1. Physics of Stationary and Dynamic Ergometers By: Nathaniel Brown Tim Beauregard Andrew DiOrio Bryan Taylor

2. Ergometer Background Exercise machine that measures work done pulling a chain. Used to simulate the motion of rowing a boat on water. Different types of ergs = different feel and performance.

3. Static Ergometer Static: Concept2 ErgometerDiagram of Static Ergometer The standard for testing a rower’s power output. Does not mimic the feeling of a boat well.

4. Dynamic Ergometer Dynamic: Oartec Slider ErgometerDiagram of Oartec Slider Better mimics the motion of a boat. Times are generally faster than stationary. Higher stroke rates are easier.

5. Problem Statement Develop an explanation for differences in measured performance for different ergometers. Create a “rule-of-thumb” formula for adjusting scores on different ergometers.

6. Approach to Problem Solving Measure locations of selected points on rower and erg using video and image tracking. Find accelerations based on data. Use the accelerations and masses to find work and power.

7. Assumptions Forces only act in x-direction. Static center of masses based on three points at the ankle, hip, and neck. Frictionless environment.

8. Expectations Static ergometer will waste more energy accelerating masses than the dynamic ergometer. The dynamic ergometer will simulate motion on water better than the static ergometer.

9. Equipment 1 Ortec Slider Ergometer 1 Stationary 2 Concept Ergometer Video Camera Image Tracking Software (Tracker) Matlab

10. Tracker Open source Tracks motion of points using image recognition algorithms Exported Data into csv files

11. Dynamic Erg with Tracker

12. Procedure Four, one minute pieces on each type of erg Two pieces at 20 spm, two at 30 spm Approximately even splits for each stroke rate (1:52 for 20 spm, 1:37 for 30 spm)

13. Results

14. Results (Cont.)

15. Rule of thumb: Static wastes 5 more watts for every beat above 16 spm.

16. Conclusion The dynamic erg is more efficient than the static erg. The efficiency gap increases with an increase in stroke rating. The efficiency gap has a significant effect on performance.