Send a rover to check the trough
When the trough sensor says the water is low or the reading looks off, you can drive out, or you can send SKD-1. It's a small open-source rover that follows GPS waypoints. This plan has it drive a saved route to the trough, take photos of the trough and fence, and come back. About $1,617.45 in parts.
Prices and links checked Oct 25, 2026. Where we couldn't confirm something, we say so.
What works and what doesn't
Shown working by the SKD-1 team
Mapping and driving to goals indoors with Nav2, including one 25 m away. Outdoors, following GPS waypoints with RTK in an open field while an operator watched.
A stretch
Driving a saved route to a trough when the sensor sends an alert, taking photos and coming back. Every piece exists, but nobody has put them together on a ranch. That part is this plan.
Not solved
Obstacle avoidance in sunlight, range much past a couple of kilometers, charging without a person, tall grass, mud and weather. See what's hard below.
SKD-1 paper, Hardware 2026, SKD-1 GPS waypoint video, SKD-1 indoor Nav2 video
The job
A trough sensor tells you the level. It can't tell you whether a float valve stuck, a pipe broke, cattle knocked something loose or the sensor itself is off. Today you find out by driving there. A rover that can drive a known route and send a few photos lets you skip the trips that turn out to be nothing, and go prepared on the ones that aren't.
SKD-1 is a four-wheel skid-steer rover from a research group in Santa Fe, Argentina. It's 410 × 260 × 370 mm, weighs 6 kg, and runs ROS 2 Jazzy with Nav2 on a Raspberry Pi 5. The authors put its parts at about $1,750, against $3,200 to $27,000 for the commercial research rovers they compared it to. It was featured in Weekly Robotics #375.
SKD-1 paper, Hardware 2026, SKD-1 on GitHub, Weekly Robotics #375
How the two builds connect
- The trough node sends its level over LoRaWAN to The Things Network.
- Node-RED sees a low or odd reading and sends an ntfy alert to your phone with a button to send the rover.
- You tap it. Node-RED tells the rover, parked on Wi-Fi at the barn, which saved route to drive.
- The rover follows the GPS points with Nav2 and sends short status messages over LoRaWAN on the way.
- At the trough it takes photos of the water and the fence line, then drives back and uploads them over Wi-Fi.
TTN webhooks, Node-RED (Apache 2.0), ntfy action buttons, Nav2 GPS navigation tutorial
See it indoors
Indoors, SKD-1 builds a map with its LiDAR and drives to goals with Nav2. The authors tested a goal 25 m away. Here it is with the robot's view in RViz and Foxglove.
What it replaces
Mostly the drive. Trough monitors tell you the level but not why it changed, and ready-made outdoor robots cost far more.
| Option | Price | What it does | Notes |
|---|---|---|---|
| Drive out and look | Your time and fuel | You check the trough and fence yourself | Still the most reliable check. The point of this build is to skip the trips that turn out to be nothing. |
| Meterra Trough | $399, then from $10 a month | Reports the water level over cellular | Tells you the level. It doesn't show you why it dropped.Meterra trough monitor |
| Ranchbot Trough Direct | $549 plus $0.75 a day at launch (Feb 2025) | Reports the water level over satellite | No current price posted.Ranchbot Trough Direct launch release, Feb 2025, Ranchbot Trough Direct |
| Husarion ROSbot 3 | About $3,200 | Small ROS 2 research robot | Price from the SKD-1 paper's comparison table.SKD-1 paper, Hardware 2026 |
| AgileX Scout Mini | About $8,300 | Skid-steer ROS research rover | Price from the SKD-1 paper's comparison table. The Scout 2.0 is listed there at about $14,200.SKD-1 paper, Hardware 2026 |
| Clearpath Husky A300 | About $27,000 | Large outdoor research rover | Price from the SKD-1 paper's comparison table. The Jackal is listed at about $17,000.SKD-1 paper, Hardware 2026 |
| This build | About $1,617.45 in parts | Drives a saved GPS route to the trough and sends back photos | Works alongside the $91 trough sensor. Short range, no obstacle avoidance in sun, and nobody has run it on a ranch yet.SKD-1 on GitHub, SKD-1 paper, Hardware 2026 |
The research rover prices are the approximate figures in the SKD-1 paper's Table 1, from European and US resellers. We didn't re-check them.
Parts
USD, as listed on each store page on Oct 25, 2026. $1,617.45 total, before shipping and tax. The paper's own parts list came to $1,709.02. Ours differs mainly because we swapped in a US battery, dropped the paper's travel router, and added a camera and a LoRaWAN board. The trough sensor itself is a separate $91.29. The custom wiring board and cables aren't priced in the paper or here.
| Part | Qty | Price | Source |
|---|---|---|---|
| Pololu 70:1 37D 12 V gearmotor with 64 CPR encoderOne per wheel, the motor the SKD-1 paper uses. Pololu was taking backorders when we checked. | 4 | $60.95 each, $243.80 | Pololu #4754 ↗checked Oct 25, 2026 |
| Pololu 37D motor bracket pairL-brackets that hold the motors to the chassis. | 2 | $11.95 each, $23.90 | Pololu #1084 ↗checked Oct 25, 2026 |
| Pololu 12 mm hex wheel adapter, 2-packConnects each 6 mm motor shaft to a 12 mm hex wheel hub. | 2 | $8.95 each, $17.90 | Pololu #2687 ↗checked Oct 25, 2026 |
| Dagu Wild Thumper 120×60 mm wheel pairPololu and the US shops we checked are sold out or have dropped it. Robot Gear in Australia had them in stock. We converted at the ECB rate of 0.70224 from Oct 23. Shipping from Australia is extra. Any 120 mm wheel with a 12 mm hex hub fits. | 2 | AUD 45.95 each, about $64.54 | Robot Gear (Australia) ↗checked Oct 25, 2026 |
| Pololu Dual G2 18v18 motor driver shieldTwo motors per board, 18 A continuous per channel. It runs on 6.5 to 30 V, so a 12.8 V LiFePO4 pack is fine. | 2 | $74.95 each, $149.90 | Pololu #2515 ↗checked Oct 25, 2026 |
| WeAct STM32 Blue PillLow-level controller for the motors and encoders, running the authors' hibachi firmware. Price from the paper's BOM (AliExpress). | 1 | $6.40 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
| Raspberry Pi 5, 8 GBRuns ROS 2 Jazzy, Nav2 and the camera. | 1 | $200.00 | Adafruit #5813 ↗checked Oct 25, 2026 |
| Yahboom Pi 5 power boardTakes 6 to 24 V from the battery and gives the Pi 5 V at 5 A. | 1 | $9.00 | Yahboom ↗checked Oct 25, 2026 |
| Pimoroni NVMe BaseHolds an M.2 SSD under the Pi, as in the paper. | 1 | $18.95 | PiShop ↗checked Oct 25, 2026 |
| Raspberry Pi NVMe SSD, 256 GBOut of stock at Adafruit and CanaKit when we checked. Any small 2230 or 2242 NVMe drive works. You can start on a microSD card instead. | 1 | $75.60 | Adafruit #6090 ↗checked Oct 25, 2026 |
| LiTime 12 V 12 Ah LiFePO4 battery153.6 Wh with a 12 A BMS. The paper used a 12 V 10 Ah pack from an Argentine maker, listed at $250. We swapped in a pack you can buy in the US. Check that it fits the battery bay (about 151 × 98 × 95 mm). | 1 | $65.99 | LiTime ↗checked Oct 25, 2026 |
| LiTime 12 V 5 A lithium chargerWaterproof LiFePO4 charger. 5 A fills the pack in under three hours. | 1 | $69.99 | LiTime ↗checked Oct 25, 2026 |
| ArduSimple simpleRTK2B Basic Starter Kit (IP65)RTK GNSS board, IP67 antenna and 5 m cable. €211 on ArduSimple's euro view. On its own it's good to about 1.5 m. Centimeter accuracy needs corrections from a base station or an NTRIP service. | 1 | $253.20 | ArduSimple ↗checked Oct 25, 2026 |
| PhidgetSpatial Precision 3/3/3 IMUThe IMU in the paper. It feeds heading to robot_localization. | 1 | $105.00 | Phidgets MOT0110_0 ↗checked Oct 25, 2026 |
| Slamtec RPLIDAR C1Used for mapping and obstacle avoidance indoors. It isn't rated for direct sun, so the authors turned obstacle avoidance off outside. | 1 | $69.00 | DFRobot ↗checked Oct 25, 2026 |
| Raspberry Pi Camera Module 3 Wide120° camera for the trough photos. Added for this plan. The paper's robot has no camera. | 1 | $38.50 | Adafruit #5658 ↗checked Oct 25, 2026 |
| Pi 5 camera cable, 200 mmThe Pi 5 uses a smaller camera connector than older boards. | 1 | $2.70 | Adafruit #5818 ↗checked Oct 25, 2026 |
| RAK WisBlock Starter KitThe same LoRaWAN kit as the trough node. On the rover it sends short status messages back over TTN when it's out of Wi-Fi range. | 1 | $24.99 | RAK WisBlock Starter Kit ↗checked Oct 25, 2026 |
| Acrylic base plateLaser-cut from the authors' files. Paper BOM price. | 1 | $20.00 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
| Acrylic coversLaser-cut body panels. Paper BOM price. | 1 set | $75.00 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
| PETG filament, 1 kgFor the printed brackets and mounts. Paper BOM price (Creality). | 1 | $21.99 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
| Switch, voltmeter, e-stop, fuse holder, DC jack, aluminum ground planeThe paper's prices for each: $4.84, $2.15, $16.71, $1.76, $1.25 and $4.39. | 1 set | $31.10 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
| Screws, nuts and standoffsPaper BOM estimate. | 1 set | $30.00 | SKD-1 paper, Hardware 2026 ↗checked Oct 25, 2026 |
Step by step
1. Build the trough monitor first
The rover only goes out when something looks wrong, so you need the alert first. Build the trough plan, get readings into TTN, and confirm ntfy reaches your phone when the level drops.
2. Get the SKD-1 files
The main repo has the ROS 2 Jazzy packages and the wiring diagram. skd1_extra has the design files and the parts list. hibachi_firmware is the Blue Pill code. It's all Apache 2.0.
SKD-1 on GitHub, skd1_extra (design files and BOM), hibachi_firmware, Apache 2.0
3. Build the base
Cut the acrylic, print the brackets in PETG, and mount the four motors, wheels and drivers. Wire the e-stop and fuse between the battery and everything else before you power anything on. The paper's appendix lists every part.
SKD-1 paper, Hardware 2026, skd1_extra (design files and BOM)
4. Bring it up indoors
Flash the Blue Pill, install ROS 2 Jazzy on the Pi, and drive it by hand. Then try mapping and Nav2 goals in a hallway, the way the authors did, before you take it outside.
git clone https://github.com/gmsanchez/skd1.git
5. Add RTK GPS and test in an open field
Mount the RTK antenna up top and set up navsat_transform and robot_localization as the repo does. You need correction data for centimeter accuracy: a second simpleRTK2B kit as a base at the barn, or an NTRIP service if you have cell coverage. Walk it through a few waypoints on open, flat ground and stay close to the e-stop.
Nav2 GPS navigation tutorial, ArduSimple, SKD-1 GPS waypoint video
6. Record the route to each trough
Drive the rover by hand from where it parks to each trough you want it to check, and save the GPS points along the way. Keep routes on tracks or mown strips. The 88 mm ground clearance won't handle tall grass or mud.
7. Add the camera and LoRaWAN status
Plug the wide camera into the Pi and take stills with rpicam-still at each stop. Wire the WisBlock to the Pi over serial so the rover can send a short status (left, arrived, photo taken, heading back, battery) over TTN while it's out of Wi-Fi range. Photos upload when it's back on Wi-Fi.
rpicam-still -o trough.jpg
8. Connect the alert to a mission
In Node-RED, listen for a low or odd reading from the trough node. Have it send you an ntfy alert with a button to send the rover. When you tap it, Node-RED tells the parked rover which saved route to run, and a small ROS 2 node sends those points to Nav2's follow_gps_waypoints. We'd keep a person tapping that button rather than dispatch it on every alert.
Node-RED (Apache 2.0), ntfy action buttons, TTN MQTT, Nav2 GPS navigation tutorial
9. Start short and stay with it
Run the first missions to a nearby trough while you watch, and keep a phone alert as the backup. Look at what the photos show and how much battery is left when it gets back before you try a longer route.
What's hard
Range on rough ground
Top speed is 0.75 m/s in software. The paper gives 1 to 2 hours a charge. Two hours at full speed is about 5.4 km of driving, so roughly 2.7 km out and back in the best case. That's our arithmetic, not a test. Grass, slopes and stops for photos will cut it, and skid-steer turns slip a lot. The authors had to scale wheel separation by 1.39 to make turns add up.
How to help: Log distance and battery on a real pasture route and share the numbers.
Battery and charging
The pack is about 120 to 150 Wh, and the paper didn't measure current draw while driving. There's no dock, so someone plugs it in after each run. Power management is on the authors' future list.
How to help: A simple drive-on charging contact at the barn would make this far more useful.
Outdoor navigation
The RPLIDAR C1 isn't rated for direct sunlight, so in the outdoor test the authors turned off obstacle avoidance and an operator supervised. The rover follows GPS points and won't stop for a calf, a rut or a fallen post on its own. The test area was open and clear of obstacles.
How to help: Test a sunlight-rated LiDAR or a depth camera, both on the authors' list, and share costmap settings that work outside.
Ground clearance and weather
88 mm of clearance and 120 mm wheels suit tracks and short grass. The body is acrylic and printed plastic with no weather rating. Rain, mud and dust are untested, and cattle may push it over.
How to help: Try a sealed enclosure and bigger wheels, and report what they cost in range.
GPS corrections and links
Centimeter positioning needs RTK corrections from a base or NTRIP. Without them it's about 1.5 m, which can miss a gate. LoRaWAN carries short status messages but not video, so you can't watch live from far away.
How to help: Share a base station setup that covers a whole property, or a cheap long-range way to send one small photo.
Nobody has done this on a ranch
SKD-1 was tested in a lab and in an open field. Sending it to a trough on a real alert is our plan, and we haven't built it.
How to help: If you try it, tell us what broke first.
Start with the trough sensor
The rover is the second half. The trough monitor plan covers the sensor, the LoRaWAN gateway and the phone alerts, for about $91.29 a trough with no monthly fee. Build that first. It's useful on its own.
What we couldn't confirm
- How far SKD-1 goes on one charge over grass. The paper says 1 to 2 hours and didn't measure current while driving.
- Whether the LiTime battery fits the battery bay as drawn. The paper used a different 12 V 10 Ah pack.
- A US store for the 120 mm Wild Thumper wheels. We priced them from Australia.
- Prices for the acrylic, filament, small electrical parts, fasteners and Blue Pill. We used the paper's figures.
- The commercial rover prices, which come from the paper.
- We haven't built one. Prices change, so check the source before you buy.
Credit and license
SKD-1 is by Guido M. Sánchez, Alejandro Capovilla, Marina Murillo, Hugo S. U. Hernández, Juan E. Benavidez, Nahuel Deniz and Leonardo Giovanini at sinc(i), FICH-UNL and CONICET in Santa Fe, Argentina. The ROS 2 packages, firmware and design files are released under Apache 2.0, and the paper is open access. The videos are Guido Sanchez's and play from YouTube. The image used when this page is shared comes from the SKD-1 repo. We found SKD-1 through Weekly Robotics, which thanked Guido, a reader, for sending it in.
SKD-1 on GitHub, SKD-1 paper, Hardware 2026, doi:10.3390/hardware4030017, Apache 2.0, Weekly Robotics #375, Weekly Robotics on X