Dr Automotive Design and Tools

This is Black Current III, a VW Beetle that's officially the fastest electric dragster in Europe. It recorded an 11.24sec ¼-mile run at Santa Pod recently, beating a Tesla Roadster by more than 1.5secs in the process.

Black Current III is the work of brothers Olly and Sam Young and is a 1960s Beetle powered by two forklift truck motors and 60x 12-volt batteries. This combination is good for 1200lb ft/lb (1626 Nm) of torque, a 0-60 time of around 3.0secs and a terminal velocity at the end of quarter-mile of 114mph.

The project started six years ago when the brothers got hold of an abandoned milk float and mated its motor to an engine-less Beetle.

The next step in the project is to get hold of some hi-tech lithium ion batteries. Considering how the Black Current boys and their forklift-powered car wiped the floor with the cutting-edge Tesla - we'd love to see what they can do with Black Current IV...

As electric vehciles go, the Segway is certainly a unique way to get around and to the casual observer, the way the device operates might seem to defy gravity. There are quite a few DIY projects around the Internet including standard two-wheeled upright versions, unicycles and one wheeled skate boards that operate on the same self-balancing principle. Now a kind soul named Geoffrey Bennett has released an open source version of the firmware required to operate a ride on robot free, allowing anyone with basic mechanical ability and some electronics skills to build their very own self-balancing transport.

The ride-on robot named "Meta" was built by Geoffrey who openly admits that “hardware isn't my thing” so mechanically it’s of fairly simple construction with dimensions based around the choice of motors and batteries used. It couldn’t be simpler, two pieces of wood, one broomstick some duct tape and miscellaneous parts from the local hardware store.

Basic construction

The basic requirements are two wheels driven by motors, a platform to stand on, batteries to provide power, sensors to detect leaning, electronics to drive the motors and software to drive the electronics. The motors selected for this project are off a used electric wheel chair. The motors come complete with a hub, wheel and gearbox all in a single unit. Some rudimentary brackets can be used to mount these between the two wooden boards. The batteries used are six 12 volt sealed lead acid batteries chosen because they are cheap, heavy for ballast and easy to recharge. These are mounted between the motors on the wood platform.

The sensors used in are an accelerometer, which measure gravity or G and a gyroscope that detects changes in angle. These components may sound exotic and something you might only find in a spacecraft. With many thanks to the auto industry these components have been in mass production for quite some time to be used in safety features such as airbags and stability control. Both the accelerometer and gyroscope chips can be bought for as little as UDS$115 on a small circuit broad from robotics hobby stores.

Affordable electronics

Next on the list of electronics is something to drive the motors. This project uses something called the Open Source Motor Controller (OCMC) and again robots enthusiast web sites come to the rescue with a 50 volt 160 amp DC motor controller being available for USD$169 in kit form. This is a simple H Bridge type motor driver and it uses one for each wheel.

The electronic fun starts with building a circuit to drive those two motor control boards. This circuit needs to take inputs from the accelerometer, gyro and steering joystick, do some calculations and send pulse width modulation signals to drive the motors. To do this we need some computer power but not the kind of PC you are no doubt reading this story on but something with a small faction of the power. This DIY project uses an Atmel 8-bit processor that only has 1kb of ram and 16kb of memory.

Most people are familiar with how a self-balancing ride on robot operates but lets review the basics. The original Segway is a 2-wheeled self-balancing vehicle. To move forward the rider leans forward, to go faster he/she leans forward more. Lean back to slow down, stop and go backwards. To turn twist the handlebars (a joystick in this case). The primary function is to remain upright. If you lean forward, the circuitry moves the wheels forward to try and make the vehicle upright again. The rider is in fact in a controlled fall towards the ground with the vehicle catching the fall. To do this with software requires some complex mathematics called Proportional Integral Derivative (PID) and that’s where the ‘open source’ part of this project comes in very handy. PID is a very well known and often used software technique but well beyond anyone with only a casual interest in mathematics or software development. Luckily there are many free examples available that are no harder to burn onto a small processor than burning a CD.

So if you want a Segway-like steed but don’t want to pay the price and don’t mind the DIY, then join the legion of high schools kids around the world who have made their own for a fraction of the cost and learned a great deal into the bargain.

Follow this link for video, code and a slide presentation on Meta.

Take one DIY Self balancing electric vehicle project, replace the wheels with 6 pars of short legs based on Theo Jansen kinetic sculptures and the result looks like something out of “Hitchhikers guide to the Galaxy”. A Dynamically Stabilised, ride-on robot that crawls.

The Cajun Crawler was built by a team of mechanical engineering students at the University of Louisiana and was inspired by Theo Jansen's leg mechanism. During their research they found no application where Jansen's leg mechanism was used in a weight-bearing application or on a vehicle.

The 6 pairs of insect like legs are machined from 5052 Aluminium and driven with two 18V hand-drill motors that drive the legs via a crankshaft. The electronics and battery packs from the cordless drills were also used to power the crawler. The Cajun Crawler uses the same Dynamic Stabilization used in the Segway, but the multiple feet give it a more stable platform with a top speed of 3 miles/hour

The materials used to make the Crawler cost approx $1100-1200 in total. Thanks to the low cost of microcontollers and electronic components DIY Segway projects have become a popular choice in university mechanical engineering labs around the world with many variations on the idea but this is the first we have seen that crawls. The original Segway came out of the first product that used Dean Kamen's balancing technology, the iBOT wheelchair which could climb stairs. We shall have to wait and see if any students try to build a balancing robot with human sized legs.

It might look ugly but this 1992 Honda Civic has double the fuel mileage of a standard Civic simply by lowering the coefficient of drag (Cd) from 0.34 to 0.17 with a little engineering savvy and $400 worth of material bought the local hardware store. In fact the drag on this 350,000 miles (563,270 km) old Civic has been reduced to the point where it is virtually equal to the radical tear drop shaped Aptera which has a Cd of 0.15.

The car's builder Mike Turner says at a highway speed of 65 mph (105 km/h) he can routinely achieve a fuel mileage of 95 MPG (2.5Lt per 100km). The most obvious feature are the wheel covers and Boat Tail which were modeled on a Vintage German 1939 Maybach. The extended tail eliminates the recirculating, low-pressure eddy that forms behind "normal" cars and that act to slow them down. More subtle but just as important additions have been a fully enclosed undertray, the removal of wing mirrors and blocking intake vents at the front of the car and exhausting the radiator air out through the front wheel wells.

Using coast down tests and a SuperMID fuel consumption computer Mike’s next target is to improve mileage during night driving as he has calculated the electrical load from the lights are costing him 2 to 3 mpg with half of this loss being from the parking lights. Mike wants to replace the parking and dome lights with LED's. Check out the Aero Civic web site.