CDR: Critical Design Review. URC requires a PDR and a SAR, and some teams run an internal CDR between them.
CG: Centre of gravity. It drives tip-over resistance on slopes and the load distribution between wheels.
CORS: Continuously Operating Reference Station, a networked RTK base station. It is not available at MDRS (Q&A Rover Q11), so teams must run their own base.
Costmap: A grid of traversability costs used by Nav2 planners, built from sensors or a prior DEM.
D
DDS: Data Distribution Service, the middleware under ROS 2. Its discovery traffic and reliability settings matter on a lossy radio link.
DEM: Digital Elevation Model. URC intends to supply a DEM of the 2027 route-finding area at 1 m or better (Q&A Autonomy Q20).
Differential bar: A linkage that couples the left and right rockers so the body stays level as wheels climb.
DoF: Degrees of freedom, the independent axes of motion. An arm’s DoF count is the central complexity and workspace trade.
Duty cycle: The fraction of time a motor or driver runs at a given load. It sets thermal sizing.
E
e-paper display: A low-power bistable display, 4.3 inch in the URC typing task, that shows the launch key to type.
E-stop: Emergency stop. URC requires one red push button that stops movement and removes all battery power, and mobile deployables need their own.
EIRP: Effective Isotropic Radiated Power, transmit power plus antenna gain. It is the regulated quantity in a link budget.
Elevation map: A 2.5D grid of terrain height used for slope and traversability analysis in hilly route-finding.
ERC: European Rover Challenge, a sister competition at Kielce, Poland, with more detailed public design documents than URC often has.
EVA: Extravehicular activity. In 2027 it is the suited team member the rover must assist, and the suit needs a camera and a microphone.
F
Fade margin: Extra received signal above the minimum sensitivity, in dB, before a link fails. Terrain and multipath consume it.
FEA: Finite Element Analysis, used for chassis and arm stiffness and strength checks.
FSPL: Free-space path loss, the geometric spreading loss in a radio link. It scales with 20·log10(distance) and 20·log10(frequency).
G
GNSS: Global Navigation Satellite System, covering GPS, Galileo, GLONASS and BeiDou. URC uses WGS 84 latitude and longitude, and RTK is strongly encouraged.
GP (gearbox): The Maxon planetary gearhead family, for example the GP 42 C, common in URC drive and arm joints.
Grouser: A cleat or bar on a wheel’s circumference that increases traction in loose soil. Too tall wastes energy; too short slips.
H
Harmonic drive: Strain-wave gearing, for example the Harmonic Drive CSF or HDUC series, with near-zero backlash and high reduction. It is expensive and compliant under load.
HDUC: The Harmonic Drive component-set series, widely copied by Chinese suppliers such as LHSG and common in URC arm joints.
I
IMU: Inertial Measurement Unit, accelerometers and gyroscopes. It is fused with GNSS and wheel odometry for localisation.
Intervention: Touching the rover in the field during a mission. It costs 20 % of that mission’s points, additively, and ends the operator’s role if they leave C2.
IP rating: Ingress Protection, for example IP54 or IP67, for dust and water. MDRS dust is fine, alkaline bentonite clay.
L
LiDAR: Light Detection and Ranging, laser ranging that produces point clouds. It is useful for terrain and obstacle detection but adds power, mass and cost.
LOS: Line of sight, a clear radio path. Delivery and the route-finding sub-mission are intentionally not LOS for parts of the course.
M
MDRS: Mars Desert Research Station, near Hanksville, Utah, the URC venue at about 1,400 m elevation in high desert.
MPC: Model Predictive Control, a receding-horizon controller used for path tracking. It handles constraints but needs a model and compute.
N
NTRIP: Networked Transport of RTCM via Internet Protocol, the usual way RTK corrections are streamed. There is no internet at MDRS, so corrections must go over the team’s own radio link.
O
OBC: On-board computer, the rover’s main compute, whether a Jetson, an x86 mini-PC or a similar module.
P
PDR: Preliminary Design Review, a URC milestone due 2026-12-02 that covers the team, the plan, the budget and the state of the design.
PID: Proportional-Integral-Derivative control, the workhorse joint and velocity loop.
PoE: Power over Ethernet, one cable for data and power to antennas and cameras, common in base stations.
Point cloud: A set of 3D points from LiDAR or stereo, used for obstacle detection and terrain modelling.
R
RCC: Remote Centre Compliance, a passive mechanism that allows lateral and angular compliance while resisting axial force. It is useful for peg-in-hole tasks such as the sample tube.
Rocker-bogie: Six-wheel suspension with a pivoting rocker on each side and a differential bar linking them. It keeps wheels loaded over obstacles and is the dominant URC architecture.
ROS 2: Robot Operating System 2, the dominant robotics middleware, with DDS transport, nodes, topics and the Nav2 stack.
RTK: Real-Time Kinematic GNSS, a differential technique that uses the signal carrier to give centimetre accuracy with a base station and a radio link.
S
SAR: System Acceptance Review, a URC milestone worth 100 of 500 points and due 2027-03-05. It is written and video, and the top 36 teams are invited to the field.
Skid steer: Driving by running left and right wheels at different speeds. It is simple and rugged but scrubs wheels and needs torque to turn in place.
SLAM: Simultaneous Localisation and Mapping, building a map while locating within it. It needs a sensor with range, such as LiDAR, stereo or visual-inertial.
Slew rate: How fast an actuator can change velocity. It matters for arm settling time and typing.
Solar gain: Heat absorbed from sunlight, the dominant thermal load on a desert rover enclosure.
Swerve drive: Independent steering and drive at each wheel. It is omnidirectional but heavy, complex and expensive.
T
Teleoperation: Direct human driving or control over a radio link. It scores lower than autonomy in the 2027 Autonomy Mission and is penalised when used to recover from an autonomous attempt.
Torque constant (Kt): Motor torque per amp, in N·m/A. With current limits it sets the achievable wheel force.
Trailing arm: A single-pivot arm carrying a wheel, a simple independent suspension with limited travel.
Tubular pin tumbler lock: A lock with pins arranged in a circle around the keyway, the 2027 key task. The key must be inserted at the right rotation and turned.
U
URDF: Unified Robot Description Format, an XML model of a robot’s links and joints used in ROS, simulation and inverse kinematics.
V
VESC: Open-source brushless motor controller, the Vedder ESC, widely used for rover drives. It supports field-oriented control, CAN and custom firmware.
VIO: Visual-Inertial Odometry, pose estimation from cameras and an IMU. It drifts over distance but works without GNSS.
W
WBS: Work Breakdown Structure, the required format for the Rover Expense Report.
WGS 84: The geodetic datum URC uses for all coordinates.