My Sumo Robot Version 2 for CMRG 2026

From Version 1 to Version 2

My first robot proved that the transmitter, receiver, Arduino program and two-motor idea could work. It also showed the weak points: the L298N motor driver wasted power, the small TT motors were not a strong competition drivetrain, loose prototype wiring could become unreliable, and the whole system needed to be designed together instead of one part at a time.

For Version 2 I kept the useful idea—a remote-controlled robot with an Arduino doing the mixing—but upgraded the parts around it. The new build uses an Arduino Nano-compatible board, HotRC radio, Cytron MDD10A dual motor driver, two GM25 metal gearmotors, a 2S HeliCoxNano battery and a regulated 5 V supply for the controller and receiver.

What I did, step by step

• Read and compared the competition information, then confirmed that the 1 kg RC class requires a programmable control board.
• Tested the HotRC receiver channels and wrote Arduino programs for reading the radio, tank mixing, motor control and signal-loss stopping.
• Used the first robot as a learning prototype before buying stronger final drivetrain parts.
• Changed to a Cytron MDD10A motor driver and a matched pair of 12 V, 580 RPM GM25 metal gearmotors.
• Planned a 2S LiPo power system with a fuse, reachable master switch, suitable wire and a converter adjusted to 5 V for the electronics.
• Measured the real components and made a Tinkercad layout inside the 200 × 200 mm starting limit.
• Left clearance for the wheels, battery, screw terminals, USB port, wire bends and removable parts instead of designing only from board outlines.
• Built and assembled the new chassis, mounted the drivetrain and added the front wedge.
• Saved the tests, diagrams, shopping decisions and mistakes so the next version—and other young builders—can learn from them.

What I learned

The biggest lesson is that a robot is a complete system. Strong motors are not enough if the driver, battery, wiring, wheels or chassis do not match. CAD is also more than making a shape: I had to think about how a screwdriver reaches a terminal, how a thick cable bends, how the battery comes out safely, and how the robot stays inside its size and weight limits.

I also learned that finishing the assembly is not the end of testing. Size, weight, radio failsafe, wheel movement, wiring security, battery condition and heat still need to be checked before a match. Whatever happens in the ring, Version 2 is already a big step from my first robot because I understand much more about why each part is there.

See the full Version 1 and Version 2 build log →

How the competition first landed on our radar

At the EasyKids sumo competition (early August 2026), we met a family touring with a coach. They were generous with their contact line. Their coach is still too busy for us right now, so we’re still looking at that path — and we started chiangmaistudio.com to explore the journey in public.

Then “Dad there” sent another lead: an education center called EDCO (Educatique Corporation) is organizing a larger competition at the end of August at Yupparaj school. Same town. Different organizer. Worth checking carefully.

Miles’s sumo bot build notes →
Looking for makers in Chiang Mai →

Our original decision

What we verified

Sources we used: the organizer site edco.co.th, the official registration form at edco.co.th/cmrg-register, and the Facebook presence for Chiang Mai Robot Games. Details below match the live registration system (as of when we checked in mid-August 2026).

Fees & registration

The registration form is clear: ฿500 per person, flat rate. That single fee covers every competition category you select for that participant. No extra per-event fee on the form.

• Register online: edco.co.th/cmrg-register
• Pay ฿500 (PromptPay / EDCO company account) and upload the slip
• Pick one or more events + age divisions
• System issues a code (e.g. CMRG-001) and a downloadable registration card
• Deadline we were given for registration: until 23 August 2026 — tight, so double-check if we decide to enter

Some flyers and word-of-mouth mention a higher package (around ฿3,400) for a KidBright kit + pre-competition workshop. That does not appear as a required entry fee on the public registration form. Treat kit/workshop packages as optional extras unless EDCO confirms otherwise.

Competition categories (from the official form)

The registration system lists 10 events and about 19 age/weight divisions. Age is calculated from birth year (Buddhist Era) against the competition date.

Main age bands used across most events:

• Junior — ages 8–14
• Senior — ages 15–19
• Open — ages 8–99 (wide participation)

What fits Miles right now?

After one sumo weekend, Miles has a real RC two-wheel bot, a lot of wiring scars, and a clearer idea of what competition day feels like. That’s a strong base — not the same as “ready for every category.”

Most realistic competitive options

1. SUMO RC (1 kg Junior, if age fits) — Same sport family as EasyKids. Rules, weight class, and arena details may differ. Our bot would need a rules check (weight, size, control method, safety) before we pay the ฿500.
2. EasyKids Ring Master — Same EasyKids name as the earlier event; could be a natural next challenge if the format matches skills he already has (control, precision) rather than a full new robot from zero.
3. Attend first, compete later — Show up as family spectators / learners, talk to teams, photograph the field, and decide about future EDCO or CMRG events with better prep time.

Harder with only ~2 weeks

• Autonomous soccer, AI car, and ROS — need platforms and programming we don’t have ready
• Programmable line-following limited to KidBright / micro:bit — different stack from our Arduino sumo
• Innovation project — doable only if we already have a clear project story and team

Pros and cons (family decision grid)

Our working recommendation

Default plan A: register only if we pick one clear category by this week (most likely SUMO RC 1 kg or Ring Master), pass a quick rules check with EDCO/LINE, and Miles still wants another ring — not just Dad wanting more content.

Default plan B (also good): don’t force a half-ready robot. Go as visitors for part of the weekend, learn the formats, collect contacts, and target the next event with better prep — while we keep hunting makers, Sunday hangouts, and that coach connection.

Either way, CMRG 2026 is worth knowing about. It’s a real node in the Chiang Mai youth robotics map, run by EDCO + Yupparaj, with open registration and a price that doesn’t block a family from trying.

Checklist if we decide to enter

1. Confirm Miles’s age band for Junior / Ring Master divisions
2. Message LINE @EDCO or call 095-693-5216: rules PDF, robot size/weight, practice schedule, language support
3. Pick one primary category (optional second only if prep is free)
4. Register at edco.co.th/cmrg-register before the deadline
5. Save the CMRG code and registration card image
6. Do a dry run of the bot against the official rules — not just “it moved last week”
7. Pack batteries, spare fasteners, tape, tools, and water for long venue days

Useful links

• EDCO home: edco.co.th
• CMRG registration: edco.co.th/cmrg-register
• Venue map: Yupparaj Wittayalai School
• CMRG on Facebook: @CMRGTH
• World Robot Games 2026 (context): wrgrobotgames.com/2026

This post is a family decision memo, not an official event page. Rules and schedules can change — always confirm with EDCO before paying or building to a deadline.