Equipment fitting system that compares swing metrics
An equipment fitting system that measures swings by a user of different pieces of equipment with inertial sensors, and analyzes sensor data to recommend which piece of equipment is optimal for the user from among those tested. Illustrative applications include fitting of baseball bats and golf clubs. Swing metrics calculated from sensor data may include an acceleration metric, a speed metric, and a momentum metric; these metrics may be combined into a metrics score for each piece of equipment. Other factors may be included in an overall score, such as the user's subjective score for each piece of equipment, and ratings from experts or other consumers. Users may assign the relative importance for the different factors to calculate an overall equipment score.
1. An equipment fitting system that compares swing metrics, comprising:
one or more inertial sensors, wherein
each inertial sensor of said one or more inertial sensors comprises
an accelerometer;
a gyroscope; and
a network interface;
each inertial sensor is coupled to one or more pieces of equipment of a plurality of pieces of equipment used by a user;
each inertial sensor is configured to capture inertial sensor data at a sequence of times during a swing of each piece of equipment of said one or more pieces of equipment to which said each inertial sensor is coupled;
a processor coupled to said one or more inertial sensors via a network connection, wherein said processor is configured to
receive said inertial sensor data associated with said swing of each piece of equipment of said plurality of pieces of equipment;
for said each piece of equipment,
calculate swing metrics based on said inertial sensor data, said swing metrics comprising
an acceleration metric;
a speed metric; and
a momentum metric; and
calculate a metrics score from said swing metrics; and,
recommend an optimal piece of equipment of said plurality of pieces of equipment for said user based on said metrics score.
2. The equipment fitting system of claim 1 , wherein said processor is further configured to calculate said metrics score as a weighted sum of said swing metrics.
3. The equipment fitting system of claim 1 , wherein said recommend said optimal piece of equipment is further based on one or more of
a user feel score provided by said user for said each piece of equipment;
an expert opinion score provided by one or more experts for each piece of equipment; and,
a consumer comparison score provided by one or more consumers for each piece of equipment.
4. The equipment fitting system of claim 3 , wherein said processor is further configured to
calculate an overall score for said each piece of equipment based on
said metrics score;
said user feel score;
said expert opinion score; and
said consumer comparison score; and,
select said optimal piece of equipment as a piece of equipment having a highest overall score.
5. The equipment fitting system of claim 4 , wherein said processor is further configured to
calculate said overall score as a weighted sum of
said metrics score;
said user feel score;
said expert opinion score; and
said consumer comparison score.
6. The equipment fitting system of claim 5 , wherein said processor is further configured to obtain or calculate weights for said weighted sum based on input from said user.
7. The equipment fitting system of claim 1 , wherein said each piece of equipment is a bat.
8. The equipment fitting system of claim 1 , wherein said each piece of equipment is a golf club.
9. The equipment fitting system of claim 1 , wherein said each piece of equipment of said plurality of pieces of equipment is associated with
a longitudinal axis;
a sweet spot position; and
an effective mass.
10. The equipment fitting system of claim 9 , wherein said momentum metric equals said effective mass times said speed metric.
11. The equipment fitting system of claim 10 , wherein
said each piece of equipment is a bat; and,
said effective mass comprises 0.75 times a mass of said bat.
12. The equipment fitting system of claim 9 , wherein said speed metric comprises a speed of said sweet spot position at an endpoint of said swing.
13. The sequipment fitting ystem of claim 12 wherein said endpoint of said swing comprises a time of said sequence of times of an impact between said each piece of equipment and an object.
14. The equipment fitting system of claim 12 wherein said endpoint of said swing comprises a time of said sequence of times when a rotational velocity magnitude of said each piece of equipment is maximum.
15. The equipment fitting system of claim 9 , wherein said acceleration metric comprises a rate of change of a centripetal acceleration of said each piece of equipment along said longitudinal axis.
16. The system of claim 15 , wherein
said processor is further configured to partition said sequence of times into phases, wherein said phases comprise
a load phase ending when said centripetal acceleration changes from positive to negative;
an accelerate phase following said load phase;
a peak phase following said accelerate phase; and
a transfer phase following said peak phase and ending at an endpoint of said swing;
said acceleration metric comprises an average rate of change of said centripetal acceleration during said accelerate phase.