BACKGROUND

Technical Field

The present disclosure relates to identifying objects using radio-frequency identification (RFID) tags, and more specifically, to identifying an object singulated by a robotic manipulator from a plurality of RFID-tagged objects.

Description of the Related Art

Automated robotics, conveyors, and other motive devices are used in many industrial or logistic applications to sort, relocate, convey, or otherwise manipulate objects in order to achieve a desired goal. Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. RFID tags typically contain at least three parts: an integrated circuit that stores and processes information and that modulates and demodulates radio-frequency (RF) signals; a means of collecting DC power from the incident reader signal; and an antenna for receiving and transmitting the signal.

The tags contain electronically stored information. Passive tags collect energy from a nearby RFID reader's interrogating radio waves. Active tags have a local power source (such as a battery) and may function farther from the RFID reader. Unlike a barcode, the tags don't need to be within the line of sight of the reader, so it may be embedded in the tracked object.

Existing technologies for identifying or singulating an RFID tag among multiple tags typically require that all of the tags be simultaneously read, or alternatively, a single tag be separated from the remaining tags by a threshold distance so that the remaining tags are not activated. When multiple RFID tags are located within a vicinity of each other, a read volume generated by an interrogating reader may be larger in size than the dimensions of a single tag, thereby causing multiple tags to be read and/or activated. This can result in read collisions and/or interference, reducing the accuracy or reliability for identifying or singulating an object attached to a particular RFID tag.

BRIEF SUMMARY

In some embodiments, a method for singulating an RFID-tagged object among multiple RFID-tagged objects includes causing a robotic manipulator to grasp one or more RFID-tagged objects from a plurality of RFID-tagged objects within an operating environment and causing the robotic manipulator to move the grasped object(s) in accordance with a target path. The method also includes obtaining signal strength data of signals emitted from RFID tags associated with the plurality of objects for a period of time during which the robotic manipulator is moving the grasped object(s), analyzing the signal strength data using one or more rules for singulating an RFID tag among multiple RFID tags, and identifying an RFID tag associated with the grasped object(s) based, at least in part, on the analysis of the signal strength data. In some embodiments, each object of the plurality of objects is associated with a distinct RFID tag.

In some embodiments, the method further includes selecting a motion profile from a plurality of motion profiles to determine the target path. In some embodiments, each motion profile indicates (a) a path to move an object and (b) one or more rules for singulating an RFID tag associated with the object among multiple RFID tags. In some embodiments, the one or more rules include at least one of a threshold, difference, ratio, or pattern of signal strength of signals emitted from an RFID tag.

In some embodiments, the target path indicates at least one of rotary, oscillating, linear, or reciprocating motion. In some embodiments, the target path indicates at least one of acceleration, velocity, or speed of movement. In some embodiments, the target path indicates at least one of a starting or ending location.

In some embodiments, a system includes one or more processors and memory storing contents. The contents, when executed by the one or more processors, cause the system to cause a target object of a plurality of objects to move, in accordance with a target path, relative to remaining objects of the plurality of objects, wherein each object of the plurality of objects is associated with a transponder, obtain signal strength information of signals emitted from the transponders for a period of time during which the target object is moved in accordance with at least a part of the target path, and identify the transponder associated with the target object based, at least in part, on analyzing the signal strength information in accordance with one or more criteria predetermined for the target path.

In some embodiments, the contents further cause the system to select the target path based on at least one of a quantity, locations, or sizes of the plurality of objects. In some embodiments, the one or more criteria includes at least one of descriptive statistics, time series analysis, or an artificial neural network. In some embodiments, the contents further cause the system to generate or change at least a part of the target path in response to a portion of the signal strength information obtained. In some embodiments, the transponders include RFID tags. In some embodiments, the system obtains the signal strength information via one or more RFID readers.

In some embodiments, one or more non-transitory computer-readable media store contents that, when executed by one or more processors, cause the one or more processors to perform actions. The actions include causing a target object of a plurality of objects to move, in accordance with a target path, relative to remaining objects of the plurality of objects, wherein each object of the plurality of objects is associated with a transponder. The actions also include obtaining signal strength information of signals emitted from the transponders for a period of time during which the target object is moved in accordance with at least a part of the target path, and identifying the transponder associated with the target object based, at least in part, on analyzing the signal strength information in accordance with one or more criteria predetermined for the target path. In some embodiments, causing the target object to move includes controlling a robotic manipulator to grasp the target object. In some embodiments, the actions further include controlling one or more antennas to emit interrogation signals during the period of time, wherein the transponders emit signals in response to the interrogation signals. In some embodiments, the actions further include selecting the target path from a plurality of predetermined paths for moving an object.

In some embodiments, the target object is a first object, the target path is a first path, and the actions further include causing a second object of the plurality of objects to move in accordance with a second path. In some embodiments, the actions further include identifying the transponder associated with the second object based, at least in part, on the moving of the second object in accordance with the second path.

