gametechmods
Off-Topic => Real Robotics => Real Robotics Discussion => Topic started by: RedSawn on December 19, 2012, 08:38:13 AM
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Nothing is really solid right now, but I might as well get the word out for opinions and advice.
I'm thinking of building a UK ant (0-150g) at some point. Probably when everything falls together. It is to my understanding the class sees a lot of action, so yeah.
Personal notes here:
- With a minimum budget of £150 and a surveying of the potential parts I will use on the Robot Marketplace money may not be too much of a problem, but the weight of parts is.
- I do not have real experience with metalworking, and only lower-school experience with electronics, but any equipment required should be attainable, and it may be possible that I have local sources to assist a project. I have previously cut wood and plastic (PVC I believe?) with workshop tools, powered and not.
- We have electric RC cars and a model airplane that may be possible to raid for parts, if only for the free battery and some crystals if required. Possibly wheels too but they may not be suitable for the job.
- Currently I am only referring to the Robot Marketplace for parts. Armor will be something to think about.
- I still have no bloody idea how I'm going to create the shell.
The primary idea:
A four wheeled box rammer/pusher inspired by New Blood Storm 2, or perhaps more simply, a lower profile, highly mobile Eye Poker (ya'know, from Stock AI) without the spikes. Even simpler if need be, Tornado.
And here's my would-be shopping list for it so far:
x4 30:1 Micro Geared Motor - About 9.64 grams each and about £9.79 each - http://www.robotmarketplace.com/products/0-PL1093.html (http://www.robotmarketplace.com/products/0-PL1093.html)
These seem to be the motor I should use for 4wd given if I go for the heavier 35:1s ( http://www.robotmarketplace.com/products/0-GM19.html (http://www.robotmarketplace.com/products/0-GM19.html) ) half of the weight of the bot would be taken up by the drivetrain. It really depends on if the other components allow for it.
x4 1.75 inch Lite Flite Wheel 2pk - About 6.52 grams each, currently discounted at about £2.45 a pair - http://www.robotmarketplace.com/products/0-DAV5517.html (http://www.robotmarketplace.com/products/0-DAV5517.html)
They seem to be a respectable choice. If the projected height of the bot is small enough I'll go for the 1.5 inch wheels ( http://www.robotmarketplace.com/products/0-DAV5515.html (http://www.robotmarketplace.com/products/0-DAV5515.html) ) instead - drilling the axle hole shouldn't be an issue.
x4 Lite Flite Hub - 1.2 grams each and about £3.06 a pair - http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html (http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html)
To attach the Lite Flites, ofcourse. Probably the most convenient because of the adhesive fixture of the wheels.
As for motor mounting I'm not sure: There's the choice of the smaller ( http://www.robotmarketplace.com/products/0-PL989.html (http://www.robotmarketplace.com/products/0-PL989.html) ) and the extended bracket ( http://www.robotmarketplace.com/products/0-PL1089.html (http://www.robotmarketplace.com/products/0-PL1089.html) ) for these micro motors.
The total cost for the motors, wheels and hubs would be about £50 and they weigh in together at about 69.44 grams, leaving 80g and £100 for other stuff.
The backup idea:
In the case four wheel drive is not viable I could instead have a fast box 2WD rammer/pusher with a resilient front end, which particularly makes me think of All or Nothing (BBEANS) except with a ramplate instead of the rows of spikes.
Would-be shopping list for it so far:
x2 35:1 Micro Geared Motor - 15 grams each, about £11.66 each - http://www.robotmarketplace.com/products/0-GM19.html (http://www.robotmarketplace.com/products/0-GM19.html)
Without the need for four motors, I can definitely use two of these heavier motors. Same again though, if the weight of the other components allows it it may be possible to go for a 1:30 COPAL ( http://www.robotmarketplace.com/products/0-COPAL30.html (http://www.robotmarketplace.com/products/0-COPAL30.html) )
x2 1.75 inch Lite Flite Wheel 2pk - About 6.52 grams each, currently discounted at about £2.45 a pair - http://www.robotmarketplace.com/products/0-DAV5517.html (http://www.robotmarketplace.com/products/0-DAV5517.html)
x2 Lite Flite Hub - 1.2 grams each and about £3.06 a pair - http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html (http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html)
An issue here would be if I go for a caster for both sides up or just have the robot's front drag across the floor.
This setup weighs about 45.44 grams and costs about £28.33 - certainly a lot cheaper and lighter, leaving 105 grams and £121.
Building a prototype in RA2 won't be a problem. Actually drawing them up is a bit hard without all of the necessary components.
Which idea is the primary and which is the 'backup' may change as describing the backup plan as All or Nothing makes me a little fonder to see it in action.
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Might I recommend Botbitz (http://www.botbitz.com/index.php?route=product/category&path=60) gear motors? You wont have to pay the price of brand names. They're just a little bit heavier than the brand name gear motors, but way cheaper.
I approve of lite flites, but I would suggest Lectra lites (http://www.robotmarketplace.com/products/0-DAVQ5300.html). They are exactly the same as Lite Flites, but are thinner and weigh less.
The type of plastic you want to use is either UHMW or HDPE. Most US builders prefer the former, and most UK builders prefer the latter.
Crystal based radios are a dieing breed, go with a inexpensive 2.4Ghz radio (http://www.hobbyking.com/hobbyking/store/__24968__Turnigy_4X_FHSS_2_4ghz_Transmitter_and_Reciever_Mode_2_.html).
That's my say.
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It's fairly worrying that the Botbitz 1:30 motors have less than half the free-run RPM for the same weight and not much difference in price than the 1:30 gearmotor I picked out, considering speed is paramount to the design (I am also speaking like I actually have an idea what I am doing and 475 RPM may really be enough and 1000 too much). Will think about it if the projected costs are higher than expected.
Hmm, when you say the Lectra Lites are lighter, I was expecting more then 0.28 grams a wheel (though saying that it's not insignificant on something so light already). If I do have to use a 1.75 diameter wheel I'll certainly think about it, but if I can use smaller diameter wheels, the 1.5" diameter Flites mentioned are 1.7 grams lighter per wheel out of the box then the 1.75" Lectras.
Thanks for the choice of plastic, having a few alternatives to metal will help.
That's a pretty damn cheap 2.4Ghz radio. I was aware of 2.4Ghz but I mentioned the crystals just to say "I -do- have a free (if lacking) alternative."
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Thanks for the tip on BotBitz and armor Vertigo. Very true with the thickness of the wheels, certainly a reason to go for the Flites over the Lectras.
(https://gametechmods.com/uploads/images/13897realconcept.png)
RA2 prototypes! In my opinion it needs more razors
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Narrow wheels have the advantage of self cleaning when they lose traction. Lite Flites and Lectra Lites have the issue of being lint rollers, trust me when I say this.
Also, you can get 1.5 inch Lectra's at finger tec robotics. They weight 4.25 grams.
If you want to build a rammer/wedge, I would suggest the 50:1 motors, not the 30:1. The reason is that you need to have very quick acceleration, like a bullet. Speed is meaningless unless you can get up to that speed quickly. This was the secret to Tornado's success.
Also, I have both a Hobby King brand radio and a Spektrum Dx5e, you have room in your budget, I would suggest the Dx5e, as it is way nicer than the Hobby King radio.
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Alright, I'll look at the 50:1s on offer when I get the chance. It was a bit of an assumption to go 30:1, as while I don't know my ratios, 1000:1 is described as fine, precise movement.
Isn't there some sort of manual method to clean foam wheels?
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Your hands are the only good tools, the wheel is too porous to use a cleaning solution.
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Alright, I'll look at the 50:1s on offer when I get the chance. It was a bit of an assumption to go 30:1, as while I don't know my ratios, 1000:1 is described as fine, precise movement.
Isn't there some sort of manual method to clean foam wheels?
yeah, its picking crap out of them or doing a burnout or something to spin the wheels against a non moving surface.
robot speed is simple math. for mph its (tire diameter * axle shaft speed / 336 = mph) for feet per second its (tire diameter * axel shaft speed / 240 = fps)
i'm not sure what usual uk ant speed is but 5mph is "fast" for a "us" 3lb or 1lb bot.
a "quick" robot can get up to speed in about 1 robot length.
if i was you i'd go with lite flites because they are thicker. if a chunk gets ripped out of one of them there will be more wheel left than if the same size chunk was ripped out of a lectra flite.
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yeah, its picking crap out of them or doing a burnout or something to spin the wheels against a non moving surface.
robot speed is simple math. for mph its (tire diameter * axle shaft speed / 336 = mph) for feet per second its (tire diameter * axel shaft speed / 240 = fps)
i'm not sure what usual uk ant speed is but 5mph is "fast" for a "us" 3lb or 1lb bot.
a "quick" robot can get up to speed in about 1 robot length.
if i was you i'd go with lite flites because they are thicker. if a chunk gets ripped out of one of them there will be more wheel left than if the same size chunk was ripped out of a lectra flite.
That's smart thinking with the burnout. Would any reasonable surface do?
So if my calculations are correct, with the 1000 RPM micro motors and 1.75" wheels that's a theorical top speed of 5.2 mph (4.4 mph with 1.5" wheels) on something I'm going to be able to measure on a 15cm school ruler? Those are.. impressive values. I'd love to get a scale speed on that.
Another good point with the wheel thickness, I'm more inclined to go for the Lite Flites at this point.
I'm looking at the battlekits ( http://www.robotmarketplace.com/BK-BKT60.html (http://www.robotmarketplace.com/BK-BKT60.html) ) and how the wheels protrude particularly out of the rear. This would solve the potential problem of being tipped onto the rear, and it would save a few grams of armor too, but I doubt it is viable with foam wheels?
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If the speed and agility would be comparable to a Rotax Max kart I've experienced something with such ludicrous speed first hand x) I've raced RC cars and 80 mph karts indoors and outdoors at varying levels. Nothing with tank steering, but it's not like I'm going at it with absolutely no experience.
It is a pretty slim chance, yeah, true.
EDIT: I found out that when I was referring to 1000 RPM I was thinking of the 1050 RPM 35:1 Micro Geared motors, the big ones currently intended for the 2WD concept.
Anyway, I was looking at the 50:1 motors on the Robot Marketplace.
http://www.robotmarketplace.com/products/0-GM11A.html (http://www.robotmarketplace.com/products/0-GM11A.html) 56:1 Micro Geared. 7.8 grams, 480 free run RPM. Would replace the 4WD motors well; they actually weigh .4 grams less but are the same size, draw nearly the same current, almost runs at the same RPM as the 30:1s (which are actually 500 rpm) but apparently has 58% more torque. Seems like a good tradeoff if you ask me.
EDIT2: I have now also found high power versions of the 30:1 and 50:1 micro motors. The current is higher across the board but performance is significantly improved.
http://www.pololu.com/catalog/product/1093/specs (http://www.pololu.com/catalog/product/1093/specs) 30:1
http://www.pololu.com/catalog/product/998/specs (http://www.pololu.com/catalog/product/2213/specs) 50:1
EDIT3: I have realized I got myself confused. There are two "30:1 Micro Geared Motors" in the Robot Marketplace store. One says it does 1000 RPM and the other does not (500 RPM). I must assume one of them is the HP version but unmarked as being such.
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1000:1 30:1s? Confusing x) Odd how they supposedly weigh significantly different. They're still 10 grams, shouldn't cause too many problems.
(https://gametechmods.com/uploads/images/2297bruteforce.png)
This is where I am now, a fast and agile 4WD box rammer/pusher with a tough front end to go head-on with whatever. A box will make for a simple first build.
It's probably in my best interests to go with the smaller micro motors in that case. Anyhow, here's a list of all three different powers of the 30:1 and 50:1 micros. It's hard to really say anything because every site has different readings for the capabilities of the motor, and the only thing they can agree on is the dimensions and weight.
Low Power 30:1 http://www.pololu.com/catalog/product/993/specs (http://www.pololu.com/catalog/product/993/specs)
Medium Power 30:1 http://www.pololu.com/catalog/product/2364/specs (http://www.pololu.com/catalog/product/2364/specs)
High Power 30:1 http://www.pololu.com/catalog/product/1093/specs (http://www.pololu.com/catalog/product/1093/specs)
Low Power 50:1 http://www.pololu.com/catalog/product/1098/specs (http://www.pololu.com/catalog/product/1098/specs)
Medium Power 50:1 http://www.pololu.com/catalog/product/2365/specs (http://www.pololu.com/catalog/product/2365/specs)
High Power 50:1 http://www.pololu.com/catalog/product/998/specs (http://www.pololu.com/catalog/product/998/specs)
It seems I must decide among these, baring in mind the motors, wheels and hubs will take up 69.44 grams though a bit less with 1.5" inch wheels, that I'll need to find and fit a battery in there suitable for the total current of whichever motors I use, and these choices must allow for the speed controller and shell of the bot :s I really have no idea what all of this is going to weigh.
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Oh x)
Sure, it'd still go fast and it'd have the pushing power too. Now I need light enough batteries to power the motors. And a speed controller.
I was turned off from the wedge because we'd literally have the same bot! Just you have Lego wheels and whatnot.
It does bring up an interesting thought though - perhaps the front could be interchangeable, a flat plate of armor or a wedge. Hell, maybe even a scoop. If it's designed to be as simple as undoing a few screws here and there, ofcourse.
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Well I'm based out of Kent, and I'll consider places as they come up.
Naturally, though it hinged on the simplicity of fixating the plate/wedge/scoop. It looks like the wedge on your bot is held on by the four large screws, which doesn't look particularly taxing to take off and put back on.
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Aaaah x) Well yeah, I only need one bot for now.
So I have the drivetrain, what about the power, speed controller and whatnot?
http://www.robotmarketplace.com/products/0-SABER2X5-RC.html (http://www.robotmarketplace.com/products/0-SABER2X5-RC.html) I'm only really aware of the Sabertooth 2X5 for a speed controller and that seems a bit heavy for UK ants/US fairys.
http://www.hobbyking.com/hobbyking/store/__11965__OrangeRx_R610_Spektrum_DSM2_6Ch_2_4Ghz_Receiver_w_Sat_Port_.html (http://www.hobbyking.com/hobbyking/store/__11965__OrangeRx_R610_Spektrum_DSM2_6Ch_2_4Ghz_Receiver_w_Sat_Port_.html) Glad to see OrangeRx was mentioned. Super lightweight 2.4 receiver compatible with Spektrum transmitters that costs just under $6? Bloody heck.
EDIT: When I searched for the Spektrum Dx5e I knew it looked familiar, and lo behold, it (kinda) did. It turns out my dad's model aeroplane uses the Spektrum DX6i ( http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPM6600 (http://www.spektrumrc.com/Products/Default.aspx?ProdID=SPM6600) ). Since he basically never uses it I may of scored a free TX. There'll be no issues using it, right?
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I would recommend the Finger Tec ESC. They are very light weight, and very easy to use.
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Convenient link since I actually had to poke around: http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2 (http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2)
You weren't kidding when you said those were lightweight. Would I need to do anything to them other then hook it up to everything? I.E is it combat ready out of the box or must I do something?
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You have to solder on both the motors and battery connectors, other wise, it's ready to go.
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The problem with them would be that you would need 2 to drive 4 motors, which then brings up the problem of mixing (which can be done on the DX6i if you're willing to mess with the settings but is still a pain in the neck).
That doesn't sound like something I can manage. Seems I'm still with the Sabertooth but isn't there a speed controller that can handle 4 motors that doesn't weigh over a tenth of my weight limit? I'm still not sure what battery I'll need but what I can tell that'll be a significant chunk of weight too, and it feels like it is adding up.
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go with the tiny escs. I've never been happy with the quality of the sabertooths. if you have any questions about mixing and wireing let me know.
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Yeah, since I'm getting all of the technical stuff and such out of the way before I even think of buying the parts I'm going to need to know how to before I can consider the Tiny Escs, or anything for that matter.
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With mixing, you can either do it on the transmitter itself or get a small plug in mixer that can be put in the robot itself.
DX6i mixing:
Lighter robot weight
Lower top speed due to how the mixing works
Onboard mixing:
Higher robot weight
Faster drive speed
I've used this one in several robots and it works great- http://www.robotmarketplace.com/products/0-DGEVMXR.html (http://www.robotmarketplace.com/products/0-DGEVMXR.html)
The fingertech one works as well, but it doesn't failsafe properly, so it may not be legal if the rules require a full drive system failsafe.
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Sounds like it'll be onboard mixing. Surely can't be that much weight difference, right?
I'm curious as to how these motors will control now. I've been looking for videos of other 150g bots and all I can seemingly find is servo drive, unless I am mistaken about other drive motors at this level.
EDIT: I'm eying this battery as a power source. http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp (http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp) Light, within the voltage range of the motors and will theorically last 30 minutes in use (400ma current total from the four motors, maybe it'll be more on a bigger voltage so maybe I need a 350maH). I can't find a better option.
EDIT2: http://www.google.co.uk/shopping/product/17294855120760941065?q=7.4v%20300mah%20lipo%20battery&ie=UTF-8&oe=UTF-8&hl=en&client=safari&sa=X&ei=ekzaUIOiNoWJ0AX0koEg&ved=0CDcQ8wIwAA#hsec:overview (http://www.google.co.uk/shopping/product/17294855120760941065?q=7.4v%20300mah%20lipo%20battery&ie=UTF-8&oe=UTF-8&hl=en&client=safari&sa=X&ei=ekzaUIOiNoWJ0AX0koEg&ved=0CDcQ8wIwAA#hsec:overview) 300maH 7.4v E-Flite in the case of needing a tad higher capacity.
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almost no US fairyweights (150g) use servos for drive.
your smaller battery should be fine.
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Sure, I just can't find any videos of 150g robots that don't look like they use servo motors. I am of the mind that the videos I am finding are of older competitions and robots where the micro geared motors were not as widely used (Apparently).
My shopping list so far, then:
x4 50:1 Micro Geared Motor HP - http://www.pololu.com/catalog/product/998/specs (http://www.pololu.com/catalog/product/998/specs)
x4 Lite Flite Wheel 2pk (1.5 inch or 1.75 inch diameter depending on robot height) - http://www.robotmarketplace.com/products/0-DAV5517.html (http://www.robotmarketplace.com/products/0-DAV5517.html) or http://www.robotmarketplace.com/products/0-DAV5515.html (http://www.robotmarketplace.com/products/0-DAV5515.html)
x4 Lite Flite Hub - http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html (http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html)
x4 Micro Metal Gearmotor Bracket - http://www.robotmarketplace.com/products/0-PL989.html (http://www.robotmarketplace.com/products/0-PL989.html)
x2 tinyESC v2 Speed Controller - http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2 (http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2)
7.4v E-Flite 200mAh Battery - http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp (http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp)
All in all about £110 and 93~96 grams. Seems like quite a lot of weight to have left, though this doesn't include the body.
To consider:
OrangeRx R610 Spektrum DSM2 6Ch 2.4Ghz Receiver - http://www.hobbyking.com/hobbyking/store/__11965__OrangeRx_R610_Spektrum_DSM2_6Ch_2_4Ghz_Receiver_w_Sat_Port_.html (http://www.hobbyking.com/hobbyking/store/__11965__OrangeRx_R610_Spektrum_DSM2_6Ch_2_4Ghz_Receiver_w_Sat_Port_.html)
500x250mm sheet of HDPE (Not sure about thickness) - http://www.directplasticsonline.co.uk/HDPESheet/Natural/ (http://www.directplasticsonline.co.uk/HDPESheet/Natural/)
Things I already have:
Spektrum DX6i TX
Spektrum Dx5e TX (Yes, turns out my dad has one of these too, and I assume the included RX would be somewhere too)
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http://www.youtube.com/watch?v=WbIm--JCXh8#ws (http://www.youtube.com/watch?v=WbIm--JCXh8#ws)
some modern 150g uk antweights.
http://robotwars101.org/forum/ (http://robotwars101.org/forum/) this might be a helpful place.
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Been thinking about this again for the last week or so. Sometimes you just get inspired and you can't think of doing something another way.
I want to make a 150g Madd, I think it's possible depending on what I do.
(https://gametechmods.com/uploads/images/35919madden.png)
(The wedgemaker and DS tooth are only there for extra damage and RA2 flipping stability, it's really all about the spike)
The drive should be fine to keep on the shopping list, as well as the battery:
x4 50:1 Micro Geared Motor HP - http://www.pololu.com/catalog/product/998/specs (http://www.pololu.com/catalog/product/998/specs)
x4 1.5 inch diameter Lite Flite Wheel 2pk - http://www.robotmarketplace.com/products/0-DAV5515.html (http://www.robotmarketplace.com/products/0-DAV5515.html) (It's pretty clear to me that I won't struggle keeping the shell under 3.5 centimetres tall while fitting the parts in)
x4 Lite Flite Hub - http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html (http://www.robotmarketplace.com/products/0-FT-LITE-HUBS.html)
x4 Micro Metal Gearmotor Bracket - http://www.robotmarketplace.com/products/0-PL989.html (http://www.robotmarketplace.com/products/0-PL989.html)
7.4v E-Flite 200mAh Battery - http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp (http://www.modellbauuk.com/e-flite-200mah-battery-for-mig-306-p.asp)
The weapon is where it gets interesting though - unlike in RA2 I have the option of using a servo to power the arm, which can be lowered/raised to get under the opponent either way up and flip with, or kept in a neutral position for a ramming spear. With mixing the drive could be entirely controlled by the left stick, and the servo the right. Regardless the inclusion of a weapon on a motor means the two TinyESCs won't do it.
Another point is that 99% of the Micro (5-10g) servos are only rated at the most 6V while I have the 7.4V battery. This is assuming these servos (Be it as light as 6g or the 9g ones) have the power to lift or flip 150g opponents with the end of a 4 or 5 cm spike. With torques from 800g/cm to 2.2kg/cm it's hard for a lamen not to make a case. If the servo has a thickness of 9mm like some of the ones I've seen it may be possible to fit it to the front end, between the motor and the front of the bot, without removing the slots for the front wheels to stick out (It would help if the servo was smaller lengthways in that case too). I've also tried doing a diagram of a layout where the servo goes under (or over) one of the drive motors, but this is really less ideal as it complicates construction that much more. This ofcourse isn't RA2, where the parts inside the chassis are fixated in time and space.
The question is if this is doable. The current shopping list weighs in at roughly 75 grams (I hope I weighed everything because that's lighter then I thought for just trading out the 1.75 inch Flites and not including the TinyESCs), not counting the brackets as they have no given weight.
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Ehh, fitting all of that in a 4x4 cube will be a bit dicey. I'm going to say it MIGHT be possible, but I wouldn't count on it. Why not go with a simple wedge?
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Well, really because I don't want to go for a cookie-cutter design x) That, and I -never- make things easy for myself (Though funny enough it usually turns out alright in the end)
EDIT: Took a little visual planning to see I wrote myself into a corner. Arranged the parts and put it to a shell, scale I used is 3 pixels for every millimetre. Sheck is the red line.
(https://gametechmods.com/uploads/images/79549maddtop.png)
From above, it's not so bad, if I haven't made an error. 8.66x3.81x7.66 cm (4 inches is 10.16cm) are the projected bot dimensions without a weapon, if more space or weight is really needed for whatever other parts are needed and I do end up using a OrangeRX, the case can be removed to save about 6g and a sizeable chunk of the main compartment. A few assumptions are made - such as being able to mount the micro motors sideways to save space and keeping the RX and battery sideways for the same reason, and that 1mm armor is enough for fairyweights/UK ants. Biggest problem here is that the side panels are not fixed very securely, that and only having space for a 9mm wide servo. I've found out about High Voltage micro servos that will run directly from 7.4v, but those are 11~12mm. There are still some 6V servos that make the cut, just the voltage to them has to be regulated by whatever means.
(https://gametechmods.com/uploads/images/9356maddfront.png)
But here there's a clear problem. Using the 1.5 inch diameter wheels, even while side-mounting the motors to save 2mm of the space, and squeezing the most room out of the chassis without extending past the wheels, the servo would have to be at the most 9mm wide, 14mm tall, and still be powerful enough to lift 150g on a 4/5 cm spike. 9x14x24.
I think I'll look at the 1.75 inch wheels again and see what comes of that. 6mm might make a big difference.
UPDATE:
(https://gametechmods.com/uploads/images/41697madd175.png)
1.75 inch wheels theoretically allow enough space for a 9x23 servo, which gives the option of the Hyperion DS09 SCD http://www.soaringusa.com/Hyperion-DS09-scd.html (http://www.soaringusa.com/Hyperion-DS09-scd.html) or something like the Ripmax SD100 http://www.sloughrc.com/default.asp?itemid=P-SD100 (http://www.sloughrc.com/default.asp?itemid=P-SD100) Ground clearance is a bit crappy though. making the chassis taller is unnecessary too.
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Anyway you could use gears or small belts to get one motor per side?
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Dude, you're going to have serious turning issues with your wheels that close. Maybe you should use 1 1/2 wheels instead of 1 3/4 wheels.
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Anyway you could use gears or small belts to get one motor per side?
That's one of the other ideas I had, and it would free up the space needed too, but I haven't built a robot before, let alone made belt drive. It might be out of reach for a first project. Then again, this bot as it stands might just be as well. Eh.
Dude, you're going to have serious turning issues with your wheels that close. Maybe you should use 1 1/2 wheels instead of 1 3/4 wheels.
I would probably use 1 1/2 anyway. I'd go for the lower profile any day when it can be helped.