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Autonomous Canyon crawler

Autonomous Canyon crawler

Old 10-05-2015, 12:13 AM
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Just finished the chassis and now I'm working on the electronics. Picked up a 5200mah lipo and charger today and installed that. It will use a Zed 3-d depth camera ( similar to a kinect but works outside ) and a lidar scanner to find objects and find its route to the destination or roam a defined area autonomously. Building it for canyon crawling with a bunch of cameras on it and to enter the autonomous rover comp that Sparkfun has each year in Colorado. The design is a single axle that supports two outriggers. The motors are attached to the ends of the outriggers and it steers with differential drive. The payload platform is supported with a pair of turnbuckles that attach to a truss on a pivot that hooks up to the red battery box on the back of the rover. A pair of Nvidia Jetson supercompters and an arduino for brains. GPS and an inertial motion unit so it knows when its upside down With all those sensors it will know where it is in the world how fast its going tilt yaw heading angle temp and humidity and light level so it knows when to switch over from the visual Zed camera to the laser ranger for mapping.











Running on ROS robot os. If you want one start saving your pennies. Once its done I'll be publishing the parts list instructions and all the code. And if any of you crawler guys see any really bad mistakes please inform me. This is my first crawler/rover build. The motor controller will work with an xbox controller radio and rx or via the serial port from the computers. All the metal parts are from Actobotics. Servocity.com. They have a ton of parts. I don't like the look of channel so I used as little as I could get by with. Wish carbon tubes weren't so expensive it would be cool to have those. But outside of drilling the holes for wires and the base its all bolt together stuff. They have step files so you can throw it into a 3-d modeler and build it before you buy as well.

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Old 10-24-2015, 12:08 AM
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That is awesome!!!! I've always wondered about automated crawling!!!
Does the suspension flex or twist? How is it regulated?
I'd totally get HB rovers tires, with 2 stage foams, or the voodoo pin tires.
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Old 12-18-2015, 03:11 PM
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The two outriggers are on a central axle so the can move however they need too. The platform all the gear rides on is leveled by the truss rod with turnbuckles attached to each outrigger. It pivots so when the outrigger goes up it doesn't push the platform up. You can see the set-up better in this pic.



Its 11inches long from the center bearing joint to the end of the outrigger. Then another 7 in on the short pieces that adjust the ground clearance. So lots of articulation. Its also set up to convert over to a 6 wheel Mars lander type system without wasting any of the parts on it now. Just cost a bunch to do that and I decided to break it into two phases. Eventually it will have a 6 wheel bogie type system. Each motor is 330oz/in 20:1 geared with a 9amp stall current. Top speed calculates out to a little over 7 mph.

To see the world and figure out its route to the destination you give it the bot uses these two sensors primarily. First is the Zed depth camera. Similar to a kinect except it can be used outside and has no ir component. Made for drones and bots pretty much plug and play with the ROS robot os.



It also has a LIDAR system. This backs up and provides conformation on the Zed depth data and also will take over should the light level get too low for the Zed. its a Pulsed Light Lidar Lite v2. Its also a 360deg scan.



All the chassis parts are off the shelf except the plastic base and top piece. Everything comes from Actobotics servocity. Wheels are proline trenchers.

You don't need to be a genius or math whiz to build an autonomous bot these days. I haven't written a single line of code yet. Outside of changing the port to the one I want to use etc its straight build the stuff from the repos. All the hard math stuff to do the location and mapping is all in packages you can download and install just like any other app. If you want to add something they don't have you don't have to write a complex driver. Just make it spit out messages in a pre defined format that ROS understands and all will be well. Now you do need to have a working knowledge of Linux and how to build programs and you will have to read a ton of stuff to figure out which packages you need to download and how it all fits together but its not rocket science. Eventually I'll be writing some custom code but to get the thing up and rolling there is only one file you need to write and its all about the measurments of your bot. Wheelbase how far the sensors are from the center point stuff like that. Diameter of the wheels how many ticks of the encoder for 1 revolution and thats about it. This information is fed to all the other packages so it knows how far to move stuff etc. Even easier is taking an existing r/c car and adding some sensors. The computer talks to the esc the same way the radio receiver does. So not a lot of complexity there. So if you want one all it takes is some effort. The sensors and other stuff you need are all over the place at all kinds of price points now. Raspberry Pi just released a 5 dollar linux computer that is perfect for retrofitting r/c's. Small and powerful. Can run ROS too. A 20 dollar ultrasonic ranger and you have a line following bot and obstacle avoiding bot. Add one of those lidar units and its full autonomous.











One other thing. The Inertial Measurement Unit can tell if the surface its rolling over is rough or smooth and that is all tied into the motor controls. Any abnormal g forces in any direction and it can respond. The IMU measures forces in 9 axis. The fuses all that information on the chip and spits out nice easy to use data.
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Old 12-19-2015, 03:28 PM
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Holy dang!!! That's fantastic!!! I'd love to see video!
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