DIY Self-Driving

-

There's nothing like  a ridiculous challenge to keep me amused, and this one is huge.  There are no instruction manuals or how-to guides, and definitely more questions than answers at this point.

I am trying to build a self-driving car.  

Not a road-going car exactly, but I have taken one of those kid's electric cars (about 10% size licensed copies of real cars), and I intend to make it capable of driving itself, following a road, avoiding obstacles and such like.

UPDATED:  Watch a timelapse (kind-of) video of the build up:



 But why use that?  Surely it would be easier to use a remote control chassis as a starting point?

 Yes, you're right.  In a lot of ways it would be easier.  The biggest problem is that those chassis are rather small, which makes packaging difficult and it can limit the options I want to add.  My method gets around that, and I get more battery power for no cost as well.  Plus it really looks like a car (if you squint hard enough, anyway).

 By way of explanation, my white convertible was made some years ago by a Taiwanese company called "LovBio", and it is called a "V6".  Externally it looks like a mid-80's Mercedes to which somebody added a BMW-esque kidney grill.

A six-volt electric motor drives the right side rear wheel, and the electronics consists of a collection of switches.

 Just like using a real car, the mechanical challenges are at least as big as the computational ones.  For starters, I have to rebuild the steering mechanism.

 The steering assembly is primitive to say the very least (see the next photo) with a "J-Hook" at the end of the steering column which pushes/pulls on steering links.  There is a lot of free play in the unit, which is probably not going to be an issue in this project.  At least in the early stages.
 
 The plan at this stage is to remove the steering column and replace the J-Hook with a heavy-duty servo.  The car is quite light, so I am guessing that a servo intended for a 1/10 or 1/8 scale model will be a good starting place.  I am going to use a "20Kg" rated model, because I have some.

 I have no brakes and only one driving wheel so the dynamics might be a bit of a challenge.  We can most likely make it two-wheel drive by installing an axle in the rear, and this will probably happen sooner rather than later.

 The motor in my car states 4A which I presume is the stall current.  This means I can use a L298D H-Bridge driver module but it's going to need a bigger heatsink. Ideally I would like to use PWM to drive the motor so I can control its speed directly.  Given the light weight and single driving wheel, this would help a lot with stability.  As tempting as build my own DSC system is, I don't want to get carried away with solving the wrong problem.

 Astute readers will note I have not mentioned any computing solutions yet.  I will get to that later, but for now there is more than enough groundwork to do.

Further Reading
Part 2 - Preparing the car
Part 3 - Wiring Harness
Part 4 - Steering
Part 5 - Sensors
Part 6 - Software
Part 7 - Final assembly and testing
 


* The sticker reads "Honk if you're autonomous"

Comments

Post a Comment

Popular posts from this blog

The QYT KT-7900D

-
Image
But is it any good? As you might have noticed, I am now a freshly licensed radio amateur .  As such I do need a transceiver or two in order to get on the air.  This is the story of one of my new radios. I have a limited discretionary budget to use for my new hobby, and I have to say from the outset that my lovely wife has been very supportive.  As such, I want to try and get the best value for our money.  One evening I stumbled upon this little item on Banggood for a little over $A150 including shipping.  Covering both 2m and 70cm bands with a claimed 20W output it seemed almost too good to be true.  I bought one. About ten days later a tiny package arrived for me.  At just 98mm x 43mm x 126mm the photos don't convey quite how small it actually is.  The entire case serves as a heatsink so it is heavier than it looks, but certainly not bulky. The standard power cable comes with a cigarette lighter plug.  As I intended to run it from home usin...
Read more

Recording weather with Arduino, Elasticsearch and Kibana

-
What do half a Bunnings weather station, an Arduino, a NodeMCU (or 3), Elasticsearch, a fishtank and swimming pool have to do with each other? Nothing unless you like to monitor and measure pretty much everything around the house.  I do, and ever since I learned to fly, I have had a fascination with the weather (I am told boaties suffer from a related affliction). I could just buy a weather station, but where's the fun in that when for the same amount of money (OK, maybe a little more) I can make my own and bore people senseless when I go on and on about it? Actually, there is a practical purpose to this as well.  I wanted to teach myself about Elastic and Kibana.  Now you can wade through dry tutorials, but nothing in my opinion beats working with real live data.  Especially if the data is of interest to you. The design What do you want to measure? This is actually pretty important (not to mention obvious), but before embarking too far; take a...
Read more

Exploring Solar Power - Let there be smoke!

-
Image
Last time I introduced my new solar power project.  By the end of that post we were monitoring the power flow from the solar panel to the battery in a simple test environment.  This time we're going to dive in and start trying to control the charge power. What's MPPT? Maximum Power Point Tracking (or Transfer , depending on whom you ask) is a condition where we can transfer the highest power from the solar panel into the battery.  The key here is power, rather than voltage or current on their own.  Remember that power is the product of voltage and current, so it is possible that you will find that perhaps higher current and lower voltage (or vice versa) is the most efficient. What makes this a little problematic is that the peak power point varies constantly depending on the battery state of charge and temperature, so it is not a set and forget operation. This is why the first thing we did was to build a power monitor.  Now we can determine at any point of time...
Read more