DIY Telepresence Robot: Part 2

I built a telepresence robot for about $400

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Meseta builds Robots

7 min readAug 6, 2020

In this section, I describe my process of building the mechanical parts of the telepresence robot. For Part 1 see here: https://medium.com/meseta-robots/diy-telepresence-robot-part-1-5243ab564cd8

Having established that my telepresence robot needed to be somewhere between average human standing and sitting height, and would need a tablet in the head, I decided to go for a fairly typical design of a heavy base and some kind of thin stalk that would hold the tablet at the top.

Selecting the Robot Base

Since I wanted to use as much off-the-shelf parts as possible, but I didn’t want it to cost too much. An obvious choice was something like the iRobot create, basically a Roomba but with the vacuum bits stripped out and sold as an educational kit.

The benefit of this option was that the charging dock was already available. but the disadvantage was that it didn’t have a very good battery life, and also was rolling around on two wheels and a castor. I wasn’t sure how much weight it would sustain, and besides, it would have cost $200, which was a bit of a gamble for something that might not have worked.

So I started looking around Aliexpress, and found all manner of DIY kits for dinky little robots, that didn’t seem like they’d be able to support a large stalk without toppling over…

…until I found this product:

I fell in love instantly. I don’t know what the intention was for this, whether it was meant to go into a toy or model tank, or something else — the holes were clearly designed for something to be mounted to it. In any case, this looked perfect: nice and large wide platform for good stability, and I could already tell that the motors had gear reductions on them, which would ensure that it had a good amount of torque to haul the weight (if slowly, but we don’t need it to go fast), and having four separate motors could only be a good sign.

A few weeks later, it arrived. It’s quite a bit wider than it appears in the product shots, and may have been a different model judging by the position of the holes in the plates. But this comes to our advantage as it provides greater stability.

A few things I noted immediately: build was kind of flimsy on the wheels (using screws and nuts as axles, not a terribly stable arrangement); and these were DC brushed motors (the seller didn’t specify in the listing), but they were of a standard size, so I would have been able to swap them with brushless inrunners if I needed more power.

A bigger issue I discovered was that the drive wheels didn’t seem to be coupled to the shaft of the motor, meaning the motors didn’t spin the wheels at all. This seemed like an odd arrangement, but I figured this model must be missing some extra plastic parts. Luckily it was relatively simple to 3D print some couplers that would grab hold of the shaft’s hexagonal head on one end, and the screws of the drive wheel on the other.

Overall, this thing strikes to me as a badly designed mistake, rejected by the company it was made for, and now all of the stock being slowly sold on AliExpress to people like me who buy dumb things on it because I think it looks cool.

Mounting the tablet

With the base sourced, the next task was figure out an arrangement to raise a tablet to about 1.5m above the floor. I thought about using various types of PVC pipe or wood dowel to raise the tablet from the base, but at some point it suddenly struck me that there was already a product that I could purchase that could do this: tablet stands. Tripods with a tablet holder on top, designed for various uses like informational displays, sheet music display for musicians, teleprompter for presentations.

These turned out to be inexpensive, and already came with tablet attachment, and I was happy to not have to figure out how to keep a pole upright. I purchased one on Amazon.

Once the tripod arrived, I explored different ways of mounting it onto the base. I thought about 3D printing holders that grabbed onto the feet, but I noticed that the tripod already had quite large rubber boots that could be slipped off. I could simply drill through and bolt each of the rubber boots to the metal frame, and then slip the tripod into them securely.

A quick test-fit shows that the tripod is at a good height, and sits quite securely in the bolted-down rubber boots.

The next issue was the tablet. The tablet I had opted to use was an old Dell Venue Pro 8, a low-cost tablet that actually runs an Intel Atom processor, meaning it runs a full Windows OS that can run basically any desktop software. This kind of tablet is ideal as it makes development very easy as no special mobile OS software needed to be made, I could use all the usual desktop scripting tools like Python or AHK (in the end, neither were needed). I had bought it in a sale some years ago for about $100, and ever since I switched to a larger phone, the tablet had been gathering dust.

Unfortunately the tripod’s tablet holder wasn’t quite the right size to grip the tablet — it didn’t open wide enough to hold the tablet in landscape, and it wasn’t narrow enough to grip the tablet in portrait. So much for the supposedly flexible design — it would have fitted larger and smaller tablets, but just not this size one.

So, yet again, 3D printer comes to the rescue. Adding a simple spacer allows the spring-loaded claws to grip the tablet again.

Mounting the batteries

I happened to have a couple of small scooter-sized 12V SLA batteries. These batteries are quite heavy, but very robust and safer to potential abuse than lithium ion. I found that they fit perfectly on the remaining space on the base, either side of the tripod.

I just needed a secure way of mounting them. For the third time, the 3D printer is there to save the day. I made a simple tray with holes that matched the existing ones on the plate. The battery sits securely in the tray, and a velcro strap secures it.

Mounting…lights?

Sure, why not? I had this LED strip lying around, so I wrap it around the base of the robot

Mounting the other stuff

With the big pieces attached to the base, there was the small issue of mounting everything else — the substantial amount of power wiring, the electronics, and the small controlling computer.

There wasn’t any remaining horizontal space, other than on top of the batteries, but there was a big gap below the tripod that wasn’t being used, it just didn’t have any surface to mount things to. So I decided to 3D print an under-carriage tray to hold all the wiring and electronics. The brackets for the tray also hold up the LED strip