29 Mar 2011
maxwell
robots
Recently, I rebuilt Maxwell's base using a new design which allows the front plate to drop down
for easy access to the ArbotiX2 prototype being used in Maxwell:
Here you can see the ArbotiX2 with dual 30A motor driver board. On the left is a step-up/down
regulator for the Kinect, this takes 9-18VDC and outputs 12VDC@1.25A. The back area of the
base is pretty much unchanged, housing the SLA battery and power terminals as seen in the
initial post about Maxwell.
22 Mar 2011
maxwell
robots
I had ordered the emergency stop when I bought the first round of parts for Maxwell, but I hadn't
actually designed a location to attach it to on the robot. This weekend I rebuild a number of
components on Maxwell, installing a new base, upgrading the torso wiring harnesses, and installing
the E-stop (seen behind the arm, protected by the torso column):
The E-stop is from
Digikey
and is the type it latches when pressed, such that you need to twist it to release and restart the
current flowing.
Maxwell's ArbotiX is powered off the USB connection, allowing all 12V power to run through the E-Stop.
Pressing the E-Stop then stops all the motors and servos, while the ArbotiX continues to run and
interact with the PC. On releasing the E-stop, everything comes back to life nicely.
20 Mar 2011
maxwell
robots
ros
Previously I've mentioned my issues with the low cost Hokuyo URG-04LX-UG01, even going so far as to say
that the laser in the Neato XV-11 robot was better. One of the major differences between Maxwell and
his little Armadillo cousin is that on Maxwell I have mounted the laser about 6" off the ground, versus
the 2" of the Armadillo. Interestingly, this has had a huge impact on performance -- our walls here in
the lab are mostly white, and the laser works much better on the walls than the black base trim:
I've also found that the same black paint is on our doors, and wreaks havoc on the Kinect. The image
below shows the RGB point cloud -- this is a Sunday, both doors are shut, yet invisible:
Luckily, it looks like the laser picks up the doors when close, so I won't have to worry about Maxwell driving through an invisible doorway.