Team Cosmos - Angry Accountant - A New Beginning.

[satacoy]

Hey Zac!

I've certainly got sucked back in a bit with the new TV show and a local competition. 

I faintly remember meeting you at a Motorama or two.  I've enjoyed following your recent projects, they're always interesting and well documented.

It'd be great to make it back out to Moto some time.  It does fall at a bad time of year for me, which makes pulling the trigger a bit harder. 

Pete - Team Cosmos

[mathias]

Autonomous with that Teensy and the IR range finders?

[satacoy]

>> Autonomous with that Teensy and the IR range finders?

That was the original plan, I'm switching to (almost) purely manual driving for this iteration.  I'll try the autonomous route with a larger bot.  I have some ideas that I'm keen on trying.

Pete - Team Cosmos

[mathias]

Cool. Are you going to keep the Teensy and use some sort of Bluetooth connection by any chance? I've been thinking about using a LightBlue Bean that I have (https://punchthrough.com/bean/) as a receiver and controller. It'd still need a motor controller, but it has an accelerometer, which could be used for some simple safety stop stuff (if flipped, too violent of an impact, etc.) And driving with a phone just seems like a funny idea :-)

Related, did you find the Sparkfun motor controller (https://www.sparkfun.com/products/9457) useful? Obviously it's lacking the smarts that something like a TinyESC has built in for motor protection, but at $8.95 it is cheaper than two tiny ESC's by a long shot.

[satacoy]

Good guesses, that's exactly what I'm planning on doing.  I'm going to use Bluetooth to transmit data back to a computer, have the computer make the decisions, and then send commands back to the bot.  I had a 6DOF IMU in there too to help w/ dead reckoning.  Instead of trying to code up all the logic on the pro-mini, it would just collect the data and transmit it.  It'd also handle commands coming back from the laptop (left motor 50%, right motor 25%, turn weapon on, etc).

I've played around with the motor controller a bit, it seems to handle the maxon motors fine, albeit with no load.  Once I get a frame in place I'll do some better tests.  I can swap in other controllers if that one proves too puny.

So I'm leaving out the sensors and IMU on this iteration, but am going to try the bluetooth/motor controller/pro-mini on this iteration of Angry Accountant.  Since I have antiquated FM transmitters/receivers, this seemed a more interesting route than just buying a new 2.4ghz radio.  Should be cheaper/smaller too, if things work out.  I picked up a SparkFun joystick setup, so that'd also plug into the laptop for this iteration, the laptop would do mixing, and broadcast to the bot.

Pete - Team Cosmos

[mathias]

Really cool! I'm going to be watching this thread with some interest -- I think combat robots with some onboard smarts are an interesting development of tiny, powerful processors and lightweight batteries. And options other than  If you end up putting the code for the Teensy online on Github or similar, or if I can help out at all (my background is in programming)

[satacoy]

I managed to get several hours in on the mill this afternoon, made some good progress on the frame.  I'd forgotten the joys of machining on a hot summer night.  The haze of cutting oil smoke, the sting of the chips landing in your flip-flops.  Ah, the memories...




Pete - Team Cosmos

[Lucas Grell]

Looks great!

[mathias]

Hey Pete,

I know you said you shelved the autonomous idea for now, but I wanted to share something I learned about.

While browsing the online store http://jsumo.com/ (which is a Robot Mini Sumo store in Turkey) I discovered that they're using these little IR sensors that work like logic switches: http://jsumo.com/shop/mz80-infrared-diffuse-type-reflexive-sensor/ They look to be a little bit more durable than the Sharp IR range finders, and they're good if you simply need to know "something is there or not in this range" rather than an actual range value. I found similar sensors for sale on Amazon for a few dollars less than the cheapest Sharp IR rangefinders: http://www.amazon.com/Geeetech-Infrared-proximity-compatible-Arduino/dp/B00AMC1V2C/

The other benefit would be that I think you can use a digital logic line interrupt in a microcontroller with these, so the main program loop doesn't have to "poll" each sensor for updates, it can simply respond when an input detects the opponent.

I'm not sure what their durability will be, but since they're mounted in a round hole, they should be easy to replace if damaged. Not sure what the actual weight is; Amazon lists the product weight (with whatever packaging) as 0.3 ounces so I'm going to assume quite light.

Thinking of using these as side and backwards sensors for both simplicity and durability of a sensor exposed on armor surface. Forward sensors might need to be something with more resolution than simply "Something is there" like the two IR range finders on the front of my mini sumo bot: the difference between their values allows the bot to know whether to turn left or right to meet the opponent as it approaches.

[satacoy]

Those do look interesting, although I wish they were smaller.  If I'm reading the description properly, they have a diameter of 20mm, which is a hair over the .75" thickness of the frame.  They're also quite long.  I'd be very tempted to do a simple "on-off" type of sensor if I could fit them in, but I think I'd have the same sizing issues as the Sharp sensors.  Something in the .25" to .50" size would be perfect. 

I spent some time on Digikey a while back looking at alternative sensors, but didn't really spot anything that looked better.

Regardless, thanks for passing the idea along.  They might make it into the slightly larger autonomous bot I hope to someday build.

Pete - Team Cosmos

[MikeNCR]

Those do look interesting, although I wish they were smaller.  If I'm reading the description properly, they have a diameter of 20mm, which is a hair over the .75" thickness of the frame.  They're also quite long.  I'd be very tempted to do a simple "on-off" type of sensor if I could fit them in, but I think I'd have the same sizing issues as the Sharp sensors.  Something in the .25" to .50" size would be perfect. 

I spent some time on Digikey a while back looking at alternative sensors, but didn't really spot anything that looked better.

Regardless, thanks for passing the idea along.  They might make it into the slightly larger autonomous bot I hope to someday build.

Pete - Team Cosmos

This page might be worth a look when it comes to autonomous combat bots- http://www.wa4dsy.com/robot/scary-go-round

[satacoy]

Summer is in full swing, but I managed to find a few hours to do a bit more machining.

I milled a few features into the frame side.  There's a hole for the motor, a dead axle, and a slot for the keyed "wing".



Here's the motor and dead axle installed.



Next are a few shots of the wing, motor, and dead axle in place.  Feels very solid, and should protect the motor and belt well.



Pete - Team Cosmos

[satacoy]

Another fun evening of removing aluminum.  I started at 8.4 ounces, ended up at 3.6.  Still some sanding of outside curves to do, but the main body is getting close.



Pete - Team Cosmos

[satacoy]

Got the frame sanded and cleaned up a bit tonight.  Starting to look like a real robot.  The raw aluminum for the frame started at 1 pound, 8 ounces, and ended up at 5.4 ounces.





Pete - Team Cosmos

[mathias]

Belt drive for everything?