Method of coupling a motion sensor to a piece of equipment
Method for coupling a sensor to a piece of equipment, such as a golf club, baseball bat, or tennis racket, that ensures that the sensor is in a known position and orientation relative to the equipment. Compensates and calibrates for degrees of freedom introduced in manufacturing and installation. The method may include manufacturing a sensor receiver that aligns with equipment in a fixed orientation, and that holds a sensor housing in a fixed orientation relative to the receiver. Remaining uncertainties in sensor position and orientation may be addressed using post-installation calibration. Calibration may include performing specific calibration movements with the equipment and analyzing the sensor data collected during these calibration movements.
1. A method of coupling a motion sensor to a piece of equipment comprising:
manufacturing a sensor receiver configured to couple to a piece of equipment, wherein said piece of equipment comprises a golf club, wherein said sensor receiver is configured to couple to said golf club at an end of said golf club opposite a clubhead of said golf club, and wherein said sensor receiver comprises
an outer surface comprising an outer receiver orientation alignment feature;
an inner surface surrounding an inner cavity that is configured to receive a sensor housing containing a motion sensor;
one or more protrusions or indentations in said inner surface that mate with one or more corresponding features on said sensor housing when said sensor housing is installed in a correct orientation into said inner cavity; and,
a protrusion from a bottom side of said sensor receiver configured to mate with a corresponding hole in a top of a golf club grip,
wherein said outer receiver orientation alignment feature comprises a flat portion of said outer surface that corresponds to a flat portion of an outer surface of said golf club grip;
coupling said sensor receiver to said piece of equipment in an orientation that aligns said outer receiver orientation alignment feature with a corresponding feature of said piece of equipment; and,
inserting said sensor housing into said inner cavity in an orientation that aligns said one or more protrusions or indentations in said inner surface with said one more corresponding features on said sensor housing.
2. The method of claim 1 wherein said inner cavity is substantially a right circular cylinder comprising a closed bottom end and an open top end.
3. The method of claim 1 wherein said sensor receiver is integrated into a golf club grip.
4. The method of claim 1 further comprising:
after inserting said sensor housing into said inner cavity, performing one or more calibration movements with said golf club;
collecting data from said motion sensor during said one or more calibration movements;
analyzing said data to calculate a position and orientation of said motion sensor relative to a reference coordinate system of said golf club.
5. The method of claim 4 wherein an origin of said reference coordinate system is on a clubface of said golf club.
6. The method of claim 4 wherein said performing one or more calibration movements with said golf club comprises:
holding said golf club in an orientation with a shaft of said golf club aligned with a gravitational direction.
7. The method of claim 4 wherein said performing one or more calibration movements with said golf club comprises:
rotating said golf club around a first axis aligned with a shaft of said golf club.
8. The method of claim 4 wherein said performing one or more calibration movements with said golf club comprises:
rotating said golf club around a second axis perpendicular to a shaft of said golf club.
9. The method of claim 4 wherein said performing one or more calibration movements with said golf club comprises:
holding said golf club in an orientation with a shaft of said golf club aligned with a gravitational direction;
rotating said golf club around a first axis aligned with said shaft of said golf club; and,
rotating said golf club around a second axis perpendicular to said shaft of said golf club.
10. The method of claim 1 wherein said motion sensor comprises:
a three-axis accelerometer; and,
a three-axis rate gyroscope.
11. The method of claim 1 wherein
said piece of equipment comprises a handle; and,
said sensor receiver is configured to couple to said piece of equipment at an end of said piece of equipment near said handle.
12. The method of claim 1 wherein
said piece of equipment comprises a tennis racquet; and,
said sensor receiver is configured to couple to said tennis racquet at an end of said tennis racquet near a handle of said tennis racquet.
13. The method of claim 1 wherein
said piece of equipment comprises a baseball bat; and,
said sensor receiver is configured to couple to said baseball bat at an end of said baseball bat near a handle of said baseball bat.
14. A method of coupling a motion sensor to a golf club comprising:
manufacturing a sensor receiver configured to couple to a golf club at an end of said golf club opposite a clubhead of said golf club, wherein said sensor receiver comprises
an outer surface comprising an outer receiver orientation alignment feature;
an inner surface surrounding an inner cavity that is configured to receive a sensor housing containing a motion sensor comprising a three-axis accelerometer and a three-axis gyroscope, wherein said inner cavity is substantially a right circular cylinder comprising a closed bottom end and an open top end;
one or more protrusions or indentations in said inner surface that mate with one or more corresponding features on said sensor housing when said sensor housing is installed in a correct orientation into said inner cavity; and,
a protrusion from a bottom side of said sensor receiver configured to mate with a corresponding hole in a top of a golf club grip,
wherein said outer receiver orientation alignment feature comprises a flat portion of said outer surface that corresponds to a flat portion of an outer surface of said golf club grip;
coupling said sensor receiver to said golf club in an orientation that aligns said outer receiver orientation alignment feature with a corresponding feature of said golf club;
inserting said sensor housing into said inner cavity in an orientation that aligns said one or more protrusions or indentations in said inner surface with said one more corresponding features on said sensor housing;
after inserting said sensor housing into said inner cavity, performing one or more calibration movements with said golf club, said one or more calibration movements comprising
holding said golf club in an orientation with a shaft of said golf club aligned with a gravitational direction;
rotating said golf club around a first axis aligned with said shaft of said golf club; and,
rotating said golf club around a second axis perpendicular to said shaft of said golf club;
collecting data from said motion sensor during said one or more calibration movements; and,
analyzing said data to calculate a position and orientation of said motion sensor relative to a reference coordinate system of said golf club.