Punching Bag

Hit Me With Your Best ShotMeasuring Forces Applied to a Punching BagDaniel Bergeron, Luke Bosse, Jennifer Farrar, Kristi Harrison, Alex Patel, and Brandon Smithhttp://www.youtube.com/watch?v=lGI7VmsTle4

AlexOpen the video link for a fun introduction. Explain how it presents our design. 1OverviewObjectiveMaterialsMethodsData and ResultsCalculationsData Logger ComparisonKid-friendly lessonConclusionLukeHere is an overview of our project. First, we have our objectives. Followed by the materials and methods. After that we are going to display some of the data collected from the punching bag, along with the results and calculations that could be made from that data. We also have a comparison between two different data loggers, our kid friendly lesson and the overall conclusion.2ObjectivesCreate a punching bag that will measure acceleration using Wiimote accelerometersCalculate a maximum applied force using acquired dataCompare two different accelerometers AlexOur design objectives that demonstrate biomechanical applications in a fun interactive way for middle/high school students. A project that allows engineers to apply concepts and learn to configure the setup and analysis of data. The main objective of our project was to create an experiment for middle and high schoolers that is not only fun and interactive but also helps to demonstrate some of the biomechanical applications we have learned throughout this course. Our goal was to create a punching bag using the accelerometer found in a wiimote along with a data collection program to calculate the applied force. We are also going to test the wiimote application to a second accelerometer. In this case the accelerometer found in one of our smartphones.3MaterialsWiimoteDarwiinRemote softwareiPhone DataLogger applicationDuffel bagScale

DanielThe wiimote contains the accelerometer used for measurement. It connects wirelessly via bluetooth to a laptop running DarwiinRemote software. DarwiinRemote is capable of capturing acceleration data from the three axis accelerometers found in the Wiimote, logging the data, and providing the operator with a real time graphical display of the data being recorded. The iPhone DataLogger application was used as a second method of measuring the acceleration. We created the punching bag using a duffle bag stuffed with tshirts and sheets because we felt a relatively soft, lightweight stuffing would be the most appropriate for a safe and fun exercise for the projected age group.A scale was used to measure the mass of the punching bag, it was found to weigh 35 lbs. 4Methods

Figure 1: (left) Punching Bag. (above) Hanging set up

To perform this experiment first we loaded the bag full of clothes and other materials until it weighed 35 lbs and hung it over the beam seen in the picture on the right. Next we placed the wiimote in the bag, as shown in the picture, and connected it to the Darwiin program via Bluetooth. After performing multiple trials that included punching and kicking the bag, we then repeated the test using our second accelerometer by placing the iphone equipped with the datalogger program in the same spot.

BrandonThe wiimote contains the accelerometer used for measurement. It connects wirelessly via bluetooth to a laptop running DarwiinRemote software. DarwiinRemote is capable of capturing acceleration data from the three axis accelerometers found in the Wiimote, logging the data, and providing the operator with a real time graphical display of the data being recorded. The iPhone DataLogger application was used as a second method of measuring the acceleration. We created the punching bag using a duffle bag stuffed with tshirts and sheets because we felt a relatively soft, lightweight stuffing would be the most appropriate for a safe and fun exercise for the projected age group.A scale was used to measure the mass of the punching bag, it was found to weigh 35 lbs. 5Data and Results

Figure 2: Acceleration output in each directional axis

BrandonShows the results of Danies first punch using the wiimoteThe graph shows the acceleration in the x y and z directions X axis-perpendicular to the punchY axis-up and down through the bagZ axis-parallel to the direction of the punchWe can see that the largest acceleration based on the wiimotes orientation was in the negative z direction. In other words, it goes away from Daniel as he punches it, just as one would expect when punching an object.

The acceleration in the y direction shows movement as well which reflects the swing of the bag, as it moves down and then swings back up because fo the rope connected to the pendulum6Data and ResultsFigure 3: Max acceleration in the z-axis

Figure 4: Resultant Acceleration

Resultant Acceleration

Brandonthe image on the left shows a second trial of punching bag, but only the z-axis because that is the main axis of motionThe image on the right shows the resultant acceleration of punch 2, based on all three axes. We found the resultant to determine the total acceleration of the bag and then used that determine the overall force of the punching bag in all three directions7Data and ResultsFigure 5: Max acceleration in z-axis. (a) amax= -4.9 g (b) amax= -4.22 g

BrandonWe did a second punch and a frontal kick for multiple trials and data.Harder Punch = Daniel.Front Kick = Jenny. As you can see, the peaks from the kick are not as high as from the punch, meaning the kick did not produce as much force as from the punchWe can see the punch has a shorter impact time based on the steeper slope of the highest peak, while the kick shows a longer impact duration.8CalculationsF=ma

TrialMass (lbs)Max Acceleration Z axis (g)ForceZ axis (lbs)Resultant Force (lbs)Punch 135 -4.18146.3 187.6Punch 235 -4.90171.5192.3Kick 135 -4.22147.7149.7Table 1: Values used to calculate max forceJennyWeighed the bag in pounds. We kept the mass/weight in pounds because it is more relatable to middle/high school kids than Newtons. Max acceleration in the z axis was found by taking the maximum value of the acceleration spike. Force=mass*acceleration (9.81 m/s2 cancels out) Force is found in pounds. Resultant force is found the same way. Comparison between force and resultant force shows how head on the punch/kick is to the bag. 9Data Logger ComparisonFigure 6: Comparison of the data collected from the Wiimote and the iPhone during the same trial

LukeWe had iPhone in with the wiimote to serve as a comparative method of analysis. This showed how the iPhone DataLogger is insufficient for our project because the application has a limited data acquisition range of 2g. 10Kid-friendly lessonWhat is an accelerometer?Newtons Second LawHow can a Wiimote be used to measure acceleration?How does the iPhone data compare to the Wiimote data?How do we use the graphs?Kristi Our punching bag uses an accelerometer. An accelerometer is a sensor that measures acceleration in all directions (Up/down, Front/back, Left/Right). The Wiimote is the device with the accelerometer. The way it connects through bluetooth is how the Wiimotes work wirelessly for all of the Wii games. All iPhones have an accelerometer that reads the direction of the phone, used in many apps like temple run. By graphing the data, the peak visually represents the maximal acceleration needed to find the maximum force applied.

11SummaryWe aimed to create a kid-friendly exercise to demonstrate biomechanical principlesAccelerometer data can easily be recorded and analyzed to calculate an applied force JennyOur goal is to create a kid friendly lesson on the use of accelerometers that can be found in everyday objects

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SummaryOur project is a very basic model with potential for numerous other applications of more technical design

Figure 7: LoadStar Sensors boxing training technologyLoadStar Sensors-real life application that is used to measure force of boxing punches.Our design is a very basic model with great potential.13Questions?