Our group is enrolled in Dr. Stephen Canfield’s Dynamics of Machinery class and have been assigned a project that will test our capabilities as engineering students as well as provide a local child who has been diagnosed with cerebral palsy with a football style arcade game that he can play.
Our team will be designing and constructing an arcade style football in such a way that it will be easily playable and accessible for a child who has cerebral palsy and is wheelchair bound. The child has a limited range of motion in his arms, therefore the football game must be made in such a way that the football is returned to the player after it has been thrown and the collection area where the football is returned must be at a proper height for him to be able to reach it whilst restrained in his wheelchair. The machine itself will need to be on adjustable legs to increase in height as the child grows and be fitted with casters to allow easier movement of the machine.
After meeting the child and seeing what is needed of this football game specifically, our team came up with some design specifications that would be required of our project. The arcade style football machine should:
There are a few options on the market for a football style arcade game, but all fail to meet our design specifications in one way or another. Most games that we could source required the child to throw the ball further than he is capable of and/or wasn’t accommodating of a wheelchair. The only desirable thing all of these premanufactured games have in common is a way to return the ball to the player. Our team will preserve the ball returning characteristics of these games and make a more accessible, heavier duty variant.
This design incorporates a rectangular body with six legs that allow a change in height, a semi-circular cutout in conjunction with a ramp that allows the ball to be returned to either side of the player, and a target board with circular cutouts that are intended to be the players target. This design remains the simple while also meeting all the project requirements.
Design 2 retains a similar overall shape to the first design but incorporates a return “box” that would return a thrown football directly in front of the player rather than to the side. It also acts as a cubby hole for the football underneath the surface of the return slope. This design also makes use of a single goal post rather than a series of holes as a target for the player.
This design is very simplistic and is constructed solely of a bent steel tube frame and a series of nets. This design would be very light weight, but at the cost of durability. Additionally, this concept doesn’t feature adjustable legs as the other two designs do. While this would possibly be the simplest design it is not as durable or adaptable as the other concepts.
Our team has chosen design #1. We’ve made this decision because we believe that this design will be the easiest to make while also meeting all the design requirements. Additionally, this design features more functionality than concept 2 and offers more adaptability than concept 3. Overall, we believe this will be the best long lasting solution, and allow our project to be used for years to come.
Our selected design features adjustable legs, so as the child ages the football table can grow with him. This machine will be quite heavy, we estimate over 200 pounds. To help with mobility we have included locking caster wheels on all six legs for easy mobility, and so that it does not roll away during use. The backboard features several different sized holes in which to throw the football through. The sides will feature a net so the ball does not roll out of the machine, since the child isn’t exactly able to pick up a football from the floor without assistance. The surface is inclined so the ball will return naturally to the child. To stop the football, there is small rail at the base so it doesn’t roll away from the child. The front section folds on top of the machine so it doesn’t take up excess space when not in use. The front two legs can then be removed from their inserts and stored inside the front section after it has been folded for ease of storage.
Our design is an arcade style football mechanism that returns a thrown projectile back to the player who is interacting with the contraption. For our design, we chose to go with a sloped incline with a cut out on the end for the player ease of access. At the top end of the incline, we designed a backboard with circle cutouts for the player to throw into. Once they contact the wall behind the target board, the footballs will roll down the slope, back to the player where the cutout will be located. Our plan is to design the walls, backstop, and the sloped surface out of ½” plywood. Those surfaces will then be attached to the frame of the design via some fasteners. The frame will be constructed out of 2×4’s. There will also be six premade adjustable legs to insure adjustability. Our major practicality point of the design will fold in half at the middle for portability. The design will fold in half by three hinges mounted the design will mostly stay in a school gymnasium, so it will need to be movable and condensable. At the end of each leg, we will incorporate 4” casters for the design to be able to move freely throughout the gym.
For the first engineering analysis, a simulation of one of the football table’s legs was conducted in Solidworks. A load that was equivalent to the weight of the entire table (560 N) was applied to the top of the leg. After running the simulation, the overall stress in the leg was very manageable and even the stress in the height adjustment pin was nowhere near the failure point.
For the second engineering analysis, a simulation of the goal board was conducted. A point load of 1100 newtons was applied to the center of the goal board to simulate the momentary force that a 0.43 kilogram football thrown at 26 meters per second would cause. These conditions were chosen because this is the average throwing speed that a NFL quarterback. Even under these conditions, the stresses produced are still less than the yield strength of the goal board components.
For the final engineering analysis, a simulation of a 2×4 of the same dimensions (57 in) used in the main frame of the football table. In this simulation, the beam was fixed at both ends and a force equivalent to the weight of the entire table (560 N) is applied to the top surface of the beam. The stresses were slightly elevated near the fixtures, but still did not exceed the yield strength of the beam.
Overall, our project, the Football Arcade Style Mechanism, allowed my classmates and I to learn a lot about working together and communicating. We were able to use our communication and collaboration skills in order to work in an orderly and efficient process. We started off meeting as a team to discuss ideas on how we would go about designing and solving the problem. Next, we moved to putting these ideas on paper, and shortly after, had the ideas incorporated into SolidWorks. This was where we did most of the design and test fitting before actually dealing with real materials. After that we began to work on measurements and design features. Then we moved to meeting in the shop every week so that we could take care of the fabrication and construction of the contraption. Finally, we put the finishing touches on the project by adding the personal touch of paint and design work. Looking back at this experience, I believe that I learned a lot about what it means to come up with a design and use a design process in a real-world scenario in order to transfer those ideas into a physical application. We think that our mechanism will help solve and make a way for the user to not only have fun, but also to be able to share the sport they love with others as well.