Agent 390 Tracked Robot

Let's Make Robots Robots
1

Intro

I started like many, hearing about then getting familiar with the Raspberry Pi, playing with digital and analog circuits controlled via its GPIO pins.

1st Mini Project

From basic circuits, I moved on to some more serious projects, such as object-detection / motion-tracking using acoustic sonar (HCSR04s).  (INSERT YOUTUBE LINK HERE).

2nd Mini Project

I bought and built the robot-car from Sunfounder.  It was fun to do but as I got deeper into projects, I realized that the car was just too limited.

3rd Mini Project

I envisioned to some day have an autonomous rover for inside my home, that would learn the layout, accept voice commands, and discern images.  Sort of a home-brew mobile personal-assistant.

(Actually, my initial motivation was to have it track down the cat and get it to stop whining at night)

I realized I was not prepared to start on a "real" robot so I concentrated my efforts on projects having to do with sensing and interaction.

More Projects

The next project after the acoustic tracking, was very similar - to detect and track an object by using infra-red.  (INSERT YOUTUBE LINK HERE)

After that, the next three projects all had to do with voice-recognition , interaction, and learning.

Finally, I did a rather quick project using the Raspberry Pi camera and some simple utilities to perform some image comparsions, and that also via training, allowed the system to "recognize" what it saw. (INSERT LINK HERE)

Finally, though, I was impatient to start work on a robot.

I realized I didn't want a toy.  Something robust.   Very quickly learned that "robust" costs money.

The least expensive tracked robot from Superdroid Robots is over $600 USD, so I went with an Agent 390 from Acrobotics.

I liked the low, large, stable platform provided by the Agent 390.  One can potentially add tall sensors such as cameras, speakers, perhap an arm instead of all that being much lower to the floor.

It's a rather large robot platform for indoors but I was thinking about the future and who knows, maybe take it outdoors, too.

One positive thing is that the track treads are not ribbed or textured so that makes it easier pivot on carpet.  However, in the future I may move to individual wheels.
The current configuration is two 313 RPM planetary motors, one Roboclaw 2x15A motor controller, one 12 sealed lead-acid AGM battery, and a series-parallel set of 18650 Li-Ion battery cells (3S2P).
The 12 SLA battery is just to provide the needed juice for the motors via the Roboclaw controller.
The home-made 18650 pack is to provide power to both the Raspberry and the Roboclaw.
Some items of note learned along the way...
Some feedback has been that everything could easily be powered by the 12V battery.  However, since that has to be fused, I didn't want the power to the Raspberry cut off without proper shutdown.
In case it's not clear, I am going for over-engineering and overkill.
Another note - the Roboclaw has a BEC (battery elmination circuit) that could supply the Raspberry with up to 3A at 5V.  But again, being a bit paranoid, I didn't want something (Roboclaw) who's main responsibility is to provide LOTS of current to some motors, to also be in charge of providing power to the Raspberry.
My thinking also was that by having separate power sources, I might greatly reduce any kickback and noise generated by the high -power circuits , that could potentially harm the Raspberry.
(INSERT CIRCUIT DIAGRAM LINK HERE)
  • Control method: autonomously controlled by onboard microcontroller and digital wireless connection from Linux workstation
  • CPU: Raspberry Pi 3B
  • Operating system: Raspbian
  • Power source: 12v SLA
  • Programming language: C++
  • Sensors / input devices: IR, HCSR04 ultrasonic sensor, Raspberry Pi camera module
  • Target environment: Indoors - Carpet / tiles, Outdoors
This is a companion discussion topic for the original entry at https://community.robotshop.com/robots/show/agent-390-tracked-robot