Weekend is done, over, in the past

Not a bot work this weekend, not a lot of sleep either, considering I put in a 40 hour weekend. It's done, it's over and I still want a nap.

Going to home depot tomorrow. Going to get the wood for the mods on the bot body. On the DPRG list there has been some concerns about the tracked body. Wheeled, tracked, legged or hovercraft type drives all have their issues. Most of them are enviromental though ie bumps in the carpet, wet spot on the hard floor, human picking up bot to examine it and setting it down somewhere else(course that could be me doing that lol) and whatever else that you can plan, program for and hope it works like you wanted it to.

I've been thinking of the navigation program and putting it somewhat on hold till the bot is actually moving and has working sensors. I figure the next few problems will be 'debouncing' the bump switches and adding on the IR range finders. Right now need to find a chip that is a volt meter to monitor the drive batteries. May have to go with a different rechargeable 9v battery than the lithium ion since they are $20 a piece and Ni-cd are around $5 to $10.

Goals for the end of September:

Modifying the body
Installing what sensors I have already(bumper switches and encoders)
Installing the L293D (yay for locomotion)
Installing the IR range finders

Tomorrow will be posting a progress report on Leo

Keeping to some decisions

Well, been thinking about a few things. Was extremely tempted to use a complex motor driver board, lots of sensors(even figured out how to read them*at least in theory*), and thought about just scrapping the present body for a bigger and better bot body. All great and wonderful ideas, but one thought kept popping up, I've not even really started my first bot, so there is nothing to improve on, yet.

Going to use the AtMega 328 for the controller still, yes there are more powerful MCUs out there, but I think to monitor 3 bumper switches, 5 IR range sensor, controlling 2 geared down DC motors, monitor 2 drive encoders and monitor the drive batteries that it is still overkill. With 14 I/O pins and 6 analog pins, 30k of memory(ty for the chip upgrade at adafruit.com).

The dozer body is small, but has enough room to hold the 4 AA batteries for the motors, a 9v battery for the MCU and sensors, the L293D with it's heatsinks and the AtMega328 after the modifications.

The motors that came with the dozer body are adequate in power to push the dozer body about, but not able to slam it into walls and furniture at high speed(under powered is good safety feature at times). Yes, it's a bit underpowered, but if I'm going to change out the motors, it might be more feasible to just use a bigger bot body and maybe a different kind of drive.

The L293D chip is the best option as far as price, size and simplicity goes. Only need to drive 2 DC motors and it only requires 4 PWM pins from the AtMega328. Yes, could just cobble together a dual H-bridge using transistors and diodes, but why? It will cost a few bucks for the chips, the socket, a pc board, connectors and heatsinks and I don't have to debug it, so a total win win situation. Using just 4 digital pins with PWM.

As far as sensors go, I'm doing the sensors in stages and in baby steps. I'll start off with the bumper switches, yes mechanical switches are bouncy, but they are reliable for the most part and easy to read(on or off), so there goes 3 digital pins and 4 more digital pins for the motor control. Then will work on the battery monitor sensor, so then will be using 7 I/O pins and 1 analog pin. I should be ready to tackle the IR ranging task by then, which when completed I'll have used up 7 I/O pins and all 6 analog pins. So then I will have 6 digital I/O pins left to play with,unless I figure out how to read the IR sensors with just one analog pin.

So far:

AtMega 328 MCU
Still going to use the dozer body
Not going to change the motors out, yet
Using a L293D Chip to drive the motors
Sensors will be bumpers, IR modules, a digital compass and battery monitor

What would be dreamy:

A hover body with a minimum of 10lb payload
Networked ARM modules
SONAR and Sharp modules
Full Stereo Vision with object recognition
A fully articulated gripper and robot arm
Speech Recognition and Synthesis
Neural Network for complex decision processing

Reality as of now:

A not yet hacked dozer body (0%)
AtMega 328 that I'm still learning how to use(I can make the LED blink)(100%)
A not yet hacked mouse(0%)
A handful of lithium ion rechargeable batteries(50%, no 9v batteries yet)
A 9volt battery clip(50% to 100%, I've not decided if the board will have a backup PS)
No other sensors(0%)
Solderless Breadboard
Misc Discrete Components

The trip to Frys

What a disappointment the trip turned out to be. Mostly bare shelves, no ICs that I needed nor that anybody else has needed in some time. Picked up some resisters, some caps, and some diodes to play around with, though. Still need some different resistors and caps, along with diodes and other discrete components. I also got a small solderless breadboard. Ah well, BGMicro.com here I write. No motor drive components or real sensor work till after I get the ICs in.

Got the arduino board in today

Well UPS came by at 4pm finally, waitied around all day for the delivery. Got the board out, installed the drivers, and did my first 'sketch'. Tinkered with it quite a bit. It did provoke a few thoughts, such as how to save data? Only a computer that is easy, you just make a file, but the AVR doesn't seem to have a system for that. I'm going to frys tomorrow to get parts for the L293, the 38mhz oscillator circuit and some pull down resisters for the bumpers. May get a few sharp sensors if they have them and some IR LEDs too, I need to start working on the body now that a few parts are available for size purposes.

In possession:

Tracked Bulldozer Body
AtMega328 (yay!)

End of August goal:

Get the AtMega328 mounted into the modified tracked drive

End of September goal:

Get both motors and all sensors operational

I will post a full progress report once a week

Rummaging today

Tomorrow is the big day, I got out my multimeter, got together a few other tools as well. Will need to purchase a better soldering iron though. I've made a few drafts on the changes in the body, but will wait to do most of the changes till I have the sensors and such. I've not been able to find sharp modules, but I've been able to find IR Detector modules that detect IR at 38mhz. Not sure if I want to use a PWM pin to drive the modules or just make a circuit to do it. Either one presents challenges. One hand, don't have to worry about if the MCU is working and there one more pin to play with and on the other hand, a few lines of code handle and it can be changed much eaiser. One way it can be tinkered with, the other way, when you are done, you are done and time to go on to other things.

Not doing the list today, but tomorrow is a big day. I will have the brain for the body, just have to integrate the two. Btw, 9volt batteries are expensive, almost $20 apiece.

Definitely committed now, wish me luck!!

A bit more research done

Looks like the L293 is an L298 with the clamping diodes built in. It means less soldering which is always a good thing in my book and it's cheaper, as well. Spent part of the day going the arduino language, which is pretty cool. I'm looking forward to playing around a bit the MCU after it's delivered on wednesday. I have been working on the design of the body modicication on the dozer, but will have to wait till I decide on the bumper design and placement of the sharp sensors. I found an old mouse in the closet and it's has the old style encoder wheels, so that task is taken care of. I did look at what it takes to build an ardiuno board from scratch, just an idea when I get some things worked out and want to make it permanent and can probably do it under $20 plus the PCB. Small bit of interest, the lists below are all balanced, each one has 5 items.

Yes, I know I'm probably the only one reading my blog, and it's ok. I will know where I've been and how I got to where I'm going to.

Decisions made and Money Spent

1. Body with tracked drive & extras (free)
2. AtMega 328 Adriano based MCU $30 (August)
3. Nine volt clip $3 (August)
4. Encoders for the drive wheels (free)
5. Rechargeable AA batteries (free)

Decisions made and probable budget

1. 1/4" thick pine for the bod mods $10 (Home Depot)
2. Bumper switches $20 (frys, radio shack, etc)
3. H-Bridge for the motors $2 to $10 (various)
4. Sharp Sensors (5 probably) Need to find out
5. Rechargeable 9 volt batteries (2 at least) Need to find out

Wish List

1. Triple axis accelorometer
2. Digital Compass
3. GPS Module
4. Better bot programming skills
5. Bigger Budget!!!

Research, research and more research

Ok, been looking for code, specifically the kind in regarding using the Ardiuno's built PWM, reading encoders, motor control, and bumper switches. I can't wait till the board comes in next week. I need to make a short shopping list for components and before I go by Fry's and pick up some misc. parts this next week.

So far I have:

Tracked bot body(needing mods)
AtMega368 (on it's way)

So far I need:

L298 H-Bridge and components
Cheap Mouse
Material for the body modifications

Right now the plan is going to be to get Leo moving and running into stuff.

That's all for now

I found the brain!! and I didn't drop it!

I didn't say I found my brain, that's still not found, probably next to my common sense too. Ah well on to the bot!

So far have a body with a tracked drive and motors, an excellent start. It's MCU is on the way. I ordered an assembled AtMega 328 and a battery cable. This is the best choice I've come across, it's pre-assembled, can communicate via USB cable, has 14k available memory, built in PWM, and has quite a bit of I/O and it's open source. I spent $40 and got ahead by three weeks on build time, win-win situation on budget and time.

So far, I have a body for Leo and his brain is on the way. Need to get a cheap mouse for his encoders and pick up some light weight wood for bumper material and body mods, along with some bumper switches(reed or such). I have been toying with different thoughts on the bumper switches, do I use reed type, momentary push button or something else? A few thoughts on the body modification, need to protect the tracks without encumbering them when the bumpers are hit, need enough enclosure to fit the AtMega 328 Adriano, an H-Bridge, batteries and maybe a cooling system(ie small cpu fan or such, I think ice would be bad there), and whatever internal sensors(triple axis accelorometer, digital compass, battery monitors and some sort of communications module....ie I can dream can't I?). Yes, I've been browsing the bot pages and want lots of things to put in Leo, but need to take baby steps so that it's all done right and not buggy.

Decisions made and Money Spent

1. Body with tracked drive & extras $30 (already had it, so really free)
2. AtMega 328 Adriano based MCU $30 (August)
3. Nine volt clip $3 (August)

Decisions made and probable budget

1. Encoders for the drive wheels $5 (cheap mouse from frys)
2. 1/4" thick pine for the bod mods $10 (Home Depot)
3. Bumper switches $20 (frys, radio shack, etc)
4. H-Bridge for the motors $2 to $10 (various)
5. Sharp Sensors (5 probably) Need to find out
6. Rechargeable 9 volt batteries (2 at least) Need to find out
7. Rechargeable AA batteries (8) Already have

Wish List

1. Triple axis accelorometer
2. Digital Compass
3. GPS Module
4. Better bot programming skills
5. Bigger Budget!!!

Hopefully, this has been at the very least entertaining, if not a bit informative.

Some decisions

I've been researching a few different avenues and decisions. First decision was I didn't want a prefab bot, not really interested in being limited by somebody else's design parameters. I don't want a huge body, nor something tiny, and not something expensive either. On the processor front, I thought about the Parallax stamp modules, 68HC11 and propellor, I have some experience with the 68hc11 series and I know that there is C compilors for them, so that's a plus.

So here's where the decisions stand today are:



Body Type : Tamiya Power Shovel/Dozer Model Kit ($29.99 and already had it)
Drive Type : Tracked (included on the body)
MCU Type : 68hc11 series
Battery Type : Lithium Rechargeable(plenty around here and not expensive)
Sensors : Encoder on the tracks, front and back bumpers
Actuator : N/A (though I think with a bit of tinkering the dozer apparatus might work)
Language : C based and free would be even better

Decisions yet to be made:

Board Type : Fingerboard, Handy Board from M.I.T., HC11 EVB {Mainly need/want 64k mem and lots of I/O)
Body Modifications : Do I keep it the way it is, do I make the bottom more into a box to house 'brains' and batteries?

Research to do

Figure out which boards have the option for 64k ext mem and lots of I/O
Bumper types and schematics
H Bridge (DPRG.org)

Shopping List


Cheap Mouse for encoder wheels and sensors (<$5) (frys.com)
1/4inch thick pine board( 1", 2" and 3" wide and various length) (homedepot.com)
Sandpaper 400 grit to smooth edges (have around here)

By the way, I did join the Dallas Personal Robotics Group mailing list. Will have to shove some money into paypal to get full membership.

Introduction

I've been working on and off in electronics and CS(or IT as it's now called) for.......a long time. One of the jobs that I've had that was the most fun was working in a computer refurb shop, well besides the nasty shock a 19inch monitor with a bad short in it can deliver. I've been off galavanting and moved back to Dallas a few years ago and finally starting to settle down a bit, so decided to find a hobby to take up some spare time. So Leo was born, the name is in reference to the zodiological sign that he came to be, not in reference to the Great Italian Master, Leonardo da Vinci.

I spent a month or so before thinking of the major decisions such as body design, MCU type, drive type, actuator or not, programming language(c preferred), sensors, and battery types.