I chose the Parallax Arlo Robot Platform for the robot base. This sturdy platform can carry payloads up to 60 lbs. I considered the Turtlebot3 because of its strong ROS community backing, but felt that its low-profile base would limit my future plans, including mounting a 3-4 ft robot body.
Getting the Parts
| Item | Qty | Source * | Notes |
| Arlo Robot Base Kit | 1 | #28960 | |
| Arlo Robot Top Deck Kit | 1 | #28965 | |
| Motor Mount & Wheel Kit – Aluminum | 1 | #28962 | |
| Caster Wheel Kit Rev. B | 2 | #28961 | |
| HB-25 Motor Controller | 2 | #29144 | |
| HB-25 Motor controller mount | 2 | #725-29144 | You can use my 3D print instead |
| Arlo Power Distribution Board | 1 | #28996 | |
| Arlo Battery Charger | 1 | #700-00240 | |
| 12v Sealed Lead Acid battery (2-pack) | 1 | Amazon | Powersonic PS-1290 ($42) |
| 8 x 8 in plastic/wood board | 1 | h/w store | (optional) for securing an Arduino board. |
| 1.5 in tall standoffs with mounting screws | 4 | h/w store | (optional) for securing an Arduino board |
| Total Cost ~ $700 USD |
While ~$700 is not cheap for a robot base, I couldn’t find a less expensive solution with comparable specs. Sure you can custom build, but that would: 1) make your project way more complex, and 2) make your design harder for others to replicate. I reduced the cost a bit by 3d-printing the mounts for the two HB-25 motor controllers and for 8 ultrasonic sensors.
I made one major change to the Arlo system design. Instead of using Parallax’s recommended Propeller board, I chose an Arduino Uno to control the motors. I did this for two reasons:
- I felt that an Arduino-based motor controller would appeal more widely to the open-source robotics community.
- I want to fully utilize the Arlo wheel encoder’s resolution and wrote an Arduino firmware code to implement this feature. It’s strange that Parallax did not do this for their board, instead settling for half resolution (64 ticks/revolution vs. the full 144 ticks).
I also added an 8 in x 8 in HPDE mounting board for the Arduino as shown below. This is optional but I find that it makes experimenting with different MCU boards easier. (I have a 2nd Arduino mounted for future sensors).
Assembly
Parallax provides an easy-to-follow Assembly Guide so just head over to their site for details.