Illustrative project: Bike Simulator
Thanks to a simulator developed at the ZHAW School of Engineering, it is now possible to test a mountain bike on a range of itineraries across different kinds of terrain without actually leaving the laboratory. In addition to enabling manufacturers to test various materials, the simulator can also help to resolve ergonomic issues.
Once you have your feet on the pedals of the Institute of Mechanical Systems (IMES)’s Bike Simulator, the screen in front of you shows the terrain you have to traverse and the handlebars directly replicate the effect of the bumps on the surface beneath you. As Daniel Baumgartner, who is managing the project for the IMES, explains, “To create itinerary profiles that are as realistic as possible, we first made recordings of real bike rides using a video recorder and an acceleration sensor.” The simulator is thus able to replicate the obstacles and shocks which occurred when a real bike was ridden over a given itinerary.
Originally, the Bike Simulator had been planned solely as a demonstration exhibit at the ZHAW School of Engineering’s Technology Night. However, even then Daniel Baumgartner and his team had considered possible industrial uses for it, such as testing bicycle forks. This in fact soon happened, when a Swiss bicycle manufacturer expressed interest in continuing the project. As a result, the project team joined forces with Thelkin, a ZHAW spin-off company, to optimise the simulator and develop it further. Thelkin developed the control mechanisms for the actuators, which are used to move the bicycle fork so that it simulates the effect of riding over the terrain of a particular itinerary. The simulator has now been developed to the point where it can be used with any bike. To achieve this, the front suspension is attached to the simulator while the back wheel is free to revolve on a roller system. The advantage of this for bicycle manufacturers is that it makes it possible to test the stability and suspension characteristics of the bicycle fork.
“The sensors measure how taut the rider’s muscles are, thus providing insights into the best possible use of his or her muscle power.”
Dr. Daniel Baumgartner, Project Manager, Institute of Mechanical Systems (IMES)
The key focus of the work carried out at the IMES’s biomechanical laboratory is however on the interaction between man and machine. Daniel Baumgartner is keen to analyse the effect of mechanical shocks on the human body. As he recalls, “First we placed sensors on the pedals so that we could measure the power the rider was applying to them. Next we placed a number of accelerometers on various parts of the rider’s body such as the head and wrists.” This makes it possible to measure and compare rates of acceleration under different conditions and to record how taut the rider’s muscles are. As Daniel Baumgartner explains, “The sensors measure how taut the rider’s muscles are, thus providing insights into the best possible use of his or her muscle power.” The effect of the mechanical shocks on the rider depends on how the bike’s suspension has been adjusted.
The results of these simulation tests can help to optimise the materials used in cycle construction, thus benefiting not only top sporting professionals but ordinary leisure riders as well. A question many mountain bikers ask themselves is how much energy they use at different suspension settings. “At the moment, people generally set the suspension according to what they think feels right, which is rarely optimal,” explains Daniel Baumgartner. “In future, it might be possible to test bikes and their settings at the sports shop in much the same way as people already test running shoes before buying them to find out which shoe is best suited to their running style or what insoles it may need.” There are also plans to develop the simulator further so that it also transmits the mechanical shocks to the rear wheel. Daniel Baumgartner believes that future bachelor and master’s degree theses could play a part in this development.