Just one of the drawings for the patent of BMW's uncrashable motorcycle

Just one of the drawings for the patent of BMW's uncrashable motorcycle

 

BMW's uncrashable motorcycle

By Ben Purvis -

New bikes

 13 February 2008 13:37

However hard kit manufacturers try to make crashing safer there’s always set to be a risk if you come off your motorcycle – but now manufacturers are working on ways to make the very act of falling off a far more remote possibility.

One of the leaders in the field is BMW, the firm that pioneered ABS brakes, electronic suspension control and traction control on bikes.

Newly uncovered patents reveal a revolutionary design of bike, which is being developed to give a level of primary safety equipment – i.e. kit developed to prevent an accident happening in the first place – that’s completely unprecedented.

The work of BMW engineer Josef Seidl, the designs add completely variable geometry to the chassis of the bike, with computer control systems to operate them.

Put simply, if the computer senses a situation that could lead to an accident – whether it’s a loss of grip or inappropriate control inputs from the rider – it will intervene and do as much as possible to ensure the bike does what the rider wanted it to do without crashing.

The idea might sound like sci-fi, but it’s exactly the sort of kit that’s already becoming commonplace in cars. On two wheels, a totally new design is required to achieve the same results, but the result should be similar; making crashes much less likely to happen.

MCN’s source in Germany said: “Seidls patent is supposed to transfer stability programs already known from cars to motorcycles by changing the chassis geometry quickly, electronically – and BMW want to be first with that.”

Car-based primary safety systems – something BMW is also pioneering – give on-board computers a level of control over power, braking and even suspension settings.

It’s not uncommon for cars to feature active stability systems that can activate individual brakes, or alter the power going to each wheel, to prevent losses of grip even when the most cack-handed driver gets behind the wheel.

And impressively, when these systems intervene, the driver feels virtually nothing, only knowing that the car has responded as he intended, even in a situation that would have led to an unavoidable crash in cars without these systems.

On a bike, getting the same result is much more difficult. Simply giving a computer control over brakes and throttle and allowing it to override inappropriate rider inputs might stop some accidents, but since bikes have a far more direct connection between the rider and the road than you’ll find in any car, intervening in the way the machine takes corners, when accidents are most likely to take place, is near-impossible.
Josef Seidl’s solution is to go completely against the normal concept of giving a bike the most rigid chassis possible, and instead adds a level of computer-controlled flexibility, allowing control systems to alter the angle of the front or rear wheel compared to the normal vertical position.

It’s made up of three individual systems, in turn affecting the steering, front wheel angle and rear wheel angle.

 
Steering:

One of the biggest limitations currently preventing a computer from overriding the inputs of a rider is the direct control a conventional motorcycle gives you over the steering.

While car-based stability systems can counter inappropriate steering by applying brakes on one side of the car or the other, effectively dragging it back into line, a bike’s single-track design makes that impossible.

So the only way to give a computer control is to allow it to intervene directly between the input at the bars and the movement of the front wheel.

Seidl’s system uses hydraulic rams to do just that. Rather than being solidly bolted to the forks, the bars are on a pivot, with a pair of rams holding them in place.

During normal riding, the rams remain static, giving the normal, direct connection between the bars and the front wheel.

However, when the computer senses a situation that requires a different input at the bars, the rams can be moved in a fraction of a second, slightly altering the position of the wheel in relation to the bars.
 
 
Front end:

Although inputs at the bars are the most obvious way of changing a bike’s trajectory, altering the angle of the front wheel in relation to the vertical will also have an effect.


Josef Seidl’s patents reveal a system that allows the entire front end – the wheel and forks – to be pivoted at the bike’s headstock, fractionally altering the angle of the front end from side-to-side in relation to the rest of the bike.

The system is the same as employed on some radio-controlled bikes, which use a similar pivot to steer the machines. These small-scale machines prove the idea works, and even on a full-size bike the result should be the same; when the front wheel is moved to the right, it will try to stay upright, so the rest of the bike will lean fractionally, giving a steering effect.

By handing over this control to a computer, it will be able to counteract inadvisable steering inputs made by a rider.

Interestingly, BMW’s design is similar to another patent from Yamaha, which aims to achieve the same result, also by tilting the entire front end.

 
Rear suspension:

Josef Seidl employs a similar idea at the back end of his concept – introducing a system that tips the rear wheel to the left or right.

This is achieved by using something that looks like a double-sided swingarm, but is actually a pair of individual arms, one for each side of the rear wheel. By putting a ball-joint on either end of the rear wheel spindle, the two arms allow it to tilt.

A pair of old-style twin shocks, each with a computer-controlled ride height adjustment system, can raise or lower the right or left side of the swingarm, tilting the rear wheel in relation to the rest of the bike.

It sounds complicated, but the drawings reveal that the system is actually surprisingly simple.

Like the variable-angle front wheel, the adjustment of the rear could influence the bike’s steering, but it could also be employed to keep the rear wheel relatively vertical in relation to the rest of the bike, reducing its lean angle and keeping more rubber in contact with the road even at extreme lean angles.

The computer:

While all these systems have the potential to give a computer a huge level of control over the bike, while still leaving the rider in overall charge where it’s going, Seidl’s patents have yet to reveal how BMW will cope with the most challenging aspect of the entire system – the computer that will decide exactly when to intervene and what to do in every situation.

Not only will this need a huge amount of processing power, but a massive number of sensors all around the bike so it has all the information it needs to achieve the desired results.

The computer will also need to be given a level of control over the bike’s power output – effectively traction control – and probably to be able to intervene in the way the machine brakes.

How these systems will work has yet to be revealed.

An extremely complicated control programme will also be needed to make absolutely certain that the computer makes the right decisions, as well as a failsafe system to lock all the moving parts in a conventional position should there be any problems with the electronics.

Our source in Germany said: “The special software still to be developed.”

While that might sound like a huge mountain to climb, such systems already exist in aeroplanes, where the latest fly-by-wire systems put all the pilot’s control inputs through a computer, which then decides how the plane should react to achieve the manoeuvre the pilot is asking for.

On a motorcycle, these systems might still be a long way from production, but even with current technology, there’s little to stop them from happening.