The plethora of rider aids available on today’s motorcycles would have been unfathomable even a decade or so ago, but Yamaha’s latest addition could be a game-changer, not only offering an extra layer of safety but also allowing for a rethink on steering geometry.
Yamaha’s electronic power steering (EPS) will be used in the All-Japan Motocross Championship for the first time on the works machines this year, but the system is set to be employed on a range of bikes in the future. It’s a rather small setup, but the fact that it’s computer-controlled means there’s a lot of room to expand its capabilities. For motocross use, however, there’s more sense in that most straightforward element of the idea; anything that can reduce rider fatigue will be a benefit.
However, lowering the amount of effort required to turn the bars is only one part of the system. It also functions as an active steering damper, absorbing external forces so you don’t have to wrestle with the bars to keep them pointing in the right direction. Again, motocross is a rigorous test of the concept, but it may be useful for road motorcycles and other racing as well.
To figure out what you want it to do, the power steering uses magnetostrictive torque sensor technology from power-assisted bicycles. These torque sensors are used on e-bikes to detect when you’re pedaling and how hard you’re pedaling, delivering that information to a control computer, which interprets the amount of electric assistance required. It does the same thing here, but with the steering of the bike.
Similarly, increased trail, which would normally make for over-heavy steering, could be adopted, using the power assistance to make it feel light. Quite simply, the system could remove the shackles currently placed on designers by the compromise between stability and responsiveness.
The technology also means that the steering may be linked to the IMU, traction control, and cornering ABS, resulting in a holistic stability control system that controls the throttle, brakes, and steering – all of the major rider inputs – to assist prevent accidents.
Yamaha’s MOTOBOT robot rider system has already demonstrated that computers can ride a motorcycle around a track, and the power steering system displayed here is the final piece of the puzzle in translating that knowledge into something that can be used on a real-world motorcycle.
Yamaha power steering
Sensing the power: The magnetostrictive torque sensor measures the amount of force you apply to the bars and sends the data to a control computer.
Control by a computer: The computer calculates the amount of steering torque you want to apply and transfers the appropriate amount of power to an actuator ahead of the steering head, which turns the front wheel.
Keeping things on track: When external forces try to move the front wheel, such as bumps, the system recognizes that the order didn’t come from the bar inputs, therefore the actuator resists the movement and acts as a steering damper.
Simple but clever: The entire arrangement is extremely compact and does not necessitate a new frame, fork, or headstock redesign. As a result, it should be simple to implement. Yamaha says the plan is to “equip EPS on various motorcycles in order to provide a wide range of riders with greater motorcycling fun, safety, and comfort.”
Time to perfection: As on cars with power steering, there’s still a physical connection between the bars and the front wheel so you don’t lose control if the system fails.
