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RoboticsDesign rev A, 27 Oct 2026: CAD for 15 parts, fit checks, assembled field model and 4 shared checks done; not built

GroundsKit

One groundskeeper's kit: GPS line marking, wet spots, tarp and rain on one post and one app

GroundsKit does the jobs of SmartLine Kit (RTK guidance and the automatic paint valve on the walk-behind striper) and FieldFlag GroundCheck (wet-spot pucks, cover tags on the infield tarp or pitch cover, a rain gauge and one timestamped ground page). SmartLine's tripod base station and GroundCheck's receiver box become one GroundBase on a fence post by the shed: one ESP32-S3 brain, one radio link to the striper that carries both the RTK corrections and the wet-spot map, one 12 V supply. The striper places each puck with its own RTK fix and holds paint on lines that run through standing water.

Who buys it
The grounds lead or athletic director at a school, small college, youth league or parks crew who marks the fields and is asked every wet morning whether the fields are playable.
Why it pays
Bought separately, SmartLine Guide ($2,490 + $29/mo) and a FieldFlag station with the GroundCheck kit ($699 + $349 + $299/yr) cost $3,538 + $647 a year. GroundsKit is $2,890 + $39/mo ($468 a year) (target): no heat station to buy first, no tripod to set up each time.
Target price
$2,890 + $39/month (target); extra wet-spot pucks $49, cover tags $39
First-minute wow
On the handlebar at 7 am: '2 wet spots, standing water in the north goal box: 38 m of line held', and the same page is already on the coach's phone with 14 mm of rain and the tarp on since 21:40.
See the CAD designConcept page
GroundsKit concept: the idea and where each part goes
The concept. The CAD design is below, under Printable CAD.

What the research found

And how this design answers it

  • Two products, two radios, two set-ups → one GroundBase on a fence post: the RTK base and the ground receiver share one box, one brain, one power supply and the antenna mast
  • Checked first: the striper visits once or twice a week but pucks report every 15 min, so the striper cannot replace the fixed receiver; the receiver moved into the base station instead
  • Dropped: SmartLine's tripod and its daily survey-in, GroundCheck's XIAO RP2040 receiver box and RS485 cable, and the need to buy a $699 heat station first
  • New shared jobs (4/4 checks pass): lines near standing water or saturated turf are held with the reason shown; a silent puck shows as missing, never dry; each puck is placed by the striper's own RTK fix
  • Rules: the kit shows readings only. It never closes a field or calls it fit; the league, umpires or parks department decide

Use case

Wet Saturday: mark or wait?

Grounds leadGroundsKitCoaches and the league

  1. 01Trigger: 14 mm of rain overnight; the infield tarp went on at 21:40
  2. 02Detection: 2 of 6 pucks report standing water by the north goal box; the rest are near their baseline
  3. 03Action: the handlebar plan paints 1,104 m and holds 38 m of goal-box lines until the spot drains
  4. 04Tell: the ground page with rain, tarp times and wet spots goes to coaches and the league at 7:30

Outcome: No paint wasted on a puddle, no second trip to re-mark, and the field decision is made by the right person with the facts (est.)

How it works

Architecture

  1. 01

    Sense: RTK rover on the striper; on the post, an RTK base and rain gauge; wet-spot pucks and tarp tags over LoRa

  2. 02

    Decide: XIAO ESP32S3 builds the wet-spot map; the handlebar ESP32-S3 splits the line plan into paint-now and hold

  3. 03

    Act: 12 V normally-closed paint valve, shut on fix loss and on held lines

  4. 04

    Tell: handlebar screen, one ground page and run log in the app

Hardware

Real parts, buyable today

Bill of materials: about $1,200 for the striper kit, GroundBase, 4 pucks and 2 cover tags (est.).

BlockPartWhy this part
RTK GNSS2x u-blox ZED-F9P (SparkFun GPS-RTK2) + 2x ANN-MB-00Rover on the striper, base fixed on the post: no tripod, no survey-in each time
LinkSparkFun SiK Telemetry Radio V3 915 MHz pairOne link carries the corrections and a 60-byte wet-spot map
GroundBase brainSeeed XIAO ESP32S3 + RAK3272S LoRa receiverHears pucks and tags, counts rain, uploads over the shed Wi-Fi
Ground nodes4 wet-spot pucks + 2 cover tags (RAK3272S each)Unchanged GroundCheck nodes, about 2 seasons on lithium cells (est.)
StriperWaveshare ESP32-S3-Touch-LCD-4.3B + 12 V valveUnchanged SmartLine Guide handlebar and valve

Mechanical

Printable CAD

15 parts, generated from code and checked as closed solids. Pick a part to inspect it, or download the STL files to print.

Loading the CAD…

Real CAD · drag to rotate · scroll to zoomReal CAD · swipe sideways

Open risks we are working on

  • Wet-spot readings depend on soil: each field needs a baseline season, and clay and sand fields are untested
  • 915 MHz SiK and LoRa share the band; the map rides in gaps of the RTK stream, unproven at 300 m
  • A club or school may read the page as a verdict; it shows readings only, never 'fit' or 'closed'
  • Walking to ±3 cm by bar graph is still unproven until the SmartLine field test

Design stage only: nothing on this page is for sale. Specifications and prices are targets.