Project Documents

Project Proposal

Final Report

Presentation

Data Analysis

We analyzed our data in MATLAB. One of the main findings of this is that each bat is unique. Our MATLAB script generated several plots: Amplitude vs. Oscillation, Amplitude vs. Distance Away From Bottom of Bat, Frequency of Oscillation vs. Distance Away From Bottom of Bat, and Amplitude vs. Frequency of Oscillation. As you can see below, each of the four bats we tested is different. The "Sweet Spot" is the point at which the vibrations are minimized (smallest amplitude) and the oscillations are quicker (larger frequency of oscillation).

BAT 1 (Cupped)

BAT 2 (Cupped)

BAT 3 (Non-Cupped)

 

BAT 4 (Non-Cupped)

Test Procedure and Results

Our test rig allowed a ball to be swung from a pendulum from 11 different heights which corresponded to hitting the bat in 11 different spots. These spots were from 0-10 inches away from the bottom of the bat. For each trial, a ball was released from 40 degrees to ensure that the bat would be hit with a constant force. While the ball was released, the accelerometer that was mounted to the handle of the bat was turned on, recording 3 seconds worth of data.

The data that came from our testing was raw accelerometer data in the X, Y, and Z directions. The data was “raw” because it was unprocessed values that came straight from the accelerometer. Over the 3 second period that each test was being administered, the accelerometer took 300 readings in each the X, Y, and Z directions. The next step is to process that data and further analyze it to find the sweet spot of each bat.  

Test Rig

Our test rig was designed on the principle of a pendulum. We chose this for two reasons, first was for its ease of repeatability with consistent results. Secondly it allowed us to hit the bat at different locations while providing a consistent force. When a pendulum of the same length is released from the same angle it will strike the bat with the same force. In order to strike the bat at different locations the height of the pendulum was raised while holding the length of the pendulum. Each bat was hit at one inch increments for the lower third (barrel part) of the bat starting at the bottom of the bat. This procedure was repeated for each bat. More information about pendulums can be found here.

3D Printing

We utilized 3D printing to create a part for our testing rig that would be too expensive to purchase and too difficult to manufacture. It saved us a lot of money and time to make a way to connect the bats to the testing rig. To get a part 3-D printed what you first need to do is create a model of your part. Once you have made your part you have to follow a specific procedure to convert into an .stl file, (the file format for 3-D). You must go to either your export button, or save as button and click .stl. Once you choose that setting it will ask you how rendered you want your part. Then just save your file. This is demonstrated in the Tutorials section.

3D Model 

Printed Part

Bat Holder in Testing Rig

Arduino

We are using an Arduino Uno to acquire our raw accelerometer data. Utilizing the Arduino coding environment, code was developed to read the accelerometer and send the data to a PC where it can be processed and further analyzed in MATLAB. The code developed for our experiment can be found in the Tutorials section.

Accelerometer in Housing

Arduino Uno

Both Attached on Bat in Testing Rig

Motivation and Deliverables

     The combination of being lifelong baseball fans/players and having an interest in the science behind sports has resulted in the idea to design and create our own wooden baseball bats. Apart from being something that just our group is interested in, wood bats are becoming more popular around baseball. The major and minor leagues have always used wood bats, but college, high school, and little leagues have traditionally used metal bats, until recently. With the technological improvements in metal bats, they have reached a point where certain materials and construction techniques are being banned for the reason of player safety. One of the main differences between metal and wood bats is that a ball flies off a metal bat much faster than a wood bat. This is concerning to the safety of the pitcher who stands just 60’6” away from the batter. Because of this, many leagues are only allowing players to hit with wood bats.
     Of the wood bat variety, both maple and white ash woods are used for bats. We have decided to do our experiment solely on white ash for several reasons: it is currently much more popular in the major leagues, it is the cheaper of the two, and white ash trees are grown locally in Pennsylvania.  

     Beyond the large market for wood bats, this project will be a great way for each of the group members to learn a great deal about several things such as: CNC machining, MATLAB, 3D printing, accelerometer uses, physics concepts, test procedure design, and machine and tool use.
     The project follows several technical challenges. The first will be to design and build an effective testing procedure that will offer consistent and correct data about the location of the sweet spot on existing wood baseball bats. We will then take what we learn from this data and once we finalize several designs, we will use the CNC lathe to create them.

     After the bat is created, we will conduct the first test over again so we can compare our bat to bats that are currently on the market. The final test will be to take the bats to a batting cage and test out the bats in a more traditional sense. Just because we find that a bat has a large sweet spot, doesn’t meant that it will be a bat that feels comfortable to the batter.

     Our desired outcome is to have a physical bat that is just as good as one that a major leaguer would use. 

     The project will be broken down into two basic sections. The first will be the data gathering and research section, from this we hope to gather information from different bat samples. We hope to be able to present the data in a way that clearly shows how different design aspects affect the vibration and sweet spot. The goal of this will be to show that there is some connection between the location of the ball striking the bat and the energy transferred. The second part will be to this design and test a final prototype. The goal is to have our bat have a better energy transfer over a larger area of the barrel.