Handbike simulator

Abstract

This report presents the design research, concept development, user test and final design for the handbike simulator. The handbike simulator is an addition for treadmills developed by ForceLink which allows handbikers to exercise on the treadmills with realistic opposing forces. Next to that it enhances the treadmill experience by offering different sensorial elements like wind, video and audio. Design research Through literature research on treadmills, interviews with handbikers and the development of theoretical model of the forces involved in handbiking, the initial problem of missing opposing forces was studied. With the theoretical model of forces involved in handbiking, a method was developed for analyzing how much wind friction force a handbiker experiences outside. With statistics from a handbiker about the average speed, average power and specifications of the handbike, an estimate can be given on the average amount of wind friction force, without the need of the wind tunnel. This model was verified with a test where the actual opposing forces of a recumbent were measured. During the literature research, several comparable studies on force simulation for treadmills were found. It was concluded that force simulation by means of mechanical tethers or slope has great potential, but that it is likely that slightly different forces have to be simulated than the actual forces experienced outside. This is due to difference in how the force is applied to a person. This meant that after developing a means for simulating force and calculating the force that has to be simulated, a test has to follow to study this effect and adjusting the actual force that has to be simulated for a satisfactory experience. From the interviews it was concluded that handbikers want a realistic and reliable training device. Independence and safety are also important issues. The most important quality of handbiking itself is the sensation of speed and should be a focus point for enhancing the treadmill experience. Concept development With the conclusions from the design research, the ideation phase started. Several brainstorms were done on two topics: simulating opposing forces and enhancing the treadmill experience. For simulating opposing force an idea was selected for further development which uses a fitness weight stack. For enhancing the treadmill experience, several ideas were selected on different sensorial fields. An idea with fans for actual wind was selected. Video projection of handbike environments were selected as well as LED strips for visual information about speed and performance. Finally the addition of sound was also selected. A prototype was built of all selected ideas for testing purposes. The prototype offered two forms of force simulation: a pulling force by means of a fitness weight stack and already built in slope function. The prototype also included a fan, video projection, LED strip and sound which were all programmed in to react to the speed of the treadmill. User test With the prototype a user test was setup. The first part of user test was to determine the how much force had to be simulated and which form of force simulation was preferred (slope force or pulling force). The second part of the user test was to evaluate the ideas for enhancing the treadmill experience. For the first part of the user test it was found that user had no preference towards pulling force or slope force. Also, users didn’t experience slope force as riding uphill, but just felt an opposing force. It was therefore concluded that slope force was the best solution for force simulation, since this didn’t require any changes to current treadmills. It was found that found that users required an average slope force of 22,6 Newton. For the second part of the user test it was found that the combination of wind from the fan and the modulated sound of wind greatly enhanced the experience. Users strongly related these two different sensorial inputs to each other, which made the treadmill experience more similar to handbiking outside. Next to that the wind created by the fan, also functions as a cooling mechanism for the handbiker. The video projections together with the LED strip were also a strong combination for enhancing the treadmill experience. With the video projection, users could imaging driving through the displayed environment. The LED strip was perceived as an extension of the video projection, with running lights passing by the user in their periphery. Objects by the side of the road on the video projection seemed to pass by them, while they were riding further on the displayed road. Final Design With the results from the user test the final design was made. A Harris profile was made for all the new elements on the treadmill to make sure none of the elements conflicted with each other and make find the most optimal overall solution. A final concept drawing was made for the handbike simulator. Finally a 3D model was created, which includes all the new parts and their measurements for the handbike simulator.