Here is the concept model for my Hex Rover with independent suspension. The suspension has not been fully designed yet, because I will need at least one custom bracket to make it work. This model shows servos, but Hex Rover will use six gear head motors. I just have not finished my 3D Model for the GHM-04 yet, but am working on it again since I actually have two of them to look at and measure. Motors are a lot easier for me to afford than a lot of servos, so I may actually get to build Hex Rover sooner than I originally thought.
I intentionally didn’t align the wheels so you could see that there really is a suspension and each wheel is independent. The inspiration for Hex Rover comes straight from the Journey Robot, created by David P. Anderson and Mike Hamilton of the Dallas Personal Robotics Group.
That jBot is pretty cool. They definitely have a slick custom chassis with the belt drives and RC suspension.
Here are a few thoughts I have about this kind of design:
In RC, independent suspension is used for racing vehicles. The vehicles built for capability (i.e. crawlers) use solid axles because they have a lot more articulation.
I would not use two shocks per wheel as in the jBot. Twelve shocks makes for a lot of shock maintenance. The newer large trucks have one big shock per wheel. Any truggy shock or the massive LST shock would be a better choice. The LST shocks are extremely cool.
It’s going to take some experimentation with different spring rates and shock mount angles to get it just right. Of course it will change as things are added to the bot and it gets heavier. You can always increase preload in the shocks, but that only gets you so far. I would anticipate this and incorporate different mounting positions for the shocks into my design.
I know this is a “hex” project, but when I make a robot built for capability, I’ll use Clod or TLT axles and a custom crawler chassis. It would go more places, and that really seems to be the objective of a capability robot. It does look like a fun project though. Good luck with it!
The only real purpose I have in wanting to build Hex Rover, other than it’s cool and something new to design and eventually build, is to just have something else different to experiment with. It will be something small on the way to something a bit more major.
I will probably be using a two or three U channel type of chassis when I actually start building the final version of the Hex Rover. A single U channel will be good for experimentation and proof of concept though. I will plan on having multiple shock mount points top and bottom.
Hex Rover is definitely a project that will be on the way to something bigger, so to speak. I’ll stay with my current basic design with independent suspension. I like to see how far I can take a given design. If it doesn’t work as I want, I redesign, take it apart, and put it back together in a different configuration and try that. The Hex Rover will have very large R/C truck wheels and tires.
It will definitely be fun! I love the Servo Erector Set!
Well, with an independent suspension, articulation is limited by the shock travel at that particular wheel, unless you build a cantilever mechanism. Just look at a real rock crawler doing its thing to see how a solid axle can articulate. Solid axle vehicles win all the crawling competitions in RC or real life.
That is the right truck. I’m personally not a fan of Integy stuff, but I’m sure those are nice. I’d probably go with genuine Losi shocks. Tower doesn’t carry Losi.
Hex Rover isn’t going to be a rock crawler. I’ll be happy to have it crawl over standard sidewalk curbs and such.
I don’t really like the style of those shocks I found, so will keep looking. I’ll keep my eyes open for the Losi shocks, and if you have a link I would like to go check them out. I have lots of time to pick final components since I am just in research mode for Hex Rover right now.
I am working on the design for a motor mount that will incorporate shock mount points as well. This new bracket will attach direct to the ball bearing hub and replace the entire servo assembly in the concept model, if it doesn’t end up being too long.
I should have been a designer, but I like seeing my creations brought to reality too.
I’ve been working on an SES compatible bracket for a GHM series gear motor that would have a place to connect a standard R/C truck shock. Here is my preliminary design.
My idea at present is for the motor to mount under the main bracket plate and for there to be shock mount points around the top extension. The top extension will mount to the ball bearing hub. This single bracket will be the complete mounting for the GHM-04 and similar motors.
I don’t know, but maybe. I’m not sure I’d find an easier to use system though.
Just out of curiosity, what would you use to build Hex Rover if you were going to build one? Also, remember that this first version is just the concept. It will not be the final one that gets built. The final body will be at least twice as wide as the concept model.
I would built a custom aluminum chassis, as I tend to put more effort into mechanical then software.
I may also use E-Maxx parts like shock towers and stuff. I am planning an outdoor rover that uses two E-Maxx front ends to make a 4 wheel steering rover.
I’ve had a standing order at the local hobby shop for used E-maxx trucks for a while now. Only one call so far, and that one was in rough enough shape that it would have had to have been the “and a half” part of the chassis, and even then, it would most likely have been for spares once I got my hands on replacement parts.
Unfortunately, people around here don’t seem to want to part with their old Emaxx trucks, even once they move on to nitro, or other hobbies. This whole project would be a whole lot easier if they would just sell the truck alone, without all the other extraneous junk (to my purposes, anyway) that they package with it.
The mechanical issues that almost made me choke when I saw the Emaxx on offer could have easily been hidden, glossed over, or lied about in an ebay listing. As it was, it was presented as being in “perfect running order”.
Nothing was said about, nor did the seller seem to think that there was anything wrong with, the fact that some of the suspension components were held on with not only the incorrect screws, but the incorrect type of screws, including a few pieces that had been through-drilled and bolted on from the other side. Also of note were steering turnbuckles that had been replaced with links the wrong size for a truck even close to that size, and a sheet of aluminum flashing about the thickness of a magazine cover, that was being used to replace the chassis screw holes, which he would later tell me were blown out when he ran it full-throttle off the deck, and it crashed down onto a concrete slab, breaking that whole corner away from the truck.
When I apologized for wasting his time in showing me the truck, he told me not to worry about it, and that he’d probably just put it on ebay. So if you see one listed there, pay especially close attention to the left front corner, and look for signs of bailing wire.
