Patent Publication Number: US-2023159307-A1

Title: Lumber grabber for automated crane

Description:
PRIORITY APPLICATION(S) 
     This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63/281,477, entitled “LUMBER GRABBER FOR AUTOMATED CRANE” filed on Nov. 19, 2021 (Attorney Docket No. IDFG 1010-1), which application is incorporated herein by reference. 
    
    
     BACKGROUND 
     The subject matter discussed in this section should not be assumed to be prior art merely as a result of its mention in this section. Similarly, a problem mentioned in this section or associated with the subject matter provided as background should not be assumed to have been previously recognized in the prior art. The subject matter in this section merely represents different approaches, which in and of themselves may also correspond to implementations of the claimed technology. 
     Processing timber involves a variety of tasks, such as stacking, moving, sawing, packaging, and shipping product and the like. During processing, timber is stacked and moved for grasping to various sizes and further processing in a timber mill or other facility. Often, large machines are used for this task. One problem with these traditional approaches is that the raw timber can be of various sizes and geometries, making the “pick and place” task difficult. The lack of flexibility is also compounded by the complexity of materials handling requirements for the timber. Rough cut timber is heavy and unwieldy, making the job of moving it into and out of the work area complex. 
     Conventional approaches to the problem of stacking timber are not flexible, nor scalable, nor cost effective, and are of very low efficiency, making their usage in scalable timber processing installations problematic. Often, conventional approaches require a variety of different inflexible “off the shelf” machines to perform the same task on different sizes of work product. Sometimes, conventional approaches require additional energy, human as well as machine, to be expended moving timber among a larger variety of machines to perform processing. 
     An opportunity arises to develop better machines and processes for positioning packages of lumber for processing into wood products. Better, more easily operated, more effective and efficient apparatus and systems may result. 
     SUMMARY 
     A simplified summary is provided herein to help enable a basic or general understanding of various aspects of exemplary, non-limiting implementations that follow in the more detailed description and the accompanying drawings. This summary is not intended, however, as an extensive or exhaustive overview. Instead, the sole purpose of this summary is to present some concepts related to some exemplary non-limiting implementations in a simplified form as a prelude to the more detailed description of the various implementations that follow. 
     The technology disclosed relates to a lumber grabber for grasping timber. The lumber grabber can achieve grasping large packages of lumber of various work lengths (e.g., packages of between 7 feet and up to greater than 20 feet in length can be grasped and positioned by an automated crane appropriately equipped with a lumber grabber employing the disclosed technology). In one configuration, the lumber grabber includes moveable forks for grasping lumber movably supported by a frame, affixable to a crane. Forks positioned at ends of the frame and arranged to open and close relative to one other under power by a source of motive force; thereby enabling grasping and ungrasping of packages of timber under programmed control of a programmable controller executing stored instructions. 
     The technology disclosed relates to a lumber grabber for grasping timber. The lumber grabber can achieve grasping large packages of lumber of various work lengths (e.g., packages of between 7 feet and up to greater than 20 feet in length can be grasped and positioned by an automated crane appropriately equipped with a lumber grabber employing the disclosed technology). In one configuration, the lumber grabber includes a frame, a set of moveable carriages movably supported by the frame, two sets of forks, each set of forks positioned on one of the movable carriages at either end of the frame and arranged diametrically opposed to each other, a motor, a set of one or more rotatable ball screw shafts connected to and driven by the motor and to the carriages, to change relative positions of the carriages at either end of the frame; thereby enabling grasping and ungrasping of packages of timber under programmed control of a programmable controller executing stored instructions. 
     In one implementation, the lumber grabber is further equipped with a self-leveling device arranged such that when it rests on the units of lumber a slight slack rope condition is created in the crane to force the forks of the lumber grabber to level themselves to the lumber stacks. Various other combinations of work product length and fork dimensions can be implemented depending on requirements of the work site. 
     In a particular implementation, the technology disclosed also provides a method of grasping large packages of lumber of up to greater than 20 feet in length. The method can include lowering using a hoist of a crane a lumber grabber down to pick up a unit of lumber, wherein a movable plate attached to the lumber grabber via a hydraulic cylinder is in a fully down position due to gravity. As the hoist lowers, the plate will make contact with a top of the lumber unit, substantially contemporaneously with the hoist of the crane continuing to lower thereby creating a slack rope condition in the hoist. Opening valving on the hydraulic cylinder allows the lumber grabber to lower. Detecting using thru-beam photo sensors mounted near a rear base of forks on either side of the lumber grabber that the lumber grabber is in a clear position to close the forks to pick up the unit of lumber is also part of the method. Closing valves on the hydraulic cylinder when the lumber grabber lowered to a commanded height to pick up the unit of lumber. Height can be sensed using a laser ranging sensor as is known and commercially available, a vision system, other types of sensors, e.g., tactile, sonic, etc., or a combination of thereof. The method also includes commencing raising by the hoist of the crane the lumber grabber the unit of lumber when the forks are closed. 
     Particular aspects of the technology disclosed are described in the claims, specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The included drawings are for illustrative purposes and serve only to provide examples of possible structures and process operations for one or more implementations of this disclosure. These drawings in no way limit any changes in form and detail that may be made by one skilled in the art without departing from the spirit and scope of this disclosure. A more complete understanding of the subject matter may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures. 
         FIG.  1    illustrates a perspective view of a lumber grabber for grasping timber. 
         FIG.  2 A  and  FIG.  2 B  illustrate a front view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. 
         FIG.  3 A  and  FIG.  3 B  illustrate a side view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. 
         FIG.  4 A  and  FIG.  4 B  illustrate a top view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. 
         FIG.  5 A  and  FIG.  5 B  illustrate a front view of another lumber grabber implementation in fully open and fully closed positions, respectively. 
         FIG.  6 A  and  FIG.  6 B  illustrate a side view of another lumber grabber implementation in fully open and fully closed positions, respectively. 
         FIG.  7 A  and  FIG.  7 B  illustrate a top view of another lumber grabber implementation in fully open and fully closed positions, respectively. 
         FIG.  8 A  illustrates a flowchart of actions for grasping timber with automated machinery like that of  FIG.  1   . 
         FIG.  8 B  illustrates a flowchart of actions for releasing grasped timber with automated machinery like that of  FIG.  1   . 
         FIG.  9 A  and  FIG.  9 B  show implementation of an electronics architecture used by the lumber grabber in which a controller processes input data comprising at least actuation data from actuators of an actuation system, image data from visual sensors in the lumber grabber, and tactile data from tactile sensors in the lumber grabber, and generates actuator command data. 
         FIG.  10 A  and  FIG.  10 B  illustrate detail views of latching mechanisms of a lumber grabber for locking the grabber in place when grasping timber. 
         FIG.  11    illustrates an example lumber processing facility in which a lumber grabber could be deployed. 
     
    
    
     DETAILED DESCRIPTION 
     The following description will typically be with reference to specific structural embodiments and methods. It is to be understood that there is no intention to be limited to the specifically disclosed embodiments and methods, but that other features, elements, methods and embodiments may be used for implementations of this disclosure. Preferred embodiments are described to illustrate the technology disclosed, not to limit its scope, which is defined by the claims. Those of ordinary skill in the art will recognize a variety of equivalent variations on the description that follows. Unless otherwise stated, in this application specified relationships, such as parallel to, aligned with, or in the same plane as, mean that the specified relationships are within limitations of manufacturing processes and within manufacturing variations. When components are described as being coupled, connected, being in contact or contacting one another, they need not be physically directly touching one another unless specifically described as such. Like elements in various embodiments are commonly referred to with like reference numerals. 
     A more sophisticated lumber grasping system and method is provided for improved efficiency in moving packages of lumber for processing into wood products. Implementations efficiently handle packages of lumber of approximately 8 to greater than 20 feet in length. 
       FIG.  1    illustrates a perspective view of a lumber grabber  100  for grasping timber. Lumber grabber  100  nominally includes a frame  10  configured to be attached to a crane (not shown in  FIG.  1    for clarity sake) that can be affixed to the sawmill or warehouse floor (see e.g.,  FIG.  11   ). A crane can position the lumber grabber  100  as well as raise and lower the lumber grabber  100  into place by means of a plurality of cables connecting a lifting/lowering mechanism (e.g., a hoist, winch, etc.) of the crane (not shown in  FIG.  1    for clarity) and crane cable sheaves  120  of the lumber grabber  100 . Height above the work area is detected using a laser ranging sensor as is known and commercially available, a vision system, other types of sensors, e.g., tactile, sonic, etc., or a combination of sensors. A set of movable carriages  20 ,  22  are movably supported by the frame  10 . Two sets of forks  30 ,  32  are positioned on one of the movable carriages  20 ,  22  at either end of the frame  10  and arranged to be approximately diametrically opposed to each other. A motor  50  is a source of motive force. A set of one or more rotatable ball screw shafts  40  connected to the motor  50  and to the movable carriages  20 ,  22 , to change relative positions of the movable carriages  20 ,  22  with respect to one another. In some implementations, an absolute encoder  41  is connected to each ball screw  40  for position feedback. Motion of the movable carriages  20 ,  22  enables grasping and ungrasping of packages of lumber (e.g., workproduct  1 ) by forks  30 ,  32  under programmed control of a programmable controller (not shown) executing instructions stored on transitory, non-transitory readable media. In an implementation, a number of turns of the ball shaft and threading of the ball shaft is used to command the movable carriages  20 ,  22  to different distances. For example, in one implementation ball shafts move a carriage ½ inch per turn. Other configurations e.g., ¼ inch to 1 inch per turn can be used in some applications. In one implementation, the operating mechanism for opening and closing the lumber grabber is a single motor connected to two ball screws through belts and sheaves. In one implementation, both sides (e.g., carriages  20 ,  22 ) of the lumber grabber  100  are actuated substantially contemporaneously by action of the motor  50  and mechanical coupling (e.g., shafts  40 , etc.). In another configuration, separate motors are used to drive each ball shaft. 
     Further, in one example implementation, each set of forks  30 ,  32  has a distance of travel of nominally 54″, however in some implementations, each set of forks has a travel distance in a range between 0 and 24 inches. In one example implementation, the forks open up to a width of nominally 108″ to drop down over a unit that is nominally 96″, however in some implementations, the sets of forks have an opening width in a range between 0 and 64 inches and some can accommodate lumber packages having a width in a range between 10 inches to 52 inches. This nominally allows 6″ of space on each side of the lumber units for the grabber to clear in one example implementation, however some applications may call for different amounts of clearance space on each side of the lumber units. 
     When the forks  30 ,  32  close on the unit of lumber, there are mechanical latches  90  that engage into slots  110  automatically under programmed control of a programmable controller (not shown). In the illustrated implementations, latches  90  are implemented using locking pins  1093 ,  1094  in  FIG.  10 A . These latches  90  lock the forks  30 ,  32  into place so that they cannot open during crane travel. 
     With continuing reference to  FIG.  1   , a nominal work product  1  is shown in relation to lumber grabber  100 . Work product  1  comprises one or more layers  1 A,  2 A of lumber products stacked into a package. Dunnage  3  is interposed between the layers  1 A and  2 A as well as beneath the first or closest layer to the floor (or other surface on which the work product  1  is resting). Dunnage  3  enables forks  30 ,  32  to be slide beneath a layer of work lumber in order to grasp and lift the lumber. In one example described with reference to  FIGS.  5 A,  5 B,  6 A,  6 B,  7 A,  7 B, and  11   , a lumber grabber configuration is described that is suitable for use with work product comprising dry finished lumber from 12 inches to 24 inches tall×44 inches wide×from 8 feet to 20 feet long. In another example described with reference to  FIGS.  2 A,  2 B,  3 A,  3 B,  4 A, and  4 B , a lumber grabber configuration is described that is suitable for use with work product comprising green lumber of 54 inches tall×8 feet wide×from 8 feet to 20 feet long. In some example applications, finished lumber product packages employ dunnage of from 1 inch to 1.5 inches thick, and green lumber product packages employ dunnage of 3.5 inches thick. 
       FIG.  2 A  and  FIG.  2 B  illustrate a front view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. 
     A self-leveling device comprised of a plate  60  is positioned so that when the plate  60  rests on a unit of lumber (not illustrated) a slight slack rope condition is created in a crane to which the lumber grabber frame  10  is attached, to force the forks  30 ,  32  of the lumber grabber  100  to level themselves to the unit of lumber. A hydraulic cylinder  70  is attached to the plate  60 , enabling height of the plate  60  to be set by allowing hydraulic fluid to flow out of a cylinder  70  as it is compressed until a hoist of the crane reaches a commanded position. In one implementation, the commanded position can be provided by a PLC controller and Inventory Management system that tracks locations and dimensions of units of lumber in a warehouse. 
     In one implementation, the exact height of the unit of lumber is further measured with a vision system for verification. When the hoist is lowering lumber grabber  100  down to pick up a unit of lumber, the plate  60  is in its fully extended (down) position due to gravity. As the hoist lowers the lumber grabber, the plate  60  makes contact with the top of the lumber unit. The hoist of the crane will continue to lower the lumber grabber creating a slack rope condition. Valving (not shown for clarity sake) on the hydraulic cylinder  70  will open allowing the lumber grabber  100  to be lowered. In some implementations, thru-beam photo-sensors  300  mounted near the rear base of the forks of the grabber (See e.g.,  FIG.  3 A  and  FIG.  3 B ). The photo-sensors  300  indicate to the controller that the lumber grabber  100  is in a clear position to close the forks  30 ,  32  to pick up the unit of lumber. When the lumber grabber  100  is lowered to the commanded height to grasp a unit of lumber, the valves are closed. Once the forks  30 ,  32  are closed the hoist begins to raise the lumber grabber  100 . 
     When the forks  30 ,  32  close on the unit of lumber, there are mechanical latches  90  that engage into slots  110  automatically under programmed control of a programmable controller (not shown). In the illustrated implementations, latches  90  are implemented using locking pins as is shown in  FIGS.  10 A and  10 B . These latches  90  lock the forks  30 ,  32  into place so that they cannot open during crane travel. In some implementations, an absolute encoder  41  (of  FIG.  3 A  and  FIG.  3 B ) is connected to each ball screw for position feedback. One or more extreme open and closed proximity switch(es) can further be used for double verification of fork position. These devices are used by the control system to make decisions as to when it is safe to (i) raise, (ii) lower, or (iii) travel in a horizontal direction with the crane. While the crane is holding the unit of lumber there are load cells (not shown) on the crane that measure the unit weight. When the load measured falls below a threshold, e.g., near zero or the weight of slack cabling, it is known that the lumber grabber is resting on the payload. 
     In this implementation, the motor is controlled by a Variable Frequency Drive that resides in the main control panel (not illustrated for clarity&#39;s sake). Motor  50  is electrically driven using power conducted by cabling from a source and dropped in overhead or via conduits through walls or flooring and can nominally output 7.5 hp. Motors having power outputs in a range of 5 to 150 horsepower can be used in some implementations. One lumber grabber configuration described with reference to  FIGS.  2 A,  2 B,  3 A,  3 B,  4 A, and  4 B  is suitable for use with work product comprising green lumber of 54 inches tall×8 feet wide×from 8 feet to 20 feet long. One particular embodiment of the lumber grabber is designed for packages of lumber that are nominally 96 inches, but some implementations can accommodate packages between 24 and 52 inches wide and varying in length from 7 feet to 20 feet or greater and has a payload range that includes a payload of 0 pounds (lbs) to up to 35,000 pounds (lbs.). 
       FIG.  3 A  and  FIG.  3 B  illustrate a side view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. In the configuration illustrated by  FIG.  3 A  and  FIG.  3 B , thru-beam photo-sensors  300  are mounted near the rear base of the forks of the grabber (See e.g.,  FIG.  3 A  and  FIG.  3 B ). The photo-sensors  300  indicate to the controller that the lumber grabber  100  is in a clear position to close the forks  30 ,  32  to pick up the unit of lumber. 
     In the frame  10  are pins  80  that project up vertically. These pins  80  lock into some receiving points on the crane trolley (not shown) itself to lock the lumber grabber  100  package into place during travel. This ensures that the unit will not sway during travel therefore making the cycle times much faster as the system does not have to wait for the load to settle when the destination of the crane is reached. This will also ensure the highest degree of accuracy when picking and placing units of lumber, as the sway of the grabber will be minimal if being hoisted down from a locked in position. 
       FIG.  4 A  and  FIG.  4 B  illustrate a top view of a lumber grabber for grasping timber in fully open and fully closed positions, respectively. In the top view of frame  10 , pins  80  that project up (+z axis is out of the page in  FIG.  4 A  and  FIG.  4 B ) vertically are depicted in relation to the frame  10  and other components of the lumber grabber  100 . These pins  80  lock into some receiving points on the crane trolley (not shown) itself to lock the lumber grabber  100  package into place during travel. 
       FIG.  5 A  and  FIG.  5 B  illustrate a front view of another lumber grabber implementation in fully open and fully closed positions, respectively. The lumber grabber implementation illustrated by  FIGS.  5 A,  5 B,  6 A,  6 B,  7 A   7 B, and  11  is dimensionally smaller than the lumber grabber illustrated by  FIGS.  2 A,  2 B,  3 A,  3 B,  4 A, and  4 B , and suited for use in warehouses containing finished product in which the packages are smaller than the rough cut lumber products handled by the larger lumber grabber, thereby enabling users to conserve space and increase the amount of inventory that can be kept in the warehouse. One lumber grabber implementation described with reference to  FIGS.  5 A,  5 B,  6 A,  6 B,  7 A,  7 B and  11    is suitable for use with work product comprising dry finished lumber from 12 inches to 24 inches tall×44 inches wide×from 8 feet to 20 feet long.  FIG.  11    illustrates an example lumber processing facility in which such a lumber grabber could be deployed. 
       FIG.  6 A  and  FIG.  6 B  illustrate a side view of another lumber grabber implementation in fully open and fully closed positions, respectively. 
       FIG.  7 A  and  FIG.  7 B  illustrate a top view of another lumber grabber implementation in fully open and fully closed positions, respectively. A compressed air system  78  provides the actuating force for the locking pins/latches  90  that prevent the forks from opening when traveling while carrying a load of lumber products. An electronics box  79  contains remote input/output (TO) ports for the programmable logic controller (PLC) and provides a point where the sensors on the grabber are wired into. 
       FIG.  8 A  illustrates a flowchart of actions for grasping timber with automated machinery like that of  FIG.  1   . The machinery is not necessarily part of the method. 
     In a block  502 , using a hoist of a crane the lumber grabber is lowered down to pick up a unit of lumber, wherein a movable plate attached to the lumber grabber via a hydraulic cylinder is in a fully down position due to gravity. 
     In a block  504 , as the hoist lowers, the plate will make contact with a top of the lumber unit, substantially contemporaneously with the hoist of the crane continuing to lower thereby creating a slack rope condition in the hoist. 
     In a block  506 , valving on the hydraulic cylinder is opened allowing the lumber grabber to lower. 
     In a block  508 , using thru-beam photo sensors mounted near a rear base of forks on either side of the lumber grabber, detecting that the lumber grabber is in a clear position to close the forks to pick up the unit of lumber. 
     In a block  510 , valves on the hydraulic cylinder are closed when the lumber grabber lowered to a commanded height to pick up the unit of lumber. 
     In a block  512 , when the forks are closed, commencing raising by the hoist of the crane the lumber grabber the unit of lumber. Some implementations employ compressed air as the actuating force for the locking pins or latches  90  that prevent the forks from opening when traveling under load. In other implementations, latches  90  can be actuated by hydraulic pressure, or electrical energy as in the case of solenoids or servomotors. 
     Other implementations of the method described in this section can include a non-transitory computer readable storage medium storing instructions executable by a processor to perform any of the methods described above. Yet another implementation of the method described in this section can include a system including memory and one or more processors operable to execute instructions, stored in the memory, to perform any of the methods described above. 
       FIG.  8 B  illustrates a flowchart of actions for releasing grasped timber with automated machinery like that of  FIG.  1   . The machinery is not necessarily part of the method. 
     In a block  522 , lowering the hoist is commenced. 
     In a block  524 , when the hoist has lowered to an approximate height, e.g., as detected by a proximity to surface sensor such as a laser ranging device/sensor, vision system, or other types of sensors, e.g., tactile, sonic, etc., or the like or a combination of thereof, a lowering rate of the hoist is slowed until load cells (sensors on the crane) detect that loading on the cable suspending the lumber grabber has fallen to/below a threshold, indicating that the unit of lumber has been fully placed. 
     In a block  526 , latch actuators are actuated, allowing the forks to open and the motor and ball screw drive are actuated to open the forks. 
     In a block  528 , raising the hoist is commenced when the forks have fully opened. 
     In a block  530 , the hydraulic valve is opened allowing the plate to lower. 
     Other implementations of the method described in this section can include a non-transitory computer readable storage medium storing instructions executable by a processor to perform any of the methods described above. Yet another implementation of the method described in this section can include a system including memory and one or more processors operable to execute instructions, stored in the memory, to perform any of the methods described above. 
     Additional features included in various implementations of the lumber grabber workstation  100  include the use of sensors such as (i) 2-axis inclinometer mounted on each grabber frame to measure the tilt in the x and y direction. This is a safety device to ensure that if the grabber frame is to catch on anything at any time during the automated process that the tilt would be captured and cause an Emergency Stop condition for the crane, (ii) current transducers allowing the motor to dynamically adjust the speed of the down motion and (ii) area sensors for detection of entry into a danger zone. Additionally, the cycle time per grasp and transport can vary based on package size and motor size, where the lumber grabber  100  is capable of adapting to various motor sizes, depending on current requirements of the mill. Motors can be changed or swapped based on various requirements. The components of lumber grabber  100  (e.g., frame, forks, etc.) and crane size can be selected and implemented based on the requirements (e.g., volume throughput) of the mill. The travel speed of the lumber grabber (e.g., 10 inches per second) as it is grasping can be adjusted based on the dimensions of the work pieces/products and requirements of the mill. This information is calculated and then passed from a programmable logic controller (PLC) to each of the cranes for initial positioning and subsequent grasping. 
     Electronics Architecture 
       FIG.  9 A  is a simple functional block diagram of an electronics architecture suitable for implementing the lumber grabber workstation  100 . In  FIG.  9 A , the electronics architecture  600 A comprises the central control unit  602  that controls the actuators (e.g., that control manipulators, such as the movable carriages/forks of the lumber grabber workstation  100 ) including sources of motive force (e.g., motor  50 ) and, therefore the linkages, joints, and forks/end effectors, etc. of the lumber grabber  100 , using the command generator  614  and/or the pre-processor  644 . 
     The lumber grabber workstation  100  includes the kinematic chain  610 , and the actuation system  620 . The lumber grabber  100  includes a central control unit  602  (i.e., controller) that in this example comprises a command generator  614  and a pre-processor  644 . The controller is in communication with the plurality of actuators and the sensors, and operates the components on the kinematic chain. The controller includes a feedback loop receiving feedback data derived from or including the actuator data and sensor data as feedback input, trained to generate actuator command data  612  to cause the lumber grabber workstation  100  to execute a task to manipulate the object responsive to the feedback data, under direct operator control and/or by programmed logic. Implementation specifics vary considerably, however in one example a Controllogix™ PLC is used to implement the central control unit  602 . Training may be implemented using programming by an operator at operators console  605 . In other embodiments, machine learning algorithms and techniques are used to generate, or augment existing, commands to the lumber grabber workstation  100 . 
     The actuation system  620  can include sources of motive force, e.g., electric motors, hydraulic cylinders, pneumatic cylinders and the like, coupling actuators, e.g., linkages, springs, levers, and so forth, and sensors affixed to one or the other, e.g., encoders, position sensors, combinations thereof, or the like. The actuation system  620  provides actuation data  622  to the central control unit  602 , and receives actuator command data  612 , including actuator commands, from the central control unit  602 . Also, the lumber grabber  100  includes as describe above, optical/visual sensors  630  generating image data  632  and range data, tactile sensors  640  in this example generating tactile sensor data  642 , proximity sensors  650  in this example generating object proximity data  652  relative to the end effectors, and pressure sensors  660  in this example generating contact pressure data  662 . The actuation data  622 , the image data  632 , the tactile sensor data  642 , the object proximity data  652 , and the contact pressure data  662  are provided to the central control unit  602 . 
     The command generator  614  can plan motion of components of the lumber grabber  100 , such as the movable carriages of the lumber grabber  100  and use this motion plan to generate a sequence of commands commanding the joints of the lumber grabber  100  for the purposes of advancing the lumber grabber  100  to a goal state provided by the pre-processor  644  to the command generator  614 . 
     The pre-processor  644  can process the actuation data  622 , the image data  632 , the tactile sensor data  642 , the object proximity data  652 , and the contact pressure data  662  to produce a state vector for the lumber grabber  100 . This state vector is produced in a time frame and manner as needed to control the state of the lumber grabber  100  and is accessible to task programming provided to the lumber grabber  100  via the operators console  605 . The pre-processor  644  can include one or more trained neural networks used for the purpose of deriving feedback data for input the neural network that generates the command data. Also, the command generator can include one or more trained neural networks. In some implementations, the command generator and the pre-processor comprise neural networks trained end-to-end using reinforcement learning. Other training procedures can be applied as well, including separate training of the neural networks in the controller. 
     Thus, the central control unit  602  processes input data comprising at least the actuation data  622  from the actuators of the actuation system  620 , the image data  632  from the visual sensors  630  if present, and if present, other sensor data such as the tactile sensor data  642  from the tactile sensors  640  of the lumber grabber  100  and generates actuator command data  612 . 
     In some implementations, with reference to  FIG.  9 B , the electronics architecture  600 B further comprises distributed local controllers that are responsible for low-level motor control, including current, velocity, and position control, evaluation of the joint sensors, output control signals to the actuator power electronics, parameterization of the actuator controllers, e.g., for gain scheduling, and data acquisition from the force/torque sensors and inertial measure measurement system. Each local controller can handle a set of actuators (e.g., one, two, or three actuators). Cable harnesses connect the actuator sensors, actuators, drives to the local controllers. The central control unit  602  and the local controllers can communicate by a high speed communication interface such as CAN, FireWire, Ethernet/IP, or SERCOS, supporting real-time control in which each new set of actuator commands is based on feedback data that indicates the effects of the immediately preceding command set on the state of the lumber grabber  100  and the object of the task. 
     Controller 
     The central control unit  602  includes the command generator  614  and the pre-processor  644 , in this example, implementing a control loop that includes processing the input data for an instant time interval, and generating the actuator command data  612  for use in a next time interval. 
     The central control unit  602  is also configured with a system file including a program file (e.g., program file  906 ) that specifies the task(s) to be executed by the lumber grabber  100 . The program file can identify the task in a sequence of sub-tasks, along with goal positions, goal angles, maximum and minimum values for sampling the goal positions and the goal angles, policy paths and trajectories, policy speedup coefficients, and feedback actions. Each “task” can be implemented to be triggered based upon a set of detected input conditions, duty cycle, operator command issued at the operators console  605  or otherwise. In one implementation, a set of weights generated by training a neural network system, including a trained neural network in a feedback loop receiving feedback data derived from or including the actuator data and the sensor data as feedback input, trained to generate actuator command data to cause the automata to execute the task to manipulate the object, or the automata in preparation for manipulation of an object, in response to the feedback data. The neural network system that can be trained using reinforcement learning algorithms and configured with a policy that implements the control feedback loop. The neural network system can use neural networks like a multi-layer perceptron (MLP), a feed-forward neural network (FFNN), a fully connected neural network (FCNN), a convolutional neural network (CNN), and a recurrent neural network (RNN). Example of the reinforcement learning algorithms include deterministic policy gradient algorithms, and policy-gradient actor-critic algorithms like deep deterministic policy gradient (DDPG) with hindsight experience replay (HER) and distributed distributional deterministic policy gradient (D4PG). 
     The input data  902  can includes the range image data  632  from the visual sensors  630  indicating the orientation and position of the timber and the lumber grabber  100  in three dimensions and time, and the actuation data  622  from the actuators of the actuation system  620 . The input data  902  can further include the tactile sensor data  642  from the tactile sensors  640  in the lumber grabber  100  or other components of the lumber grabber  100 . The input data  902  can further include the object proximity data  652  from the proximity sensors  650 . The input data  902  can further include the contact pressure data  662  from the pressure sensors  660 . The input data  902  can further include external motion tracking data from an external, stand-alone motion tracking system like OptiTrack™ type motion capture system that tracks motion of the lumber grabber  100  and the object in a three-dimensional space. The input data  902  can be used as feedback data in the feedback loop, and can be used to derive feedback data, and both. 
     The actuator command data  612  updates one or more of the actuator parameters of the actuators. Examples of the actuator command data  612  include position updates, absolute positions, angle updates, absolute angles, torque updates, absolute torques, speed updates, absolute speeds, velocity updates, absolute velocities, acceleration updates, absolute accelerations, rotation updates, and absolute rotations. The actuator command data  612  is used to update the respective states of the actuators in the next time interval, which in turn causes the tendons, the joints, the body parts, and other components of the lumber grabber  100  to transition to a different state (e.g., tension, position, orientation) in the next time interval. 
     The actuator command data  612  can include commands for each of the actuators or only a subset of the actuators. Each command can include an actuator ID, and a numerical value or values used to drive the actuator to a next state. 
     In the implementation listed above, the actuator command data  612  provided as output of the controller comprising a vector of drive changes for differential positioning, or a vector of position mode target positions, or a vector of force/torque values, and various combinations of differential mode commands, position mode command as suitable for the actuators under control. 
     The actuators execute the commands specified in the actuator command data  612  and generate the actuation data  622  for the next time interval, and cause generation of the image data  632  by the visual sensors  630  and the tactile sensor data  642  by the tactile sensors  640  for the next time interval. The process is iterated by the control loop implemented by the controller  630 . 
     In some implementations, the actuator command data  612  generated by the controller  602  is processed by a calibration module (not shown) that generates a calibrated version of the actuator command data  612  which is specific to the configuration of the lumber grabber  100 . The calibrated version of the actuator command data is used to update the respective states of the actuators. 
     Additional features included in various implementations of the lumber grabber  100  include the use of sensors such as (i) encoders for movement measurement of various components of the lumber grabber  100 ; (ii) current transducers allowing the system to automatically detect a stall or jamb condition of the lumber grabber  100  and signal for assistance; and (ii) area sensors for detection of entry into a danger zone. 
     Latching Mechanisms 
       FIG.  10 A  and  FIG.  10 B  illustrate detail views of latching mechanisms of a lumber grabber for locking the grabber in place when grasping timber. Latching mechanism  90  shown in  FIGS.  10 A and  10 B  is suitable for implementing latching functionality that holds moveable forks  30 ,  32  in place when lumber is grasped. As shown, latching mechanism  90  can include a mounting base  1090  having a pair of actuators  1091 ,  1092  affixed thereto. Actuators  1091 ,  1092  can be implemented using electrically operated solenoids or servo motors, or hydraulically actuated cylinders or pneumatic cylinders. Each of actuators  1091 ,  1092  is mechanically coupled to a locking pin  1093 ,  1094 , enabling the locking pins  1093 ,  1094  to be extended into or withdrawn from engaging slotted members  1010  of moveable carriages  20 ,  22  through guide members  1095 ,  1097  and  1096 ,  1098  respectively. In a present embodiment, locking pins  1093 ,  1094  include a 45-degree chamfer on their top surface to facilitate locating a slot  110  in slotted members  1010 . Other angles e.g., from 10 degrees to 70 degrees are also suited for chamfering the surface of locking pins  1093 ,  1094 . 
     Some Particular Implementations 
     We describe various implementations of lumber grabber workstation. 
     The technology disclosed can be practiced as a system, method, or article of manufacture. One or more features of an implementation can be combined with the base implementation. Implementations that are not mutually exclusive are taught to be combinable. One or more features of an implementation can be combined with other implementations. This disclosure periodically reminds the user of these options. Omission from some implementations of recitations that repeat these options should not be taken as limiting the combinations taught in the preceding sections—these recitations are hereby incorporated forward by reference into each of the following implementations. 
     A system implementation of the technology disclosed includes a lumber grabber for grasping timber. The lumber grabber can achieve grasping large packages of lumber of up to greater than 20 feet in length. In one configuration, the lumber grabber  100  includes a frame, a set of movable carriages movably supported by the frame, two sets of forks, each set of forks positioned on one of the movable carriages at either end of the frame and arranged diametrically opposed to each other, a motor, a set of one or more rotatable ball screw shafts connected to and driven by the motor and to the movable carriages, to change relative positions of the movable carriages at either end of the frame; thereby enabling grasping and ungrasping of packages of lumber under programmed control of a programmable controller executing stored instructions. 
     This system implementation and other systems disclosed optionally include one or more of the following features. System can also include features described in connection with methods disclosed. In the interest of conciseness, alternative combinations of system features are not individually enumerated. Features applicable to systems, methods, and articles of manufacture are not repeated for each statutory class set of base features. The reader will understand how features identified in this section can readily be combined with base features in other statutory classes. 
     One lumber grabber workstation implementation further includes a self-leveling device comprised of a plate positioned so that when the plate rests on a unit of lumber a slight slack rope condition is created in a crane to which the lumber grabber frame is attached, to force the forks of the grabber to level themselves to the unit of lumber. 
     In one lumber grabber workstation implementation, a hydraulic cylinder attached to the plate, enabling height of the plate to be set by allowing hydraulic fluid to flow out of a cylinder as it is compressed until a hoist of the crane reaches the commanded position. 
     In one lumber grabber workstation implementation, the commanded position is given by a PLC controller and Inventory Management system that tracks locations and dimensions of units of lumber in a warehouse. 
     One lumber grabber workstation implementation further includes a vision system that measures an exact height of the unit of lumber for verification. 
     One lumber grabber workstation implementation further includes thru-beam photo sensors mounted near the rear base of the forks to tell the programmable controller that the frame is in a clear position to close the forks to pick up the unit of lumber. 
     In one lumber grabber workstation implementation, a payload range includes a payload of up to 35,000 pounds (lbs). 
     In one lumber grabber workstation implementation, a width of lumber packages movable by the lumber grabber workstation is in a range between 72 inches to 96 inches. 
     In one lumber grabber workstation implementation, each set of forks has a travel distance in a range between 0 and 54 inches. 
     In one lumber grabber workstation implementation, the sets of forks have an opening width in a range between 0 and 108 inches. 
     In one lumber grabber workstation implementation, further includes mechanical latches that engage into slots automatically locking forks into place so that the forks cannot open during crane travel. 
     In one lumber grabber workstation implementation, further includes a set of absolute encoders, each connected to each ball screw to provide position feedback. 
     In one lumber grabber workstation implementation, further includes an extreme open and closed proximity switch for double verification of fork position. 
     A method implementation of the technology disclosed includes a method of grasping packages of lumber of 8 feet up to greater than 20 feet in length. The method can include lowering using a hoist of a crane a lumber grabber down to pick up a unit of lumber, wherein a movable plate attached to the lumber grabber via a hydraulic cylinder is in a fully down position due to gravity. As the hoist lowers, the plate will make contact with a top of the lumber unit, substantially contemporaneously with the hoist of the crane continuing to lower thereby creating a slack rope condition in the hoist. Opening valving on the hydraulic cylinder allows the lumber grabber to lower. Detecting using thru-beam photo sensors mounted near a rear base of forks on either side of the lumber grabber that the lumber grabber is in a clear position to close the forks to pick up the unit of lumber is also part of the method. Closing valves on the hydraulic cylinder when the lumber grabber lowered to a commanded height to pick up the unit of lumber. The method also includes commencing raising by the hoist of the crane the lumber grabber the unit of lumber when the forks are closed. 
     Each of the features discussed in this particular implementation section for the first system implementation apply equally to this method implementation. As indicated above, all the system features are not repeated here and should be considered repeated by reference. 
     In one implementation, our method further includes measuring with load cells a weight of the unit of lumber while the lumber grabber is holding the unit of lumber. 
     In one implementation, our method further includes moving the unit of lumber with the crane to a next drop position under guidance from a 3D vision system, a proximity to surface sensor such as a laser ranging device/sensor, vision system, or other types of sensors, e.g., tactile, sonic, etc., or the like or a combination of thereof. 
     In one implementation, our method further includes lowering the hoist. When the hoist has lowered to an approximate height, e.g., as detected by a proximity to surface sensor such as a laser ranging device/sensor, vision system, or other types of sensors, e.g., tactile, sonic, etc., or the like or a combination of thereof, slowing a lowering rate of the hoist until load cells (sensors of the crane) detect that loading on the cable suspending the lumber grabber has fallen to/below a threshold, indicating that the unit of lumber has been fully placed. Actuating latch actuators allowing the forks to open; commence raising the hoist when the forks have fully opened; and open the hydraulic valve allowing the plate to lower are also part of this implementation of our method. 
     In one implementation, our method further includes tracking, using an Inventory Management system, locations of units of lumber in a warehouse in which the lumber grabber is situated. 
     In one implementation, our method further includes tracking, using an Inventory Management system, dimensions of units of lumber in a warehouse in which the lumber grabber is situated. 
     Other implementations may include a non-transitory computer readable storage medium storing instructions executable by a processor to perform a method as described above. Yet another implementation may include a system including memory and one or more processors operable to execute instructions, stored in the memory, to perform a method as described above.