Tracked Robot Tank questions (many of them) (could help others)

Let's Make Robots Project Ideas
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I’m new to the forums here somewhat, I lurk every once in a while. Glad to be here and looking forward to the training I’ll receive from all of you. :slight_smile:

I short background on myself and my username. My name comes from my attempt to build a android that walks like a human, I did NOT start the build of this, it was only in planning, but after a month of research I decided that it would be a bad, very bad choice for my first robot. I have no experience in programming and some in digital electronics.

I went to college for computer and electronics technology, which included computer hardware, basic, analog and digital electronics, but haven’t use the electronics portion much aside from the occasional black box of [insert something for helping testing small/passive components here, ie. resistors, LED’s, etc.)].

Anyways, I have no knowledge of microprocessor programming, though I did do a little during training on a 8088 mcu XD

A few weeks ago I decided I wanted to try my hands at building a tracked robot (tank style), I’ve read quite a few websites for these but would like to have more direct (updated) information from other users.

The robot I’m researching to build will (hopefully) follow the guidelines below:

  • Arduino Uno USB Microcontroller (a little over kill for the time being. I decided that if I wanted to add more stuff later on it would be a good thing to get this now.)
  • Dimensions: L x W x H: 24" x 15-18" x 5-10(?)" (Measurements are only a thought at this time, might have a longer length and width before I finish the chassis of this.) The height is mainly for the overall height of the tank itself, from the bottom of the tracks on the ground to the top of the tank. This does not reflect any items mounted on top (such as camera(s), grabbing arm, and other sensors)
  • Movement functions required: Forward, Reverse, Left, Right, Stop
  • Other functions for future additions: Camera Tilt & Pan, grabbing arm (more on this at the bottom of this list),
  • Max carrying capacity 250+ lbs
  • Custom tracks 3-4" wide, Length to be determined after chassis has been made and proto-wheels created and attached.
  • Angle of climb of >=30 degree’s
  • Torque to help climb, pull and carry objects
  • Max Speed of 5-6mph. Realistically, I would like it to do 4-6 mph unloaded and 2-3 mph at half-to-full-load. (I know this might not be able to done since I can’t have both high-torque and high speed, per se.)
  • 12-24 volts and 12Ah battery .
  • Skid-steering
  • 2 wheel drive with two motors
  • 2.4GHz TX and RX
  • Track driven
  • I’m going to see if I can find a battery that is 12-18v 10000-mAh or so, or maybe a small lawn-mower battery.
  • I plan on adding in a arm to grab stuff, would like to try to have it pick up to 1-2 lbs. I’m thinking this will require a large actuator. I have a few old window motors and windshield wiper motors laying around somewhere. Would those items work?
  • I have a few 12v 12Ah Sealed Lead-Acid batteries sitting around collecting dust, I can use those for the power needs.

On to the questions:

  1. With the guidelines stated above:
    a) what would be the best motors for my application?
    b) could someone also explain, in plain English, how the gear ratio works? I’m a bit confused about it now. I read the Build Your Robot tutorial the other day, I’m still confused.

  2. I’ve been doing some research for 2.4GHz TX’s and RX’s. I’m lost on them now.
    a) How many channels would be required for my application?
    b) What would you recommend for the TX and RX?
    c) Would like to keep this between $200 - $400 USD.
    d) ability to switch between multiple “profiles.” Such as robot movement, another profile for camera movement, another profile for the arm movement.
    e) I’d like to be able to fully control the speed of the robot with slight movements. I’m not fond of analog systems like the cheap RC vehicles you buy at WalMart.

  3. I’ve searched the internet for different track designs. I’ve seen from wood to carbon fiber to door-hinges. Those three are out of the question since they would be too weak, to expensive and probably too heavy. What would you recommend for this? I’m open to buying them in a kit, but I would rather build them myself. I’ve had the idea of using chains and sprockets from old bikes, with small pieces of metal for the tracks, using two chains per track.

  4. Grabbing Arm, I highly doubt that I would be able to successfully build one on my own. What would you recommend for an arm? (Don’t forget the guideline for this above.)

  5. Gear Sprockets for the treads. How would I know what to buy/make for these? I would like to have the bottom of the frame about 3-4 inches off the ground so it doesn’t bottom out.

  6. Driver Motor, I almost forgot about this. I know it depends on the motor specs. Depending on the motor, how would I decide what to get? Is it compatible with the Arduino Uno?

  7. How do I interface the Arduino to the TX and RX? I might have to wait a bit to go into more details. I need to focus on finding all the parts, building the parts, building it up into what I want.

  8. Any other information that I might have missed, suggestions, comments, etc., I’d like to hear about them all :slight_smile:

If something doesn’t make since, please let me know. Its late here and it was a long day at work.

Thank You
BipedAndriod (Crap, I just noticed I misspelled my name when registering XD, that’s what I get for not paying attention XD )

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Thank You, glad to be here.

Thank you for replying back.

I’ll make some changes based on your suggestions.

Lets say 25-50 pound max carrying capacity. What would you suggest for a motor?

I had figured that there wouldn’t be a DC motor for this. Never hurts to ask, right? :slight_smile:

So a larger gear with more teeth would be for torque? and a smaller gear with less teeth for speed?

Okay, thats what I figured.

Okay so without any extra devices, I’m looking at 4-channels mininum. But I would most likely get the TX you recommened below.

I think I can spend the extra money for a TX/RX system. Be better in the long run anyway.

I forgot to mention that this robot will be for outdoors only, running through grass, dirt, sand, mud, ect., so the little one’s won’t fair very well.

That’s what I figured too. I suppose I don’t need all the features I listed right away. :slight_smile:

Very nice to know this. I’ll need a motor and the controller to handle this. I’ll research this a bit more.

Very true here.

Most likely I will see if I can find some old multi-speed bikes and grab the sprockets from them and work with them. If not I’ll jump into CAD and see what I can come up with.

I was looking through them for quite sometime. As for now, I guess I don’t need one. Less programming and R&D I’ll have to deal with. :slight_smile:

YAY! More research. LOL

True, this slipped my mind when I typed this up. It was late and very tired after a 12-hour work day. I’ll do a little more research for motor controllers.

Okay. I’ll have to look at this more closely. I have no programming background, and will need help with it. I’ve already downloaded the Arduino program and looking at libraries and what-not. I’m reading more into the programming, but from the looks of it, I’ll need a lot of help with it.

I’m thinking about $2000usd max on it. (This does not include any extra stuff such as camera, arms, etc., just the basic frame with tracks attached, the electronics, motors, TX/RX, etc.

I’ve already planned on building the frame, tracks, sprockets from scrap items. The sprockets and chains will come from old multi-speed bikes. The frame, I’m sure that I can find some old scrap metal laying around my shop from old car projects I’ve worked on. If not it shouldn’t be too hard or to expensive to buy some scrap metal from a junk yard.

Yes, this is more of a long term project taking place over a few months of building. 3-5 months of R&D. 1-2 months for the basic frame and tracks.

It has helped me more than you think.

Thank you for taking your time with me and explaining the different areas of this.

Would this motor be good for anything that I’m asking about?
robotshop.com/banebots-first-cim-motor-1.html

I would also need this for it to (I think):
robotshop.com/banebots-p80-single-cim-gearbox-27.html

Sorry if I’m overwhelming you and/or others on this matter.

I know I should start with a smaller size, but I have a set mind, once I start something I hate to drop it. I do my best to succeed when I can. If I fail at it, then I know that I failed. Instead of not attempting something and wondering if I could or could not do it. (if that makes since).

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sweet, I could hug you right now!

I was looking at that motor controller the other day, but didn’t think anything about it at the time. (mainly cause I didn’t know what I was looking for or what I needed XD )

As for the budget increase, I really didn’t give one except for the TX/RX. I planned on this costing anywhere from $1000. to $2000. usd (more or less depending on what I decide to go with and add and whatnot)

I’m comfortable working with hi-current devices/batteries. Used to build custom wiring harnesses for vehicles (headlights, horns, tail-lights, interior devices, etc.) so I know the dangers of the high voltages. Thank you for the warning :slight_smile:

Just to make sure I’m not mistaken here for the motor, as long as it is 30:1 OR MORE it will be fine and if its a CIM (per se)?

Also, when talking about “Gear down” and “gear up,” how is this done? what do I look for? What is it? I might be thinking too hard about it and its right in front of my eyes right now XD

I’m going to ask, I might be wrong though, reading what you said, I’m thinking that:

  1. the smaller the gear, the more speed it has (meaning the higher its mph or so is)
  2. the bigger the gear, the more torque it has (meaning more pulling power, hauling power, climb angle)
    Am I correct on this?

Another question for the motor above… What else, other than the controller, would I need? (I may end up using the robot frame as the motor mount, just need to get the specs on the motor mount hole dimensions. But not sure if this is a good idea or not, as it may be abused on bumpy terrain!)

Thank you
Biped Andriod

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I think I understand it now. We’ll see when I start designing everything and putting it together.

I watched the nasa video… really cheesy no doubt about it, but very helpful and understandable. Thank you for the link to it. I knew some stuff they were saying, but other parts I wasn’t. After watching it, I have better knowledge of it all now. But like I said above, I’ll see what I’ve learned when I start building the chassis and tracks.

I knew there would be mechanical portions, but looking at this it might be more indepth than I was thinking of. Though I think I will be able to do it with help.

So if I wanted extreme torque I could go with 200:1 gearing (hypothetically speaking of course). I know to get the right torque and speed that I’m looking for will require some math :frowning: and other stuff.

I’m quite tired from work today, I’ll check over everything and start more R&D on this project tomorrow.

Thank you again :slight_smile:

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Thank you for the reply and the motor suggestion. :slight_smile:

I still have not had the chance to do anything on this since last year. RL work getting in the way of things again :frowning:

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Hello I am new here. You might try looking at the NPC motors they will carry the weight you were talking about.
I am working on a track system using Powerchair motors (electric wheelchair) The tracks will be on the powerchair. I am in the process of researching the availability of tracks and options like chain and timing belts. None of these are cheap.

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Hi BipedAndroid,

Welcome to the RobotShop Forum.

For 250 pound payload capacity? Gasoline - something like what is used on an ATV. The equivalent DC gear motor would be very expensive. You may want to lower your payload capacity to <25 pounds if your budget is <$1000, otherwise you’ll be trying to find used / spare / free parts.

A motor (DC or gas) spins very fast but with little torque (“turning power”). A DC motor may spin at 10,000 revolutions per minute (RPM) but you can stop it easily with your fingers. Adding a gear ratio has the effect of slowing down the rpm while at the same time increasing the torque. The shaft after the geardown will spin much more slowly but have alot more “rotating power”.

The main differences are the number of channels and extra features.

You need one channel per “degree of freedom”. For example on a skid steered vehicle, you need one channel for the left motor and one channel for the right motor. If you want a gripper, you’ll need another channel. If you want that gripper mounted to a rotating base, you’ll need another, and so forth. A skid steered base with a “normal” arm (two motions at the shoulder, one at the elbow, one at the wrist and a gripper) would need 7 channels.

Controlling a robot arm using an R/C system is not ideal. If you really want it though, you would need to invest in a 9 channel remote.

The cost of the remote alone is $460. For $200 you are looking at a desktop rover similar to the RobotShop Rover.

This would need a microcontroller or more advanced RC system.

That depends on many factors including the remote control itself, the motor controller, the motor and the gears.

Only you know your fabrication options. If you are willing to custom make tracks, you have many options. The harder part is making a drive sprocket which can properly mesh with them.

We offer a selection of robotic arms and most are DC gear motor or servo based. If you go with the easier servo-based arm, each joint will cost about $30 to $50 each…

You’ll need matching chain and then add segments ot that chain.

You don’t worry about compatibility of the motor with the microcontroller because the microcontroller should not drive the motors directly. You need a motor controller. We suggest you use the RobotShop Drive Motor Sizing Tool.

You can connect the servo pinout to the analog pins of the Arduino and use a timer, though the Arduino Uno only has one timer. If you want dual control, you will need either a more complex system or quite a bit of programming.

A few things, the most important being your budget vs your wants… To get what you want you will either need to “scrap build” everything which takes significant time and knowledge, or scale back to roughly 1/10 what you envision. It’s easy (and can be fairly cheap) to build a frame which can support the payload, but as soon as you want to make it move, the cost increasts significantly. What you envision here sounds like a better long-term project rather than a “starter” one.

Hope this helps,

8

Hi,

Happy to help. Posting it here on the forum also means that other people get to benefit from the conversation. Since you have increased your budget, the Banebots CIM motor plus a gear down is the best way to go. The smaller the geardown, teh faster the robot, but the less it can carry. The higher the geardown, the slower the robot but the more it can carry. Don’t worry about teeth.

The CIM motor with at least a 30:1 should give you the flexibility you want with good payload capacity. You can start off with a 12V car battery (please… be careful since we’re talking very high current). Note that it is a high current motor and you’ll need a high current (50A or more) dual motor controller. Consider the Sabertooth Dual 50A driver (this can connect to an R/C interface).

Hope this helps,

9

Hi,

To make an R/C system:

]R/C motor controller with two channels/:m]
]Two gear motors/:m]
]Two wheels/:m]
]Two hubs (to connect the wheels to the hubs)/:m]
]Battery/:m]
]Wiring/:m]
]R/C system/:m]
Sound like you want to learn more about gear ratios, so try the following links:
Howstuffworks: Gears
Nasa eClips: How Gears Work (overlook that it’s part of a kids show)
en.wikipedia.org/wiki/Gear_ratio

The larger the gear ratio, the slower the rpm and the more torque at the output shaft.

Basically, when you “gear down” a motor it means that you couple a gearbox to it (e.g. 10:1, read “ten to one”) that will decrease its speed and thus increase its torque (e.g. a 10:1 gearbox will reduce the speed tenfold and increase the torque tenfold). This is useful when driving vehicles since usually electric motors spin very fast but do not provide lots of torque. Following with the same reasoning, a 100:1 gearbox will increase the torque 100 times while the output shaft will spin 100 times slower.

The opposite can be true also. There are situations (e.g. when driving a propeller) when you want a motor to spin even faster so you need to gear it up (e.g. 1:10).

For your situation, you will find all the available gearboxes for the CIM motor here:
robotshop.com/search/sear…ds=cim%20motor