Abstract: Apparatus and methods relating to circulation of air within a plethysmographic measurement chamber are provided. An air circulation system, comprised of one or more pumps, is coupled to a plethysmographic measurement chamber using one or more inlet and exhaust tubes. The air circulation system renews the air within the measurement chamber using ambient air, or air derived from a controlled temperature environment.

Abstract: Apparatus and methods for generating repeatable closure of a volume measurement chamber are provided. More particularly, in one embodiment of the present invention, a dual articulating hinge is used to affix a chamber door to a volume measurement chamber, providing repeatable closure of a chamber door. In another embodiment of the invention, a laterally compliant magnetic latch is used to fasten a chamber door to a volume measurement chamber. In a third embodiment, a chamber door lid is mounted to a hinge bar via a ball joint, allowing the chamber door lid to self center about the chamber opening.

Abstract: Apparatus and methods relating to circulation of air within a plethysmographic measurement chamber are provided. An air circulation system, comprised of one or more pumps, is coupled to a plethysmographic measurement chamber using one or more inlet and exhaust tubes. The air circulation system renews the air within the measurement chamber using ambient air, or air derived from a controlled temperature environment.

Abstract: Methods and apparatus for calibrating volume measurement in a plethysmographic chamber are described. The present invention involves the use of a calibration volume chamber of known volume coupled to a plethysmographic measurement chamber in a plethysmographic measurement system for determining body composition, wherein a computer system calibrates the measurement system prior to conducting a volume measurement of a test subject, by measuring the chamber volume before and after opening an electronically controlled valve that connects the controlled calibration volume to the plethysmographic chamber, and comparing the measured chamber volumes based on the known reference volume.

Abstract: Apparatus and methods relating to plethysmographic measurement of infant body composition are provided. A tray for receiving the infant subject to be measured is coupled to a sliding mechanism that slides the tray in and out of a plethysmographic measurement chamber, thereby reducing the footprint of said chamber and facilitating infant comfort during measurement. Further, an integrated weighing function is provided that determines the infant's weight while conducting body composition measurements.

Abstract: Apparatus and methods for generating repeatable closure of a volume measurement chamber are provided. More particularly, in one embodiment of the present invention, a dual articulating hinge is used to affix a chamber door to a volume measurement chamber, providing repeatable closure of a chamber door. In another embodiment of the invention, a laterally compliant magnetic latch is used to fasten a chamber door to a volume measurement chamber. In a third embodiment, a chamber door lid is mounted to a hinge bar via a ball joint, allowing the chamber door lid to self center about the chamber opening.

Abstract: Apparatus and methods relating to plethysmographic measurement of infant body composition are provided. A tray for receiving the infant subject to be measured is coupled to a sliding mechanism that slides the tray in and out of a plethysmographic measurement chamber, thereby reducing the footprint of said chamber and facilitating infant comfort during measurement. Further, an integrated weighing function is provided that determines the infant's weight while conducting body composition measurements.

Abstract: Methods and apparatus for calibrating volume measurement in a plethysmographic chamber are described. The present invention involves the use of a calibration volume chamber of known volume coupled to a plethysmographic measurement chamber in a plethysmographic measurement system for determining body composition, wherein a computer system calibrates the measurement system prior to conducting a volume measurement of a test subject, by measuring the chamber volume before and after opening an electronically controlled valve that connects the controlled calibration volume to the plethysmographic chamber, and comparing the measured chamber volumes based on the known reference volume.

Abstract: A recumbent bilateral reciprocal isokinetic leg exerciser wherein first and second reciprocating members are slidingly coupled to a linear track so that they move with linear bilateral reciprocal motion. Both reciprocating members are coupled to associated hydraulic cylinders so that hydraulic fluid is drawn into or forced out of the hydraulic cylinders as the reciprocating members move along the track. A valve assembly is coupled to the hydraulic cylinders for controlling fluid flow into and out of the hydraulic cylinders so that the reciprocating members move isokinetically. The valve assembly may be set for simultaneous movement of the first and second reciprocating members or for movement of one reciprocating member by itself. To ensure accurate measurement of patient effort, a strain gauge assembly is disposed on each reciprocating member for detecting deformation of the reciprocating member along multiple axes.

Abstract: A horizontal support arm is mounted for upward and downward movement on a vertical support column. An interface unit having an actual mass value is disposed on a free end of the horizontal support arm and is adapted to be grasped and lifted by a human subject. A simulated mass value independent of said actual mass value may be set for the interface unit, and the amount of vertical force exerted by the human subject upon the interface unit is measured. An exercise control unit provides for controlled vertical movement of the interface unit as a function of the simulated mass value such that the interface unit responds to a lifting force by the human subject in a manner that simulates the inertia of an object having a mass value equal to the simulated mass value in a gravitational field.

Abstract: A recumbent bilateral reciprocal isokinetic leg exerciser wherein first and second reciprocating members are slidingly coupled to a linear track so that they move with linear bilateral reciprocal motion. Both reciprocating members are coupled to associated hydraulic cylinders so that hydraulic fluid is drawn into or forced out of the hydraulic cylinders as the reciprocating members move along the track. A valve assembly is coupled to the hydraulic cylinders for controlling fluid flow into and out of the hydraulic cylinders so that the reciprocating members move isokinetically. The valve assembly may be set for simultaneous movement of the first and second reciprocating members or for movement of one reciprocating member by itself. To ensure accurate measurement of patient effort, a strain gauge assembly is disposed on each reciprocating member for detecting deformation of the reciprocating member along multiple axes.

Abstract: An isokinetic exercise system includes an active exercise resistance unit and a computer controller. The active exercise resistance unit includes a lever arm assembly attached to a motor, and a patient attachment cuff is slidingly mounted to the lever arm assembly. A potentiometer is used to determine the length of the patient's limb, and a potentiometer/optical encoder assembly is used to determine the angular position of the lever arm assembly as the limb is exercised. A strain gauge assembly is used to determine the torque applied to the lever arm assembly. The limb length, position and torque values are converted into digital form and supplied to a computer. The computer accepts selected velocity and maximum torque value from the operator and uses these values to control the velocity of and torque applied to the lever arm assembly. More specifically, the computer predicts a subsequent lever arm angular position based on the set velocity.

Abstract: Muscle exercise and diagnostic apparatus with an output shaft, a servo motor coupled in driving relation to the output shaft, and a support mechanism for mounting the output shaft and the servo motor in a selectable stationary position. A plurality of work simulation tools and coupling arrangements are provided, including coupling arrangements on the output shaft and each of the tools for removably coupling one of the tools to the output shaft. A composite output shaft with a larger diameter, high torque section and a smaller diameter, low torque section, each with its own separate torque measuring strain gauge arrangement is provided. A shaft position sensor senses the angular position of the output shaft and produces an output shaft position signal. A servo control circuit responds to a preselected command signal measuring device for measuring a preselected servo control signal parameter associated with the servo motor and shaft and operatively related to the command signal.

Abstract: Method and apparatus for volume measurement and body composition estimation provides an accurate, non-invasive estimation of the body volume and body composition of an object or body such as a human being. The present invention provides a first chamber with a door or closable means of entry through which an object or a subject may enter, along with a second chamber and means to cyclically perturb the volumes of the two chambers in a precisely complementary fashion. The present invention also measures the pressure in each of the chambers, controls in real time the volume perturbation and analyzes the pressure records so as to yield volume and body composition estimations.

Abstract: A method for diagnosis and/or training of proprioceptor feedback capabilities of a muscle and joint system of a human patient using an exercise system having a patient attachment device and an arrangement for controlling parameters of an exercise movement in response to a control signal derived from one or more measured exercise parameters. A patient performance goal is defined as a real time function of preselected exercise parameters. A perturbation signal function is defined for the control signal; and the control signal is modified by the perturbation function value during a patient exercise motion. The defined performance goal is displayed during the patient exercise motion and the actual patient performance relative to the performance goal is also tracked and displayed. An error value is measured as the difference between actual patient performance and the patient performance goal.

Abstract: A muscle exercise and diagnostic system which includes a lever arm, a mounting arrangement for mounting the lever arm for rotation about a fixed axis, and a connecting arrangement for connecting a selected portion of the human body to the lever arm for rotation with the lever arm about a selected anatomical axis of rotation. The connecting arrangement establishes a fixed tangential mounting relation and a sliding radial mounting relation between the lever arm and the body portion. This permits free radial movement of the connecting arrangement relative to the fixed axis during an exercise motion. A velocity control arrangement is coupled to the lever arm for limiting the maximum permitted rotational velocity to a value predetermined in accordance with a preselected velocity control function which includes measured values of the distances from the point of attachment to the anatomical axis and to the fixed axis. An arrangement is provided for inputting these measured values to a velocity control arrangement.

Abstract: A muscle exercise and diagnostic system which includes a lever arm, a mounting arrangement for mounting the lever arm for rotation about a fixed axis, and a connecting arrangement for connecting a selected portion of the human body to the lever arm for rotation with the lever arm about a selected anatomical axis of rotation. The connecting arrangement establishes a fixed tangential mounting relation and a sliding radial mounting relation between the lever arm and the body portion. This permits free radial movement of the connecting arrangement relative to the fixed axis during an exercise motion. A velocity control arrangement is coupled to the lever arm for limiting the maximum permitted rotational velocity to a value predetermined in accordance with a preselected velocity control function which includes measured values of the distances from the point of attachment to the anatomical axis and to the fixed axis. An arrangement is provided for inputting these measured values to the velocity control arrangement.

Abstract: An oxygen detection system including two equal and symmetrically constructed major DC magnetic circuits each having an air gap which is alternatively filled with a sample and a reference gas. A magnetic bridge arm connects the major magnetic circuits in series opposition to derive a null response when the flux carried in the magnetic circuits is equal and a component of varying flux when the sample and reference gases are interchanged to cause an unequal flux to be developed in the circuits caused by a change in the reluctance across the gaps. An encircling inductance coil senses the flux in the null bridge arm which is electronically sampled in sychronism with the sample and reference gas interchange to develop a difference signal directly derived and proportional to the difference in magnetic susceptibility of the sample and reference gases. An active magnetic shield cancels stray fields from affecting the sensor.

Abstract: The pressure difference across a pneumotach restriction is sampled with a gas chopper connected across a pressure difference detecting transducer. The gas chopper alternates the pressures backward and forward in application to the transducer so that the latter develops an AC sampling signal, the strength of which is related to flow. This AC signal is sampled in synchronism over intervals having a duration related to the power line frequency to develop an integrated value of the pressure difference free of drift caused by power line interference. The resultant signal is smoothed and summed in alternating response at double the gas chopper sampling rate to give a smooth output which is then multiplied by a linearizing circuit to obtain a flow signal which is proportional to the pressure difference. Specific gas flow structures and electronic sampling circuitry are disclosed.

Abstract: Gas analyzing system using sonic wave shift over tubular gas column. Reference gas passed through column calibrates system to zero reference level. Sample gas having unknown amount of known gas component causes shift of wavelength distance in column. Phase comparator looks at shifted signal over .+-.90.degree. of phase shift. Integrator responds to comparator output to give dc output signal proportional to phase shift. Compensating circuits in final amplifier estimate probable final value based on rate of change of initial comparator output and use same to drive output meter.