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ME 3057
Experiment Design and Project Plan
This project is an experiment planning exercise; students are to design, plan and present a
measurement project in a document that can be reviewed and understood by the client and that
can be successfully conducted by a technician (or team) hired by the client.
This is an individual project. Students may not share files, or explanations. Students may use the
information and diagrams in this assignment file, with attribution.
Problem
After biking across Hawkins for the 100th time to save the day, the kids decide they want to
quantify their cycling power output to improve their response time. Being this is the early 80’s,
there are no commercially available power meters on the market. They are going to have to use
the computers and resources available at the local Radio Shack. Suzie and Dustin’s idea, as shown
in Figure 1, is to use a force transducer to measure the torque being applied to the chain ring of
their bikes, condition the resulting signal, and acquire it using a data acquisition system which
will store the force transducer voltage data to 5.5” floppy disk (1.2 MB of storage). Later analysis
will determine the torque, crank speed, and power from the force voltage data.
Figure 1: Concept schematic of homemade bike power meter and acquisition system
You are working a summer job at the Radio Shack between semesters at the Georgia Institute of
Technology and have decided to help them with the instrumentation design. Based upon the
bikes they will be using you have come up with a preliminary design of the system, shown in
Figure 2, which will measure the total torque which results from the left, , and right, , pedal
forces on the cranks of lengths . The applied torque can then be determined from a force
ME 3057 Fall 2022
transducer measure the force, , being applied to the chain ring where it connects to the hub
at a distance, . The crank speed, , will be determined by post-processing the data as it is
anticipated that the torque data for one revolution will show two maximums like the sample data
shown in Figure 3. It is expected that the data will be collected at a known constant sampling
rate, so only the force transducer data will need to be stored to perform the analysis. The bike
specifications can be found in Table 1.