Patent Application
20230158676
Robots have been provided to perform a variety of tasks, such as manipulating objects. For example, a robotic arm having an end effector may be used to pick and place items. Examples of commercial applications of such robots include sortation, kitting, palletization, depalletization, truck or container loading and unloading, etc.
In some contexts, the objects to be handled vary considerably in size, weight, packaging, and other attributes. Typically, a robotic arm is rated to handle up to a maximize size, weight, etc. of object. In some contexts, the conventional approach may require a robotic arm able to handle the largest, heaviest, and/or otherwise most difficult object that may be required to be handled.
Various embodiments of the invention are disclosed in the following detailed description and the accompanying drawings.
The invention can be implemented in numerous ways, including as a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer readable storage medium; and/or a processor, such as a processor configured to execute instructions stored on and/or provided by a memory coupled to the processor. In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Unless stated otherwise, a component such as a processor or a memory described as being configured to perform a task may be implemented as a general component that is temporarily configured to perform the task at a given time or a specific component that is manufactured to perform the task. As used herein, the term ‘processor’ refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions.
A detailed description of one or more embodiments of the invention is provided below along with accompanying figures that illustrate the principles of the invention. The invention is described in connection with such embodiments, but the invention is not limited to any embodiment. The scope of the invention is limited only by the claims and the invention encompasses numerous alternatives, modifications and equivalents. Numerous specific details are set forth in the following description in order to provide a thorough understanding of the invention. These details are provided for the purpose of example and the invention may be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical material that is known in the technical fields related to the invention has not been described in detail so that the invention is not unnecessarily obscured.
A system is disclosed to coordinate and control the use of multiple robots to collaboratively pick and place a package. In various embodiments, a system as disclosed herein may have one or more of the following technical features:
In various embodiments, multiple robotic arms are used to collaboratively pick and place a single package. In some embodiments, a robotic singulation (or other pick/place) system detects that an object should be picked collaboratively using two or more robots, e.g., due to the object's size, weight, previous failed pick attempts, visual classification and/or affordance mismatch between objects and individual robot grippers.
In various embodiments, when both robots have stopped picking independently, the system decides how best to pick the object, ensuring that the grasp points are within reach of the robots, and on opposite sides of the object. Robots clear any surrounding packages that might block the robots from picking the desired package. The robots plan paths independently to get to the pick positions on either side of the object. Once both are in place, the lead robot begins moving back, and the following robot maintains its relative position/orientation to the lead bot, while also using force control to maintain contact with the box, which allows the robots to collaboratively lift and move heavy or oversized objects.
Additional techniques implemented in various embodiments include, without limitation, one or more of:
To initiate the operation, in various embodiments, as “leader” robotic arm 202 would move its end effector 204 to the position shown and would then grasp the box 210, e.g., by moving the end effector 204 into a position in contact or nearly in contact with the side of box 210 and applying suction. A signal may be sent to the other robot (and/or a process to control the other robot) to indicate that the leader has completed its grasp. The follower, e.g., robotic arm 206 in this example, would then grasp the box 210, e.g., at a side opposite from the side at which the leader (i.e., robotic arm 202) had grasped the box 210. The follower would record a transform based on the position and orientation of the leader's end effector 204 and the relevant dimension of box 210. For example, the vision system and/or other sensors may be used to measure the dimension, or to recognize the box 210 (e.g., specifically and/or by type) and to use the item and/or type information to determine the dimension, e.g., by look up.
As shown in
Once the object (box 210) has been placed in the destination position, as shown in
In the example shown, robotic control system 302 includes a hierarchical planner, scheduler, and/or control module comprising a robot cooperation facilitation module 304 configured to facilitate cooperative performance of tasks by two or more robots, as disclosed herein, and robot-specific controllers 306 and 308. For example, robot 1 controller 306 may be associated with robotic arm 102 of
In various embodiments, the respective robots associated with robot 1 controller 306 and robot 2 controller 308, respectively, each may operate independently, e.g., to pick and place objects the robot is able to handle singly. In various embodiments, cooperative tasks using two or more robots may be initiated and/or performed by one or more of communications sent between robot 1 controller 306 and robot 2 controller 308; bilateral communications between robot cooperation facilitation module 304, on the one hand, and the respective robot 1 controller 306 and robot 2 controller 308, on the other; and/or communications among all three (or more) entities.
In the example shown, robotic control system 302 further includes a computer vision subsystem 310 configured to receive image and depth data from one or more 3D cameras and/or other sensors, such as camera 114 of
In the example shown, in state 402 a robot works independently to perform tasks. For example, the robot may independently pick and place items, such as to fill a box or other receptacle in a kitting operation, place items on a conveyer belt or other conveyance in a sortation operation, stack items on a pallet, etc. Upon receiving an indication that help is needed to perform a task (404), such as an indication that an item that has been perceived and which needs to be picked and placed is too large to grasp and move with one robot, the robot and/or controller transitions to a state 406 in which cooperative performance of the task is initiated. For example, a communication may be sent to another robot (e.g., from robot 1 controller 306 to robot 2 controller 308 of
In the example shown, the robot and/or controller may transition back to working independently in state 402, via a “cancel help” transition 408. For example, the robot/controller and/or a higher-level planner/scheduler may determine that the task has already been performed by and/or assigned to one or more other robots.
In some embodiments, in the “initiate cooperation” state 406, the robot/controller that is initiating cooperative performance of the task communicates directly or indirectly with a helper robot, e.g., by requesting help. Another robot may be assigned to help and/or may agree to help. The robot may be assigned and/or agree to help at a future time or upon occurrence of a future condition, such as completion of a task the helper robot has already started and/or a task that has higher priority. For example, a task to clear other objects from around the large or heavy object, to facilitate the cooperative task, may have a higher priority and therefore may be completed first. Once the helper robot is ready to perform the cooperative task, the helper robot informs the task initiator, directly or indirectly (e.g., via a higher-level planner/scheduler, such as robot cooperation facilitation module 304 of
Once all participating robots are ready in the “start cooperation” state 412, a “leader” is determined, if needed, and the leader transitions (416) to “do leader” state 418 while the follower(s) transition (420) to “do follower” state 422. In the “do leader” state 418 and “do follower” state 422, the leader and follower(s) cooperate as disclosed herein to cooperative perform the task, such as to pick and place a large or heavy object, as in the example illustrated in
In the example shown, at 502 an indication to begin a cooperative task (with one or more other robots) in the role of “leader” is received. For example, an indication to cooperatively perform a pick and place task may be received. At 504, the leader determines a location at which to grasp the object and plans a trajectory to safely move its end effector into position to grasp the object and at 506 the leader moves its end effector along the trajectory to the grasp position. At 508, the leader determines (independently of any other robot) a trajectory to move the object to an associated destination. For example, a model of the robot and its kinematics and image and/or other information about the workspace (e.g., configuration data, CAD files, etc.), one or more attributes of the object (e.g., dimensions, rigidity, etc.), and image/sensor data may be used to plan the trajectory. At 510, an indication is received from the “follower” robot(s) with which the robot implement process 500 is to cooperate that the follower robot(s) is/are ready to begin cooperative performance of the task. In response, at 512 the “leader” robot moves its end effector (and the object in the joint grasp of the leader and follower(s)) to the destination along the trajectory determined by the leader. At 514, upon placing the object at the destination the leader robot releases its grasp and informs the follower robot(s) that the task has been completed. In various embodiments, the leader then resumes operating independently.
In the example shown, at 522 an indication is received to begin performing a task cooperatively with one or more other robots in the “follower” role, as disclosed herein. At 524, the follower determines a grasp point—e.g., one on an opposite side of the object from the side at which the “leader” has indicated it will grasp the object—and plans a trajectory to move into position to grasp the object at that point. At 526, the follower moves its end effector to the determined grasp position and grasps the object, e.g., in response to receiving an indication that the leader has completed its grasp. At 528, the leader's end effector position and orientation information are received, and the follower uses this information along with information about the object (e.g., the size of the object in the dimension that separates the leader's end effector and the follower's end effector) and computes a transform. In various embodiments, the transform comprises a matrix or other mathematical construct that can be applied to the position and orientation of the leader's end effector, typically expressed in the leader's frame of reference, to provide a corresponding position and orientation for the follower's end effector that would maintain the relative position and orientation of the follower's end effector with respect to the leader's end effector as the end effectors and the object grasped between them are moved through the workspace to the destination at which the object is to be placed. At 530, the follower robot informs the leader that the follower is “ready”, e.g., the follower has grasped the objected, computed the transform, and is ready to maintain the position of its end effector relative to (e.g., opposite) the leader's end effector.
At 532, as the leader robot begins to move along the trajectory determined independently by the leader, the follower uses the transform it computed and successively received position and orientation information for the leader's end effector, as it is moved through the workspace. For example, for each of at least a subset of the received positions and/or orientations of the leader's end effector, the follower computes a new goal position and/or orientation for its own end effector and applies torques to it motors as determined to be needed to minimize the error (e.g., difference) between the current position and/or orientation of its end effector and the current goal.
At 534, the follower receives an indication (e.g., from the leader) that the cooperative task is “done”, in response to which the follower releases its grasp and the process 520 ends.
In various embodiments, techniques disclosed herein are used to cooperatively perform pick and place tasks, e.g., in connection with singulation/sortation, kitting, palletization or depalletization, and/or truck or other container loading or unloading.
In various embodiments, in the mode of operation shown in
In various embodiments, robots 202, 206 cooperate as disclosed herein to pick and place the large box. For example, robot 202 may operate as the “leader” robot, implementing process 500 of
Once done placing the large box shown in
In some cases, a robot may not be able to see its pick location clearly. In some embodiments, such a robot may use force sensors or other tactile feedback to feel its way into position to grasp the object.
Once every participating robot has a clear path to its pick position (712, 714), the robots work cooperatively to perform the pick and place task, as disclosed herein. For example, one robot may operate as the “leader”, implementing process 500 of
In various embodiments, techniques disclosed herein may be employed to use two or more robots to cooperatively pick and place an object, such as an object that is too heavy, floppy, bulky, etc. for a single robot to pick and place.
Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative and not restrictive.
This application claims priority to U.S. Provisional Patent Application No. 63/274,465 entitled CONTROLLING MULTIPLE ROBOTS TO COOPERATIVELY PICK AND PLACE ITEMS filed Nov. 1, 2021, which is incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63274465 | Nov 2021 | US |
