Time to put the lower platform together and do a test fit. Looks here:
Lower Platform Build
The lower platform consists of four major components:
- VESC – Electronic Speed Controller
- 7 Port USB Hub – Amazon Basics
- A NVIDIA Jetson Development Kit, Here we use a Jetson TX1.
- A Sparkfun IMU (Not shown in video)
Note: This is the second of three prototype builds for the Jetson RACECAR. A full bill of materials will be published for the third prototype.
The electronic components are attached to a laser cut, 1/4″ ABS platform using 1/4″ aluminum standoffs. The USB Hub and the VESC are attached using 3M Dual Lock Reclosable Fastener.
3M Dual Lock
Most people associate Velcro, the original hook and loop fastener with these types of applications. While Velcro is a good alternative, the 3M Dual Lock solution provides some advantages for our application. First, Velcro has a tendency to allow “give”, the attached objects can still move around a little when fastened together. Second, sometimes it’s hard to tell when the fastener is fully engaged. Third, the adhesive on the back of the Velcro has a tendency to lose grip when hot. The industrial versions of Velcro are better, of course.
Dual Lock works differently than Velcro. The fastener consists of continuous polyolefin stems having a mushroom shape. The mushroom heads allow the fasteners to easily slide over each other allowing positioning of parts before they are “snapped” together creating a firm fastening attachment. Where Velcro consists of two different tapes, a hook and a loop tape, the Dual Click consists of one. Dual Lock attaches to itself.
By varying the density of “mushrooms” on the tape, different levels of strength can be achieved. This allows users to mix and match tapes to achieve different strength levels of bonding. Also, Dual Lock offers both rubber and acrylic based adhesives on the back of the tape. The acrylic adhesive offers bonding up to 200 degrees fahrenheit.
The Dual Loop should easily hold the USB hub, we’ll have to experiment a little with the VESC to make sure it holds under heavy use and high heat. However, if the VESC is running close to 200 degrees something else is probably wrong.
There appears to be about 3/16″ clearance with the top platform and the top of the Jetson TX1 heatsink/fan. It’s a pretty tight fit. Have a look:
Check out the video for the test fit, everything appears to line up.
There’s some wiring to do to hook everything up, we’ll have to add batteries. On the MIT RACECAR, they use an extra router for better communications with a base station. We’ll have to think about that, and figure out if we think autonomous means round tripping with other stationary computers. It might be good for testing though …
Are you building a Jetson RACECAR type of vehicle, or other interesting type of Jetson based project? Let us know!