#001

Andino

Ground — wheeled · Differential rover

Differential-drive ground robot

FailHarness checks: 2 clean · 1 warn · 0 err · 29 not checkedLatest recorded run: drive 0.347% · turn 9.104° vs ground truth

Evidence: the recorded runs and their sources ↓

An open-source ROS 2 robot from Ekumen, built to teach real robotics on a budget: two driven wheels and a caster, a spinning lidar on top, a Raspberry Pi for a brain. It is the first robot in the Robodex that RobotForge did not design — its spec here was read out of the official project's own files.

Spec

Battery	3x 18650 Li-ion cells, ~11.1 V nominal (official BOM holder); capacity varies by cell — the spec uses 2600 mAh as a labelled estimate
Chassis	0.25 m long x 0.10 m wide base deck (official URDF base.yaml); overall width 0.153 m across the wheels, wheel track 0.128 m
Computer	Raspberry Pi 4 + Arduino Nano (official BOM)
Drivetrain	differential — 2 driven wheels + ball caster
Ground clearance	~0.03 m — estimate; the URDF base plane rides at wheel radius (0.0331 m)
Height	~0.18 m — estimate derived from the URDF deck stack
Mass	3.364 kg — the sum of the official URDF link masses (several are round values upstream)
Motors	2x DG01D-E gearmotors with encoders, 48:1 gearbox, rated 3-9 V (SparkFun listing linked from the official BOM), driven via an L298N
Sensors	RPLIDAR A1M8 2D lidar (top), Raspberry Pi Camera V2 (front), BNO055 IMU, wheel encoders
Wheels	66.2 mm diameter x 25 mm — official wheel.yaml radius 0.0331 m

Source: Ekumen-OS/andino (official project repository) · linkLicense: BSD-3-ClauseSpec file: examples/andino.jsonLicense is per-package LICENSE files in the repo (each reads BSD 3-Clause, (c) 2023 Ekumen Inc.); the repo root carries no single LICENSE file. Spec values were read from andino_description/config/andino/*.yaml and the andino_hardware BOM.

Gate runs

Measured against simulator ground truth at the locked thresholds: pass ≤ 5% / 5°, fail over 10% / 10°. The gate tests the spec's simulated twin, not a physical robot.

Run	Drive vs truth	Turn vs truth	Odometry distance	Odometry heading
Run 1	1.497%	3.425°	0.003%	8.285°
Run 2	0.347%	9.104°	0.003%	11.624°

Run 1: Gate run 1 on scythe, 2026-10-26, build/gate-andino-1/gate-report.json — run verdict MARGINAL (motion vs ground truth PASS; odometry heading MARGINAL)
Run 2: Gate run 2 on scythe, 2026-10-26, build/gate-andino-2/gate-report.json — run verdict FAIL (turn vs ground truth MARGINAL at 9.104 deg; odometry heading FAIL at 11.624 deg)

Two recorded runs on scythe (2026-10-26), no PASS — recorded as measured; the locked thresholds were not touched. The drive is excellent in both runs (1.497% / 0.347% against ground truth, odometry distance error 0.003%), but the pivot turn is the failure mode: the robot is heavy (3.364 kg — the sum of the official URDF link masses) on two passive caster balls, so in a turn it physically under-rotates while its wheel odometry (perfect joint integration) over-reads heading by 8.285-11.624 degrees. The gate's own suspect line names wheel_separation / caster scrub. Diagnosis recorded; the verdict was not massaged.

Harness checks

Electrical checks over this robot's documented wiring. Not a simulation; the headline is counts, never a blanket pass.

Harness checks: 2 clean · 1 warn · 0 err · 29 not checked

2 checked clean · 1 with warnings · 0 with errors · 2 partial · 29 not checked · missing data: cable.gauge_awg ×12, connector at both ends (connector_from / connector_to) ×12, current_a for nano ×7

Check-by-check counts and missing data

Check	Checked	Partial	Not checked
voltage drop	0	0	6
ampacity	0	0	6
logic levels	3	0	3
rail budget	0	2	2
connector match	0	0	12

Findings (1):

[WARN] controller -> nano: logic levels 3.3 V and 5 V do not agree and no level shifter is recorded on the link — a 3.3 V input is not 5 V tolerant; add a shifter or record one

Missing data — the datasheets still to hunt. A check that could not run says what it needs:

Missing input	Blocks	Needed by
`cable.gauge_awg`	12	battery -> driver, battery -> regulator, regulator -> controller, controller -> nano …
`connector at both ends (connector_from / connector_to)`	12	battery -> driver, battery -> regulator, regulator -> controller, controller -> nano …
`current_a for nano`	7	battery -> regulator, regulator -> controller, controller -> nano, controller rail
`cable.length_mm`	6	battery -> driver, battery -> regulator, regulator -> controller, controller -> nano …
`current_a for motors`	5	battery -> driver, driver -> motors, driver rail
`connection voltage (volts)`	2	driver -> motors, controller -> lidar
`current_a for controller`	1	regulator rail
`current_a for driver`	1	battery rail
`current_a for regulator`	1	battery rail
`logic_v for camera`	1	controller -> camera
`logic_v for imu`	1	controller -> imu
`logic_v for motors`	1	motors -> nano
`rated output current for battery`	1	battery rail
`rated output current for controller`	1	controller rail

Report: catalog/harness-reports/andino.json · checked 2026-10-27 · reproduce with robotforge harness examples/andino.json

Take it apart

Every spec becomes a kit of simple, 3D-printable parts (robotforge cad). This viewer lays the kit out the way the kit's own assembly file does, straight from the spec's numbers — flat views, or in 3D with the toggle. Click any part.

Loading examples/andino.json…

Parts kit

The take-apart kit robotforge cad generates from this robot's spec: every part the generator defines, what it does, and the parameters worth tweaking with the values this robot's kit ships with. Each parameter carries the generator's own source label — from spec numbers come out of the spec, derived numbers are computed from them, and assumption numbers are typical values the spec does not carry.

Chassis plate ×1

parts/chassis_plate.scad

The deck everything else bolts to.

250 x 100 mm footprint, 4 mm thick

Parameter	Value	Where the number comes from
`chassis_length_mm`	250 mm	from spec length_m
`chassis_width_mm`	100 mm	from spec width_m
`plate_thickness_mm`	4 mm	assumption — not in the spec
`corner_radius_mm`	6 mm	assumption — not in the spec
`mount_hole_diameter_mm`	3.4 mm	assumption — M3 bolt clearance
`mount_hole_inset_mm`	12 mm	assumption — not in the spec

Print note: Print flat as modeled. Suggestion: 3-4 walls, ~25% infill.

Wheel ×2

parts/wheel.scad

Rolls on the ground; one per wheel position on the robot.

66.2 mm diameter x 25 mm wide, 6 mm shaft hole

Parameter	Value	Where the number comes from
`wheel_diameter_mm`	66.2 mm	from spec wheel.diameter_m
`wheel_width_mm`	25 mm	from spec wheel.width_m
`shaft_diameter_mm`	6 mm	assumption — typical DC gearmotor shaft; measure yours
`hub_diameter_mm`	26.5 mm	derived — 0.4 x wheel diameter, for looks/strength
`lightening_hole_diameter_mm`	7.9 mm	derived — decorative; delete the loop below for a solid wheel

Print note: Print flat as modeled. Suggestion: print one first and check the shaft fit before printing the rest.

Motor mount ×2

parts/motor_mount.scad

Side plate that holds one drive motor so its shaft lines up with a wheel's axle.

41 mm wide plate, shaft hole at axle height 33.1 mm

Parameter	Value	Where the number comes from
`shaft_center_height_mm`	33.1 mm	from spec wheel radius (diameter_m / 2) — the axle height above ground
`mount_width_mm`	41 mm	derived — wheel width + 16 mm of plate around the motor
`mount_height_mm`	44.1 mm	derived — reaches from the ground past the axle to the chassis plate
`mount_thickness_mm`	4 mm	assumption — not in the spec
`shaft_hole_diameter_mm`	6.4 mm	derived — shaft diameter + 0.4 mm slip fit
`flange_depth_mm`	16 mm	assumption — how far the bolting flange reaches under the chassis
`flange_hole_diameter_mm`	3.4 mm	assumption — M3 bolt clearance

Print note: Suggestion: 40% infill — this part takes the motor's twist. The motor itself is not a printed part.

Caster ×2

parts/caster.scad

Ball caster that keeps a two-wheel robot level (one front, one rear). Placeholder for a real ball-caster unit.

ball diameter 30 mm (= ground clearance, so the ball tops out at the deck)

Parameter	Value	Where the number comes from
`caster_ball_diameter_mm`	30 mm	from spec ground_clearance_m — ball top meets the deck underside
`caster_stem_height_mm`	10 mm	derived — reaches into/past the deck plate for bolting
`caster_stem_diameter_mm`	15 mm	derived — half the ball diameter

Print note: Suggestion: expect a loose fit — sand or scale 1-2% for a snug cup. A bought ball caster rolls far better.

Lidar mount ×1

parts/lidar_mount.scad

Post that raises the 2D lidar to the top of the robot so its scan plane clears the chassis.

post 170 mm tall, top disc 70 mm diameter

Parameter	Value	Where the number comes from
`post_height_mm`	170 mm	derived — spec height minus deck and disc thicknesses
`post_diameter_mm`	12 mm	assumption — not in the spec
`lidar_disc_diameter_mm`	70 mm	assumption — typical 2D lidar puck; measure yours
`disc_thickness_mm`	3 mm	assumption — not in the spec

Print note: Print upright as modeled. Suggestion: ~25% infill; the lidar itself is not a printed part.

Camera bracket ×1

parts/camera_bracket.scad

Bracket that holds a camera (rgb_camera) at the front of the robot.

44 x 34 mm plate, 12 mm lens hole

Parameter	Value	Where the number comes from
`bracket_width_mm`	44 mm	assumption — small-camera class; not in the spec
`bracket_height_mm`	34 mm	assumption — not in the spec
`bracket_thickness_mm`	3 mm	assumption — not in the spec
`lens_hole_diameter_mm`	12 mm	assumption — measure your camera
`foot_depth_mm`	20 mm	assumption — how far the bolting foot reaches

Print note: Print flat as modeled. Suggestion: the lens hole is a visual guide — measure your camera before drilling.

Reproduce it

Run these from a clone of the repository.

robotforge validate examples/andino.json
robotforge urdf examples/andino.json --out build/andino.urdf
robotforge cad examples/andino.json
robotforge run-gate examples/andino.json
robotforge harness examples/andino.json