Method for determining aerodynamic characteristics of a golf ball
AssigneeAcushnet Company
InventorsDouglas Winfield, William Gobush
Life of this patent
Estimating the term…
Abstract
A method for determining the lift and drag coefficients of a golf ball includes launching the ball along a flight path, measuring the velocity at two positions along the flight path, using the measured velocities to determine the coefficients of lift and drag. The step of measuring the velocity includes taking two images of the ball at the two positions, where the time interval between images at each position is less than about 0.01 seconds.
Claims23
A method of determining a lift coefficient and a drag coefficient for a golf ball along a flight path, wherein the method comprises the steps of:
- a. providing a launching device for launching the golf ball along the flight path;
- b. launching the golf ball along the flight path from the launching device;
- c. taking two images of the ball at a first position spaced from the launching device, a first time interval between taking the images at the first position being less than 0.01 seconds;
- d. taking two images of the ball at a second position, a second time interval between taking the images at the second position being less than 0.01 seconds;
- e. using the images at the first position to determine a first measured velocity at the first position;
- f. using the images at the second position to determine a second measured velocity at the second position;
- and
- g. calculating the drag coefficient and the lift coefficient using the first measured velocity and the second measured velocity.
A method of determining a lift coefficient and a drag coefficient for a golf ball along a flight path, wherein the method comprises the steps of:
- a. providing a launching device for launching the golf ball along the flight path;
- b. launching the golf ball along the flight path from the launching device;
- c. measuring a first measured velocity at a first time and at a first position spaced from the launching device;
- d. measuring a second measured velocity at a second time and a second position spaced from the first position;
- e. estimating a lift coefficient and a drag coefficient;
- f. determining a first predicted velocity at the first position and the first time and determining a second predicted velocity at the second position and the second time using the lift and drag coefficients;
- g. solving a Jacobian matrix including the lift coefficient, the drag coefficient, the first predicted velocity and the second predicted velocity to determine a Jacobian solution;
- h. calculating a first velocity difference between the first predicted velocity and the first measured velocity and calculating a second velocity difference between the second predicted velocity and the second measured velocity;
- and
- i. calculating a new drag coefficient and a new lift coefficient using the Jacobian solution, the first velocity difference and the second velocity difference.
A method of determining a lift coefficient and a drag coefficient for a golf ball along a flight path, wherein the method comprises the steps of:
- a. providing a launching device for launching the golf ball along the flight path at an initial speed and initial spin rate;
- b. launching the golf ball along the flight path at the initial speed and initial spin rate at an initial time from the launching device;
- c. measuring a first measured velocity at a first time and at a first position spaced from the launching device;
- d. measuring a second measured velocity at a second time and a second position spaced from the first position;
- e. measuring at least one additional measured velocity at an additional time and an additional position spaced from the second position;
- f. estimating a lift coefficient and a drag coefficient;
- g. determining a first predicted velocity at the first position and the first time, determining a second predicted velocity at the second position and the second time, and determining additional predicted velocities at the additional positions and the additional times using the lift and drag coefficients;
- h. solving a Jacobian matrix including the lift coefficient, the drag coefficient, the first predicted velocity and the second predicted velocity to determine a Jacobian solution;
- i. calculating a first velocity difference between the first predicted velocity and the first measured velocity, calculating a second velocity difference between the second predicted velocity and the second measured velocity, and calculating additional velocity differences between the additional predicted velocities and the associated additional measured velocity;
- and
- j. calculating a new drag coefficient and a new lift coefficient using the Jacobian solution, the first velocity difference, the second velocity difference, and the additional velocity difference.
Dependencies are inferred from the claim text.