Patent Description:
Cargo handling systems for aircraft typically include various tracks and rollers disposed on a cargo deck that spans the length of a cargo compartment. Cargo may be loaded from an entrance of the aircraft and transported by the cargo system to forward or aft locations, depending upon the configuration of the aircraft. Cargo handling systems, such as, for example, those used on aircraft for transport of heavy containerized cargo or pallets, also referred to herein as unit load devices (ULDs), typically include roller trays containing transport rollers that support and transport the containerized cargo or pallets. Motor driven rollers are typically employed in these systems. In certain aircraft, a plurality of motor driven power drive units (PDUs) is used to propel the containers or pallets within the cargo compartment. This configuration facilitates transportation of the containers or pallets within the cargo compartment by one or more operators or agent-based systems controlling operation of the PDUs.

<CIT> shows an intelligent restraint system architecture for aircraft cargo. The intelligent restraint system architecture includes restraints arrayed along a cargo deck and local restraint control panels (RCPs). Each restraint is configured to normally assume a retracted condition at which cargo movement proximate to the restraint is permitted and to selectively assume an erected condition at which cargo movement proximate to the restraint is inhibited by the restraint. The local RCPs are respectively coupled to proximal restraints. Each local RCP is receptive of a signal indicative of a cargo movement status and is configured to automatically control each of the proximal restraints to selectively assume the erected condition or to re-assume the retracted condition in accordance with the signal being received and content thereof.

<CIT> shows a loading system comprising a restraint module having a restraint, a pair of rollers and a restraint control panel to control the position of the restraint.

A cargo handling system according to claim <NUM> is disclosed.

A method for storing and restraining cargo is provided in accordance with appended claim <NUM>.

Preferred embodiments are defined in dependent claims <NUM> to <NUM> and <NUM> to <NUM>.

While these various embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that changes may be made without departing from the scope of the invention defined in the appended claims.

With reference to <FIG>, a schematic view of an aircraft <NUM> having a cargo deck <NUM> located within a cargo compartment <NUM> is illustrated, in accordance with various embodiments. The aircraft <NUM> may comprise a cargo load door <NUM> located, for example, at one side of a fuselage structure of the aircraft <NUM>. A unit load device (ULD) <NUM>, in the form of a container or pallet, for example, may be loaded through the cargo load door <NUM> and onto the cargo deck <NUM> of the aircraft <NUM> or, conversely, unloaded from the cargo deck <NUM> of the aircraft <NUM>. In general, ULDs are available in various sizes and capacities, and are typically standardized in dimension and shape. Once loaded with items destined for shipment, the ULD <NUM> is transferred to the aircraft <NUM> and then loaded onto the aircraft <NUM> through the cargo load door <NUM> using a conveyor ramp, scissor lift or the like. Once inside the aircraft <NUM>, the ULD <NUM> is moved within the cargo compartment <NUM> to a final stowed position. Multiple ULDs may be brought on-board the aircraft <NUM>, with each ULD <NUM> being placed in a respective stowed position on the cargo deck <NUM>. After the aircraft <NUM> has reached its destination, each ULD <NUM> is unloaded from the aircraft <NUM> in similar fashion, but in reverse sequence to the loading procedure. To facilitate movement of the ULD <NUM> along the cargo deck <NUM>, the aircraft <NUM> may include a cargo handling system as described herein in accordance with various embodiments.

Referring now to <FIG>, a portion of a cargo handling system <NUM> is illustrated, in accordance with various embodiments. The cargo handling system <NUM> is illustrated with reference to an XYZ coordinate system, with the X-direction extending longitudinally and the Z-direction extending vertically with respect to an aircraft in which the cargo handling system <NUM> is positioned, such as, for example, the aircraft <NUM> described above with reference to <FIG>. In various embodiments, the cargo handling system <NUM> may define a conveyance surface <NUM> having a plurality of trays <NUM> supported by a cargo deck <NUM>, such as, for example, the cargo deck <NUM> described above with reference to <FIG>. The plurality of trays <NUM> may be configured to support a unit load device (ULD) <NUM> (or a plurality of ULDs), such as, for example, the unit load device (ULD) <NUM> described above with reference to <FIG>. In various embodiments, the ULD <NUM> may comprise a container or a pallet configured to hold cargo as described above. In various embodiments, the plurality of trays <NUM> is disposed throughout the cargo deck <NUM> and may support a plurality of conveyance rollers <NUM>, where one or more or all of the plurality of conveyance rollers <NUM> is a passive roller.

In various embodiments, the plurality of trays <NUM> may further support a plurality of power drive units (PDUs) <NUM>, each of which may include one or more drive rollers <NUM> that may be actively powered by a motor. In various embodiments, one or more of the plurality of trays <NUM> is positioned longitudinally along the cargo deck <NUM> - e.g., along the X-direction extending from the forward end to the aft end of the aircraft. In various embodiments, the plurality of conveyance rollers <NUM> and the one or more drive rollers <NUM> may be configured to facilitate transport of the ULD <NUM> in the forward and the aft directions along the conveyance surface <NUM>. During loading and unloading, the ULD <NUM> may variously contact the one or more drive rollers <NUM> to provide a motive force for transporting the ULD <NUM> along the conveyance surface <NUM>. Each of the plurality of PDUs <NUM> may include an actuator, such as, for example, an electrically operated motor, configured to drive the one or more drive rollers <NUM> corresponding with each such PDU <NUM>. In various embodiments, the one or more drive rollers <NUM> may be raised from a lowered position beneath the conveyance surface <NUM> to an elevated position above the conveyance surface <NUM> by the corresponding PDU. As used with respect to cargo handling system <NUM>, the term "beneath" may refer to the negative Z-direction, and the term "above" may refer to the positive Z-direction with respect to the conveyance surface <NUM>. In the elevated position, the one or more drive rollers <NUM> variously contact and drive the ULD <NUM> that otherwise rides on the plurality of conveyance rollers <NUM>. Other types of PDUs, which can also be used in various embodiments of the present disclosure, may include a drive roller that is held or biased in a position above the conveyance surface by a spring. PDUs as disclosed herein may be any type of electrically powered rollers that may be selectively energized to propel or drive the ULD <NUM> in a desired direction over the cargo deck <NUM> of the aircraft. The plurality of trays <NUM> may further support a plurality of restraint devices <NUM>. In various embodiments, each of the plurality of restraint devices <NUM> may be configured to rotate downward as the ULD <NUM> passes over and along the conveyance surface <NUM>. Once the ULD <NUM> passes over any such one of the plurality of restraint devices <NUM>, such restraint device returns to its upright position, either by a motor driven actuator or a bias member, thereby restraining or preventing the ULD <NUM> from translating in the opposite direction.

In various embodiments, the cargo handling system <NUM> may include a system controller <NUM> in communication with each of the plurality of PDUs <NUM> via a plurality of channels <NUM>. Each of the plurality of channels <NUM> may be a data bus, such as, for example, a controller area network (CAN) bus. An operator may selectively control operation of the plurality of PDUs <NUM> using the system controller <NUM>. In various embodiments, the system controller <NUM> may be configured to selectively activate or deactivate the plurality of PDUs <NUM>. Thus, the cargo handling system <NUM> may receive operator input through the system controller <NUM> to control the plurality of PDUs <NUM> in order to manipulate movement of the ULD <NUM> over the conveyance surface <NUM> and into a desired position on the cargo deck <NUM>. In various embodiments, the system controller <NUM> may include a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or some other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. The cargo handling system <NUM> may also include a power source <NUM> configured to supply power to the plurality of PDUs <NUM> or to the plurality of restraint devices <NUM> via one or more power busses <NUM>. As described below, in various embodiments, the system controller <NUM> may be complimented by or substituted with an agent-based control system, whereby control of each PDU and associated componentry - e.g., the restraint devices - is performed by individual unit controllers associated with each of the PDUs and configured to communicate between each other.

Referring now to <FIG>, a PDU <NUM>, such as for example, one of the plurality of PDUs <NUM> described above with reference to <FIG>, is illustrated disposed in a tray <NUM>, in accordance with various embodiments. The PDU <NUM> may rotate the drive roller <NUM> in one of two possible directions (e.g., clockwise or counterclockwise) to propel the ULD in a direction parallel to the longitudinal axis B-B' of the tray <NUM>. The PDU <NUM> may comprise a unit controller <NUM>, a unit motor <NUM> and a drive roller <NUM> mounted within an interior section <NUM> of the tray <NUM>. The drive roller <NUM> may comprise a cylindrical wheel coupled to a drive shaft and configured to rotate about an axis A-A'. The drive roller <NUM> may be in mechanical communication with the unit motor <NUM>, which may be, for example, an electromagnetic, electromechanical or electrohydraulic actuator or other servomechanism. The PDU <NUM> may further include gear assemblies and other related components for turning or raising the drive roller <NUM> so that the drive roller <NUM> may extend, at least partially, above a conveyance surface <NUM> which, in various embodiments, may be defined as the uppermost surface <NUM> of the tray <NUM>. At least partial extension of the drive roller <NUM> above the conveyance surface <NUM> facilitates contact between the drive roller <NUM> and a lower surface of a ULD, such as, for example, the ULD <NUM> described above with reference to <FIG>. In various embodiments, the unit controller <NUM> is configured to control operation of the drive roller <NUM>. The unit controller <NUM> may include a processor and a tangible, non-transitory memory. The processor may comprise one or more logic modules that implement logic to control rotation and elevation of the drive roller <NUM>. In various embodiments, the PDU <NUM> may comprise other electrical devices to implement drive logic. In various embodiments, a connector <NUM> is used to couple the electronics of the PDU <NUM> to a power source and a system controller, such as, for example, the system controller <NUM> described above with reference to <FIG>. The connector <NUM> may have pins or slots and may be configured to couple to a wiring harness having pin programing. The unit controller <NUM> may be configured to receive commands from the system controller through the connector <NUM> in order to control operation of the unit motor <NUM>.

In addition, a restraint device <NUM>, such as, for example, one of the plurality of restraint devices <NUM> described above with reference to <FIG>, is illustrated as disposed within the tray <NUM> and configured to operate between a stowed position, whereby the ULD may pass over the restraint device, and a deployed position (as illustrated), whereby the ULD is restrained or prevented from translation in a longitudinal direction (e.g., along a longitudinal axis B-B') without the restraint device <NUM> first being returned to the stowed position. The restraint device <NUM> includes a restraint controller <NUM> and a restraint motor <NUM>. In various embodiments, the restraint device <NUM> may be in mechanical communication with the restraint motor <NUM>, which may be, for example, an electromagnetic, electromechanical or electrohydraulic actuator or other servomechanism. In various embodiments, the restraint controller <NUM> is configured to control operation of the restraint device <NUM>. The restraint controller <NUM> may include a processor and a tangible, non-transitory memory. The processor may comprise one or more logic modules that implement logic to control operation of the restraint device <NUM> between the stowed and the deployed positions.

In various embodiments, the PDU <NUM> may also include a radio frequency identification device or RFID device <NUM>, or similar device, configured to store, transmit or receive information or data - e.g., operational status or location data. Additionally, a ULD sensor <NUM> may be disposed within the tray <NUM> and configured to detect the presence of a ULD as the ULD is positioned over or proximate to the PDU <NUM> or the restraint device <NUM>. In various embodiments, the ULD sensor <NUM> may include any type of sensor capable of detecting the presence of a ULD. For example, in various embodiments, the ULD sensor <NUM> may comprise a proximity sensor, a capacitive sensor, a capacitive displacement sensor, a Doppler effect sensor, an eddy-current sensor, a laser rangefinder sensor, a magnetic sensor, an active or passive optical sensor, an active or passive thermal sensor, a photocell sensor, a radar sensor, a sonar sensor, a lidar sensor, an ultrasonic sensor or the like.

Referring now to <FIG>, a schematic view of a cargo handling system <NUM> positioned on a cargo deck <NUM> of an aircraft is illustrated, in accordance with various embodiments. The cargo deck <NUM> may comprise a plurality of PDUs <NUM>, generally arranged in a matrix configuration about the cargo deck <NUM>. Associated with each of the plurality of PDUs <NUM> may be one or more drive rollers <NUM> and a restraint device <NUM>. In various embodiments, the plurality of PDUs <NUM>, the one or more drive rollers <NUM> and the restraint device <NUM> share similar characteristics and modes of operation as the PDU <NUM>, drive roller <NUM> and restraint device <NUM> described above with reference to <FIG>. Each of the one or more drive rollers <NUM> is generally configured to selectively protrude from a conveyance surface <NUM> of the cargo deck <NUM> in order to engage with a surface of a ULD <NUM> as it is guided onto and over the conveyance surface <NUM> during loading and unloading operations. A plurality of conveyance rollers <NUM> may be arranged among the plurality of PDUs <NUM> in a matrix configuration as well. The plurality of conveyance rollers <NUM> may comprise passive elements, and may include roller ball units <NUM> that serve as stabilizing and guiding apparatus for the ULD <NUM> as it is conveyed over the conveyance surface <NUM> by the plurality of PDUs <NUM>.

In various embodiments, the cargo handling system <NUM> or, more particularly, the conveyance surface <NUM>, is divided into a plurality of sections. As illustrated, for example, the conveyance surface <NUM> may include a port-side track and a starboard-side track along which a plurality of ULDs may be stowed in parallel columns during flight. Further, the conveyance surface <NUM> may be divided into an aft section and a forward section. Thus, the port-side and starboard-side tracks, in various embodiments and as illustrated, may be divided into four sections - e.g., a forward port-side section <NUM>, a forward starboard-side section <NUM>, an aft port-side section <NUM> and an aft starboard-side section <NUM>. The conveyance surface <NUM> may also have a lateral section <NUM>, which may be used to transport the ULD <NUM> onto and off of the conveyance surface <NUM> as well as transfer the ULD <NUM> between the port-side and starboard-side tracks and between the aft section and the forward section. The configurations described above and illustrated in <FIG> are exemplary only and may be varied depending on the context, including the numbers of the various components used to convey the ULD <NUM> over the conveyance surface <NUM>. In various embodiments, for example, configurations having three or more track configurations, rather than the two-track configuration illustrated in <FIG>, may be employed.

Each of the aforementioned sections - i.e., the forward port-side section <NUM>, the forward starboard-side section <NUM>, the aft port-side section <NUM> and the aft starboard-side section <NUM> - may include one or more of the plurality of PDUs <NUM>. Each one of the plurality of PDUs <NUM> has a physical location on the conveyance surface <NUM> that corresponds to a logical address within the cargo handling system <NUM>. For purposes of illustration, the forward port-side section <NUM> is shown having a first PDU <NUM>-<NUM>, a second PDU <NUM>-<NUM>, a third PDU <NUM>-<NUM>, a fourth PDU <NUM>-<NUM>, a fifth PDU <NUM>-<NUM> and an N-th PDU <NUM>-N. The aforementioned individual PDUs are located, respectively, at a first location <NUM>-<NUM>, a second location <NUM>-<NUM>, a third location <NUM>-<NUM>, a fourth location <NUM>-<NUM>, a fifth location <NUM>-<NUM> and an N-th location <NUM>-N. In various embodiments, the location of each of the aforementioned individual PDUs on the conveyance surface <NUM> may have a unique location (or address) identifier, which, in various embodiments, may be stored in an RFID device, such as, for example, the RFID device <NUM> described above with reference to <FIG>.

In various embodiments, an operator may control operation of the plurality of PDUs <NUM> using one or more control interfaces of a system controller <NUM>, such as, for example, the system controller <NUM> described above with reference to <FIG>. For example, an operator may selectively control the operation of the plurality of PDUs <NUM> through an interface, such as, for example, a master control panel (MCP) <NUM>. In various embodiments, the cargo handling system <NUM> may also include one or more local control panels (LCP) <NUM>. In various embodiments, the master control panel <NUM> may communicate with the local control panels <NUM>. The master control panel <NUM> or the local control panels <NUM> may also be configured to communicate with or send or receive control signals or command signals to or from each of the plurality of PDUs <NUM> or to a subset of the plurality of PDUs <NUM>, such as, for example, the aforementioned individual PDUs described above with reference to the forward port-side section <NUM>. For example, a first local control panel LCP-<NUM> may be configured to communicate with the PDUs residing in the forward port-side section <NUM>, a second local control panel LCP-<NUM> may be configured to communicate with the PDUs residing in the forward starboard-side section <NUM>, and one or more additional local control panels LCP-i may be in communication with the PDUs of one or more of the aft port-side section <NUM>, the aft starboard-side section <NUM> and the lateral section <NUM>. Thus, the master control panel <NUM> or local control panels <NUM> may be configured to allow an operator to selectively engage or activate one or more of the plurality of PDUs <NUM> to propel the ULD <NUM> along conveyance surface <NUM>.

In various embodiments, each of the plurality of PDUs <NUM> may be configured to receive a command from the master control panel <NUM> or one or more of the local control panels <NUM>. In various embodiments, the commands may be sent or information exchanged over a channel <NUM>, which may provide a communication link between the system controller <NUM> and each of the plurality of PDUs <NUM>. In various embodiments, a command signal sent from the system controller <NUM> may include one or more logical addresses, each of which may correspond to a physical address of one of the plurality of PDUs <NUM>. Each of the plurality of PDUs <NUM> that receives the command signal may determine if the command signal is intended for that particular PDU by comparing its own address to the address included in the command signal.

With reference to <FIG>, a schematic view of a portion of the cargo handling system <NUM> and the cargo deck <NUM> is shown in accordance with various embodiments. By way of non-limiting example, the system controller <NUM> is configured to send a command signal through the channel <NUM> to at least the first PDU <NUM>-<NUM> and the second PDU <NUM>-<NUM> of the forward port-side section <NUM>. The command signal may, for example, comprise an instruction to activate or deactivate a first motor <NUM>-<NUM> associated with the first PDU <NUM>-<NUM> or a second motor <NUM>-<NUM> associated with the second PDU <NUM>-<NUM>. The command signal may also comprise a first address that corresponds to the first location <NUM>-<NUM> or a second address that corresponds to the second location <NUM>-<NUM>. A first unit controller <NUM>-<NUM> of the first PDU <NUM>-<NUM> may receive the command signal through a first connector <NUM>-<NUM> and a second unit controller <NUM>-<NUM> of the second PDU <NUM>-<NUM> may receive the command signal through a second connector <NUM>-<NUM>. Following receipt of the signal, the first unit controller <NUM>-<NUM> and the second unit controller <NUM>-<NUM> may determine whether the command is intended to affect operation of the first PDU <NUM>-<NUM> or the second PDU <NUM>-<NUM>, respectively, by comparing a location address contained within the signal to a known address associated with the respective PDUs. In various embodiments, the first address associated with the first PDU <NUM>-<NUM> may be stored in a first RFID device <NUM>-<NUM> and the second address associated with the second PDU <NUM>-<NUM> may be stored in a second RFID device <NUM>-<NUM>. Additionally, a ULD sensor, such as the ULD sensor <NUM> described above with reference to <FIG> is disposed proximate each PDU and configured to detect the presence of a ULD as the ULD is positioned over or proximate to the PDU. Accordingly, a first ULD sensor <NUM>-<NUM> is disposed proximate or within the first PDU <NUM>-<NUM> and a second ULD sensor <NUM>-<NUM> is disposed proximate or within the second PDU <NUM>-<NUM>.

Turning now to <FIG>, a schematic diagram of an agent-based control system <NUM> is illustrated, in accordance with the various embodiments. Agent-based, as used herein, indicates that each of a plurality of PDUs includes logic for self-control based on various status indicators concerning the states of surrounding PDUs and the locations of one or more ULDs. As described below, the agent-based control system <NUM> may be employed to control the loading and unloading of a ULD (e.g., the ULD <NUM> described above with reference to <FIG>) by selectively powering a plurality of PDUs <NUM> (e.g., the plurality of PDUs <NUM> described above with reference to <FIG>).

In various embodiments, the agent-based control system <NUM> includes a plurality of PDUs <NUM>, such as, for example, the plurality of PDUs <NUM> described above with reference to <FIG>. In various embodiments, the plurality of PDUs <NUM> may be arranged in a first section <NUM> and a second section <NUM>, such as, for example, the forward port-side section <NUM> and the forward starboard-side section <NUM>, respectively, described above with reference to <FIG>. In various embodiments, each PDU comprising the first section <NUM> includes a PDU Agent. For example, a first PDU <NUM>-<NUM> of the first section <NUM> includes PDU Agent N1l and an i-th PDU <NUM>-i of the first section <NUM> includes PDU Agent N1i. Similarly, in the second section <NUM>, a first PDU <NUM>-<NUM> includes PDU Agent N2l and an i-th PDU <NUM>-i includes PDU Agent N2i. Also included in the first section <NUM> and the second section <NUM> is a series of powered latches. For example, a first powered latch <NUM>-<NUM> (Powered Latch N1l) and aj-th powered latch <NUM>-j (Powered Latch N1j) are arranged in the first section <NUM> and a first powered latch <NUM>-<NUM> (Powered Latch N2l) and aj-th powered latch <NUM>-j (Powered Latch N2j) are arranged in the second section <NUM>. In various embodiments, a powered latch is positioned between each pair of adjacent PDUs.

The agent-based control system <NUM> may further include an aircraft power and communication interface <NUM>. In various embodiments, the aircraft power and communication interface <NUM> includes an AC/DC Conversion module <NUM>, a GUI Interface Server module <NUM> and a Wireless Relay module <NUM>. The agent-based control system <NUM> is powered by a power module <NUM> which, in various embodiments, may comprise a 115V AC power source that may be supplied by the aircraft (e.g., from an auxiliary power unit) or from a source external to the aircraft. The agent-based control system <NUM> may further include circuit breakers <NUM>, a proximity sensor data module <NUM> and an aircraft maintenance communication module <NUM>. In various embodiments, the circuit breakers <NUM> serve to protect the agent-based control system <NUM> from power surges. The proximity sensor data module <NUM> is configured to receive sensor data concerning the current state of each of the plurality of PDUs <NUM> distributed, for example, throughout the first section <NUM> and the second section <NUM>. The sensor data may, in various embodiments, be transmitted to the aircraft maintenance communication module <NUM> and then analyzed to determine whether maintenance is required for any of the plurality of PDUs <NUM>. In various embodiments, power from the power module <NUM> (or circuit breakers <NUM>) and data from the proximity sensor data module <NUM> and the aircraft maintenance communication module <NUM> may be provided to the aircraft power and communication interface <NUM> through a single aircraft connection <NUM> (e.g., an electrical plug) that combines a power bus <NUM>-<NUM>, a proximity sensor data bus <NUM>-<NUM> and an aircraft maintenance communication bus <NUM>-<NUM> into a combined power and data bus <NUM>-<NUM>.

The agent-based control system <NUM> may further include direct current supply interfaces, such as, for example, a high-power DC supply interface <NUM> and a low-power DC supply interface <NUM>. In various embodiments, the high-power DC supply interface <NUM> is configured to provide a 270V DC power supply directly to each one of the plurality of PDUs <NUM> and the low-power DC supply interface <NUM> is configured to provide a 28V DC power supply to a wireless network <NUM>. In various embodiments, each of the PDU Agents is powered by a 12V DC supply provided by their associated PDU following conversion of the 270V DC power supply to the 12V DC power supply. In various embodiments, the wireless network <NUM> provides a communication network between the PDU Agents within the plurality of PDUs <NUM> and one or more operator interface devices, such as, for example, a Wireless Mobile Operator Interface Device (WMOID) <NUM>. In various embodiments, the WMOID <NUM> comprises a hand-held communication device, such as, for example, a smartphone or tablet device configured to communicate with the PDU Agents over the wireless network <NUM> through one or more wireless links <NUM>. In various embodiments, one or more wireless relays <NUM> provide an interface between the WMOID <NUM> the various PDU Agents through a power line communication bus <NUM> or a controller area network bus <NUM>. A joystick <NUM> which, in various embodiments, may be permanently affixed to the aircraft, may provide an optional operator interface to the wireless network <NUM>.

Referring still to <FIG>, operation of the agent-based control system <NUM> may be described, in accordance with various embodiments. An operator enters a "goal" using, for example, the WMOID <NUM>. In various embodiments, the goal includes information concerning the location where a particular ULD is to be positioned. The goal is output from the WMOID <NUM> onto the wireless network <NUM>, received by one or more of the wireless relays <NUM> and provided to the various PDU Agents via the power line communication bus <NUM> or the controller area network bus <NUM>. In one non-limiting example, the goal may provide instructions to transport a ULD from a first location corresponding to the first PDU <NUM>-<NUM> of the first section <NUM> to an i-th location corresponding to the i-th PDU <NUM>-i of the first section <NUM>. In so doing, a series of sensors, including a first sensor <NUM>-<NUM>, associated with the first PDU <NUM>-<NUM>, and an i-th sensor <NUM>-i, associated with the i-th PDU <NUM>-i, locate the current position of the ULD. In various embodiments, one or more of the series of sensors may comprise the ULD sensor <NUM> described above with reference to <FIG>, though other sensors may be employed. If the series of sensors confirm the current position is the first location corresponding to the first PDU <NUM>-<NUM>, then the logic within each of the PDU Agents in the first section <NUM> are employed to activate a first drive roller (e.g., the drive roller <NUM> described above with reference to <FIG>) associated with the first PDU <NUM>-<NUM> and deactivate the other drive rollers in the first section <NUM>. As the first drive roller transports the ULD in the direction of the ith PDU <NUM>-i, the ULD will eventually disengage with the first drive roller and engage with a second drive roller associated with a second PDU in the first section <NUM>. At that point, a second sensor associated with the second PDU will detect the presence of the ULD, causing a second PDU Agent to activate the second drive roller and the PDU Agents associated with the remaining PDUs to deactivate the associated drive rollers.

Consistent with the above operational description, the ULD will eventually arrive at the i-th location corresponding to the i-th PDU <NUM>-i of the first section <NUM>. An i-th drive roller then transports the ULD to an i-th restraint device (e.g., the restraint device <NUM> described above with reference to <FIG>). The i-th sensor will then detect contact or sufficient proximity between the ULD and the i-th restraint device and then activate the i-th restraint device in order to restrain the ULD in the desired position. In various embodiments, the operation then continues with subsequent ULDs being transported from the first location corresponding to the first PDU <NUM>-<NUM> to the desired location specified in the goal and, upon arrival at the desired location, activation of the appropriate restraint device. While the foregoing describes sequential loading and restraining of a plurality of ULDs into the first section <NUM>, un-restraining and unloading of the plurality of ULDs proceeds in a similar operation, excepting in reverse order.

Claim 1:
A cargo handling system (<NUM>, <NUM>), comprising:
a conveyance surface (<NUM>, <NUM>, <NUM>);
a first power drive unit (<NUM>, <NUM>, <NUM>-<NUM>, <NUM>) having a first drive roller (<NUM>, <NUM>, <NUM>);
a first restraint device (<NUM>, <NUM>, <NUM>);
a first sensor (<NUM>, <NUM>-<NUM>) disposed proximate the first power drive unit and configured to provide positional data corresponding to a current location of a unit load device (<NUM>, <NUM>, <NUM>) on the conveyance surface (<NUM>, <NUM>, <NUM>); and
a first power drive unit agent (N1l) configured for communication with the first sensor (<NUM>, <NUM>-<NUM>), the first power drive unit agent (N1l) configured to selectively activate and deactivate the first drive roller (<NUM>, <NUM>, <NUM>) and the first restraint device (<NUM>, <NUM>, <NUM>) based on the positional data; and
a second power drive unit (<NUM>, <NUM>, <NUM>-<NUM>, <NUM>) having a second drive roller (<NUM>, <NUM>, <NUM>);
a second sensor (<NUM>, <NUM>-<NUM>) disposed proximate the second power drive unit and configured to provide positional data corresponding to the current location of the unit load device (<NUM>, <NUM>, <NUM>) on the conveyance surface (<NUM>, <NUM>, <NUM>);
a second power drive unit agent (N1i) configured for communication with the second sensor (<NUM>, <NUM>-<NUM>), the second power drive unit agent (N1i) configured to selectively activate and deactivate the second drive roller (<NUM>, <NUM>, <NUM>) based on the positional data;
wherein the first power drive unit agent (N1l) is configured to activate the first drive roller and to deactivate the second drive roller (<NUM>, <NUM>, <NUM>) of the second power drive unit (<NUM>, <NUM>, <NUM>-<NUM>, <NUM>) based on the positional data corresponding to the first power drive unit; and
wherein the second power drive unit agent (N1i) is configured to activate the second drive roller and to deactivate the first drive roller (<NUM>, <NUM>, <NUM>) of the first power drive unit (<NUM>, <NUM>, <NUM>-<NUM>, <NUM>) based on the positional data corresponding to the second power drive unit.