View Full Version : [Project] Monster Truck Rover - Semi-teQ II

11-01-2009, 10:57 PM
i started a blog for the project, but ill probably end up finishing it here

here is the intro and the plans


i was trying to figure out the best drive system setup. as of now this is how i have planned. i will have 2 stationary shafts acting like front axle and back axle, then on each side of the axles i will have dual roller chain idler sprockets, one chain will go down to the tire, and another will go to the motor positioned in the middle of the bot, this said, that means the motors will have 2 sprockets on them, one to go to the rear axle sprocket and the other to the front, then the wheels will have their own drive system with a set of pillow block bearings, axle, and sprocket.

if you were keeping track, that's a total of 16 sprockets for the bots drive system!, i don't know where you get your sprockets from but that is pretty pricey

so i came up with another idea, i was thinking to get rid of the back axle, and put the motors there instead of the middle. still having 2 sprockets on the motors shaft, this time one goes straight down to the tire, and the other to the front axle. this will still be a hefty 12 sprockets but that's not to to bad...

so my question is what do you guys thinks would be a better drive setup? having the motors in the back or in the front?

11-01-2009, 11:17 PM
here is a quick drawing i made in paint

11-02-2009, 10:08 AM
I don't think that it matters if drive is front center or back, since they are all chained together. If it needs to do some serious rock crawling, then weight should be as forward and low as possible. Motors don't weigh much, so battery, and other electroics placement, are probably a lot more important. You could also do axle driven system with steering, instead of skid steering and dealing with all the sprockets and chains. But locking differentials at such a long chassis would make turning difficult, even with 4ws.... As I foun out the hard way myself lol. However, there are many options for that, as there are lots of rc crawlers in the market now, lots of great parts to choose from.


11-02-2009, 01:12 PM
I don't think that it matters if drive is front center or back, since they are all chained together. If it needs to do some serious rock crawling, then weight should be as forward and low as possible. Motors don't weigh much, so battery, and other electronics placement, are probably a lot more important.
ya, i didn't think it would make a difference either, i learned my lesson with battery placement with my first robot, as i have 2 40 pounds SLA's and i think the 3rd is 10 pounds, and if im not mistaken the motors are a little under 15 pounds each. so about 120 pounds of motors and batteries, and i was thinking to make weight distribution as even as possible, unless it won't really make a difference of the motors are in the front or back...

You could also do axle driven system with steering, instead of skid steering and dealing with all the sprockets and chains. But locking differentials at such a long chassis would make turning difficult, even with 4ws.... As I found out the hard way myself lol. However, there are many options for that, as there are lots of rc crawlers in the market now, lots of great parts to choose from.
what do you mean about locking differentials at such a long chassis, and skid steering/ can you elaborate more please.

the setup will be like tank style steering.


11-02-2009, 01:19 PM
Those are some big motors. I have 1000wt, 36v motors that weigh less than half that, and each one will accelerate an adult to 18mph.

Skid steering = tank-style-steering = skid-steer.

Ref: http://en.wikipedia.org/wiki/Skid_steer
Ref: http://www.howstuffworks.com/skid-steer.htm

11-02-2009, 01:24 PM
sorry my mistake, i just went out an weighed them, they are 16.5 pounds each.

they are wheel chair motors so they have a gearbox too

11-02-2009, 01:32 PM
I mean if you need 6 wheels, then you have 2 choices that I can think of....

1) tank like system like you're thinking of.... either one power source with a clutch for skid steering for either side, or a power source on either side. Turning is made by powering right or left wheels in forward or reverse.

2) using axels like a car...it'd be a rock crawler truck with 6 wheels. So you'd have either one power source and using axles to route the power to each of the wheels (like a 4x4 truck, but in this case 6x6) or use multiple power sources to drive the wheels. Turning then is done by steering like you would with a car. You can make it 4 wheel steering for better turning. The problem with this, as I was pointing out, is that in order to turn well, you'd need a differential between each wheel axle, because right and left sides will be running at different speeds as you turn. But because of having differentials, it makes climbing difficult, as the diff will allow free spining wheels to accept all of the power, and the stuck wheel to have none. So if you are climbing rough terrain, it gets stuck easily. This is why crawlers usually have the diffs locked, meaning they act as a single rotating thing, not allowing right and left to spin at different speeds.

I've built a contraption before with 6x6 with 4ws as described above. It carries a lot of weight with not much power, and with the diffs locked, it will not turn.... the chassis is way too long. Here is the link: http://www.crabfu.com/steamtoys/rc_steam_rover/

the videos shows the diffs unlocked, and it can pull quite a bit of weight, and does fine in grass and minor bumps, but does not do well at climbing rocks.

Here is a video of my electric r/c mini rock crawler: http://www.youtube.com/cfhelis#p/a/u/0/Btob_YW2xb0 it does have the diffs locked all around, and is 4x4 with 4ws. It works well because it is low weight, all of the weight is as forward and low as possible, and turns ok. It can climb just about anything, and is just a traditional axle driven truck with a lot of very soft suspension travel :)


11-02-2009, 01:49 PM
those are some pretty nice projects!

my bot will have only 4 wheels. the axles are bolted down and not meant to spin. this is why im going to use idler sprockets with a bearing in them. the left motor controls the left front and back tires, and the right motor controls the right front and back tires, the controller has built in differential mode settings.

11-03-2009, 06:19 PM
i was kinda iffy on the dimensions that i picked for the bot, so like i did with the first semiteq, i threw together a quick cardboard mock up of everything so that i can see how parts are going to fit and get a real idea and feel of the whole thing.

(sorry for the bad iphone pics)
i put a spray paint can, one of the motors, and a battery so that you can get an idea of the size:)

i also decided on putting the motors in the center, later on down the line i am going to try and implement a suspension or hydraulic system.

11-04-2009, 01:55 PM
Wow that is huge... awesome!

11-04-2009, 02:56 PM

its all designed around the wheels, i think the size of the body to wheels ratio worked out nicely:)


11-11-2009, 07:38 PM
hello all,

i been busy searching parts and stuff, i got some new tires and ordered a big order for the drive system.

TheBigBearingStore.com is an amazing place, i love to buy from them, here is the stuff i ordered.
8 - pillow block bearings 3/4 shaft
4 - 4 bolt flange bearings 3/4 shaft
1 - 3' 3/4 keyed shaft
1 - 20' #40 roller chain
8 - #40 roller chain connector links
12 - 18 tooth 3/4 bore sprockets (4 for the wheel axles, and 2 for each drive side)
4 - 18 tooth 5/8 bore sprockets (will be milled to 17mm, 2 for each motor)

i have a local friend that has a contract with a hospital and he gets all their junk, i got my old robots back tires from there.

so i revisited him and got 4 more tires, 2 of them were the same size and but wrong style hub. the other 2 where to big but the right hub, so i bought all of them and changed out the hubs.

the top 2 tires in the picture below are the original tires
the middle 2 tires are the ones that im going to swap the rims with the bottom rims
if i do find 2 more tires the same size as the bottom ones ill go with those instead, they are i think 15 inches, and the tires im using are 13 inches.

till the shipment comes, for pictures:)

11-12-2009, 09:15 PM
bought the controller, my old robot's AX2550 controller unfortunately messed up (tear, $500 bucks)

I bought the AX3500 (http://www.roboteq.com/brushed-dc-motor-controllers/ax3500-dual-60a-brushed-dc-motor-controller.html) this time, it has more features, however it is half the amps of the AX2550, which is 120amp

some weight specs of the bot will be as follows
2 X 55 AH 12V SLA's - 40 LB each
1 X 33 AH 12v SLA ~ 24 LB (might have 2)
2 X geared motors - 16.5 LB each
55 pounds worth of chain, sprockets, bearings and shaft. (says ups)
4 X 13 IN Tires - 9.5 LB each

so about 230 pounds with no frame, so maybe a little over 250 pounds with frame

till next week

11-12-2009, 10:09 PM
That's a pretty expensive 40A controller (60A peak, but that's marketing for ya)

I'm a big fan of the RS-80D in that size range (80A continuous per channel, but I've peaked them much higher before) for about $100 less.

11-14-2009, 12:24 PM
yeah it was, but i like them, im used to their system, and im not a good programmer yet, and their product comes with software that gets the bot moving, so i can learn at the same time.

those are nice controllers, I'd probably change it up with my next robot and use one of those. I've seen them before, on this tank http://www.eigenspace.net/robot/ (nice work he has done i might add)


11-16-2009, 10:27 PM
well its Monday, drive parts came in

now i need to more the wheel hubs to a standard size and then the first column of sprockets on the right need to be bored about a millimeter bigger (17 mm)

you'll notice there is 10 pillow blocks, guess someone got confused with all the stuff i had bought and put 2 extra in:P bill said 8

anyways still Wednesday when the controller comes in:)

11-19-2009, 09:55 PM
here is the controller, the serial cable, and the rc outputs

im going to try and start building the frame this weekend so stay tuned:)

04-22-2010, 10:58 PM
hello all, long time no post, i got pretty busy with school and work and i put the project aside, summer time = full force work on rover:)

i have the frame built and i mounted most of the bearings, sprockets, and chains, however i had to order more chain and pillow blocks for the wheels, but those should be here sometime next weekend, im definitely trying to get some pictures uploaded but im having a hard time with my camera, so keep a lookout for some pictures in the next few posts.

i took the advantage while i wait for the rest of the drive system, and started laying out the electrical components. i would like to make the electrical system neat and professional, with terminal blocks and crimps

i was wondering if anyone knew of a good source for a small low count fuse terminal block?


02-07-2011, 01:06 PM
hello everyone, again long time no post, but i have been working on the project every second i get, i attached some pics i randomly took. i plan to make this into a humvee style rover instead of a monster truck. colors are planned to be beige and blue.

i actually got rid of the tank steering setup, and reduced the whole drive system down to a couple of sockets and direct chain drive.

- the paintball turret is fully working, video's coming soon! (when i get more co2)
- burned the dc dc converter for the computer so i been running everything off a netbook for now
- bought a kinect for the main rover camera, and a normal webcam for the turret
- just started to plan and mount a 20" lcd in the back
- need to calibrate the steering system, and possibly add limit switches
- programed a joystick to control the rover as well as the turret with roborealm
- need to program the autonomous stuff in roborealm (need to get a fully driving rover first)
- plans for neon lights and speakers
- body and paint work

one very big thing that completely slipped my mind,
i have purchased the emotiv epoc headset for my rover. i'm still trying to get my brain wrapped around programing it, but it is definitely underway. for those who haven't heard about the emotiv headset, it reads brain wave, so mind controlled rover/turret soon!

any questions fell free to ask!


02-07-2011, 08:37 PM
i did some work on the lcd setup today.

- installed plywood and metal surface for mounting the lcd pcb's on

waiting for
- ac/dc converter to mount on the new electronics deck
-- the converter is for powering the lcd at 120 vac and provide system 5v (usb) for servo controller and maybe turret servo's

i bent the tie rods while trying to calibrate the steering system, i should have them replaced by this weekend as well as more co2 for the paintball gun. hopefully videos then!


02-12-2011, 11:10 PM
i started building the body cover. the front is some scrap aluminum that i bent with a hammer just for testing. i just wanted to see the look of the rover covered, im going to make a clean one tomorrow.

you will see the first picture is the back piece bent up, and the second picture the tabs bent down and the opening for the lcd cut. i still need to trace/measure and cut the side panels and glue them to the side tabs with some kind of adhesive like liquid nails or pl.

after all that i need to do a coat of bondo on the corners to unify everything before i start to fiberglass.

02-14-2011, 10:32 PM
the body is coming along perfectly, everything is aligning just right. tomorrow will be a fun glue day.

02-15-2011, 04:46 PM
Nice, looking good.

How are you getting on with Roborealm?

I made a smaller platform some time ago but never really probed into all RR could do.


02-15-2011, 11:54 PM
the body is all glued up, and is getting a full day of curing before i mess with it.

@Orac, thank you, the project has a lot of different things being worked on at the same time. one of the biggest things is control, im using rr as the main control program.

in rr, i made a simple button gui to enable the system, enable autonomous functions or manual joystick functions, and under those i have drive only and turret only controls.

the autonomous functions aren't done yet, that will be the last part of the project i work on, i just bought the kinect for the robot and im experimenting with it in rr.

the joystick has ranges x(-1000,1000) and y(-1000,1000) so i just used vb to write a simple formula to map the correct servo and joystick values. holding a button on the joystick will disable robot control and enable turret control with fire button firing the paintball gun. manually control work great! however i haven't gotten a chance to really test rr manual control out in the open yet, im hoping this weekend i will get a chance.

i like your rc monster truck project, it looked like the bare bones were perfect to work off of. i noticed its a few years old though. im not sure how much you keep up with rr, but they have added many new modules to it. in particular the navigator module, it seems like they are moving into the object tracking fields for robot/turret control. you should definitely check out the new stuff. i love working with rr its a well developed/supported piece of software.

02-16-2011, 02:26 PM
Yep, had a look at the RR website, looks like I may need to bite the bullet and ...... Pay for something :sad:

Don't really mind giving as its a worthy cause :)

02-16-2011, 03:18 PM
Oh ya, haha that too, they changed the licensing