Intel OTIS Robot Build With Pololu Robotics Parts
Part 1: Mechanical
When we first saw the Intel Euclid Development Kit at Maker Faire Bay Area this summer, we were pretty intrigued. The unit combines optical and depth cameras, with an IMU, and a quad-core CPU to create an all-in-one ROS-fuelled robot vision controller.
Recently, Intel also released a robot they call OTIS, based on the Intel Euclid Developer Kit. OTIS is a simple framework for incorporating the sensor onto a moving platform powered by two wheels and a simple motion control system. Although the build instructions on the Euclid Community Site are decent, they omitted a lot of details about the actual parts and procedures needed to assemble and wire OTIS. We decided to write up a tutorial for people that wanted a start-to-finish build of OTIS along with a list of parts and where to buy them.
We decided to see if we could build OTIS exclusively out of parts available from Pololu Robotics, as they are one of the best sources for robot parts on the Internet, and are very reliable and quick to ship parts on every order we have placed there. Hands down, if you’re trying to make a robot, Pololu is the place to start.
We were happy to find parts that fit the bill at Pololu. Here is our Bill of Materials (BOM):
- Wheels – 2 x Solarbotics GMPW-R Red Wheel (Many different colours are available depending on your intended paint scheme for OTIS)
- Ball Casters – 2 x Pololu Ball Caster with 1″ Plastic Ball (We used the Old Version because these casters seemed to line up properly with the bolt pattern in the base of the OTIS model)
- Motors – 2 x 120:1 Plastic Gear Motor, 90 Degree Output
- Motor Driver – 1 x TB6612FNG Dual Motor Driver Carrier (Handles two motors)
- Battery Holder – 1 x 4-AA Battery Holder (We initially started with a 3-AA battery holder, but the extra voltage from the 4th cell is definitely helpful for propelling OTIS, so we switched to 4 cells)
- Header Pins and Sockets – You will find it useful to have some pins and sockets that match the pitch of Arduino and the Motor controller. Grab a handful. You can cut or break them to the sizes you want.
- Small Breadboard or Protoboard – We started by temporarily wiring up to a small breadboard, and then once everything was working, we soldered down onto a protoboard.
- Assorted Wire, Etc. – If you don’t already have a bench with wires, tools, soldering, etc. that’s a bit of a different topic. We used some solid core, and some braided wire. There are lots of options and tutorials on stocking a bench. We’ll assume you’ve got those supplies.
Step 1: Printing
The parts for OTIS are available on Thingiverse. We ended up printing on an Ultimaker 3 and Lulzbot TAZ5, which had enough bed area to fuse together many of the pieces at print time, omitting the need for clips and some of the other assembly details that were specified in the original assembly guide. If you have a large enough print area, this is definitely the recommended approach as it saves a bunch of steps.
The original assembly guide is available on the Euclid Community Page in the “Building OTIS” section.
Regardless of how you choose to print and assemble the mechanical components of OTIS, we will assume you’ve got mechanical assembly sorted before advancing to Step 2.
Step 2: Mount the Motors and Wheels
In our case, we printed the two halves of the platform as one on our TAZ 5 with a MOARStruder. The beefy MOARStruder extrudes a 1.2mm bead, making for a very solid mechanical platform for the robot. However, we had some slight problems with the large bead size where the corners in the motor mounting positions were rounded off a bit making a difficult fit. A little bit of Dremel work to flatten them out fixed everything up so that we had a flush fit on between the gearbox and the platform. Your mileage may vary, but make sure to test fit your motors into the gaps.
Once you’ve got a good fit, you can screw the motors into place with some small screws:
Wheels were pretty straight forward – the Solarbotics wheels we specified in the BOM are a direct fit onto the output shaft of the Pololu gearbox. They come with a small mounting screw to fasten them onto the shaft. Simply stretch the rubber band around the wheel to form the “tire” and then mount the wheel on the motor shaft:
The ball casters come with all the hardware needed to mount them to the base. There are 3D printed spacers as part of the Thingiverse package for OTIS. These are exactly the correct height for mounting the Pololu casters we specified in the BOM. We needed to drill out our holes in the platform a bit to mount, but otherwise, the process was pretty trivial.
Pro Tip – A small amount of Loctite “Blue” Threadlocker on the bolts going into the ball casters will help prevent the hardware from loosening off over time due to shock and vibration. It’s not strictly necessary, but if you have some around, it doesn’t hurt.
Once you’ve finished up, with the mounting, you’ve got a rolling OTIS chassis!