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.

A sensor module includes an X-axis angular velocity sensor device that outputs digital X-axis angular velocity data, a Y-axis angular velocity sensor device that outputs digital Y-axis angular velocity data, a Z-axis angular velocity sensor device that outputs digital Z-axis angular velocity data, an acceleration sensor device that outputs digital X-axis, Y-axis, and Z-axis acceleration data, a microcontroller, a first digital interface bus that electrically connects the X-axis angular velocity sensor device, the Y-axis angular velocity sensor device, and the Z-axis angular velocity sensor device to a first digital interface, and a second digital interface bus that electrically connects the acceleration sensor device to a second digital interface.

A portable sensor device is provided. The portable sensor device may at least include a first angular rate sensor, a second angular rate sensor, and a gyroscope. The first angular rate sensor may include two or more accelerometers, whereas the second angular rate sensor may include an accelerometer and a magnetometer. In some instances, the portable sensor device may determine when to use the first angular rate sensor, when to use the second angular rate sensor, and when to use the gyroscope to obtain angular rate measurements indicative of angular motion of the portable sensor device. Further, the portable sensor device may determine one or more angular motion parameters describing angular motion of the portable sensor device using data from the first angular rate sensor, the second angular rate sensor, the gyroscope, or combinations of the first angular rate sensor, the second angular rate sensor, and/or the gyroscope.

An angular acceleration sensor includes a planar surface extending along an X-Y plane, a fixed portion, a weight, a beam, and piezoresistors. The weight is supported by the fixed portion. The beam extends along a Y-axis and is connected to the fixed portion and the weight. A width of the beam in an X-axis direction is larger than a width of the connection portion at which the beam is connected to the fixed portion.

An accelerometer arrangement and method are described for determining accelerations of an inground tool. First and second triaxial accelerometers are supported such that a normal sensing axis of the first triaxial accelerometer is at least generally orthogonal to the normal sensing axis of the second triaxial accelerometer for determining the accelerations along the three orthogonal axes based on a combination of sensing axis outputs from one or both of the triaxial accelerometers. A weaker sensing axis of one triaxial accelerometer can be supported at least approximately normal to a weaker sensing axis of another triaxial accelerometer such that the weaker axes are not used. The triaxial accelerometers can be supported such that one axis of one accelerometer can be redundant with respect to another axis of another accelerometer. One triaxial accelerometer can be mounted on a tilted plane with respect to another triaxial accelerometer.

An accelerometer arrangement and method are described for determining accelerations of an inground tool. First and second triaxial accelerometers are supported such that a normal sensing axis of the first triaxial accelerometer is at least generally orthogonal to the normal sensing axis of the second triaxial accelerometer for determining the accelerations along the three orthogonal axes based on a combination of sensing axis outputs from one or both of the triaxial accelerometers. A weaker sensing axis of one triaxial accelerometer can be supported at least approximately normal to a weaker sensing axis of another triaxial accelerometer such that the weaker axes are not used. The triaxial accelerometers can be supported such that one axis of one accelerometer can be redundant with respect to another axis of another accelerometer. One triaxial accelerometer can be mounted on a tilted plane with respect to another triaxial accelerometer.

A ground surface position lateral acceleration calculator calculates ground surface position lateral acceleration based on lateral acceleration detected by an acceleration sensor, a yaw rate and a roll rate detected by a gyro sensor, yaw angular acceleration and roll angular acceleration calculated by an angular acceleration calculator, a roll angle calculated by a roll angle calculator, and specification information stored in a storage. A vehicle lateral force calculator calculates a vehicle lateral force based on the roll angular acceleration calculated by the angular acceleration calculator, the roll angle calculated by the roll angle calculator, the ground surface position lateral acceleration calculated by the ground surface position lateral acceleration calculator and the specification information stored in the storage.

Operation of a hubodometer includes orbiting detection and cancelation. In particular, in a hubodometer having a housing that rotates relative to a pendulous assembly, such operation includes detecting, by at least one orbiting sensor operatively connected to the pendulous assembly, an orbiting condition of the pendulous assembly, the orbiting condition being at least partly defined by an orbiting direction. Thereafter, and responsive to the detection of the orbiting condition, operation of the hubodometer further comprises applying, by an electric actuator operatively connected to the pendulous assembly, a countervailing force to the pendulous assembly in a direction opposite the orbiting direction. Through application of the countervailing force, the orbiting condition may be canceled.

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.

In an inertial sensor, an acceleration sensor element section includes a first movable section configured to respond to acceleration applied thereto and a diagnosis electrode configured to displace the first movable section with an electrostatic force according to voltage application from a control circuit section. An angular velocity sensor element section includes a second movable section configured to respond to an angular velocity applied thereto and a driving electrode configured to displace the second movable section with an electrostatic force according to voltage application from the control circuit section. A voltage signal input to the driving electrode and a voltage signal input to the diagnosis electrode are the same voltage signal. The voltage signal input to the diagnosis electrode is a signal for detecting a mechanical failure. Carrier signal for detecting displacement of the first movable section has frequency higher than frequency of signal applied to the diagnosis electrode.