Patent Description:
Motion control systems utilizing movers and linear motors can be used in a wide variety of processes (e.g. packaging, manufacturing, and machining) and can provide an advantage over conventional conveyor belt systems with enhanced flexibility, extremely high speed movement, and mechanical simplicity. The motion control system includes a set of independently controlled "movers" each supported on a track for motion along the track. The track is made up of a number of track segments that, in turn, hold individually controllable electric coils. Successive activation of the coils establishes a moving electromagnetic field that interacts with the movers and causes the mover to travel along the track. Sensors may be spaced at fixed positions along the track and/or on the movers to provide information about the position and speed of the movers.

Each of the movers may be independently moved and positioned along the track in response to the moving electromagnetic field generated by the coils. In a typical system, the track forms a path, which could be a closed path, over which each mover repeatedly travels. At certain positions along the track other actuators may interact with each mover. For example, the mover may be stopped at a loading station at which a first actuator places a product on the mover. The mover may then be moved along a process segment of the track where various other actuators may fill, machine, position, or otherwise interact with the product on the mover. The mover may be programmed to stop at various locations or to move at a controlled speed past each of the other actuators. After the various processes are performed, the mover may pass or stop at an unloading station at which the product is removed from the mover. The mover then completes a cycle along the path by returning to the loading station to receive another unit of the product.

One manner of controlling movers on a track is known as "centralized" control. Under centralized control, a single controller is used to define precise, time dependent motion for movers traveling on the track. With centralized knowledge of the motion of each mover, such control can advantageously allow movers to move more closely together along the track with less concern of collision. Also, such control can advantageously allow improved coordination with industrial processes or machines to which the movers align. However, centralized controllers may be limited in the maximum number of axes available for defining motion for each of the movers. As a result, the system may be limited with respect to a maximum number of movers which may be supported unless increased resources are provided.

Another manner of controlling movers on a track is known as "distributed" control. Under distributed control, segment controllers corresponding to segments of the track are used to define the motion for the movers which travel on their respective segments. As movers transition from one segment to another, the segment controllers can transfer control with respect to the movers to next segment controllers. By not requiring each mover to be controlled by a common, centralized controller, such distributed control can enable larger automatic assembly lines with large numbers of movers in the system. However, distributed controllers may still be limited with respect to a maximum number of movers which may be supported in the system in order to ensure collision avoidance. In particular, without centralized knowledge of the motion of each mover, the segment controllers typically maintain a minimum separation distance between movers which would allow one mover to avoid a collision should an adjacent mover come to an immediate stop. This is also referred to as "brick-wall" collision avoidance in which it is desirable for a mover to avoid a collision if an adjacent mover should come to an immediate stop, thereby appearing like the mover collided with a brick-wall.

Thus, it would be desirable to provide a linear drive system which eliminates one or more of the foregoing disadvantages. <CIT> relates to a system and method for controlling a moving element in a linear motor conveyor. A system for controlling moving elements includes: a zone controller; a first network and a second network operatively connected to the zone controller; at least one first motor gateway associated with a portion of the conveyor and assigned to the first network; and at least one second motor gateway associated with a different portion of the conveyor and assigned to the second network; wherein the zone controller, the at least one first motor gateway, and the at least one second motor gateway are configured to: communicate data related to control of the moving elements via the first network and the second network in a structured manner to compensate for network or processing timing. <CIT> relates to a method and system for merge control in an automated vehicle system. The method comprises: Defining a merge control zone associated with a merge point, the merge control zone defining at least respective sections of the upstream tracks leading to the merge point; detecting a vehicle entering the merge control zone on a first one of the upstream tracks; allocating a passage time to the vehicle, the passage time being indicative of a time at which the vehicle is scheduled to pass the merge point; wherein allocating the passage time is based on a merge priority assigned to the vehicle according to a predetermined set of merge priority rules; controlling a speed of the vehicle responsive to the allocated passage time. <CIT> relates to a method for controlling the movement of a drive axis of a drive unit. It is the object of the present invention to provide a system to more efficiently control a group of movers.

A linear drive system provides a combination of distributed control to increase the number of movers which may be supported in the system and centralized control to reduce the separation distance between movers by grouping movers together and placing a reference mover of the group under central control with remaining movers of the group under distributed control. In addition, in precise working locations, or "synchronization zones," each of the movers can be temporarily placed under central control to further reduce the separation distance and allow improved coordination with industrial processes or machines in the system.

In one aspect of the invention, a Tour Group Operation (TGO) mode can be provided for independently controlling movers/vehicles. In the TGO mode, a dynamically selected group of adjacent vehicles on the track can be grouped together in a "tour group. " One vehicle, which could be the lead vehicle, is designated as a reference vehicle or Tour Guide Vehicle (TGV). All vehicles in the same tour group following the TGV can be instructed to maintain an ordered distance with respect to the TGV, or an ordered distance with respect to one another, chaining with respect to TGV.

In the absence of centralized control, the TGV can generate its own motion profile. The group of vehicles can move synchronously as one independently controlled vehicle. When the TGV is under centralized control, the TGV can receive and follow a motion profile from the centralized controller. The group of vehicles can move synchronously as one controlled vehicle.

Vehicles in a same tour group, with the exception of the TGV, can be controlled by the centralized controller, or segment controllers of the track segments (the motor). Consequently the number of motion axes maintained by the centralized controller can be significantly reduced by vehicle grouping. Accordingly, TGO can enable the centralized controller to control systems with larger numbers of vehicles. The architecture can include: (a) dividing all vehicles into groups; (b) placing the lead vehicle, the TGV, under centralized control; (c) placing the rest of the vehicle in the group under distributed/segmented control; and (d) maintaining specified vehicle spacing of all vehicles within the same group.

In another aspect of the invention, throughput at a given work station on a track can be improved by implementing synchronized vehicle control. A section of the track within a given work station can be constructed as a "synchronization zone. " The segments of the track can be connected to synchronization-control hardware. In the synchronization zone, motion profiles are no longer generated per vehicle under distributed control, but rather under centralized control. Effectively the vehicles are temporarily put under centralized control in the synchronization zone. Vehicle spacing smaller than that under brick-wall control can be achieved by carefully calculated motion profiles for all vehicles in the synchronization zone.

Accordingly, in one control scheme, a vehicle, typically a lead vehicle, can be designated to be a reference vehicle during an ordered move. The profile of the reference vehicle can be used to generate the profiles of vehicles that follow the lead vehicle. The following vehicles then follow the generated profiles above without the need to calculate their own motion profiles, as would be the case under ordinary distributed control. The calculated profile typically involves simple addition or subtraction of a constant following distance, or "offset," thereby requiring minimal computational overhead of the segment controller. As a result, overall CPU computational bandwidth may be reduced by simplification of profile generation of all following vehicles.

In another control scheme, a customized motion profile can be stored in a controller's non-volatile memory. This pre-configured profile can be used as a reference profile in lieu of a profile of the referenced vehicle in the scheme.

These and other advantages and features of the invention will become apparent to those skilled in the art from the detailed description and the accompanying drawings. It should be understood, however, that the detailed description and accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration and not of limitation.

Turning initially to <FIG>, an exemplary transport system for moving articles or products includes a track <NUM> made up of multiple segments <NUM>. According to the illustrated embodiment, multiple segments <NUM> are joined end-to-end to define the overall track configuration. The illustrated segments <NUM> are both straight segments having generally the same length. It is understood that track segments of various sizes, lengths, and shapes may be connected together to form the track <NUM> without deviating from the scope of the invention. In one embodiment, track segments <NUM> may be joined to form a generally closed loop supporting a set of movers <NUM> movable along the track <NUM>. The track <NUM> is illustrated in a horizontal plane. For convenience, the horizontal orientation of the track <NUM> shown in <FIG> will be discussed herein. Terms such as upper, lower, inner, and outer will be used with respect to the illustrated track orientation. These terms are relational with respect to the illustrated track and are not intended to be limiting. It is understood that the track may be installed in different orientations, such as sloped or vertical, and include different shaped segments including, but not limited to, straight segments, inward bends, outward bends, up slopes, down slopes and various combinations thereof. The width of the track <NUM> may be greater in either the horizontal or vertical direction according to application requirements. The movers <NUM> will travel along the track and take various orientations according to the configuration of the track <NUM> and the relationships discussed herein may vary accordingly.

According to the illustrated embodiment, each mover <NUM> is configured to slide along the channel <NUM> as it is propelled by a linear drive system. The mover <NUM> includes a body <NUM> configured to fit within the channel <NUM>. In one embodiment, the body <NUM> includes a lower surface <NUM>, configured to engage the bottom surface <NUM> of the channel, and side surfaces <NUM> configured to engage the side walls <NUM> of the channel. The mover <NUM> further includes a shoulder <NUM> extending inward from each of the side surfaces <NUM>. The shoulder <NUM> has a width equal to or greater than the width of the rail <NUM> protruding into the channel. A neck of the mover then extends upward to a top surface <NUM> of the body <NUM>. The neck extends for the thickness of the rails such that the top surface <NUM> of the body <NUM> is generally parallel with the upper surface of each rail <NUM>. The mover <NUM> further includes a platform <NUM> secured to the top surface <NUM> of the body <NUM>. According to the illustrated embodiment, the platform <NUM> is generally square and the width of the platform <NUM> is greater than the width between the rails <NUM>. The lower surface of the platform <NUM>, an outer surface of the neck, and an upper surface of the shoulder <NUM> define a channel <NUM> in which the rail <NUM> runs. The channel <NUM> serves as a guide to direct the mover <NUM> along the track. It is contemplated that platforms or attachments of various shapes may be secured to the top surface <NUM> of the body <NUM>. Further, various workpieces, clips, fixtures, and the like may be mounted on the top of each platform <NUM> for engagement with a product to be carried along the track by the mover <NUM>.

The mover <NUM> is carried along the track <NUM> by a linear drive system. The linear drive system is incorporated in part on each mover <NUM> and in part within each track segment <NUM>. One or more drive magnets <NUM> are mounted to each mover <NUM>. With reference to <FIG>, the drive magnets <NUM> are arranged in a block on the lower surface of each mover. The drive magnets <NUM> include positive magnet segments <NUM>, having a north pole, N, facing outward from the mover and negative magnet segments <NUM>, having a south pole, S, facing inward to the mover. According to the illustrated embodiment, two positive magnet segments <NUM> are located on the outer sides of the set of magnets and two negative magnet segments <NUM> are located between the two positive magnet segments <NUM>. Optionally, the positive and negative motor segments may be placed in an alternating configuration. In still other embodiments, a single negative magnet segment <NUM> may be located between the positive magnet segments <NUM>. Various other configurations of the drive magnets <NUM> may be utilized without deviating from the scope of the invention.

The linear drive system further includes a series of coils <NUM> spaced along the length of the track segment <NUM>. With reference also to <FIG>, the coils <NUM> may be positioned within a housing <NUM> for the track segment <NUM> and below the bottom surface <NUM> of the channel <NUM>. The coils <NUM> are energized sequentially according to the configuration of the drive magnets <NUM> present on the movers <NUM>. The sequential energization of the coils <NUM> generates a moving electromagnetic field that interacts with the magnetic field of the drive magnets <NUM> to propel each mover <NUM> along the track segment <NUM>.

A segment controller <NUM> is provided within each track segment <NUM> to control the linear drive system and to achieve the desired motion of each mover <NUM> along the track segment <NUM>. Although illustrated as blocks in <FIG> external to the track segments <NUM>, the illustration is to facilitate illustration of interconnects between controllers. As shown in <FIG>, it is contemplated that each segment controller <NUM> may be mounted in the lower portion <NUM> of the track segment <NUM>. Each segment controller <NUM> is in communication with an adjacent segment controller <NUM> and a central controller <NUM> which is, in turn, in communication with an industrial controller <NUM>. Accordingly, each segment controller <NUM> can interact with other controllers to establish routing and global move parameters to re-create overall commands from the industrial controller <NUM>. The industrial controller may be, for example, a programmable logic controller (PLC) configured to control elements of a process line stationed along the track <NUM>. The process line may be configured, for example, to fill and label boxes, bottles, or other containers loaded onto or held by the movers <NUM> as the travel along the line. In other embodiments, robotic assembly stations may perform various assembly and/or machining tasks on workpieces carried along by the movers <NUM>. The exemplary industrial controller <NUM> includes a power supply <NUM> with a power cable <NUM> connected, for example, to a utility power supply; a communication module <NUM> connected by a network medium <NUM> to the central controller <NUM>; a processor module <NUM>; an input module <NUM> receiving input signals <NUM> from sensors or other devices along the process line; and an output module <NUM> transmitting control signals <NUM> to controlled devices, actuators, and the like along the process line. The processor module <NUM> may identify when a mover <NUM> is required at a particular location and may monitor sensors, such as proximity sensors, position switches, or the like to verify that the mover <NUM> is at a desired location. The processor module <NUM> transmits the desired locations of each mover <NUM> to a central controller <NUM> where the central controller <NUM> operates to generate commands for each segment controller <NUM>.

With reference also to <FIG>, the central controller <NUM> includes a processor <NUM> and a memory device <NUM>. It is contemplated that the processor <NUM> and memory device <NUM> may each be a single electronic device or formed from multiple devices. The processor may be a microprocessor. Optionally, the processor <NUM> and/or the memory device <NUM> may be integrated on a field programmable array (FPGA) or an application specific integrated circuit (ASIC). The memory device <NUM> may include volatile memory, non-volatile memory, or a combination thereof. An optional user interface <NUM> may be provided for an operator to configure the central controller <NUM> and to load or configure desired motion profiles for the movers <NUM> on the central controller <NUM>. Optionally, the configuration may be performed via a remote device connected via a network and a communication interface <NUM> to the central controller <NUM>. It is contemplated that the central controller <NUM> and user interface <NUM> may be a single device, such as a laptop, notebook, tablet or other mobile computing device. Optionally, the user interface <NUM> may include one or more separate devices such as a keyboard, mouse, display, touchscreen, interface port, removable storage medium or medium reader and the like for receiving information from and displaying information to a user. Optionally, the central controller <NUM> and user interface may be an industrial computer mounted within a control cabinet and configured to withstand harsh operating environments. It is contemplated that still other combinations of computing devices and peripherals as would be understood in the art may be utilized or incorporated into the central controller <NUM> and user interface <NUM> without deviating from the scope of the invention.

The central controller <NUM> includes one or more programs stored in the memory device <NUM> for execution by the processor <NUM>. The central controller <NUM> can receive instructions for coordinating with industrial processes or machines. In one aspect, known as "centralized" control, the central controller <NUM> can determine one or more motion profiles for the movers <NUM> to follow along the track <NUM>. A program executing on the processor <NUM> is in communication with each segment controller <NUM> on each track segment via a network medium <NUM>. The central controller <NUM> may transfer the one or more motion profiles to segment controllers <NUM> for execution of the motion profiles to move the movers <NUM>. However, in another aspect, known as "distributed" control, the central controller <NUM> may be configured to transfer the information from the industrial controller <NUM> identifying one or more desired movers <NUM> to be positioned at or moved along the track segment <NUM>, and the segment controllers <NUM> may determine the appropriate motion profile for each mover <NUM>. Distributed control can minimize the amount of communication in the system by allowing segment controllers <NUM> to control the movers <NUM> (as opposed to the central controller <NUM>).

A position feedback system provides knowledge of the location of each mover <NUM> along the length of the track segment <NUM> to the segment controller <NUM>. In one embodiment, the position feedback system can include one or more position magnets <NUM> mounted to the mover <NUM> and an array of sensors <NUM> spaced along the side wall <NUM> of the track segment <NUM>. The sensors <NUM> are positioned such that each of the position magnets <NUM> are proximate to the sensor as the mover <NUM> passes each sensor <NUM>. The sensors <NUM> are a suitable magnetic field detector including, for example, a Hall Effect sensor, a magneto-diode, an anisotropic magnetoresistive (AMR) device, a giant magnetoresistive (GMR) device, a tunnel magnetoresistance (TMR) device, fluxgate sensor, or other microelectromechanical (MEMS) device configured to generate an electrical signal corresponding to the presence of a magnetic field. The magnetic field sensor <NUM> outputs a feedback signal provided to the segment controller <NUM> for the corresponding track segment <NUM> on which the sensor <NUM> is mounted. The feedback signal may be an analog signal provided to a feedback circuit <NUM> which, in turn, provides a signal to the processor <NUM> which corresponds to the magnet <NUM> passing the sensor <NUM>.

The segment controller <NUM> also includes a communication interface <NUM> that receives communications from the central controller <NUM> and/or from adjacent segment controllers <NUM> in a path. The communication interface <NUM> extracts data from the message packets on the communication network and passes the data to a processor <NUM> executing in the segment controller <NUM>. The processor may be a microprocessor. Optionally, the processor <NUM> and/or a memory device <NUM> within the segment controller <NUM> may be integrated on a field programmable array (FPGA) or an application specific integrated circuit (ASIC). It is contemplated that the processor <NUM> and memory device <NUM> may each be a single electronic device or formed from multiple devices. The memory device <NUM> may include volatile memory, non-volatile memory, or a combination thereof. The segment controller <NUM> receives the motion profile or desired motion of the movers <NUM> and utilizes the motion commands to control movers <NUM> along the track segment <NUM> controlled by that segment controller <NUM>.

Each segment controller <NUM> generates switching signals to generate a desired current and/or voltage at each coil <NUM> in the track segment <NUM> to achieve the desired motion of the movers <NUM>. The switching signals <NUM> control operation of switching devices <NUM> for the segment controller <NUM>. According to the illustrated embodiment, the segment controller <NUM> includes a dedicated gate driver module <NUM> which receives command signals from the processor <NUM>, such as a desired voltage and/or current to be generated in each coil <NUM>, and generates switching signals <NUM>. Optionally, the processor <NUM> may incorporate the functions of the gate driver module <NUM> and directly generate the switching signals <NUM>. The switching devices <NUM> may be a solid-state device that is activated by the switching signal, including, but not limited to, transistors, thyristors, or silicon-controlled rectifiers.

In one embodiment, the processor <NUM> can also receive feedback signals from sensors providing an indication of the current operating conditions within the power segment or of the current operating conditions of a coil <NUM> connected to the power segment. According to the illustrated embodiment, the power segment includes a voltage sensor <NUM> and a current sensor <NUM> at the input of the power segment. The voltage sensor <NUM> generates a voltage feedback signal and the current sensor <NUM> generates a current feedback signal, where each feedback signal corresponds to the operating conditions on the positive rail <NUM>. The segment controller <NUM> also receives feedback signals corresponding to the operation of coils <NUM> connected to the power segment. A voltage sensor <NUM> and a current sensor <NUM> are connected in series with the coils <NUM> at each output of the power section. The voltage sensor <NUM> generates a voltage feedback signal and the current sensor <NUM> generates a current feedback signal, where each feedback signal corresponds to the operating condition of the corresponding coil <NUM>. The processor <NUM> executes a program stored on the memory device <NUM> to regulate the current and/or voltage supplied to each coil and the processor <NUM> and/or gate driver <NUM> generate switching signals <NUM> which selectively enable/disable each of the switching devices <NUM> to achieve the desired current and/or voltage in each coil <NUM>. The energized coils <NUM> create an electromagnetic field that interacts with the drive magnets <NUM> on each mover <NUM> to control motion of the movers <NUM> along the track segment <NUM>.

In operation, the central controller <NUM> receives a command from an external controller, such as the industrial controller <NUM> shown in <FIG>, corresponding to a desired location, trajectory or motion for each mover <NUM>. For particular movers <NUM> on the track <NUM> and/or movers <NUM> on particular synchronization sections of the track <NUM> (known as "synchronization zones") in which synchronized control is desired, a synchronization controller <NUM> ("sync controller") can perform processing on the information from the industrial controller <NUM> to generate one or more motion profiles, including commands with respect to speed, position and time, and transmit such motion profiles to the corresponding segment controller <NUM>. The synchronization controller <NUM> can include a a communication interface <NUM>, a memory device <NUM>, a processor <NUM> and an optional user interface <NUM> for an operator to configure the synchronization controller <NUM> and to load or configure desired motion profiles for the movers <NUM> in synchronization zones. The synchronization controller <NUM> includes one or more programs stored in the memory device <NUM> for execution by the processor <NUM>. The synchronization controller <NUM> can receive instructions for synchronizing the movers <NUM> in synchronization zones as described below with respect to <FIG> and <FIG>. In synchronization zones, the synchronization controller <NUM> can determine motion profiles for the movers <NUM> to follow along the track <NUM>. A program executing on the processor <NUM> is in communication with each segment controller <NUM> on each track segment corresponding to a synchronization zone via a network medium <NUM>. The synchronization controller <NUM> may transfer the one or more motion profiles to segment controllers <NUM> for the synchronization zones for execution of the motion profiles to move the movers <NUM>.

In addition, for particular movers <NUM> on the track <NUM> and/or movers <NUM> on remaining areas of the track <NUM> in which distributed control is desired, the central controller <NUM> can relay the information from the industrial controller <NUM> to the appropriate segment controller <NUM> with the corresponding mover <NUM> present along the track segment <NUM>.

The segment controller <NUM>, in turn, controls operation of the mover <NUM> to execute the motion profile, whether generated by the central controller <NUM> or generated locally. The segment controller <NUM> may include a position and/or a velocity loop to regulate the position of each mover <NUM>. Each mover <NUM> includes at least one position magnet <NUM> and, according to the illustrated embodiment, each mover <NUM> includes an array of position magnets <NUM> mounted on the mover <NUM>. In another aspect, one or more magnets can instead be used as both the drive magnet and the position magnet. The position magnets <NUM> pass by an array of position sensors <NUM> as the mover <NUM> travels along the track segment, generating position feedback signals <NUM>. A position loop may utilize the position feedback signals <NUM> directly to regulate the position of the mover <NUM> to achieve a desired position or desired position profile along the track segment <NUM>. The processor <NUM> in the segment controller <NUM> may also convert the position feedback signals <NUM> to a velocity feedback signal according to known methods and provide the velocity feedback signal to a velocity loop to achieve a desired speed or desired speed profile along the track segment <NUM>.

Referring to <FIG>, a logical representation of the exemplary control system of <FIG> is provided in accordance with an aspect of the invention. The illustrated linear drive system can provide a combination of distributed control to increase the number of movers <NUM> which may be supported in the system and/or centralized control to reduce the separation distance between movers <NUM> by grouping movers <NUM> together into groups <NUM> and assigning a reference mover <NUM>' of each group <NUM> with remaining movers <NUM> of the group 250following the reference mover. In addition, in precise working locations, or synchronization zones <NUM>, each of the movers <NUM> can be temporarily placed under the control of a synchronization controller <NUM> to further reduce the separation distance and allow improved coordination with industrial processes or machines <NUM> in the system.

By way of example, a first set of movers <NUM>, identified as movers A, B, C and D, can be placed in a first group 250a, and a second set of movers <NUM>, identified as movers E, F, G and H, can be placed in a second group 250b. In addition, one of the movers <NUM> of each group <NUM> can be designated as a reference mover <NUM>'. For example, in the first group 250a, mover D may be a reference mover <NUM>', with movers A, B and C being "grouped movers" following the reference mover D in a direction of travel along the track <NUM>, and in the second group 250b, mover H may be a reference mover <NUM>', with movers E, F and G being "grouped movers" following the reference mover H in a direction of travel along the track <NUM>. Accordingly, the first and second groups 250a and 250b, respectively, are in Tour Group Operation (TGO) mode. Although the reference mover <NUM>' is shown as the lead mover <NUM> of each group <NUM> for convenience and ease of understanding, it should be appreciated that assignment of the reference mover <NUM>' could be given to any one of the movers <NUM> of the group <NUM> within the scope of the invention.

In TGO mode, motion of the reference mover <NUM>' for each group <NUM> is determined according to a motion profile <NUM> defined by the central controller <NUM> or a segment controller <NUM> of any track segment <NUM> in which the reference mover <NUM>' is traveling. For example, motion for reference movers D and H for the first and second groups 250a and 250b can be determined according to motion profiles 260d and <NUM>, respectively, as defined by the central controller <NUM>. However, alternatively, motion for reference movers D and H for the first and second groups 250a and 250b, respectively, can be determined according to motion profiles as defined by a segment controller <NUM> of any track segment <NUM> in which the reference mover <NUM>' is traveling, such as the segment controller 50a for the reference mover D, and the segment controller 50b for the reference mover H. Motion of any grouped mover <NUM> is determined as an offset from the reference mover <NUM>' by a segment controller <NUM> of any track segment <NUM> in which the grouped mover <NUM> is traveling. For example, motion for grouped movers A, B and C in the first group 250a is determined according to motion profiles 262a, 262b and 262c, respectively, which could reflect offsets with respect to the reference mover D as defined by segment controller 50a while grouped movers A, B and C are traveling on track segment 12a. Similarly, motion for grouped movers E, F and G in the second group 250b is determined according to motion profiles 262e, 262f and <NUM>, respectively, which could reflect offsets with respect to the reference mover H as defined by segment controller 50b while grouped movers E, F and G are traveling on track segment 12b. Accordingly, the grouped movers <NUM> of each group <NUM> are under distributed control based on offsets in the group, which may be incrementally increasing predetermined separation distances for each of the grouped movers <NUM>.

As reference movers <NUM>' (D and H) transition from one track segment <NUM> to the next, reference movers <NUM>' can remain under the control of the motion profile <NUM> defined by the central controller <NUM>, and/or transition under the control of the one segment controller <NUM> to the next. However, as grouped movers <NUM> (A, B, C and E, F, G) transition from one track segment <NUM> to the next, control of the grouped movers <NUM> can transition from one segment controller <NUM> to the next. For example, as grouped mover C transitions from track segment 12a to track segment 12b (following reference mover D), control with respect to the motion profile 262c of grouped mover C (which could reflect an offset relative to reference mover D) transitions from segment controller 50a providing the motion profile 262c to segment controller 50b providing the motion profile 262c.

In one aspect, this distributed control transition can be realized by each segment controller <NUM> maintaining a data structure storing records <NUM> for each mover <NUM> that is located on its respective track segment <NUM>. Each record <NUM> can include for a respective mover <NUM>: a unique identifier; a maximum velocity rating; a maximum acceleration rating; a destination; a group assignment identifier; and/or a centralized control or distributed control flag. Each segment controller <NUM> can detect presence of a mover <NUM> on its respective track, including with respect to position, velocity, and in some embodiments, unique identifier. Also, each segment controller <NUM> can receive a message from a neighboring segment controller <NUM> for incoming movers <NUM>, and each segment controller <NUM> can send a message to a neighboring segment controller <NUM> for outgoing movers <NUM>, via the network medium <NUM>. Accordingly, as a grouped mover <NUM> transitions from one track segment <NUM> to the next, one segment controller <NUM> can send a message to an adjacent segment controller <NUM> including a record <NUM> for the grouped mover <NUM>, and the adjacent segment controller <NUM> can receive the message and the record <NUM> and detect presence of the incoming grouped mover <NUM>. When a group <NUM> transitions from one segment controller <NUM> to the next, motion profiles can be correspondingly communicated from one segment controller <NUM> to the next, including from a segment controller <NUM> for a track segment <NUM> on which a reference mover <NUM>' is traveling to another segment controller <NUM> for another track segment <NUM> with the rest of the group <NUM>, as motions for the grouped movers <NUM> are based on the reference mover <NUM>'. In some aspects, the reference mover <NUM>' can span more than one track segment <NUM>, and motion profiles (which could be adjusted for the next mover <NUM> in line) could be passed from one segment controller <NUM> to the next until the end of a group <NUM> is reached.

Providing TGO mode allows more movers <NUM> to be controlled with greater flexibility. To maximize efficiency, each segment controller <NUM> can provide motion profiles <NUM> for grouped movers <NUM> to move as closely as possible to the reference mover <NUM>', with reduced separation distance. Accordingly, while grouped movers <NUM> are travelling on a track segment <NUM> corresponding to a segment controller <NUM>, that segment controller <NUM> can execute to move the grouped movers <NUM> into close positions with respect to the reference mover <NUM>', following one another, based on the maximum velocity and acceleration ratings of the respective movers <NUM>. For example, with additional reference to <FIG>, based on detection of the reference mover D moving through a motion profile 260d, using the sensors <NUM>, the segment controller 50a, in turn, can define and execute motion profiles 262a, 262b and 262c for grouped movers A, B and C, respectively, to follow the reference mover D with an offset that is a predetermined, ordered separation distance. Also, such predetermined separation distance can be a minimal separation distance as determined by the segment controller <NUM> based on the maximum velocity and acceleration ratings of the respective movers <NUM>.

Referring again to <FIG>, in synchronization zones <NUM>, all movers <NUM>, whether grouped or otherwise, can be temporarily placed under synchronized control to allow individual control of each mover <NUM> for improved coordination with industrial processes or machines <NUM> in the system, such as actuators configured to interact with the movers <NUM>. Such synchronized control, in combination with the TGO mode, can also allow a reduced separation distance as compared to brick wall control. In one aspect, a section <NUM> of the track <NUM> could be a synchronization zone <NUM>. In the synchronization zone <NUM>, motion profiles <NUM> for any mover <NUM> can be defined by the synchronization controller <NUM>, including reference movers <NUM>' which might otherwise be controlled by the controller <NUM>. For example, in the synchronization zone <NUM>, which might be located on track segment 12c, movers I, J, K and L, which might otherwise comprise a third group 250c of movers <NUM> elsewhere on the track <NUM>, are each placed under synchronized control, which control is carried out by the segment controller 50c. Accordingly, motion for movers I, J, K and L are determined according to motion profiles 270i, 270j, <NUM> and <NUM>, respectively, as defined by the synchronization controller <NUM>, so that the movers I, J, K and L can be spaced even more closely together as illustrated and can be aligned more precisely with the industrial processes or machines <NUM>. Although the synchronization zone <NUM> in <FIG> is shown as corresponding to a single track segment 12c by way of example, in other configurations, the synchronization zone <NUM> can span multiple track segments <NUM>.

While movers <NUM> can be processed in the synchronization zone <NUM> under synchronized control, in another aspect of the invention, movers <NUM> can also be processed by varying the TGO mode as described above with respect to <FIG>. Referring to <FIG>, various states for another exemplary synchronization zone <NUM>' on the track <NUM> are shown in accordance with an aspect of the invention. The synchronization zone <NUM>' can be a working area <NUM> in which movers <NUM> can be precisely positioned with the industrial processes or machines <NUM>, such as actuators configured to interact with the movers <NUM>, with minimal separation distances, by varying grouping modes. For efficient operation, a queuing area <NUM> may precede the working area <NUM>, and an exit area <NUM> may follow the working area <NUM>. In the queuing area <NUM>, movers <NUM> can arrive in a preexisting group mode, and in the exit area <NUM>, movers <NUM> can exit with the preexisting group mode.

In <FIG>, in a first state <NUM>, movers <NUM>-<NUM> have been processed in the working area <NUM>. Meanwhile, movers <NUM>-<NUM> arrive in the queuing area <NUM> to wait for processing in their preexisting modes.

Next, in <FIG>, in a second state <NUM>, movers <NUM>-<NUM> are formed into a TGO group of eight with mover <NUM> being the TGV or reference mover <NUM>'. Then, the TGO group of eight can be moved the equivalent of four mover lengths so that movers <NUM>-<NUM> are in the working area <NUM> and movers <NUM>-<NUM> are out of the working area <NUM>.

Next, in <FIG>, in a third state <NUM>, movers <NUM>-<NUM> can be positioned in the working area <NUM>. Accordingly, movers <NUM>-<NUM> are ready to be processed.

Next, in <FIG>, in a fourth state <NUM>, while movers <NUM>-<NUM> are been processed, movers <NUM>-<NUM> can be formed into a TGO group of four with mover <NUM> being the TGV or reference mover <NUM>'. Then, movers <NUM>-<NUM> can leave the exit area as a TGO group. Meanwhile, movers <NUM>-<NUM> can move closer to the working area <NUM> in the queuing area <NUM>.

Then, in <FIG>, in a fifth state <NUM>, movers <NUM>-<NUM> can be processed. These states may then continuously repeat, back to the first state <NUM>, to efficiently process movers <NUM> in relation to the industrial processor machine <NUM> in the working area <NUM> with minimal separation distance and improved alignment.

Claim 1:
A linear drive system comprising:
a plurality of movers (<NUM>), wherein each of the plurality of movers includes at least one position magnet (<NUM>) mounted to the mover for providing a location of the respective mover;
a track (<NUM>) including a plurality of track segments (<NUM>) defining a path along which each of the plurality of movers travels, wherein each of the plurality of track segments includes:
(a) a plurality of drive coils (<NUM>) spaced along the track segment; and
(b) a segment controller (<NUM>) configured to operate the plurality of drive coils, wherein operating a drive coil of the plurality of drive coils proximal to a mover of the plurality of movers causes the respective mover to travel along a portion of the track segment; and
a central controller (<NUM>) in communication with the segment controllers (<NUM>); and
wherein motion of a mover of the plurality of movers is determined according to a motion profile defined by the central controller or a segment controller of any track segment of the plurality of track segments in which the mover is traveling,
characterized in that the plurality of movers is arranged in a group (<NUM>), wherein one mover of the plurality of movers is a reference mover (<NUM>') and any other mover of the plurality of movers is a grouped mover, wherein motion of the reference mover is determined according to a motion profile (<NUM>) defined by the central controller or the segment controller of any track segment in which the reference mover is traveling, and wherein motion of any grouped mover of the plurality of movers is determined according to an offset with respect to the reference mover,
wherein motion of any grouped mover of the plurality of movers is determined by a segment controller of any track segment in which the grouped mover of the plurality of movers is traveling,
wherein each segment controller is configured to define a motion profile for any grouped mover of the plurality of movers to cause the grouped mover to maintain a predetermined separation distance from the reference mover.