Indoor positioning and navigation systems and methods

A method for inspecting or maintaining a storage tank, comprising:

• positioning a vehicle at a first location inside the storage tank by a propulsion unit of the vehicle, the vehicle comprising at least one acoustic receiver (RX), at least one acoustic transmitter (TX), at least one inertial measurement unit (IMU);
• emitting, by the at least one TX of the vehicle, a first acoustic signal toward an acoustic hydrophone attached to the storage tank in a first location;
• determining a distance from the at least one TX of the vehicle to the acoustic hydrophone attached to the storage tank;
• emitting, by the at least one TX of the vehicle, a second acoustic signal toward a bright acoustic reflector attached to the storage tank in a second location;
• receiving, by the at least one RX of the vehicle, a second reflected acoustic signal from the bright acoustic reflector;
• determining a first azimuth angle of the vehicle with respect to a longitudinal axis of the vehicle and a first distance from the bright acoustic reflector;
• moving the vehicle in a direction of an azimuth direction to a second location of the vehicle inside the storage tank;
• and
• determining a second azimuth angle of the vehicle at the second location with respect to a second distance from the acoustic hydrophone and a second distance from the bright acoustic reflector.

A method for inspecting or maintaining a storage tank, comprising:

• traversing a vehicle inside the storage tank;
• determining properties of a storage tank by at least one sensor of the vehicle;
• navigating the vehicle by a navigation system comprising:
• an acoustic transmitter (TX) carried by the vehicle, an inertial measurement unit (IMU) sensor configured to at least partially determine a location of the vehicle with respect to the storage tank, and a propulsion unit configured to move the vehicle within the storage tank;
• and
• sending acoustic signal by the TX carried by the vehicle to an acoustic receiver (RX) fixed with respect to the storage tank, wherein the vehicle moves inside the storage tank in concentric arcs with respect to the RX fixed with respect to the storage tank, wherein the RX is a center point of the concentric arcs.

A system for inspecting or maintaining a storage tank, comprising:

• a vehicle comprising:
• a propulsion unit configured to move the vehicle within the storage tank;
• at least one sensor for determining properties of the storage tank;
• at least one inertial measurement unit (IMU) sensor configured to at least partially determine a location of the vehicle with respect to the storage tank;
• at least one acoustic transmitter (TX) carried by the vehicle;
• and
• at least acoustic receiver (RX) carried by the vehicle;
• an acoustic hydrophone attached to the storage tank in a first location;
• and
• a bright acoustic reflector attached to the storage tank in a second location, wherein the system comprises a non-transitory computer-readable medium having computer-executable instructions stored thereon that, in response to execution by one or more processors of a computing device, cause the computing device to perform actions comprising:
• positioning the vehicle at a first location inside the storage tank by the propulsion unit of the vehicle, the vehicle comprising at least one inertial measurement unit (IMU);
• emitting by the at least one TX of the vehicle, a first acoustic signal toward an acoustic hydrophone attached to the storage tank in a first location;
• determining a distance from the at least one TX of the vehicle to the acoustic hydrophone attached to the storage tank;
• emitting, by the at least one TX of the vehicle, a second acoustic signal toward a bright acoustic reflector attached to the storage tank in a second location;
• receiving, by the at least one RX of the vehicle, a second reflected acoustic signal from the bright acoustic reflector;
• determining a first azimuth angle of the vehicle with respect to a longitudinal axis of the vehicle and a first distance from the bright acoustic reflector;
• moving the vehicle in a direction of an azimuth direction to a second location of the vehicle inside the storage tank;
• and
• determining a second azimuth angle of the vehicle at the second location with respect to a second distance from the acoustic hydrophone and a second distance from the bright acoustic reflector.