A range-finding and/or object-positioning system comprises one or more target devices; one or more reference devices communicating with said one or more target devices via one or more wireless signal sets, each wireless signal set comprising at least a first-speed signal having a first transmission speed and a second-speed signal having a second transmission speed, and the first transmission speed being higher than the second transmission speed; and at least one processing unit performing actions for determining at least one distance between one target device and one reference device based on the time difference between the receiving time of the first-speed signal and the receiving time of the second-speed signal of the wireless signal set communicated between said reference and target devices.

The present technology may be directed a system for determining an angle and distance between a positioning node and secondary device using a plurality of acoustic transmitters to transmit acoustic ranging signals that are modulated using ranging sequences, respectively. The system includes an acoustic receiver to detect the acoustic ranging signals, and a signal processor to calculate times of arrival and a plurality of aliased angles of arrival of the acoustic ranging signals. An anti-aliasing module may select an angle of arrival from the calculated plurality of aliased angles using the times of arrival of the acoustic ranging signals. A time of flight may be calculated from a comparison of times of arrival for radio signals and the acoustic signals. The time of flight may be used to calculate the distance between the positioning node and secondary device.

An apparatus for collision avoidance by surface proximity detection includes a plurality of piezoelectric elements disposed adjacent to a surface of an object, a memory storing instructions, and at least one processor configured to execute the instructions to control a first one among the piezoelectric elements to generate an acoustic wave along the surface of the object, and receive, via a second one among the piezoelectric elements, an acoustic wave signal corresponding to the generated acoustic wave. The at least one processor is further configured to execute the instructions to filter the received acoustic wave signal, using a band-pass filter for reducing noise of the received acoustic wave signal, obtain a proximity signal for proximity detection, from the filtered acoustic wave signal, using a linear time-invariant filter, and detect whether an obstacle is proximate to the surface of the object by inputting the obtained proximity signal into a neural network.

An apparatus for collision avoidance by surface proximity detection includes a plurality of piezoelectric elements disposed adjacent to a surface of an object, a memory storing instructions, and at least one processor configured to execute the instructions to control a first one among the piezoelectric elements to generate an acoustic wave along the surface of the object, and receive, via a second one among the piezoelectric elements, an acoustic wave signal corresponding to the generated acoustic wave. The at least one processor is further configured to execute the instructions to filter the received acoustic wave signal, using a band-pass filter for reducing noise of the received acoustic wave signal, obtain a proximity signal for proximity detection, from the filtered acoustic wave signal, using a linear time-invariant filter, and detect whether an obstacle is proximate to the surface of the object by inputting the obtained proximity signal into a neural network.