1 EXS 587 – Advanced Biomechanics Fall 2007 Dr. Moran Laboratory Experience: Force Plate (Software - MS Excel) Date: November 20, 2007 • Lab Purpose: This lab is intended to provide the students with experience working with embedded force plate commonly used within a gait lab. You will collect ground reaction force (GRF) data on yourself from a walking trial with shoes and without shoes. Instructions: Please follow the step-by-step instructions – if you have any issues, please raise your hand and I will be by to assist. Importing/Manipulate Data into Microsoft Excel I. Download .RAW files to a folder or a desktop (these files will be emailed to you) II. Open Microsoft Excel and select File > Open a. Find the .RAW file that you just downloaded [in order to open it you will need to change the file type that Excel (“Files of Type”) is looking for to “All Files”] b. A dialog box will appear asking how to import the data. Be sure to chose DELIMITED and then select COMMA. c. You should now see 8 columns of data d. You may disregard Column A e. Plot Column B – What was the purpose of this data? In what frame did the values shoot up? In what frame did the values shoot back down? These frame numbers are important and correspond to an event that occurred? f. Delete all rows before Event Marker #1 and Event Marker #2 g. Now insert into Column I the TIME. The data was collected at 120 Hz h. Plot Columns C, D, and E versus COLUMN I (time) i. Use this plot to determine which values (Anterior-Posterior Force, Medial-Lateral Force, Vertical Force) are in columns C, D and E ii. Insert a ROW above first data points and LABEL your columns of data2 i. REPEAT all these steps for your other Data file and put this information in another worksheet in the same FILE. j. Save you Excel file as your lastnameFP.xls Generate Plots/Answer Questions I. How long was your foot in contact with the force plate for the two conditions? What is a potential reason of why they are different? If you were doing a study how could you better control for this? II. Make a plot (put in a separate worksheet) of the vertical GRF versus time for the two different conditions. a. What does the first “hump” of the vertical GRF indicate? b. What does the second “hump” of the vertical GRF indicate? c. Which condition had the greater initial hump? Was this what you expected? Why or why not? III. Make a plot (put in a separate worksheet) of the Anterior-Posterior GRF versus time for the two different conditions. a. What does the positive initial spike indicate? Hint: the sign indicated the direction of force b. What does the negative final spike indicate?3 c. Which condition had the greater initial hump? Was this what you expected? Why or why not? IV. If the researcher wanted to know the exact location of the resultant GRF relative to the ankle joint (for inverse dynamics purposes), then what would the researcher have needed to