Keres is my latest combat robot project. This is my smallest robot to date, weighing in at just under 150g.
The main motivation for this build was to test out the prototype "Mini-Spark" gearmotors from FingerTech Robotics (http://www.fingertechrobotics.com/) that should be released in the very near future.
The attached .rar contains the drawings for the top plate, bottom plate and weapon bar as well as the .stl you would need to have the chassis printed. The chassis is also available on shapeways at http://www.shapeways.com/model/769811/kereschassisv3.html if you would prefer to just order it. I used White, Strong, & Flexible, which is laser sintered nylon.
The main motivation for this build was to test out the prototype "Mini-Spark" gearmotors from FingerTech Robotics (http://www.fingertechrobotics.com/) that should be released in the very near future.
The attached .rar contains the drawings for the top plate, bottom plate and weapon bar as well as the .stl you would need to have the chassis printed. The chassis is also available on shapeways at http://www.shapeways.com/model/769811/kereschassisv3.html if you would prefer to just order it. I used White, Strong, & Flexible, which is laser sintered nylon.
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Signing UpStep 1: Component Selection
Component selection for robots this small is fairly limited, but luckily there are still a decent number of quality parts available that aren't too large for the minuscule weight budget.
The radio system is a Spektrum dx6i, as that is what I already had and there was no point buying new radio equipment when my current gear can handle several more robots.
The receiver is a hobbyking R410 OrangeRX. It is one of the smallest receivers on the market that I am aware of with programmable failsafes that is also compatible with the dx6i. For a robot this small with the dx6i, it is one of the best receiver options. (http://www.hobbyking.com/hobbyking/store/__11972__OrangeRx_R410_Spektrum_DSM2_Compatible_4Ch_2_4Ghz_Receiver.html)
The battery is another hobbyking product, the Turnigy Nano-Tech 180mAh 2s lipo battery. I've run the larger cousin in my 30lb robot Nyx successfully, so it was an easy decision when I was looking for a small two cell battery. (http://www.hobbyking.com/hobbyking/store/__23135__Turnigy_nano_tech_180mah_2S_25_40C_Lipo_Pack.html)
The weapon motor controller is a Plush10 from hobbyking. These are a common brushless controller that appears to pair well with my weapon motor. (http://www.hobbyking.com/hobbyking/store/__4204__TURNIGY_Plush_10amp_9gram_Speed_Controller.html)
The weapon motor is an Emax GT Series 1560kv brushless outrunner. The original motor I was looking at went out of stock and instead of waiting and hoping that it would return to stock, I found this and have been happy with the performance. (http://www.himodel.com/electric/EMAX_GT_Series_1560KV_Outrunner_Brushless_Motors_Type_GT2203.html) One minor change I have made is the stock shaft has been replaced with one of the spare hardened 3mm shafts discussed in my instructable on my 1lb robot, Algos (http://www.instructables.com/id/One-Pound-Fighting-Robot-Algos/step5/Shaft-Replacement-and-Hardening/)
In addition to the weapon shaft, Keres uses the same weapon hub as my antweight Algos. The lightweight 3mm hub from ServoCity seems to work quite well in this application. (https://www.servocity.com/html/lightweight_set_screw_hub__3mm.html)
Drive motor controllers are FingerTech TinyESC's. I've used these in all of my small robots and they have proven to be a fantastic brushed motor controller. At this point, I use them in any application that they're appropriate for. (http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2)
The drive motors are 20:1 prototype Mini-Sparks which will be available soon at http://www.fingertechrobotics.com
One additional component will be added shortly before the debut event for Keres. In addition to being used to test the Mini-Spark gearmotors it will be testing a prototype power switch also from FingerTech Robotics.
The chassis is held together via 3 7/16" long aluminum standoffs. The McMaster part number is 93330A515. These press into the printed nylon chassis.
The radio system is a Spektrum dx6i, as that is what I already had and there was no point buying new radio equipment when my current gear can handle several more robots.
The receiver is a hobbyking R410 OrangeRX. It is one of the smallest receivers on the market that I am aware of with programmable failsafes that is also compatible with the dx6i. For a robot this small with the dx6i, it is one of the best receiver options. (http://www.hobbyking.com/hobbyking/store/__11972__OrangeRx_R410_Spektrum_DSM2_Compatible_4Ch_2_4Ghz_Receiver.html)
The battery is another hobbyking product, the Turnigy Nano-Tech 180mAh 2s lipo battery. I've run the larger cousin in my 30lb robot Nyx successfully, so it was an easy decision when I was looking for a small two cell battery. (http://www.hobbyking.com/hobbyking/store/__23135__Turnigy_nano_tech_180mah_2S_25_40C_Lipo_Pack.html)
The weapon motor controller is a Plush10 from hobbyking. These are a common brushless controller that appears to pair well with my weapon motor. (http://www.hobbyking.com/hobbyking/store/__4204__TURNIGY_Plush_10amp_9gram_Speed_Controller.html)
The weapon motor is an Emax GT Series 1560kv brushless outrunner. The original motor I was looking at went out of stock and instead of waiting and hoping that it would return to stock, I found this and have been happy with the performance. (http://www.himodel.com/electric/EMAX_GT_Series_1560KV_Outrunner_Brushless_Motors_Type_GT2203.html) One minor change I have made is the stock shaft has been replaced with one of the spare hardened 3mm shafts discussed in my instructable on my 1lb robot, Algos (http://www.instructables.com/id/One-Pound-Fighting-Robot-Algos/step5/Shaft-Replacement-and-Hardening/)
In addition to the weapon shaft, Keres uses the same weapon hub as my antweight Algos. The lightweight 3mm hub from ServoCity seems to work quite well in this application. (https://www.servocity.com/html/lightweight_set_screw_hub__3mm.html)
Drive motor controllers are FingerTech TinyESC's. I've used these in all of my small robots and they have proven to be a fantastic brushed motor controller. At this point, I use them in any application that they're appropriate for. (http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2)
The drive motors are 20:1 prototype Mini-Sparks which will be available soon at http://www.fingertechrobotics.com
One additional component will be added shortly before the debut event for Keres. In addition to being used to test the Mini-Spark gearmotors it will be testing a prototype power switch also from FingerTech Robotics.
The chassis is held together via 3 7/16" long aluminum standoffs. The McMaster part number is 93330A515. These press into the printed nylon chassis.
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Do you pretend to compete at RoboGames this year?
I have a few more questions:
Did any robot heavily damage your nylon armor?
I'm also building a horizontal spinner, what's your opinion on these weapon motors?
http://www.hobbyking.com/hobbyking/store/__26482__2205C_1400Kv_Brushless_motor_USA_Warehouse_.html
http://www.robotmarketplace.com/products/0-EFLM1130.html
Does the price of RMP worth?
Thanks again!
The RMP motor is likely higher quality, but the shape makes it appear that mounting could be an issue. They're a great source if you need good parts quickly. The hobbyking motor you linked is a good bit heavier than the one I used, so torque will likely be better but you'll also have to find some more weight to fit it in the 150g limit.
Thank again for your help
Do you think a 100:1 SRV Drive Motor would work fine insted of Mini-Spark motors??
Do you think fitting the wheels on the D shaped output shaft with FingerTech Lite Hubs would be difficult to stay balanced? I'm talking about the robot market place one.
Are you going to participate on any tournaments this year?
More detailed info on the motor controllers can be found here: http://www.fingertechrobotics.com/proddetail.php?prod=ft-tinyESCv2
The trick to getting the shaft to fit just right is to sand it down by either clamping it in a drill chuck or a lathe and slowly turning it down till it just barely goes into the bearings in the stator half of the motor. For this, I suggest 3mm shaft that has a tolerance range above, but not below 3mm as that should allow you to size it for a tight slide fit in the bearings and a press fit into the can. Cut the shaft long at first, then trim to the final length after it has been installed and you know where it needs to sit to result in the robot resting horizontally.