An underwater active sonar system and method for measuring instrument velocity with respect to a boundary surface is disclosed. The system includes an acoustic transducer configured to transmit and receive a plurality of acoustic beams in different directions. The system also includes a processor configured to detect a boundary surface within each beam; iteratively filter received acoustic signals backscattered from the transmitted beams with an adaptive filter and associated bandwidth that is successively decreased for each iteration; and measure instrument velocity with respect to the boundary surface.

A method for measuring, using a radar or sonar, the velocity with respect to the ground of a carrier moving parallel to the ground, includes the following steps: a) orienting the line of sight of the radar or sonar toward the ground; b) emitting a plurality of radar or sonar signals (P.sub.1-P.sub.N) that are directed toward the ground, and acquiring respective echo signals (E.sub.1-E.sub.N); c) processing the acquired echo signals so as to obtain, for one or more echo delay values, a corresponding Doppler spectrum; d) for the or at least one the echo delay value, determining a high cut-off frequency of the corresponding Doppler spectrum; and e) computing the velocity of the carrier with respect to the ground on the basis of the one or more high cut-off frequencies. A system allowing such a method to be implemented.

A method for measuring, using a radar or sonar, the velocity with respect to the ground of a carrier moving parallel to the ground, includes the following steps: a) orienting the line of sight of the radar or sonar toward the ground; b) emitting a plurality of radar or sonar signals (P.sub.1-P.sub.N) that are directed toward the ground, and acquiring respective echo signals (E.sub.1-E.sub.N); c) processing the acquired echo signals so as to obtain, for one or more echo delay values, a corresponding Doppler spectrum; d) for the or at least one the echo delay value, determining a high cut-off frequency of the corresponding Doppler spectrum; and e) computing the velocity of the carrier with respect to the ground on the basis of the one or more high cut-off frequencies. A system allowing such a method to be implemented.

A vehicle includes a propulsion unit configured to move the vehicle and to change a characteristic of the environment of the vehicle. The vehicle also includes a proximity sensor configured to detect the characteristic of the environment of the vehicle. The characteristic of the environment is changed by operation of the propulsion unit. The vehicle further includes obstacle detection circuitry configured to determine a presence of an obstacle in the vicinity of the vehicle based on a comparison between the detected characteristic of the environment and a reference value.

A method for detecting a ground echo signal of an ultrasonic sensor of a vehicle. The ultrasonic sensor emits a signal at a first frequency or having a first frequency profile, the signal is reflected by a roadway surface and the reflected signal is received by the ultrasonic sensor and/or by an additional ultrasonic sensor. The received echo signal is filtered with the aid of a matched filter, the matched filter being adapted to the emitted signal and having a characterizing frequency. In this way a ground echo signal is determined from the filtered signal. The instantaneous vehicle speed is determined and an expected Doppler shift of the reflected signal is determined as a function of the instantaneous vehicle speed. The first frequency or the first frequency profile and/or the characterizing frequency of the matched filter is/are adapted as a function of the Doppler shift to be expected.

A method for detecting a ground echo signal of an ultrasonic sensor of a vehicle. The ultrasonic sensor emits a signal at a first frequency or having a first frequency profile, the signal is reflected by a roadway surface and the reflected signal is received by the ultrasonic sensor and/or by an additional ultrasonic sensor. The received echo signal is filtered with the aid of a matched filter, the matched filter being adapted to the emitted signal and having a characterizing frequency. In this way a ground echo signal is determined from the filtered signal. The instantaneous vehicle speed is determined and an expected Doppler shift of the reflected signal is determined as a function of the instantaneous vehicle speed. The first frequency or the first frequency profile and/or the characterizing frequency of the matched filter is/are adapted as a function of the Doppler shift to be expected.

A practically implementable robust direction-of-arrival (DoA) estimation approach that is resistant to localization errors due to mobility, multipath reflections, impulsive noise, and multiple-access interference. As part of the disclosed invention the inventors consider infrastructure-less 3D localization of autonomous underwater vehicles (AUVs) with no GPS assistance and no availability of global clock synchronization. The proposed method can be extended to challenging communication environments and applied for the localization of assets/objects in space, underground, intrabody, underwater and other complex, challenging, congested and sometimes contested environments. Each AUV leverages known-location beacon signals to self-localize and can simultaneously report its sensor data and measurement location. The approach uses two known location beacon nodes, where the beacons are single-hydrophone acoustic nodes that are deployed at known locations and transmit time-domain coded signals in a spread-spectrum fashion.

A practically implementable robust direction-of-arrival (DoA) estimation approach that is resistant to localization errors due to mobility, multipath reflections, impulsive noise, and multiple-access interference. As part of the disclosed invention the inventors consider infrastructure-less 3D localization of autonomous underwater vehicles (AUVs) with no GPS assistance and no availability of global clock synchronization. The proposed method can be extended to challenging communication environments and applied for the localization of assets/objects in space, underground, intrabody, underwater and other complex, challenging, congested and sometimes contested environments. Each AUV leverages known-location beacon signals to self-localize and can simultaneously report its sensor data and measurement location. The approach uses two known location beacon nodes, where the beacons are single-hydrophone acoustic nodes that are deployed at known locations and transmit time-domain coded signals in a spread-spectrum fashion.

A motion state estimation method and apparatus relate to the fields of wireless communication and autonomous driving/intelligent driving. The method includes a step of obtaining a plurality of pieces of measurement data using a first sensor, where each of the plurality of pieces of measurement data includes at least velocity measurement information. The method further includes obtaining a motion state of the first sensor based on measurement data in the plurality of pieces of measurement data that corresponds to a target reference object, where the motion state includes at least a velocity vector of the first sensor. In the present disclosure, a more accurate motion state of the first sensor can be obtained, and a vehicle's autonomous driving capability or advanced driver assistant system (ADAS) capability is further improved.

A survey system including a multibeam echo sounder having a projector array and a hydrophone array in a Mills Cross arrangement uses a multi-component message to ensonify one or more fans to estimate a Doppler velocity.