Abstract: A method for retrieving a mobile platform from inside a tank having an energetic substance includes configuring a retrieval carrier to have an intermediate span for which a majority of a cross-sectional area includes a braided synthetic fiber rope having a porosity of at least ten percent and an elastic compressibility sufficient to reduce the porosity of the braided synthetic fiber rope by at least fifty percent. The intermediate span does not have a fluid tight passage enabling fluid communication between a location outside of the tank and the mobile platform. The method further includes configuring a retrieval assembly to have an energetic substance extractor that has opposing surfaces defining a passage, passing the intermediate span through the passage, and compressing the intermediate span between the opposing surfaces to extract a majority of the residue of the liquid energetic substance retained by the intermediate span upon entering the passage.

Abstract: A method of performing a selected task in a tank at least partially filled with an energetic substance includes, in part, configuring a mobile platform to be inherently safe by positioning spark-generating components in either or both of: (i) an inherently safe enclosure that prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure, and (ii) a spark-neutralizing body formed of at least one non-flammable substance and positioned inside an enclosure, the spark-neutralizing body blocking direct contact between a spark from the enclosed spark-generating component and an energetic substance from occurring inside the at least one enclosure. The method also includes positioning at least one spark-generating component not inside any inherently safe enclosure that prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure. The sparks are capable of igniting the energetic substances.

Abstract: A method of retrieving a mobile platform from a tank at least partially filled with a non-conductive, energetic substance includes configuring the mobile platform to include at least a retrieval system including a buoyant body, an electrically conductive member, and a tether. The tether electrically isolates the buoyant body from the enclosure.

Abstract: A method for controlling charge accumulation on a mobile platform in a tank containing a non-conductive, energetic substance includes configuring the mobile platform to include at least an electrical power supply and a charge accumulation control system. The power supplied from the electrical power supply to one or more electrical power consumers associated with the mobile platform adds an electrical charge to the mobile platform. The charge accumulation control system controls an accumulation of the electrical charge on the mobile platform by one of: (i) reducing the supplied power and preventing an increase in the supplied power later while the mobile platform is inside the tank, and (ii) disengaging the electrical power consumer(s) from the supplied power and preventing a reengagement of the supplied power with the electrical power consumer(s) later while the mobile platform is inside the tank.

Abstract: A method for retrieving a mobile platform from inside a tank having an energetic substance includes configuring a retrieval carrier to have an intermediate span for which a majority of a cross-sectional area includes a braided synthetic fiber rope having a porosity of at least ten percent and an elastic compressibility sufficient to reduce the porosity of the braided synthetic fiber rope by at least fifty percent. The intermediate span does not have a fluid tight passage enabling fluid communication between a location outside of the tank and the mobile platform. The method further includes configuring a retrieval assembly to have an energetic substance extractor that has opposing surfaces defining a passage, passing the intermediate span through the passage, and compressing the intermediate span between the opposing surfaces to extract a majority of the residue of the liquid energetic substance retained by the intermediate span upon entering the passage.

Abstract: A method of retrieving a mobile platform from a tank having a hatch and at least partially filled with a non-conductive, energetic substance includes configuring the mobile platform to include at least a retrieval system disposed at least partially on an enclosure. The retrieval system includes at least: a primary tether connected to a buoyant body and to the enclosure, and a secondary tether connected to the buoyant body and to the enclosure. The method further includes: predetermining a buoyant body retrieval zone within the tank, and positioning a released buoyant body within the buoyant body retrieval zone by using the primary tether. The method also includes retrieving the primary tether by using the buoyant body; using the primary tether to release the secondary tether; and inserting a retrieval member through the hatch to retrieve the buoyant body, the primary tether, and/or the secondary tether.

Abstract: A method of performing a selected task in a tank at least partially filled with an energetic substance includes, in part, configuring a mobile platform to be inherently safe by positioning spark-generating components in either or both of: (i) an inherently safe enclosure that prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure, and (ii) a spark-neutralizing body formed of at least one non-flammable substance and positioned inside an enclosure, the spark-neutralizing body blocking direct contact between a spark from the enclosed spark-generating component and an energetic substance from occurring inside the at least one enclosure. The method also includes positioning at least one spark-generating component not inside any inherently safe enclosure that prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure. The sparks are capable of igniting the energetic substances.

Abstract: A method of performing a selected task in a tank containing an energetic substance uses an inherently safe mobile platform that includes a marker detector, a control unit, a power supply, a propulsion system, and an inherently safe enclosure. The inherently safe enclosure prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure. All spark-generating components of the mobile platform are positioned inside the inherently safe enclosure. The method includes lowering the mobile platform into the tank, at least partially submerging the mobile platform in the energetic substance, and detecting a marker using the marker detector. No active physical carrier connects the mobile platform to an object exterior of the tank while the mobile platform is in the tank.

Abstract: A mobile platform uses a charge accumulation control system to control a charge accumulation while the mobile platform is in the tank. Alternatively or additionally, the mobile platform includes a retrieval system having a buoyant body, a primary tether, and a secondary tether. Alternatively or additionally, an electrical cable is used to reduce a voltage difference between the mobile platform and the tank or other structure by electrically connecting to an electrically conductive member on the mobile platform.

Abstract: A mobile platform uses a charge accumulation control system to control a charge accumulation while the mobile platform is in the tank. Alternatively or additionally, the mobile platform includes a retrieval system having a buoyant body, a primary tether, and a secondary tether. Alternatively or additionally, an electrical cable is used to reduce a voltage difference between the mobile platform and the tank or other structure by electrically connecting to an electrically conductive member on the mobile platform.

Abstract: A method of performing a selected task in a tank containing an energetic substance uses an inherently safe mobile platform that includes a marker detector, a control unit, a power supply, a propulsion system, and an inherently safe enclosure. The inherently safe enclosure prevents a spark occurring inside the inherently safe enclosure from passing to an exterior of the inherently safe enclosure. All spark-generating components of the mobile platform are positioned inside the inherently safe enclosure. The method includes lowering the mobile platform into the tank, at least partially submerging the mobile platform in the energetic substance, and detecting a marker using the marker detector. No active physical carrier connects the mobile platform to an object exterior of the tank while the mobile platform is in the tank.

Abstract: A mobile platform uses a charge accumulation control system to control a charge accumulation while the mobile platform is in the tank. Alternatively or additionally, the mobile platform includes a retrieval system having a buoyant body, a primary tether, and a secondary tether. Alternatively or additionally, an electrical cable is used to reduce a voltage difference between the mobile platform and the tank or other structure by electrically connecting to an electrically conductive member on the mobile platform.