Instructables

Combat Robotics Tutorial

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***DISCLAIMER: Some of this information could be better or is inaccurate.  Specifically how big of a battery you need.  I plan on making a new tutorial eventually, but for the most part this tutorial is accurate.***

Have you ever wanted to build a combat robot (battlebot), but gave up because you didn’t know where to start? Well, hopefully this tutorial/instructable will help. I condensed a lot of information down into a step by step process, taking out most of the stuff you really don’t need to know, but leaving the crucial information. This tutorial is focused on the insect weight robots (75grams to 6 pounds), because the majority of competitions held are for insect weight robots, and they are the least expensive.

Throughout this tutorial I will be putting a robot together for demonstration. I used wood for a material,and you shouldn't.  The reason why I used wood, was because I was just putting the robot together for this tutorial, and I am never going to compete with it.  In fact I already threw it away, because it was a mix-match of a bunch of different ways to do things.

 
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Step 1: Weight Classes

Picture of Weight Classes
Before you do anything else, you have to pick a weight class. The weight constraint helps determine which parts are needed.

Insect Weight class:
• 75g Fleaweight (not common)
• 150g Fairyweight (5.3oz)
• 1lb Antweight
• 1kg Kilobot (Canada Only)
• 3lb Beetleweight
• 6lb Mantisweight (not common)

I suggest building an antweight or a beetleweight as a first robot, because you don’t have to be as concerned about weight as with lighter robots. It is less expensive to build a antweight, but you will find it easier to stay under the 3 pound limit. Also, beetleweights are more common than antweights, but any competition that has beetleweights will have antweights, and vice-versa. So, it is really up to you, just pick a weight class and go with it, you can always build another robot for a different weight class.

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bccase164 months ago

what did you make your drum out of? what would be a good weight for a drum in the beetleweight class?

Fragmaster5 months ago

Hi Jared

Can you suggest an ESC for this weapon motor?

http://www.hobbyking.com/hobbyking/store/__39038__...

Since the motor will be driving a weapon with far too much angular momentum, I need it to be able to coast to a stop. The 30A ESC that I already bought occasionally makes weird sounds and stops responding if I let go of the stick and let it spin down. It works fine if I program it to enable braking, but that just won't be feasible when I attach the weapon to it. Here's the ESC that I bought:

http://www.hobbyking.com/hobbyking/store/__30931__...

JaredsProjects (author)  Fragmaster5 months ago

The ESC you have should work when braking is disabled. It's hard to tell exactly what the problem is without being able to see it. If you could post a video to youtube and then send me the link I'd be able to help you more.

I can't post a video until this weekend since I don't have it with me at the moment. Maybe it's just a defective ESC. I bought another one at the same time, which burnt up. So perhaps they are just especially poor quality.

Here's an animation of what the final product is going to look like. (SolidWorks is awesome)

kooljo1 year ago
hi I am just a beginner. i am wondering what type of battle bot i should start out with. thank you
JaredsProjects (author)  kooljo1 year ago
I recommend building a wedge as your first robot because they are easier to build. I now well antweight kits that are great for beginners if you are interested in those. They are available at http://www.titantechindustries.com/
thank you im more interested in building my battlebot from scrach instead of a kit but i will check kits out to. thanks again
JaredsProjects (author)  kooljo12 months ago
I can understand that, building from scratch is very rewarding. If you build your first robot from scratch I recommend mainly focus on just getting it to function. It may not do great at a competition, but just taking a functional robot to a competition is a great place to start. You'll learn a lot in the building process and at the event that you can use on a second version. My first robot (the one in the main picture) was actually kind of terrible. I did a lot of things wrong, but just by taking it to a competition I learned a ton. Even though it wasn't a good robot it somehow managed to get 3rd place, which is ridiculous. There were a lot of other robots at the competition that were better so I just got really lucky.
i am a beginner and want to make a combat robot i like one in the range of 2-10 pounds .Can you give me some suggestions on what type of robot to make
JaredsProjects (author)  gokulsmail4u1 year ago
The best kind of robot to build as your first robot is a wedge, because you don't have to deal with the complications of a weapon. Usually 1lb robots are the easiest to build as your first robot. 3lb robots are also fairly easy because you have more weight to work with.
yvesyuzo1 year ago
Hi,
Do you recommend another motor for fairyweight? a faster one with a shaft large enough to fit finger tech wheels (0.5in or 0.75 inches of Width)

Thank you
JaredsProjects (author)  yvesyuzo1 year ago
Are you building a featherweight (30lb) or fairyweight (150g) robot? For a fairyweight I recommend the new mini sparks that fingertech will be releasing soon. There will likely be several gear ratios to pick from that will determine the speed. The shafts on these motors will likely be 3mm (~1/8") as that is what the size of hubs wheels fingertech makes.

If your original question about motor mounts was about fairyweights rather than featherweights, then absolutely you can use UHMW as a motor mount material. That would likely be my material of choice of a fairyweight motor mount because it is strong enough and very light. In my last reply I said I didn't have much experience with featherweights. However, I am much more experienced with fairyweights as I have built one and I am familiar with the components because they are sold on the websites I frequently by things from for my antweights (1lb).

If this is your first robot I recommend building a fairyweight or an antweight because they are much less expensive and are easier to build than a featherweight.
Im building both!
But Im focus on the fairy now.
I dont have time and I need a fairyweight motor to fit FT wheels.
The 100:1 RMP is to slow and the 30:1 is to short on the shaft, even the lectra wheels wont fit.
Do you think 5mm armor wall's will be fine on combat?
Thank you for the help!
JaredsProjects (author)  yvesyuzo1 year ago
The 30:1 should be fine for the lectra and lite flite wheels if you use a lite flite hub that fingertech sells. The shaft doesn't have to go very far into those because the set screw part is about 1/4" deep. I used some 30:1s with lite flite hubs and they worked fine in my fairyweight.

Depending on the material 5mm should be plenty. My current antweight uses 3mm UHMW in some places. I'm not expecting the 3mm to hold against most weapons though but it should be thick enough to protect the electronics even if the UHMW gets torn up during a hit.
I dindn't knew about that, I though the lite flite hub couldn't support the wheels.
Do you know any material besides titanium, to use on a vertical spiner weapon?
JaredsProjects (author)  yvesyuzo1 year ago
For a 150g 1/8 Ti should be fine. For higher weight classes I recommend heat treated S7. It will hold up well to almost anything.
yvesyuzo1 year ago
Thanks for the answer!!
I have another question, about speed controlers and motors.
If for instance i have a Victor 884 with the Maximum Current of 40A continuous, and use it to control the CIM Motor(12V DC), with a Stall Current of 133A. In the case of conecting a LiPo battery(12v) to control the motor the Esc's will burn? No way I could use this combination?
Btw do you have a active robot for this year??
Thank you
JaredsProjects (author)  yvesyuzo1 year ago
Victor 884's should be able to control a the CIM motor you're talking about, I put the numbers from the motor into this calculator, http://www.architeuthis-dux.org/torquecalc.asp, and it shouldn't get close to stalling. Most of the time motors won't reach their stall current because the wheels will start to spin before then. I only build insect weight robots, so I don't have much experience with what motors people are using for featherweights. People from the RFL Forum or the Facebook group called Robotics Community are more knowledgeable in the higher weight classes than I am. You might want to ask around on those forums to see what parts they use. I do have an active robot. It is an antweight called Guildenstern and I plan to compete with it at the Central Illinois Bot Brawl in April (http://www.buildersdb.com/eventdetail.asp?eventid=363). It's been about a year and a half since my last competition and I've been working on the robot on and off since then. If you have any other questions please ask, I'll do my best to answer them.
yvesyuzo1 year ago
Hi!
Do you think UHMW motor mounts should work fine on Featherweight?
JaredsProjects (author)  yvesyuzo1 year ago
UHMW probably wouldn't be the best material in a featherweight. I recommend aluminum because if you face mount the motor (screw through the mount into the front of the motor) UHMW wouldn't hold up too well if one of the wheels gets hit. Also, if you use a clamp style mount with UHMW in a featherweight the torque the drive motors in that class generate could make the motors spin inside the mounts because UHMW is kind of a slippery material.
ahleagle1 year ago
hello im trying to make a beetle weight bot and I'm trying to figure out what battery to get. the motors im planning on using are the "FingerTech spark 20:1 Gear motor" and im looking at this battery it is a E-Flite 1800mAh 2S 7.4V 20C LiPo Battery, 13AWG EC3. i am also using the smallest sabertooth esc the one rated for 5amp continuous and 10amp max per channel. I would greatly appreciate any feed back you can give on the battery subject. Is it a good one? will it work? and why are there two leads comming off of the battery?
the links to the above mentioned items are below. thank you for any help you can give in advance.

-ahleagle

motor:
(http://www.robotmarketplace.com/products/0-FT-SPARK16-20.html)

esc:
http://www.robotmarketplace.com/products/0-SABER2X5-RC.html

battery:
(http://www.amazon.com/E-Flite-1800mAh-7-4V-Battery-13AWG/dp/B000YUTIVI/ref=sr_1_1?ie=UTF8&qid=1356744401&sr=8-1&keywords=lipo+battery+7.4v+e-flite)
JaredsProjects (author)  ahleagle1 year ago
For the drive motors I recommend that you don't use the gold version of the sparks. They are not intended for combat. Silver spark are much more suitable for combat and are made by the same company. You should be able to find them from robot marketplace. I have never used silver sparks in a beetleweight but I know of other builders who have and they have had success with them. You will probably have to run the motors at 4S (14.8V) for them to work effectively in a beetleweight though. If you don't plan on having a weapon the silver sparks won't be powerful enough for a wedge robot.

For the ESC I recommend fingertech tinyescs. They are the same price (or pretty close) as the sabertooth and are tremendously better. I have used the sabertooth escs before and had a lot of issues with them. If you get the tinyescs you have to buy two, one for each motor.

The battery had two leads because it is Lithium Polymer (LiPo). One lead has the positive and negative (red and black) wires which connect into you robot, these are like the normal terminals on a battery. The other lead has the wires which connect to each individual cell of the battery. This lead is used when charging the battery, because the cells need to be kept within .1V of each other to avoid damage to the battery. LiPo battery chargers take care of keeping the cells within .1V of each other when charging.

That battery is likely too low of voltage if you use silver sparks, and too high of a capacity. I don't know what capacity you need for sure with out knowing weapon specs, drive motor, and tire size. But, 1800mAh is a little overkill unless the weapon draws a tremendous amount.

This will help with motors and battery choice, at least for drive anyway.
http://www.killerbotics.com/kbtools/TentacleTools/
Silver Sparks aren't an option so you will have to input their specs from fingertech's website.
ahleagle1 year ago
What gear ration would you recommend for a Beetleweight in the finger tech spark series silver motors?
black hole2 years ago
Perhaps a good defence against saws might be multiple thin plates that could get torn off without doing major damage to the robot. It also might work against spear bots.(The top layer cracks, then the next... giving you more time)
what about carbon nano-fibers? they are very strong and durable. stronger than diamond, actually.
And they can't be produced in useful quantities yet, or for a reasonable cost.
i have an idea. how about using a mag lev to hold up the upper half? neodymium magnets work best for mag levs.
cmcmillan3 years ago
how would i make a flametrower i mean i know how like all i need is some wd40 and like a candle but i dont know how tospray the wd40 from a good distancent
please i just advise that you keep the wd40 away from flames even read it on the safety label if you really want more info in fact it is a hexagon danger of flammablity and same with pioson
If you watch the UK robot wars, you see that Seargeant Bash has a massive nozzle and underneath it, there is a tiny little flame. Gas goes through the metal tube,and through the metal nozzle, so the flame 'throws' itself. You might find it a bit hard, but that's all my knowlege. Good luck!
JaredsProjects (author)  cmcmillan3 years ago
You could just mount a servo on top of the can of WD-40 to press it down.  It should spray far enough by itself if it has a straw on it.  Also, you would have to use some sort of electric ignition device (way too fancy of a name), like a wire that gets hot or a gas grill sparker, because they wouldn't let you have a candle on your robot.  Most competitions don't let you have flamethrowers at all.
sampson1113 years ago
why dont u hav wheels on the front of the robot i im making one too ill take photos and put them up
JaredsProjects (author)  sampson1113 years ago
The extra wheels would have added too much more weight.  Also two drive motors was enough torque.  In insect weight robots it is much more common to have 2 drive wheels instead of 4.
wat if the front wheels had no drive motor and just rolled when the two back motors were going but even then it would be still to heavy depends on witch weights classes ure in
JaredsProjects (author)  sampson1113 years ago
It is easier to use a caster, or a carriage bolt instead of having two more wheels in the front.  On the robot in most of pictures I used a caster, but it wasn't very durable, so I suggest a carriage bolt.  Also like you said, it does depend on the weight class, it would be much easier to keep a beetleweight at 3 pounds with the extra wheels, than keeping an antweight at 1 pound.

-TTR
sampson1113 years ago
kool thanks that helped alot
sampson1113 years ago
what sort of wheels are u using were can i get them thanks
JaredsProjects (author)  sampson1113 years ago
I used banebots wheels, they come in many different sizes and 3 different hardnesses.  The hubs they make come in a couple of different shaft diameters.  Lite-Flite wheels are much more common though, because they offer a good blend of light-weight and grip.

-TTR
JaredsProjects (author)  JaredsProjects3 years ago
Forgot to mention, both of those types of wheels are available from Robot Market Place.  That is where those links are to.

-TTR
lordi873 years ago
Where do you get your weights from?
I tried google products and ebay but couldn't find them
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