The team members involve in this project are :
The system under consideration is a device that will be applied to the training of ultimate Frisbee players. This is facilitated by the repeated throws of Frisbee into the pitch, towards players by the Frisbee launcher device. It will mainly serve as training for players to catch discs, in the different situation of plays (attack plays and defense plays), but also for diving.
This system is an electromechanical Frisbee launching machine similar to the examples on figures 1 and 2. The purpose of the machine is to launch Frisbee towards one of several players at a steady rate for training or recreation. The launcher is made of four main parts:
o First, the stand which is similar to a table with a height and a slope modifiable by the user.
o Second, the rail in which the disc will be guided before the launch.
o Then, the spinning wheel which will provide sufficient energy into the disc to make it fly.
o Finally, the electronic system, whose main component is a motor, to transform electrical energy into mechanical energy.
Figure 1: First example of Frisbee launcher
The user has to insert a disc in the rails. Besides, the disc will slide on the stand, between the rails, thanks to the friction force made by the spinning wheel. And when the disc arrives at the end of the rails, its spinning and translational speed make it flyin the air.
One of the team member, Ismael, is interested in designing the Frisbee launcher to study in what extend it could improve the ultimate Frisbee training. As a result, we have come together to work on the system design. We would like to know if the mechanism will suit such needs in term of lifetime (a system which could last several hours per week at plenty use, for several years), power (disc could be launched at 50 meters), comfort (as simple as possible to use), repeatability and precision (a 20% precision is acceptable). That is why a model must be created and several parameters need to be chosen.
Since we want to design a user-modifiable system in term of power, height and slope of the stand, the team has the authority to change the design parameters to improve the performance of the machine.
You can watch these very well and impressive realized examples on Youtube.com:
Our system is made of different components which are:
1. The stand of the machine
2. The spinning wheel
3. The electrical part of the machine, mainly composed of a DC motor and a battery
4. A Frisbee
5. A friction force between the wheel and the Frisbee
6. A friction force between the Frisbee and the rail (an extension of the stand)
electrical part of the machine provides a torque through a shaft thanks to the
DC motor. This shaft is then connected to the wheel to provide energy through
the wheel and make it spin. The Frisbee will be in contact with the spinning
wheel and will move thanks to the Coulomb friction between the wheel and the
Frisbee. The Frisbee will also experiment Coulomb friction between itself and
the rail. The spinning wheel and the Frisbee will lie on the stand but without
considering any friction.
Due to the complexity of our model, we did not consider the elasticity of the Frisbee at the moment. We also have not considered the air friction on the Frisbee while it is moving, because we believe that the aerodynamics of the Frisbee make the air friction negligible compared to the Coulomb friction. As a result the only phenomenon we consider here is the Coulomb friction.
For the tests of the model, we
simulate the acceleration of the Frisbee on a long interval. Meanwhile, in
order to have access to real value of the speed when the Frisbee will be
launched, we will limit the simulation thanks to the value of the angle of the
arm: depending of the performance, we will stop the simulation when this angle
will be equals to 90 or 180°.
Figure 3: Dymola model of the Frisbee launcher
As you can see, we used the Multibody library of Dymola. You can watch this animation of the simulation:
The Homework assignments:
Last modified 03/17/2009 05:35 AM