The Saab 9000 drive-by-wire ‘Joystick’ project
November 12, 2009 in Saabology
A little while ago I showed you some images of Saab prototype cars that were stored out the back of the Saab Museum in Trollhattan.
One of those cars was a Saab 9000 with the steering wheel removed, replaced by a joystick type controller. Here’s the image again:
Dave R, who was with me on that day at the museum, has dug out a magazine clipping from the era, with a story written about the project by Anders Tunberg (the guy who wrote a number of books about Saab and new Saab models over the last 25 years). Unforuntately the clipping is in Swedish, so only those blessed with Saab’s native tongue will be able to read it. Fortunately for the rest of us, I’ve found an article in English as well.
At least we can all appreciate the picture of the system in action. Click either image to enlarge.
The following article about the project was published in The Independent back in 1992. I don’t believe a link exists for the article there, but I found it here.
It’s interesting to note that according to Saab’s expectations at the time, we should all be getting joystick-mobiles in the next one to six years
CAR FIRM FORGES AHEAD WITH DRIVE-BY-WIRE PROTOTYPE
SAAB, the Swedish car maker, seems untouched by recent controversy over fly-by-wire aircraft, and is pressing ahead with plans for a drive-by-wire car. Fly-by-wire aircraft rely on software controls to a far greater extent than conventional aircraft. Three fatal crashes of the A320 aircraft have raised fears over the safety of such systems, and how easy they are to fly.
Saab’s parent, the Saab Scania Group, has experience of computer-controlled transport, having built the Grippen fly-by-wire fighter aircraft. Its automotive engineers have produced a prototype computer-controlled car. The Independent took a brief test drive yesterday. The car felt very smooth to drive, and remarkably easy to handle, although we did only a few miles an hour.
Saab concedes that safety fears could be one of the biggest obstacles to selling such a radical change in car design. But it predicts that by the time the car is in production people will be more confident about computer-controlled transport.
There is no steering wheel, but a joystick to one side of the driver. There is no mechanical link between the joystick and the wheels a computer intervenes to control and optimise the hydraulic steering. The car has a back-up control system that performs the same basic tasks as the computer, but uses traditional electronics. This is ready to switch into action if any part of the computer fails, or the driver hits an emergency “stop” button. To steer, the driver turns the joystick from side to side, and the computer translates this into
wheel movement. The car senses the driver’s movements on the joystick, translates these into the optimum wheel angles and feeds back information to the driver by altering the response felt through the joystick. At low speeds, for manoeuvres such as parking, a small movement of the joystick produces a large change in direction of the wheels. At higher speeds this relationship changes, so a larger movement of the joystick is needed to shift the wheels.
The prototype has a computer keyboard and flat-screen display in the passenger seat, so the driver can modify the software to change the “feel” of the joystick. Per Branneby, the Saab test engineer who heads the steer-by-wire project, said: “I can make it feel like a go-kart or an American limousine.”
The idea is that driving without a steering wheel is physically safer, because you can fit an airbag where the steering wheel would be and avoid the crushing injuries often sustained by drivers in accidents.
It should also be safer because the computer and hydraulics in between the wheels and the joystick filter out “noise” from the road that would normally make the steering wheel shake and judder such as stones in the road or gusty winds.
Mr Branneby said drivers get most of the information they need to steer the car by monitoring sideways forces on their seat. In the Saab car, the computer is fed data from sensors that tell it about these forces, as well as the car’s speed and acceleration. The car does not sense the environment it is in, so cannot respond automatically and change its steering to deal with a bumpy or icy road, or a skid. This is the next stage in Saab’s research.
The two-litre Saab 9000 Turbo used to test the active steering has automatic gears and anti-lock brakes and a conventional accelerator, although Mr Branneby said these may eventually be linked to the central computer. He does not envisage production models of cars using steer-by-wire joysticks until 2010 or 2015, although a version with active steering applied to a conventional steering wheel may come sooner. He also said a production model would probably have two joysticks one for each arm so the driver can swap the arm in control.