Making Slot Car Tires

As Christmas approached when I was a kid and Rudolph the Red Nosed Reindeer aired on the TV, Dad would return from the garage with an enormous box emblazoned with "Thunderbolt III" and a picture of two race cars battling to victory.

We set up the Strombecker slot car tracks and, grasping the blue speed controllers, we brought to life the epic struggle of white Chaparral 2D and yellow Ford GT 40 Mk II, father versus son.

I still have that old slot car set. And now a child of my own. And though Dad left this life in 2010 and mom passed away in September, they'd be happy to see my 7 year old daughter and I reliving those moments from my own childhood.

Except... when I finally unwrapped the cars, stored carefully 35 years ago, the tires fell apart in my hands. Rats.

After some online research, I discovered one can create custom slot car tires using a 2-part RTV silicone rubber. So that's what I did.

Hello LED

My wife and daughter adore Hello Kitty. No, I mean really, really adore her. No, see, I don't think you quite understand. Here, let me just show you what Christmas looks like at the Bot Thoughts laboratory:

This Christmas we faced a major problem that would totally ruin our holiday season.

At night, the smallest of the inflatable Hello Kitties were really dim! And the lights inside them were --gasp-- not user replaceable!

Before: Small kitties are dim!

Well, we are not users, are we, gentle reader? With a little knowledge of electronics, we can fix the "unfixable". Here's how things looked with only 3 kitties left to fix.

All but three kitties have been upgraded

So, here's how we brightened up our Christmas Kitties...

DIY Vehicle Speed Sensor Buffer

Here's the riveting tale of how I created a Vehicle Speed Sensor (VSS) interface circuit for my Jeep Grand Wagoneer (yeah, that Jeep).

Jeep VSS

Speed sensors are used by cruise control systems and by fuel injection computers. Jeep used one for the former.

I wanted the sensor for the GM throttle body injection (TBI) system I retrofitted onto the Jeep's old AMC 360 c.i. V8.

Back when my Jeep was built, vehicle speedometers were driven by a flexible steel cable, the speedometer cable, connected by a tiny gear to the output shaft of the transmission.

Jeep, as with other vehicles of the era, split the speedo cable in half and stuck the VSS in between.

So, with insufficient hobby funds to buy an expensive, off-the-shelf Vehicle Speed Sensor/Buffer, but wanting to reap the benefits of a VSS, I created my own interface. Here's how it went down...

Teaching Programming to Kids (Cont'd)

After much struggle to select a microcontroller and programming system for teaching programming to my 5th grade club, everything suddenly came together.

In a flash I remembered PICAXE, which are low cost BASIC-programmable microcontrollers.

Even better, since all the kids have Chromebooks, PICAXE can be programmed with a Chrome App using the Google Blockly graphical programming framework.

For example, an LED blinky program looks like this:

As pointed out by my SHARC pals during a lunch discussion, 5th graders aren't expert typers so this kind of graphical block system sidesteps a lot of frustration. And I feel this system is better suited for robotics than native Scratch is.

The PICAXE Blockly IDE has some neat features.

First, the IDE includes a simulator so kids can run their code safely before trying it on the robots.

Second, they can see the BASIC language program by clicking a tab so they can get an introduction to standard programming languages.

My sample PICAXE-14M2 is now successfully blinking an LED on pin B.5. Soon I'll be prototyping motor control using the Pololu DRV8835 driver breakout boards I bought during the Black Friday sale.

And, I'm almost done designing a baseboard, similar to my PIPduino, that uses a Pololu step-up/step-down regulator (S10V4F5) for power, also a Black Friday purchase.

Since the PICAXE programmer cables are too costly for our budget I'm going to find or make cheap FTDI breakout boards or else put an FTDI and USB connector onboard.

It feels good to have finalized the MCU and programming system for the kids' robots. I'll order the baseboards soon and hopefully I won't have screwed up anything so we can get started programming in 2-3 weeks.

Black Friday / Cyber Monday

Here's a list of sales you'll want to check out this Holiday:

Pololu Black Friday - already started! And an awesome sale with great deals once again. My order is placed :) Switching power supplies, robots (Zumo, 3pi, and the new Romi chassi); IR rangers from Sharp, Polou, and a time-of-flight breakout; wheels, motors, motor controllers, the cool A* ATmega32U4 controllers, and lots, lots more. Plus freebies and free(ish) shipping.

Sparkfun Black Friday / Cyber Monday - a wide range of items on sale this year. I'm eyeing the ESP8266 boards, MicroView, as well as the HackRF and RockBLOCK Iridium SatComm module. The FLiR Lepton board is on sale too.

BGMicro has a sale going right now, too. Take 10% off your ENTIRE order by using the code TTM at checkout through 11/23.

• Click Here To Check Out The Items On The Wholesale Page
• Click Here to Check Out 1/2 Price PICs
• Click Here To Check Out The Items On The Pack Page 

Parallax has a sale going too. Save $30 or more on:

• Scribbler 3 (S3) Robot
• Arduino Shield-Bot Kit
• BlocklyProp Starter Kit [This looks cool; I'm considering Blockly for my 5th graders] 
• ELEV-8 v3 Quadcopter Kit
• ELEV-8 v3 Quadcopter Starter Pack

Trossen robotics: 

We're taking 20% off RobotGeek and Interbotix products! Use coupon code "Friday16" at checkout.

Newark has tons of overstock stuff for sale

On Teaching 5th Grade Programming

I know that 5th graders can code. 

The kids last year did a great job programming their Lego Mindstorm NXT robots in LabView, although I witnessed some confusion about the graphical representations. Perhaps Scratch, specifically Scratch 4 Arduino (S4A), might be an option. MiniBloq would be another possibility.

Still, I feel it will be easier for kids to learn a syntactically simple text-based language, like Python, Lua, BASIC, or SPIN. Why not C-syntax languages? I have witnessed too much time wasted on syntax problems--semicolons and braces--which I think distracts from core learning.

It is a bit of a quandary for me. What do you think?

Microcontroller Board

Low cost is a key factor. We'll have 5-7 teams, so anything that costs $25 or less would be affordable.

With DIP microcontrollers, we could use breadboards (adding slightly to cost) but kids may spend more time troubleshooting loose wires than solving the problem so I'd prefer to build a baseboard.

I am a huge fan of 3-pin servo-style connectors for my robots which greatly simplifies wiring, but non-reversable connectors would be better.

There's always the Raspberry Pi Zero at only $5. The cost is right but the kids may have to learn some basic Linux and we'd need a baseboard with serial or bluetooth. And honestly a Pi is way overpowered for what I have in mind.

Python

Since learning Python, it feels like the BASIC of the new century. It's way more powerful, but simple to learn the basics, is wildly cross-platform portable, hugely popular, and much more. 

And of course I'm a big fan of MicroPython, which powers OpenMV Cam.

However, it is quite a challenge to find an suitable microcontroller board with a full MicroPython port that doesn't cost too much. PyBoard is over budget and requires a baseboard too. Teensy 3.5 and is powerful and low cost, but requires a baseboard and the port isn't done yet. 

Lua

Seems good for education and the interpreter is somewhat lightweight like MicroPython but, similarly, choices of microcontroller boards appear to be limited. And Lua is nowhere near as popular as Python so they might struggle more to find help after the club.

BASIC

This old language lends itself well to education. It's about as lightweight as interpreters come, so I should be able to get a BASIC implementation running on my PIPduino, which would be free for the club (thanks to glacially slow sales).

Coridium's $10 ARM-based BASIC Chip, which is an LPC1114, is designed for embedded use and even the cost of fabbing a baseboard wouldn't kill the budget.

But BASIC isn't standardized across platforms so I'm not sure they could readily apply what they've learned on their PCs like they could with Python or even Lua.

Teaching 5th Grade Electronics

I'm pleased to say that I'm shaping young minds into engineers, leading an after-school club called Technology - Robotics - Innovation at my daughter's elementary school.

Week 3 is coming up this Thursday.

Week 1 was introductory and included a fun bridge-building team exercise where we got to flex our teamwork and problem-solving muscles. 

Week 2 the kids had fun learned about electronics: voltage, current, LEDs and built their own LED circuit on breadboards. 

Great news: half the kids build non-working circuits. Exactly what I'd hoped for! See, I didn't tell them that LEDs conduct current in one direction so that they could learn through thinking and discovery. 

Students came up with great ideas on what might be wrong and some discovered that flipping the battery connections lit the LED (nice!). When I told them about LEDs and diodes, they fixed their circuits by flipping the LEDs.

We'll build on the LED circuit and their light-sensing soldering kit circuit to develop sensors for line following. After Thanksgiving, they'll build team robots. Then we'll start on programming!

I plan to publish the curriculum and materials as open source / creative commons for others to use and help us improve it.

This is a dream come true. I've been wanting to teach these things for several years now and I'm super excited to finally have that opportunity!

Robot Sumo with Lego Mindstorms

Two deadly, plastic opponents face off.

Their beeps and whirs are drowned out by the deafening cheer echoing in the elementary school auditorium.

Two robots enter the sumo ring. Only one emerges, victorious. The other? Tipped over, out of the ring, parts scattered, wheels spinning in futility...

The culmination of many weeks of tinkering, teams from the Robot Club at my girl's elementary school faced off against teams from two other schools in a Lego Mindstorms Sumo death match (ok, they didn't call it a death match... but I sure will).

For several weeks I came in every week to help the kids design, build, and code their robots and it was incredibly fun and rewarding. Turns out 5th graders are really smart. The kids had no trouble with the LabView-style graphical programming and had working robots quickly.

There were a few physical design issues. Teachable moments in the area of physics were plentiful. Center of gravity. How caster wheels work. Traction, friction. Stuff like that. In the end our school fielded some very competitive robots!

One team started a few weeks behind but was able to build a tracked robot (below) based on some instructions I dug up. They fought against time for weeks and finally, in true robot experimenter fashion, got their code working only days before the competition.

I built one, also. And battled the kids. And lost more matches than I won!

I guess I am not smarter than a 5th grader.

But I definitely couldn't be more proud of these kids for sticking to it, never forgetting to have fun, and building some awesome sumo bots.

Sparkfun AVC 2016

Sparkfun announced that the 2016 Autonomous Vehicle Competition will be happening in September this year!

That's good. It'll be cooler than summer, almost certainly sunny and a pleasant 70-80 degrees. Plus we have loads of extra time to procrastinate. Win-win!

The big news is they're making some kind of addition to the AVC involving -- if the pictorial hint is to be believed -- little kids driving around in home made go-karts?!? Or... I really don't know...

What does it mean!?!?!?

Maybe autonomous road racing? That'd be sweet. Maybe kids will race with bots? Maybe robot kids will... nevermind.

What about me? Though life has been leaving boot prints on my backside for the better part of the last year, IF the AVC additions are super-interesting, Data Bus may have to make a comeback.

I haven't forgotten about rovers. In fact, I've been working on some Rover-related goodies in the meanwhile...

Chinese Robot Kit

Kids can build robots, sure, but... which robot kit should be their first?

Lego Mindstorms? Pololu 3pi or Zumo? What would you recommend?

Every time I show my robots to elementary school kids that are really interested in building their own, I realize that I can't recommend a good starter robot kit. Why not?

I feel prospective roboteers deserve a kit that is low cost, can do two or more interesting things, is expandable, and is accompanied both by quality learning material and programming software that younger kids can understand and use.

So, I want to roll my own kit. But, where to start? Maybe... here:

I searched for a low-cost chassis and found vendors on AliExpress selling a robot kit.

It includes an Arduino clone, sensor shield, battery holder, motor driver / regulator board, motors, encoder discs, wheels, caster, and an acrylic chassis.

All for a ridiculously low price. Was it any good? Read on...