Abstract: A robot is placed on a first surface of a panel. The robot includes a body and first and second feet connected to the body via joints. A flux conducting device is positioned on an opposing second surface of the panel, opposite the robot, so that each foot of the robot is magnetically coupled to the flux conducting device. The flux conducting device is moved along the exterior surface to pull the robot along the interior surface until an obstacle on the first surface is encountered. The robot decouples one of the feet from the flux conducting device, lifts the decoupled foot above the obstacle, and moves the decoupled foot past the obstacle.

Abstract: An apparatus and methods for adaptive and autonomous calibration of pulse transit time measurements to obtain arterial blood pressure using arterial pressure variation. The apparatus and methods give pulse transit time (PTT) devices an ability to self-calibrate. The methods apply a distributed model with lumped parameters, and may be implemented, for example, using pulse transit time measurements derived from a wearable photoplethysmograph (PPG) sensor architecture with an intervening pressurizing mechanism.

Abstract: A robot is placed on a first surface of a panel. The robot includes a body and first and second feet connected to the body via joints. A flux conducting device is positioned on an opposing second surface of the panel, opposite the robot, so that each foot of the robot is magnetically coupled to the flux conducting device. The flux conducting device is moved along the exterior surface to pull the robot along the interior surface until an obstacle on the first surface is encountered. The robot decouples one of the feet from the flux conducting device, lifts the decoupled foot above the obstacle, and moves the decoupled foot past the obstacle.

Abstract: An apparatus and methods for adaptive and autonomous calibration of pulse transit time measurements to obtain arterial blood pressure using arterial pressure variation. The apparatus and methods give pulse transit time (PTT) devices an ability to self-calibrate. The methods apply a distributed model with lumped parameters, and may be implemented, for example, using pulse transit time measurements derived from a wearable photoplethysmograph (PPG) sensor architecture with an intervening pressurizing mechanism.

Abstract: An apparatus and methods for performing a circulatory measurement on an extremity, such as a hand, of a subject. The circulatory measurement results in the derivation of an output circulatory metric that may encompass blood pressure or various other circulatory metrics. An indicator of an input circulatory metric at a locus on the extremity is measured, such as a pulse transit time, and calibrated to account for the hydrostatic component of blood pressure arising due to vertical displacement of the extremity with respect to the heart.

Abstract: Methods and a computer program product for using a circulatory measurement on an extremity of a particular subject to derive an aortic blood pressure for that subject. A model is constructed that maps a peripheral cardiovascular waveform to a central cardiovascular waveform on the basis of a plurality of model parameters. A time record is obtained using a non-invasive blood pressure sensor disposed at a solitary position periphery of the cardiovascular system of a subject. The time record is then transformed to obtain a plurality of test central blood pressure waves, with a single test central blood pressure wave is based on each of a plurality of sets of values of the model parameters. An optimum set of values of the model parameters is then selected, based on a specified criterion applied to the plurality of test central blood pressure waves, so that the aortic circulatory waveform of the subject can be obtained.

Abstract: Methods and apparatus for measuring arterial blood pressure at an extremity of a subject. Arterial blood pressure is derived from a circulatory measurement performed on an extremity of a subject and the circulatory measurement is normalized to account for the instantaneous vertical displacement of the extremity. The vertical displacement of the extremity relative to the heart of the subject is obtained using the angular orientation of the subject's extremity. An improved photoplethysmograph can discriminate light traversing the extremity from ambient light on the basis of differential response. The apparatus may have a conducting polymer actuator for applying pressure to the extremity of the subject. A pulsatile waveform from the photoplethysmographic signal may be obtained at a plurality of externally applied pressures to calibrate the photoplethysmograph.

Abstract: A method of encoding a transmission signal to reduce multiple access interference at a receiver. A data source signal including a plurality of source symbols is received into a transmitter. The source symbols are encoded using low energy encoding forming encoded codewords. An identifying pattern is applied to the encoded codewords forming a transmission signal. In one embodiment, the identifying pattern is a unique pseudo-random pattern identifying the data source. Once the pattern has been added, multiple transmission signals can be summed together and then modulated onto a carrier wave. The transmission signals are then transmitted on the carrier wave which is at a pre-selected frequency. The low energy encoding format is such that a sequence of signals forming codewords is created. Each sequence of signals is characterized by an energy and normally a high bit consumes energy whereas a low bit requires substantially less energy.

Abstract: Multi-channel blind system identification is utilized to identify a patient's cardiac functions without catheterization. The approach is adaptive to each patient's cardiovascular system variations. The cardiac functions can be determined by formulating an auto-regression moving average model utilizing either finite impulse response systems or a group of infinite impulse response systems. Both of these models identify the system functions by solving a set of linear equations using the least-squares method. The system input is then identified by deconvolving the system output and the estimated impulse response of each channel. These models can be augmented to obtain an estimate of the maximum order of the cardiac functions when they are unknown a priori. The approach can also be modified to obtain the cardiac functions by first resolving the distinct dynamics associated with each channel, then determining the common dynamics and ultimately determining the system input.

Abstract: A method and an apparatus for distinguishing concentrations of blood constituents among distinct vascular components in situ. The method has steps of inducing periodic vibration, characterized by a frequency, in a limb of a person in such as manner as to selectively excite a resonant response in a specified blood vessel of the person, an artery or a vein, illuminating the limb of the person with a light source, and synchronously detecting a plethysmographic signal for discriminating response attributable to the specified blood vessel.

Abstract: A method and an apparatus for distinguishing concentrations of blood constituents among distinct vascular components in situ. The method has steps of inducing periodic vibration, characterized by a frequency, in a limb of a person in such as manner as to selectively excite a resonant response in a specified blood vessel of the person, an artery or a vein, illuminating the limb of the person with a light source, and synchronously detecting a plethysmographic signal for discriminating response attributable to the specified blood vessel.

Abstract: A ring plethysmograph having a pressure adjustment for locally pressurizing one side of a finger thereby biasing the pressure on an artery wall so that the plethysmograph is optimally sensitive without interfering with blood flow. An auxiliary photodetector, possibly with a second light source, is disposed on the low-pressure side of the finger for two purposes: providing a noise reference for canceling noise on the plethysmograph signal, and also for providing a separate motion signal for monitoring the activity level of a patient.

Abstract: Multi-channel blind system identification is utilized to identify a patient's cardiac functions without catheterization. The approach is adaptive to each patient's cardiovascular system variations. The cardiac functions can be determined by formulating an auto-regression moving average model utilizing either finite impulse response systems or a group of infinite impulse response systems. Both of these models identify the system functions by solving a set of linear equations using the least-squares method. The system input is then identified by deconvolving the system output and the estimated impulse response of each channel. These models can be augmented to obtain an estimate of the maximum order of the cardiac functions when they are unknown a priori. The approach can also be modified to obtain the cardiac functions by first resolving the distinct dynamics associated with each channel, then determining the common dynamics and ultimately determining the system input.

Abstract: A method of encoding a transmission signal to reduce multiple access interference at a receiver. A data source signal including a plurality of source symbols is received into a transmitter. The source symbols are encoded using low energy encoding forming encoded codewords. An identifying pattern is applied to the encoded codewords forming a transmission signal. In one embodiment, the identifying pattern is a unique pseudo-random pattern identifying the data source. Once the pattern has been added, multiple transmission signals can be summed together and then modulated onto a carrier wave. The transmission signals are then transmitted on the carrier wave which is at a pre-selected frequency. The low energy encoding format is such that a sequence of signals forming codewords is created. Each sequence of signals is characterized by an energy and normally a high bit consumes energy whereas a low bit requires substantially less energy.

Abstract: A method and apparatus for telemetering data on a channel having a maximum data rate by utilizing a power efficient communication protocol is provided. The data to be telemetered comprises a number of source symbols where each source symbol is characterized by a probability of occurrence. A sequence of signals forming codewords having an energy and a length is produced. The length for the codewords is based at least on the number of symbols to be coded. Each codeword signifies a specified source symbol on the basis of a mapping between source symbols and codewords. The mapping is such that each source symbol of lower probability of occurrence is associated with a codeword of at least equal energy.

Abstract: A ring plethysmograph having a pressure adjustment for locally pressurizing one side of a finger thereby biasing the pressure on an artery wall so that the plethysmograph is optimally sensitive without interfering with blood flow. An auxiliary photodetector, possibly with a second light source, is disposed on the low-pressure side of the finger for two purposes: providing a noise reference for canceling noise on the plethysmograph signal, and also for providing a separate motion signal for monitoring the activity level of a patient.

Abstract: A device for noninvasive, continuous monitoring of arterial blood pressure for advanced cardiovascular diagnoses. Most of the current noninvasive, continuous blood pressure measurement devices are mechanically intrusive and, therefore, cannot be used for long-term ambulatory monitoring. This new approach requires only simple, noninvasive monitoring devices such as finger photoplethysmographs and an electrical impedance photoplethysmograph (EIP) to monitor the dynamic behavior of the arterial blood flow. In this approach, measured signals from these noninvasive sensors on an arterial segment are integrated to estimate the blood pressure in the segment based on a hemodynamic model. A mathematical model of the arterial blood flow is derived and transformed into a state-space representation.

Abstract: A monitoring system for monitoring the health status of a patient by performing measurements such as skin temperature, blood flow, blood constituent concentration, and pulse rate at the finger of the patient. The monitoring system has an inner ring proximate to the finger as well as an outer ring, mechanically decoupled from the inner ring, that shields the inner ring from external loads. Measurements are performed in accordance with a protocol that may be preprogrammed, or may be modified on the basis of real-time data or by command from a remotely located medical professional.

Abstract: A device for detecting the posture a finger or forces applied to a finger, the finger having a fingernail illuminated by light, comprises at least one photodetector for measuring a change in light reflected by an area of the finger beneath the fingernail in response to the posture of the finger or forces applied to the finger. The photodetector provides a signal corresponding to the change in light reflected. The device also includes a processor for receiving the signal and determining whether the change corresponds to a specified condition. The photodetector may be enclosed in a housing and coupled to the fingernail.

Abstract: A device for detecting the posture a finger or forces applied to a finger, the finger having a fingernail illuminated by light, comprises at least one photodetector for measuring a change in light reflected by an area of the finger beneath the fingernail in response to the posture of the finger or forces applied to the finger. The photodetector provides a signal corresponding to the change in light reflected. The device also includes a processor for receiving the signal and determining whether the change corresponds to a specified condition. The photodetector may be enclosed in a housing and coupled to the fingernail.