JetsonHacks

JetsonBot Part 4 – A Vision Robot with a Create 2 Base – Second Prototype

Test drive of the 2nd JetsonBot prototype

After taking the JetsonBot out for a demo test drive, it was time for a brief discussion of next steps. Looky here:

With the acquisition of some 1/4″ ABS 12.5″ rounds, it took just a little work to bring up the second prototype of the JetsonBot. There is a video of the assembly. Looky here:

Once assembled, the time had come to go out for another test drive. Looky here:

Background

I just happen to live about 20 minutes away from Burbank, which is in the center of most of the Hollywood studios. There are a large number of specialty shops which supply the movie industry with material to build props and sets. While almost any plastics shop can provide you with 1/4″ ABS black 12.5″ rounds, do they have this kind of customer service?

I didn’t think so. I know you’re jealous. Actually the studio across the street from the plastic store is Jim Henson Studios, where they produce the Muppets, so it might not be as scary as it seems. I’m not quite sure about the story of my friend above, but my guess is that the shop is a very strange place late at night. They have a different definition of Hacker than people in the computer industry.

The rounds were around $15 USD apiece, cut on a CNC machine. You can make your own, of course. The ABS is textured on one side in a Haircell Finish. As you know, ABS is the plastic which Legos are made. Of course, the rounds are black because as Batman says in the ‘Lego Movie’, “I only work in black, or sometimes very, very dark grey”.

Installation

Installation is the same as shown in previous articles, the instructions are reprinted here for convenience.

Preparation

First prepare the iRobot Create 2 base.

The JetsonBot has two platforms that are mounted on top of the iRobot Create 2 base. The platforms are each mounted on 3″ 4-40 stainless steel standoffs, available from McMaster Carr (part number 91075A700).

The platform layout is taken from the original TurtleBot, available at Download TurtleBot 1 Documentation. This information is combined with the layout information from the Create 2 cutting guide template and transferred to the round.

In the video, you will notice that Brass Heat Set Inserts are used. I ordered them from McMaster Carr: Brass Heat-Set Insert for Plastics Tapered, 4-40 Internal Thread, .219″ Length. The insert provides a place to mount the standoffs. I also used a specially designed soldering iron tip (also available from McMaster Carr), but most soldering irons will probably work.

One of the advantages of using plastic is that is relatively malleable, and that the tolerances do not have to be quite as strict in order to get things lined up. The brass inserts are a neat little solution especially tailored to plastic which allows a connection which is nearly equivalent to the strength of the plastic.

Installing the Jetson on Top Platform

The next step is to install the Jetson TK1 on to the top platform, along with a platform for the RGB3D camera.

The Jetson TK1 is mounted in the middle of the platform, and is mounted on 1/4″ 4-40 standoffs that are screwed into Brass Inserts that are placed in the platform. A rectangular platform that is 2″ wide by 8.5″ long made out of 1/4″ ABS is used to mount the RGBD camera. The camera platform is mounted on 3″ 4-40 standoffs screwed into Brass Inserts inset in to the platform where the Jetson is mounted.

A useful tool is a carpenter’s square (A Stanley 24-Inch x 2-Inch Steel Rafter/Roofing Square was used in the video).

The main challenge is finding the center of the round platform, the carpenter’s square makes that easy. For the most part, layout was done on a paper copy of the Create 2 cutting guide template and transferred to the round.

Assembly

Lower Platform

On the lower platform, a 4 port USB hub (AmazonBasics 4-Port USB 2.0 Ultra-Mini Hub) is attached to the platform using 3M Dual Lock Reclosable Fastener TB4575 . 3M Dual Lock is an alternative to velcro fastening. In this application, it is useful as there will probably be experimentation with component placement. Dual Lock is strong enough to make sure components don’t wander, but can be removed if the need arises. The cable from the Create 2 base is attached to the USB hub. The hub will be attached to the Jetson, and the RGBD camera will also be attached to the hub.

Next, a platform for the a Venom 20C 3S 2100mAh 11.1 LiPO Battery (available from Amazon) is attached to the platform, and fitted with Traxxas 5722 Battery Straps. The battery will power the Jetson TK1. You can read more about powering the Jetson with a battery Battery Power for NVIDIA Jetson TK1. A Venom Low Voltage Monitor is used to monitor the LiPo battery voltage.

Upper Platform

After attaching the Jetson TK1 to the upper platform on 1/4″ 4-40 standoffs, the upper platform is attached to the lower platform. Next the RGBD camera, an ASUS Xtion Live Pro, is mounted on the camera platform, held in place with battery straps for the time being. The USB hub is plugged into the Jetson TK1, then the RGBD camera is plugged into the USB hub.

Note:
In the Jetson’s mPCIe slot an Intel Network 7260 WiFi Wireless/BT card is installed, and antennas attached.

Ready for a test drive! Next up is installing ROS software to run the robot.

I could not resist another shot of my new friend:

Off to Part 5 – USB FTDI Module