OSEPP tank chassis any good?
Looking for something a little larger and more robust than the ActivityBot chassis w/ the tank treads. The goal is to mount one of Bill Henning's RoboPi boards w/ the Propeller, a Raspberry Pi3, and a small Lider unit on the body.
Fry's has this chassis on sale the next few days for $69, wondered if it was halfway decent, or if someone can point me to a better/stronger one?
https://www.osepp.com/robotic-kits/4-tank-mechanical-kit
Thanks for any thoughts.
Fry's has this chassis on sale the next few days for $69, wondered if it was halfway decent, or if someone can point me to a better/stronger one?
https://www.osepp.com/robotic-kits/4-tank-mechanical-kit
Thanks for any thoughts.
Comments
An advantage of any robot that uses the Tamiya rubber is that replacements are cheap and easy.
Are you sure about this? Does Tamiya make more than one kind of track?
The tracks on the OSEPP bot don't look like they're the same as the tracks on the Arm Crawler erco recently told us about.
If you want to go for a larger treaded vehicle, you could use the treads made by Vex. Here's a thread on the topic of Vex treads.
I like my robots to have encoders. I like the Tamiya Arm Crawler but it doesn't lend itself to easily add encoders.
Dagu sells a Rover 5 treaded vehicle which can be purchased with included encoders. Here's a thread with some discussion about this option.
I'm adding one the pan/tilt mechanisms described in this post to my Arm Crawler. Those pan/tilt mechanisms are pretty inexpensive but often the tilt part of the mechanism isn't needed so just a bracket to attach sensors to a servo is all one needs.
The tank tread kit was the first thing I've bought from Parallax that left me going hmmm... (And that's out of lots of stuff so their hit rate is very good!) I can confirm what Mr. McComb said, the pieces are from a model, as in a plastic model of a tank I would have built when I was young. My issue with it, is that it seems easy for the treads to slip past the gears, the tracks aren't very straight, (and possibly because of this?) it wants to track slightly to the left, instead of straight like it does with the ActivityBot wheels. But we keep in mind it was only $30; I didn't have big expectations. More of an experiment.
I like the idea of tank treads, but I can see where it's easier and more practical to have a bot with wheels, especially when it comes to fine tuning movement. So I'm open to a chassis with 4 wheels too, if that's better.
For my next bot (my first one beyond the three ActivityBots my daughter and I built), would be nice to have something a little larger than the ActivityBot so that it can pack a somewhat larger payload. I'm not thinking Arlo huge yet. Maybe something 1.5 to 2X the ActivityBot in size.
Payload so far will be:
Bill Hening's RoboPi w/Propeller for motor & real time sensor control
Raspberry Pi3 for running the LIDAR and hopefully ROS or something similar
Scanse Sweep LIDAR
Raspberry Pi camera module
Any other sensors needed for redundancy like Ping))), Sharp IR, etc.
With all that in mind, would those of you with more experience recommend a tank tread, 4WD, or maybe even a 2WD base with a round top? Some of those look like they could hold a bit of weight for their size.
Heck, maybe I should steal a page out of Erco's book and repurpose an old 4WD radio control truck.
Thanks for any discussion on the differences or what I should look for in a more robust chassis!
He also has another saying, just add more power.
With that anodized aircraft grade aluminum, your not going to get much stronger vs weight. Titanium, but your not taking it into battle. There looks like some room to make some form of tread guide, a channel or even rims around the wheels, providing the track is thick enough. Or replace the track with some custom wheels. And do what I mentioned above.
BTW: That sale price sounded very reasonable.
Anyone have comments on these two (compared to the OSEPP kit for $69 in the OP?)
DFRobot Devastator Tank: $73 on Amazon
Intelligence RC Tank Mount Car Truck Robot Chassis $165 (this thing looks pretty killer, not sure how real life application would be though?)
Some neat interplay witrh three mecanum bots:
Guess I'll just have to sleep on it and figure out what I'm really after. Maybe even something like this would work: DFRobot 2WD Mobile Platform
Just wanted a chassis that's somewhat bigger and able to move around good with the extra payload.
If you haven't seen it, make sure an watch this video sometime.
It's long but really good.
IMO, the Vex Mecanum wheels are the best for the money (about $60 for a set of four).
I added a set of Vex Mecanum wheels to a Rover 5 after learning about the wheels from erco. Here's a link to my Mecanum wheeled Rover 5 project on Hackaday.io.
There's also information on my this project in this thread but the thread is not well structured.
I believe I posted control algorithm in the last thread I linked to. If you don't find the algorithms there, I'm sure I could find them.
The Rover 5 works well enough with the Mecanum wheels but I intend to make another version using more powerful motors. I'll likely use motors similar to the motors used in my Vex treads project.
Vex makes a lot of cool wheels. Before using their Mecanum wheels, I used their omni wheels.
Here's a video showing a bot with omni wheels.
I like the three wheeled omni bot since at first glance it looks like it should should just spin in place. People always like the omni bot when I show it off but the Mecanum wheeled robot is even more popular than the omni bot.
There are lots of practical applications for these omni wheels. They can be used in conjunction with normal wheels to reduce the skidding which occurs with deferentially powered wheels.
That is awesome. So that is what you have been working on in your secret lab.
Duane's Omnibot is cool too.
Are these wheels strictly smooth floors and low pile carpet?
I want to make a house robot about the size of a Heathkit Hero, and that would be perfect for mobility, maybe.
How does it handle human or dog hair? Are the wheels cleanable, the more axles and wheels, the more to get dirty. And the bigger the chassis, the less I want to have to upkeep something like that.
I'm talking about the Activity Bot tread kit. The Osepp robot looks like it already has its treads, and those are not a separate kit.
RC cars tend to be a little fast, and if that's what you want they're fine, but be sure you're not looking for a robot with a more traditional travel speed.
You can get make some nice tracked robots using a toy tank. The one in the picture was especially nice, with unitized parts that permitted easy modification. I just took the top off, unclipped the wires to the IR sensor and turret motor (used for something else), and bolted on a plastic platform for my electronics and circuits. I found this at an independent toy reseller in the Los Angles wholesale district. (Many of these are also cash-and-carry so you don't need a resale licence to buy them).
Like the Tamiya treads, though, these are all-rubber, and they lasted only a few years. The best is rubberized plastic, plastic with rubber cleats, or fabric reinforced rubber.
WHAT!? Fry's of all places. Unreal. They have that chassis for $130 at my Fry's, because everything at my Fry's starts $30-$300 over retail for their fake sales at MSRP pricing. At $130, I'd buy a chop saw and some aluminum square tube!
The chassis is great, I've seen many at maker events. There are a lot of configuration options, like erector set. It's also very pretty, if you're into that (and paying for it). You didn't mention what battery you plan to use. If you can fit everything on there, you'll love it. Considering you're getting it at a low price, you could probably sell it for the same price if it doesn't work out.
If you want to build something simple, a couple of gear motors, two tires, and a plywood slab with a caster is tough to beat!
Edit - I just noticed there are different versions of the track kit. I thought you were getting this for $70 - https://www.osepp.com/robotic-kits/3-triangulartank
It's neat to see Osepp's website, never seen it before. I bought some CR servos off Ebay from some funky vendor which were Osepp, the only other time I heard of them.
Yeah, that is a good price on the OSEPP Tank Kit and it looks very much like the Makerblock Starter Kit minus the controller board and sensors and such, but that would be replaced with a Propeller anyways.
makeblock.com/starter-robot-kit
I believe with the OSEPP Tank you have to provide your own controller board (A Propeller or BASIC Stamp or Bill's RoboPi would be an awesome choice). It would be interesting if an Activity Board or a Propeller BOE would drive these.
Looking at the specs for the OSEPP Tank kit, the motors are 9V DC motors so that is something to keep in mind.
I've tried Tamiya tank trends similar to the ones that Parallax offers but they are really only good on flat surfaces and not very durable. The Tank Tread Kit would be a great addition to a BOE-Bot or Activity Bot though and is only $34.
The other option is to get a Radio Controlled car with trends and change out the guts with something else to make it Zigbee or Bluetooth controllable.
@Gordan, erco, and the others - that makes sense, I think what I'm looking for on this next bot is the ability to have it just "'be there" without me having to mess with it much, i.e. not worrying about it getting stuck a lot, etc.
In your opinions, which is more stable for an indoor bot: a tank tread chassis like the OSEPP, etc, or a 2WD w/caster wheel and a round chassis?
I really appreciate all the help, this is great stuff for me to learn and I will finish the second half of that video this evening.
http://www.ebay.com/itm/Light-Damping-balance-Tank-Robot-Chassis-Platform-DIY-suspension-tank-/272563860079
Ever heard of batteries? Slung underneath they dramatically lower the CG.
In tests I don't think it ever tipped over. It had a very wide stance, almost a square-shaped footprint.
But isn't the bottom the top now? No matter, Lipos don't weight nuthin' these days anyhow.
I can see why some of the ROS crowd re-purposes roomba / iRobot vacuum cleaners for their base. Makes a lot of sense after watching that video. Anyone here ever done a larger bot off one of those bases or considered the pros/cons of it?
I think I must not have read the post carefully. Thanks for clarifying.
Not too long after I started experimenting with robots, I purchased a Roomba. This was a time before I made videos of my robots in action so I don't have any video showing the robot. Here's the thread where I describe my attempts.
The way the Roomba serial protocol describes turns makes navigating with a Roomba a bit trick. Turns with a Roomba are described with by diameter (or radius I don't recall which).
I hope to revisit my Roomba project in the near future sometime but I've been saying this for five years.
Agreed.
I used the advice offered by David Anderson when I built my robot "Cleaver". The Parallax aluminum wheel kit really looks nice but it's also a bit pricey. Fortunately I received the cool hardware in exchange for porting the Eddie firmware (and improving it some) for use with the Propeller Activity Board.
Cleaver and the robot with Vex treads both use expanded PVC (ePVC). A material I learned about from Gordon McComb. It looks like the treaded vehicle Gordon recently posted uses ePVC. This is a great building material for robots.
Speaking of Gordon, if you don't have the latest edition of Robot Builder's Bonanza, you should seriously consider purchasing it. It's full of great stuff about building robots. I wish I had purchased the book (not that it was available at the time) when I first started making robots.
It's really not hard to put together a very basic robot. I posted some ideas of making cheap bots in this thread.
When I went looking for cheap wheels, it turned out Vex's small wheels were a pretty good deal.
Make sure you check out HobbyKing. They have great prices on lots of robot related gear.
Yeah, I like treaded robots. I think they look cool. They do burn up batteries faster than wheeled bots. Treaded bots aren't as good at odometry as wheeled robots but I think encoders are still really useful on a treaded bot.
Actually the robot was designed to have no top or bottom, and to equalize the top weight with that on the bottom. It's CG was exactly in the middle. I don't know many people that use their small tracked robots over outdoors "rough" terrain -- this one was designed to do a Donald O'Conner and roll up a wall when it encountered one. In testing it never tilted over because of its wide stance. (Because of the wide track distance, the actual amount of tread touching the ground had to the reduced, or else it could have trouble in a turn over a high-stiction surface like a recentty waxed kitchen floor.)
http://www.trossenrobotics.com/robotgeek-whegly-arduino-wheg-robot-kit
That's awesome! That looks like an easy mod to any servo powered bot to get much better traction.