Building the Robot Base

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

ItemQtySource *Notes
Arlo Robot Base Kit1#28960
Arlo Robot Top Deck Kit1#28965
Motor Mount & Wheel Kit – Aluminum1#28962
Caster Wheel Kit Rev. B2#28961
HB-25 Motor Controller2#29144
HB-25 Motor controller mount2#725-29144You can use my 3D print instead
Arlo Power Distribution Board1#28996
Arlo Battery Charger1#700-00240
12v Sealed Lead Acid battery (2-pack)1AmazonPowersonic PS-1290 ($42)
8 x 8 in plastic/wood board1h/w store(optional) for securing an Arduino board.
1.5 in tall standoffs with mounting screws4h/w store(optional) for securing an Arduino board
Total Cost ~ $700 USD
Parts sourced from Parallax unless otherwise noted. Prices quoted in 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:

  1. I felt that an Arduino-based motor controller would appeal more widely to the open-source robotics community.
  2. 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).

My Arlo robot base with top deck removed to show the 8in x 8in mounting board (black HPDE sheet), with 2 Arduino Unos attached via metal standoffs.
My Arlo robot base and 8in x 8in mounting board, with 2 Arduino Unos attached.

Assembly

Parallax provides an easy-to-follow Assembly Guide so just head over to their site for details.

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