In one aspect, a swimjet system may include a reverse thrust system worn by a swimmer proximate the frontal upper torso. The system provides a variable amount of reverse thrust such that the user can swim-in-place or make gradual forward progress. Importantly, this may enable a user to effectively “extend” a small residential pool to serve the same function as a twenty-five meter pool typically found at commercial or government facilities. The system also provides laminar current under the user while swimming, which solves the problems of “leg drop,” the need to “out-kick” the arm stroke, and turbulence and wave action around the head associated with conventional swim-in-place devices. Still further, in certain embodiments the system provides a relatively strong current in the region of the arm stroke moving away from the swimmer which provides enhanced “resistance” for proficient swimmers.

A force sensor including: a first part including a detection coil; a second part positioned opposite the first part and including: a ferromagnetic plate translationally movable relative to the first part to move towards the first part when a force is transferred to the sensor and to reduce reluctance of a magnetic circuit formed by the first and second parts in series with a variable gap; and an electronic detection circuit configured to generate a signal dependent on the reluctance of the magnetic circuit. The ferromagnetic plate is formed by an amorphous metal alloy.

A force sensor including: a first part including a detection coil; a second part positioned opposite the first part and including: a ferromagnetic plate translationally movable relative to the first part to move towards the first part when a force is transferred to the sensor and to reduce reluctance of a magnetic circuit formed by the first and second parts in series with a variable gap; and an electronic detection circuit configured to generate a signal dependent on the reluctance of the magnetic circuit. The ferromagnetic plate is formed by an amorphous metal alloy.

Fixed-element, digital-optical measuring devices are disclosed, as are methods for using these devices. The measuring devices have two separate optical pathways with fixed elements that produce a stereo image. The optical pathways may include mirrors, prisms, beam splitters, and other such elements, or two digital sensors may be used. Image distance between stereo copies of a point of interest in the stereo image is measured digitally and converted to a physical distance from the measuring device. The conversion may be done with a non-trigonometric function, such as a function created using empirical data. In some cases, the function may be a function-of-functions that provides a calibration for a number of different lens focal lengths.

The present disclosure relates to systems and methods for balance index determination. For example, a wearable apparatus may have at least one gyroscope configured to measure angular velocity about a first axis; at least one inertial measurement device (IMU) configured to measure deviation along a second axis and a third axis; at least one memory storing instructions; and at least one processor configured to execute the instructions to: receive angular velocity measurements over a period of time from the at least one gyroscope; receive deviations from the second axis and from the third axis over the period of time from the at least one IMU; weight the deviations based on directions associated with the deviations; and generate a composite balance index based on the angular velocity measurements, the weighted deviations from the second axis, and the weighted deviations from the third axis.

A swimming exercise device, comprising a restraint including an opening and a contact portion, the restraint configured to receive a head of a user through the opening and to restrain the user, via contact between shoulders of the user and the contact portion, such that the user is held substantially stationary during forward motion of the user against the restraint and an abutment structure configured to contact a pool surface and transmit forces associated with the forward motion of the user against the restraint to the pool surface.

A swimming exercise device, comprising a restraint including an opening and a contact portion, the restraint configured to receive a head of a user through the opening and to restrain the user, via contact between shoulders of the user and the contact portion, such that the user is held substantially stationary during forward motion of the user against the restraint and an abutment structure configured to contact a pool surface and transmit forces associated with the forward motion of the user against the restraint to the pool surface.

The present invention is a tethered resistance swim training apparatus with a pulley that includes an electronic tachometer to measure the rotations of the wheel of the pulley and strain gauge to measure the force pulling on the body of the pulley. The pulley, also referred to as “smart pulley”, can be implemented in many tethered swim training apparatuses of different arrangements. With the tachometer and strain gauge the power and other performance metrics can be calculated while a swimmer is using the apparatus. A load cell or similar can be used in place of a strain gauge. The sensors may be connected via wired or wireless communications to a computer (tablet, laptop, personal computer, server, or the like) for processing of the signals and display on an electronic display.

The present invention is a tethered resistance swim training apparatus with a pulley that includes an electronic tachometer to measure the rotations of the wheel of the pulley and strain gauge to measure the force pulling on the body of the pulley. The pulley, also referred to as “smart pulley”, can be implemented in many tethered swim training apparatuses of different arrangements. With the tachometer and strain gauge the power and other performance metrics can be calculated while a swimmer is using the apparatus. A load cell or similar can be used in place of a strain gauge. The sensors may be connected via wired or wireless communications to a computer (tablet, laptop, personal computer, server, or the like) for processing of the signals and display on an electronic display.

This invention is an inexpensive, easy-to-use, and easy-to-manufacture device that can be placed on the edge of a pool so that a swimmer can use it to count laps without significantly disrupting the swimming. The invention is lightweight and portable so that one person can carry it around, place it on the pool before swimming laps, and remove it afterwards.