Determination of spin parameters of a sports ball
First Claim
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1. A method of estimating a spin frequency of a rotating sports ball in flight, the method comprising:
- receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the rotating sports ball;
deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the rotating sports ball, the signal being frequency modulated by a modulation frequency; and
estimating, via the radar arrangement, at at least a single point in time, the spin frequency of the rotating sports ball based on at least one frequency distance between a harmonic of the modulation frequency and one or more of;
the first frequency and an additional harmonic of the modulation frequency.
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Abstract
A method of determining spin parameters of a spot ball, such as spin axis and rotation velocity of a golf ball. The spin axis is determined solely from the trajectory of the flying ball, and the rotational velocity is determined from a frequency analysis of a signal provided by a radar, which signal comprises spectrum traces positioned equidistantly in frequency, which frequency distance relates to the spin velocity.
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Citations
39 Claims
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1. A method of estimating a spin frequency of a rotating sports ball in flight, the method comprising:
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receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the rotating sports ball; deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the rotating sports ball, the signal being frequency modulated by a modulation frequency; and estimating, via the radar arrangement, at at least a single point in time, the spin frequency of the rotating sports ball based on at least one frequency distance between a harmonic of the modulation frequency and one or more of;
the first frequency and an additional harmonic of the modulation frequency. - View Dependent Claims (3, 4, 5, 13, 19, 20, 21, 22)
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2. A method of estimating a spin frequency of a rotating sports ball in flight, the method comprising:
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receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the rotating sports ball; deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the rotating sports ball, the signal being modulated by a modulation frequency; and estimating, via the radar arrangement, at at least a single point in time, the spin frequency of the rotating sports ball as a frequency distance between the first frequency and an adjacent first harmonic of the modulation frequency or a frequency distance between two adjacent harmonics of the modulation frequency. - View Dependent Claims (6, 7, 8, 11, 23)
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9. A system for estimating a spin frequency of a rotating sports ball in flight, the system comprising:
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a receiver adapted to, at a number of points in time during the flight, receive electromagnetic waves reflected from the rotating sports ball and provide a corresponding signal; means for performing a frequency analysis of the signal, and detecting one or more sideband harmonics, the one or more sideband harmonics being spaced by the spin frequency and around a frequency corresponding to a velocity of the rotating sports ball; and means for estimating the spin frequency from a frequency distance between the frequency corresponding to the velocity of the rotating sports ball and one of the one or more sideband harmonics in a first case, or the distance between two of the one or more sideband harmonics in a second case, wherein there are at least two sideband harmonics in the second case. - View Dependent Claims (10, 12)
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14. A system for estimating a spin frequency of a rotating sports ball in flight, the system comprising:
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a receiver of a radar arrangement configured to, at at least one point in time, receive electromagnetic waves reflected from the rotating sports ball and provide a corresponding signal, which is frequency modulated by a modulation frequency, wherein the radar arrangement is configured to perform a frequency analysis of the frequency modulated signal and detect at least one harmonic of the modulation frequency, the radar arrangement being further configured to estimate the spin frequency from a frequency distance between a first frequency corresponding to a velocity of the rotating sports ball and said at least one harmonic or a second frequency distance between said at least one harmonic and an additional harmonic of the modulation frequency. - View Dependent Claims (15, 24, 25, 26, 27)
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16. A system for estimating a spin frequency of a rotating sports ball in flight, the system comprising:
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a receiver of a radar arrangement configured to, at least one point in time, receive electromagnetic waves reflected from the rotating sports ball and provide a corresponding signal, which is modulated by a modulation frequency, wherein the radar arrangement is configured to perform a frequency analysis of the modulated signal and estimate the spin frequency as a frequency distance between a first frequency corresponding to a velocity of the rotating sports ball and an adjacent harmonic of the modulation frequency or a frequency distance between two adjacent harmonics of the modulation frequency. - View Dependent Claims (28, 29)
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17. A method of estimating spin frequency of a rotating sports ball in flight, the method comprising:
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receiving, using a receiver of a radar arrangement, electromagnetic waves reflected from the rotating sports ball; deriving from said received electromagnetic waves, via the radar arrangement, a signal having a first frequency corresponding to a velocity of the rotating sports ball, the signal being modulated by a modulation frequency; and estimating, via the radar arrangement, at at least a single point in time, a spin frequency of the rotating sports ball based on, in a first case, at least one frequency distance between a harmonic of the modulation frequency and the first frequency or, in a second case, between two harmonics of the modulation frequency, wherein the spin frequency is determined by dividing the frequency distance by a harmonic number of the harmonic in the first case or a difference in harmonic number of the harmonics in the second case. - View Dependent Claims (30, 31, 32, 33, 34, 35)
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18. A system for estimating a spin frequency of a rotating sports ball in flight, the system comprising:
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a receiver of a radar arrangement configured to, at at least one point in time, receive electromagnetic waves reflected from the rotating sports ball and provide a corresponding signal, which is modulated by a modulation frequency, the signal having a first frequency corresponding to a velocity of the rotating sports ball, wherein the radar arrangement is configured to perform a frequency analysis of the modulated signal and estimate the spin frequency based on, in a first case, at least one frequency distance between a first harmonic of the modulation frequency of the modulated signal and the first frequency or, in a second case, between two harmonics of the modulation frequency of the modulated signal, and wherein the spin frequency is determined by dividing the frequency distance by a harmonic number of the harmonic in the first case or a difference in harmonic number of the harmonics in the second case. - View Dependent Claims (36, 37, 38, 39)
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Specification