Patent ID: 8460127

Claim:
An apparatus for characterizing a golf swing, comprising: a shank having a cup shaped to receive a golf ball at an upper end and a lower end, wherein at least a portion of the shank is formed of a material having a Young's modulus substantially the same as polyurethane; an articulated joint connected to the lower end of the shank, the joint including: a ball element coupled to the shank, wherein the ball element includes a first recess at a pole location and a second recess, the second recess being at least partially circumferential at approximately an equator location; and a cap shaped complementary to the ball element, the cap having a slot sized to allow the shank to deflect: (i) approximately ninety-degrees from a reference vertical, and (ii) at least forty five degrees from a reference azimuth; a base having a cavity, a spike at a lower end and a seat at an upper end, the seat being shaped to receive the ball element and to mate with the cap; and a motion control device that includes a spring element and a detent element disposed in the cavity, wherein the detent element is compressed against the ball element by the spring element, the detent element engaging the first recess to maintain the ball element in a nominal position before the golf swing and engaging with the second recess to maintain the ball element in a deflected position after the golf swing.