Laser triangulation sensors from Micro-Epsilon are being used to measure the lateral position of rail bogie wheels relative to the rail head in a groundbreaking rail traction technology project by UK based company, SET Limited.
ActiWheel is an innovative traction system that uses artificial intelligence to guide trains along the tracks, enabling quicker, smoother and more economical rail travel. The solution could dramatically change the way that rail vehicles run on the railway. As Martin Whitley, Director at SET Limited explains: “This revolutionary wheel motor can be controlled to produce more driving force on one side or the other in order to steer the wheelset down the centreline of the track. For the last 200 years, conventional rail vehicles have only had a solid axle and wheel coning providing this capability which drives some significant compromises and issues. What we want to do is to see this technology implemented as the technology of choice for rail passenger vehicles of the future.”
In the ActiWheel solution, the motor is integrated in the wheel, which means there is no transmission between the two and no moving parts beyond a bearing which every wheel and axle has. In addition, there is no friction braking systems, so there would be a significant reduction in the amount of maintenance required.
Neil Cooney, Technical Director at SET Limited comments: “One of the biggest issues facing the rail infrastructure is Rolling Contact Fatigue [RCF], which occurs due to the energy in the contact between the wheel and the rail. Conditions under the contact patch are always severe and the yield stress of the rail wheel is always exceeded, on at least a microscale.”
“Actively yawing the wheels along with active torque control, manages the contact patch at the optimum point of the rail, practically eliminating RCF. This is because ideal [close to radial] steering reduces the energy in the contact patch to a point where RCF does not occur and wear is very small.”
Reliable, durable and lightweight
The ActiWheel is a very high reliability, very durable system and Cooney expects his wheels to last somewhere between four to 10 times longer than a conventional set up. There is virtually no wear, which means the rail isn’t being damaged and the wheels don’t deteriorate. The solution is also lightweight, which means it’s a lot easier to accelerate and decelerate the train and there is additional carrying capacity for passengers.
For the last nine months, ActiWheel has been put through its paces in a technical demonstrator project. An ex-London Underground train with a single carriage was fitted with an ActiWheel system on each of its eight wheels. The project was a success, says Cooney, with the results proving that wear and RCF were almost negligible. The project has already received some significant industry interest and SET Ltd is engaged in developing a system to a network rail.