A compound bow includes a riser, an upper limb, and a lower limb, the upper limb and lower limbs coupled to the riser. The compound bow may include a draw sensor. The compound bow includes a performance module coupled to the riser, the performance module operatively coupled to the draw sensor. A compound bow may include an arrow chronometer assembly. A method may include determining draw weight or length based on measurements of the draw sensor. A method may include determining arrow speed based on measurements of the arrow chronometer assembly.

A compound bow includes a riser, an upper limb, and a lower limb, the upper limb and lower limbs coupled to the riser. The compound bow may include a draw sensor. The compound bow includes a performance module coupled to the riser, the performance module operatively coupled to the draw sensor. A compound bow may include an arrow chronometer assembly. A method may include determining draw weight or length based on measurements of the draw sensor. A method may include determining arrow speed based on measurements of the arrow chronometer assembly.

A device of or attached to a roller body determines a rotational frequency of the roller body (or other object) rotating about an axis of rotation includes an acceleration sensor that detects an acceleration signal of an acceleration in a first direction extending in a radial or tangential direction to the axis of rotation of the roller body; and an electronic processing unit and configured to low-pass and high-pass, particularly adaptively high-pass filter, the detected acceleration signal, perform a derivation, with respect to time, of the filtered signal, optimize the signal with a subsequent absolute-amount generation and with moving averaging, and ascertain a frequency of the filtered acceleration signal, which corresponds to the rotational frequency of the roller body.

Systems and methods are provided for estimating a walking speed of a subject. A method comprises mounting an inertial measurement unit (IMU) on a wrist of the subject, the IMU configured to generate acceleration and rate of turn signals; processing the acceleration and rate of turn signals from the IMU to generate a pitch angle and a roll angle; processing the pitch angle and the roll angle to generate a rotation matrix from a sensor frame of the IMU to a navigation frame of the subject; applying the rotation matrix to the acceleration signals and removing gravitational acceleration to generate an external acceleration signal; processing the external acceleration signal to determine a principal horizontal axis and to generate a principal component acceleration signal representing external acceleration along the principal horizontal axis; and processing the principal component acceleration signal using a regression-based method to determine an estimated walking speed of the subject.

Systems and methods are provided for estimating a walking speed of a subject. A method comprises mounting an inertial measurement unit (IMU) on a wrist of the subject, the IMU configured to generate acceleration and rate of turn signals; processing the acceleration and rate of turn signals from the IMU to generate a pitch angle and a roll angle; processing the pitch angle and the roll angle to generate a rotation matrix from a sensor frame of the IMU to a navigation frame of the subject; applying the rotation matrix to the acceleration signals and removing gravitational acceleration to generate an external acceleration signal; processing the external acceleration signal to determine a principal horizontal axis and to generate a principal component acceleration signal representing external acceleration along the principal horizontal axis; and processing the principal component acceleration signal using a regression-based method to determine an estimated walking speed of the subject.

A human-powered vehicle control device includes an electronic controller that controls a motor. The motor assists in propulsion of a human-powered vehicle including a transmission configured to change, in steps, a first ratio of a rotational speed of a drive wheel to a rotational speed of a rotary body to which human drive force is input. The controller changes a motor control state from a third control state to a fourth control state when the first ratio is changed by the transmission or a signal is received for changing the first ratio. The controller changes the motor control state from the fourth control state to a fifth control state in accordance with a value related to at least one of a speed of the human-powered vehicle, the human drive force, an inclination angle of the human-powered vehicle, and a state of a rider of the human-powered vehicle.

Embodiments of the present disclosure provide an optical encoder for an electronic device. The optical encoder comprises an elongated shaft having an encoding pattern made up of axial markings and radial markings. The encoding pattern may be disposed around a circumference of the elongated shaft. The optical encoder also includes an optical sensor. In embodiments, the optical sensor includes an emitter and a photodiode array. The emitter causes light to shine on the encoding pattern. The encoding pattern reflects the light back to the photodiode array and the photodiode array determines movement of the shaft based on the reflected light.

Embodiments of the present disclosure provide an optical encoder for an electronic device. The optical encoder comprises an elongated shaft having an encoding pattern made up of axial markings and radial markings. The encoding pattern may be disposed around a circumference of the elongated shaft. The optical encoder also includes an optical sensor. In embodiments, the optical sensor includes an emitter and a photodiode array. The emitter causes light to shine on the encoding pattern. The encoding pattern reflects the light back to the photodiode array and the photodiode array determines movement of the shaft based on the reflected light.

A system, apparatus, and method for determining a velocity. A voltage is detected for a planar sensor array while the planar sensor array is moving though a magnetic field, wherein the planar sensor array comprises conductive channels formed in a substrate, wherein the conductive channels are connected in series, and wherein the voltage is generated by the planar sensor array in response to a movement of the planar sensor array through the magnetic field and wherein the voltage is proportional to a velocity of the planar sensor array moving through the magnetic field. The velocity of the planar sensor array is determined using the voltage detected for the conductive channels.

A system, apparatus, and method for determining a velocity. A voltage is detected for a planar sensor array while the planar sensor array is moving though a magnetic field, wherein the planar sensor array comprises conductive channels formed in a substrate, wherein the conductive channels are connected in series, and wherein the voltage is generated by the planar sensor array in response to a movement of the planar sensor array through the magnetic field and wherein the voltage is proportional to a velocity of the planar sensor array moving through the magnetic field. The velocity of the planar sensor array is determined using the voltage detected for the conductive channels.