Monday, February 15, 2016

Saturday meeting

We got together on the 13th for a bit of chat and fiddling with our projects.

The yet-unnamed Water Tank Bot  (WTB?) took a big step forward with test mounting the body.   It has 3D printed custom brackets mounting the tank bottom to the supporting seat frame atop the wheelchair chassis.

The tank doors came out really nice using a very simple but smart build sequence.  First, the hinge line was cut in the tank.   Next, the piano hinges were mounted via pop rivets, and then the final cuts in the tank were made on the top, bottom and split center of the doors.   The doors swing easily and have perfect alignment.

Behind WTB? is the CopperBot, which recently had some detail work for better antenna mounts, less camera vibration, and securely mounting the RCA 833A tube.

The First Person View base station was rigged up on the bench for a demo and to measure power requirements.   With the receiver and 7" display, it's pulling 0.416 amps off a 12v SLA.   It will need a bit more power with a small audio amp and speaker.

Tuesday, February 2, 2016

Copperbot Moving Test

Here is a short video of the CopperBot driving around:

The speaker and FPV video camera servos are being exercised by the Raspberry Pi through their range of movement while it's driving under remote control.    While this may not appear exciting, two problems had to be solved to get here:

First, the Raspberry Pi would reset whenever the R/C started driving the bot around.   This was solved by adding some electrolytic capacitors on the power supply at the Arduino and servo boards.

Next, driving the bot was difficult to control, which turned out to be bad configuration of the Sabretooth controller.   Switching the mode to "independent" matched the R/C transmitter programming, and now it's much intuitive to control.

The Raspberry Pi also recorded compass, accelerator and gyro data while moving.   Later processing it in a spreadsheet, I was able to derive code that will give it good compass heading data.   The sensor suffered from a lot of vibration, however, so the frame needs reinforcing and the data will need smoothing to hopefully mitigate the shaky information.