Human Power Team Delft & Amsterdam - Human Power Team Delft
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The team
Human Power Team is a team from the Delft University of Technology and the VU University of Amsterdam with the aim to design, build and race a streamlined recumbent bike.
The team has started in September 2010 and achieved a European and student record of 129km/h during the World Human Powered Speed Challenge at Battle Mountain, Nevada, in September 2011. At this moment a new team of students is working on a new, faster, better and more innovative human powered vehicle (HPV) to break the current world speed record of 133 km/h. Besides this record, we also want to break the hour record, currently at 91.6 km/h.
The challenge of reaching world record speeds is highly multidisciplinary. It is not only about making a vehicle that is highly aerodynamic, efficient and lightweight but also about getting the most out of a cyclist by selection and training.
Human Power Team is Recruiting Students for 2012/2013
Because the technological development never stops, next year we want to let an enthusiastic new team make the next step in the development of the ultimate human powered vehicle.
Within the team, there are many different tasks for a future team member. In addition to the technical issues such as aerodynamics, dynamics and strength calculations, there are also management and acquisition tasks. There is also a possibility to actively cooperate with the department of movement Sciences, for example, to investigate a new drive train.
You can support the team in different ways. If you choose to be a full-time core team member you are at the basis of the design and all the things that are important. A full-time function can be combined with a D: dream minor. Instead of full-time, you can also support the team part-time.
Pleas fill in the form if you are interested in the team and like to take on this sporting and technical challenge!
Physical ergonomic
Industrial Design Engineering (IDE) as it is taught in Delft is a profession that can bridge the gap between man and machine/product. We learn to make technology usable by others taking into account the body: physical ergonomics. Most of the people on the team are cyclists. These people know how to tune their ride to fit them perfectly. So they also know: the better your bike is fitted to yourself, the better you can perform.
We found that there was little academic knowledge on the effect of a recumbent seat on the rider’s performance. Probably because the recumbent industry is not as big as the road bike industry. Obviously, a back support differs from a butt support.
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Conventional recumbent seat |
Superseat |
Our IDE expertise and these insights led to the decision to redesign the previous bicycle seat. We decided to take a user centric approach and started by evaluating the previous seat with the previous riders. We found that not only the seat, but also part of the frame was used as a body support when used in full sprint. We also found that the seat caused pressure marks in places where the bone was closer to the skin.
What we thought we could improve was:
1. A higher efficiency of the exerted force by the riders body to the pedals. We presumed the upper body acts as a damper when the forces of the legs go through the whole of the body instead of being counteracted around the waist. This presumption was confirmed by research done on the superseat. (http://superseat.nl/)
2. A better body support that would even out the loads, preventing damage to the rider’s tissue. In return, this could allow the seat to be stiffer, diminishing energy loss through flexion.
The riders position in the bike is kept the same as well as the overall curvature along the spine. We assumed this was needed to fit with the structural design of the bicycle. The riders themselves also deemed it a good cycling position.
There are rules of thumb to what the curvature should be for an office chair. However, these should fit a large variance of people (and butts) and are made in large series. Because carbon fiber is the main material for the bicycle it was readily available and besides having the required lightness and stiffness it is perfect for making single custom components. Thus, we are producing a tailored seat for all the four riders. How do we do this?
We make a scan of the rider’s back with equipment from IDE. That gives us a point cloud or mesh. To simulate the position the rider has in the bicycle we flip him upside down (on his knees) and press the old seat into his back to create the right curvature.
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3D Scan equipment |
Results in CAD |
Then we CNC mill the negative shape from green high density foam. This block of foam is consequently used as a fitting device for the rider. We install the block on a bike in the same position as it would be in the bicycle. Then, together with the rider, we test if the body support is desirable and adjust by sanding. To make sure we do not only depend on the rider’s verbal information, we have a mat with a pressure sensor array telling us how the loads are distributed over the seat while cycling.
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CNC mold of the negative shape |
Final result |
Finally this same block is used to laminate and vacuum bag the seat. After the first few layers of carbon fiber, foam along the spine and waist covered with more carbon fiber is added for stiffness.
The seat is a success with the first seat finished and the second one is almost finished. If this method proves to be successful for the second time we will create the other two in parallel.
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