Patent Application
20210023713
Industrial robots are well known in the art. Such robots are intended to replace human workers in a variety of assembly tasks. It has been recognized that in order for such robots to effectively replace human workers in increasingly more delicate and detailed tasks, it will be necessary to provide sensory apparatus for the robots which is functionally equivalent to the various senses with which human workers are naturally endowed, for example, sight, touch, etc.
In robotic picking applications for small part assembly, warehouse/logistics automation, food and beverage, etc., a robot gripper needs to pick an object, then insert/place it accurately into another part. There are some traditional solutions: (1.) Customized fingers on the gripper can self-align the part to a fixed location relative to the gripper. But for different shape of the part, a different type of finger has to be made and changed. (2.) After picking up the part, the robot brings the part in front of a camera and a machine vision system detects the location of the part relative the gripper. But this extra step increases the cycle time for the robot system. (3.) The part is placed on a customized fixture and the robot is programmed to pick up the part at the same location each time. But various fixtures have to be made for different parts which may not be cost effective to produce.
Of particular importance for delicate and detailed assembly tasks is the sense of touch. Touch can be important for close-up assembly work where vision may be obscured by arms or other objects, and touch can be important for providing the sensory feedback necessary for grasping delicate objects firmly without causing damage to them. Touch can also provide a useful means for discriminating between objects having different sizes, shapes or weights. Accordingly, various tactile sensors have been developed for use with industrial robots.
However, there are problems such as easy wear and tear damage with this sensor for robotic picking and assembly applications that need to be overcome. In this problem, the robot hand is constantly picking parts and assembling parts which means that the finger/gripper surface is prone to abrasion/wear. This implies that any tactile sensing which employs fragile thin film coatings at grip points can easily wear off. Also, any elaborate light/LED source configuration limits the size of the in-hand object location system. An additional problem is the size of the light source and sensor are too big to mount on small robotic fingers to pick up small objects. Thus, mounting an elaborate light source for in-hand perception is not feasible. The current state of the art lacks information on object handling/gripping as a part of the robot hand.
Further, there are problems such as easy wear and tear damage with this sensor for robotic picking and assembly applications that need to be overcome. In this problem, the robot hand is constantly picking parts and assembling parts which means that the finger/gripper surface is prone to abrasion/wear. This implies that any tactile sensing which employs fragile thin film coatings at grip points can easily wear off. Also, such an elaborate light/LED source limits the size of the in-hand object location system. Therefore, an additional problem is the size of the light source and sensor may be too big to mount on small robotic fingers to pick up small objects. Thus, mounting an elaborate light source for in-hand perception is not feasible. Another problem is that adding an in-hand light source and detector means that there will be a need for an extra calibration step.
The invention provides a method of automated in-hand calibration including providing at least one robotic hand including a plurality of grippers connected to a body and providing at least one camera disposed on a periphery surface of the plurality of grippers. The method also includes providing at least one tactile sensor disposed in the at least one illumination surface and actuating the plurality of grippers to grasp an object. The method further includes locating a position of the object with respect to the at least one robotic hand and calibrating a distance parameter via the at least one camera. The method also includes calibrating the at least one tactile sensor with the at least one camera and generating instructions to grip and manipulate an orientation of the object via an image feed from the at least one camera for a visualization of the object. The at least one robotic hand, the plurality of grippers, the at least one camera and the at least one tactile sensor are electrically connected to a controller. The method further includes gripping and manipulating the object based on the generated instructions and a first determining whether or not a feed from the visualization of the object correlates with the generated instructions. The method also includes a first correcting the gripping and manipulating of the object based on the first determining and a second determining whether or not a feed from the at least one tactile sensor correlates with the generated instructions. The method further includes a second correcting the gripping and manipulating of the object based on the second determining and placing the object in an assembly of parts.
The invention provides a robotic hand including a plurality of grippers and a body and at least one camera disposed on a periphery surface of the plurality of grippers. The invention also includes at least one illumination surface disposed on a periphery surface of the plurality of grippers and at least one tactile sensor disposed in the at least one illumination surface. The at least one robotic hand, the plurality of grippers, the at least one camera, the at least one illumination surface and the at least one tactile sensor are electrically connected to a controller.
The invention provides a non-transitory computer-readable medium storing instructions that, when executed by a processor of a computer, cause the processor to perform operations which include actuating the plurality of grippers to grasp an object and locating a position of the object with respect to the at least one robotic hand. The invention also includes calibrating a distance parameter via the at least one camera and calibrating the at least one tactile sensor with the at least one camera. The invention further includes generating instructions to grip and manipulate an orientation of the object via an image feed from the at least one camera for a visualization of the object.
All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
The lack of information about the workpiece/object and its dimensions/surface characteristics is a major hurdle in planning the next optimization steps for object handling. Such an in-hand object recognition system can not only provide information about the object but also serve as a method for automatic calibration for the in-hand object location system, wherein a known motion is performed with the object as a reference point.
Referring now to
Referring now to
Referring now to
Referring now to
Further, the in-hand sensor 40 may include a block of transparent rubber or gel, one face of which is coated with metallic paint. When the paint-coated face is pressed against an object, it conforms to the object's shape. The metallic paint makes the object's surface reflective, so its geometry becomes much easier for computer vision algorithms to infer. Mounted on the sensor opposite the paint-coated face of the rubber block are colored lights/LEDs 50a-d and a single camera 45. This system needs to have colored lights at different angles, and then it has the reflective material, and by looking at the colors, a computer can figure out a 3-D shape of what is being sensed or touched.
Referring now to
In some embodiments, gripping surfaces 75a, 75b include a layer of pressure generated illumination surfaces 85 comprised of pressure sensitive luminescent films. Using an in-hand object location system with pressure sensitive illumination can allow easy perception of the part of an object that has been gripped without the need for an elaborate light source. Illumination surfaces 85 may generate enough light to act as a light source for camera 80 to receive better imagery of object 90 as it is manipulated in-hand. In some embodiments, surfaces 85 illuminate upon coming into contact with an object 90 via a pressure-activated glow effect triggered by pressure on object 90. Gripping surfaces 75a, 75b, camera 80 and grippers 95a, 95b may be electrically and mechanically connected to a power source and control system 103 (
In
One embodiment of the invention can be a rod or object 90 that needs to be picked and inserted into a fixture (not shown). In order for the in-hand object location system 70 to automatically calibrate itself, the robotic hand at 70 gets close enough to the object 90 and glides over the object 90 in a way that it covers one end of the rod or object 90 to the other. Now the robotic hand at 70 has information about the geometry of the object 90 relative to the robotic hand at 70. It may to do the same process for the fixture as well. Now as a form of smart training, the robotic hand at 70 will grasp this rod or object 90 from an end opposite to an end being inserted into the fixture.
Referring now to
Referring now to
In certain embodiments, the in-hand object location system 70 may be calibrated in two ways: 1.) The first form of calibration is an intrinsic parameter calibration, includes conversion of the analog sensor signal to the location of the object 90 relative to in-hand sensor with approximately mm resolution. This may also include the conversion of pixel location to xyz coordinates. This calibration may be to compensate for distortion due to degradation of sensor or slight orientation corrections; and 2.) The second form of calibration is an extrinsic parameter calibration. The extrinsic parameters are for the model which transforms the object 90 coordinates relative to the in-hand sensors 75a, 75b to coordinates relative to the robot tool at 95a, 95b.
Referring now to
At 182, object 90 is picked using training data and calibration data. At 184, once picked, the object 90 is visualized using the in-hand objection location system 70. If the visualization is different from the training steps discussed above, then at 186 a check is performed to see if the robotic hand at 70 can correct the difference. If the robotic hand at 70 cannot make the correction, the object 90 is dropped and re-picked to restart the process. If the robotic hand at 70 can make the correction, a manipulation at 190 is performed to make such correction. At 198, the robotic hand at 70 places the object 90 or performs an assembly of parts and the process ends or restarts to pick the next object. At 184, if the object is the same as in the training step a successful pick at 199 is performed. Then at 198, as discussed above, the robotic hand at 70 places the object 90 or performs an assembly of parts and the process ends or restarts to pick the next object.
At 192, a sensor 75a, 75b check is performed to see if the sensor data looks as expected based on object 90. If the sensor data does look as expected, then at 194 a calibration for intrinsic parameter changes (such as degradation of sensor) and extrinsic parameter changes (such as change of in-hand location) is performed. At 196, if the sensor data deviation when compared to the calibration data is under a threshold, then the object pick continues without correction.
In certain embodiments, a robotic hand at 70 can generate a known motion at 99 to calibrate the in-hand object location system 70. This would involve the robotic hand at 70 to repeat a gripping action or traversing the entirety of the object 90 in a known trajectory to calibrate according to the object's location information, such as the relative distance between different features on the object 90 or the relative distance the object 90 and the robotic hand itself. Since the image feed can serve as a calibration of distance of the grippers 95a, 95b from object 90 and dimensional information about the object 90 itself, this can allow automated calibration of the in-hand object location system 70. This will significantly optimize how the robotic hand at 70 will proceed with the next steps for object 90 manipulation, can be used to generate a smart suggestion for easier picking/gripping.
In some embodiments, the interesting utility of this invention also lies in the fact that the calibration can not only be done as an automatic calibration operation, as shown in the flowchart of
The scope of the in-hand calibration movement 99 or grasping-attempts can also feed into the data already received by the vision system 170 and the initial synthetic data about the object 90.
Referring now to
Referring now to
Referring now to
The various embodiments described herein may provide the benefits of a reduction in the engineering time and cost to design, build, install and tune a special finger, or a special fixture, or a vision system for picking, placing and assembly applications in logistics, warehouse or small part assembly. Also, these embodiments may provide a reduction in cycle time since the robotic hand can detect the position of the in-hand part right after picking the part. Further, these embodiments may provide improved robustness of the system. In other words, with the highly accurate in-hand object location and geometry, the robot can adjust the placement or assembly motion to compensate for any error in the picking. Moreover, these embodiments may be easy to integrate with general purpose robot grippers, such as the robotic YUMI hand, herein incorporated by reference, for a wide range of picking, placing and assembly applications.
The techniques and systems disclosed herein may be implemented as a computer program product for use with a computer system or computerized electronic device. Such implementations may include a series of computer instructions, or logic, fixed either on a tangible/non-transitory medium, such as a computer readable medium 300 (e.g., a diskette, CD-ROM, ROM, flash memory or other memory or fixed disk) or transmittable to a computer system or a device, via a modem or other interface device, such as a communications adapter connected to a network over a medium.
The medium 300 may be either a tangible medium (e.g., optical or analog communications lines) or a medium implemented with wireless techniques (e.g., Wi-Fi, cellular, microwave, infrared or other transmission techniques). The series of computer instructions (e.g.,
Furthermore, such instructions (e.g., at 400) may be stored in any tangible memory device 405, such as semiconductor, magnetic, optical or other memory devices, and may be transmitted using any communications technology, such as optical, infrared, microwave, or other transmission technologies.
It is expected that such a computer program product may be distributed as a removable medium with accompanying printed or electronic documentation (e.g., shrink wrapped software), preloaded with a computer system (e.g., on system ROM or fixed disk), or distributed from a server or electronic bulletin board over the network (e.g., the Internet or World Wide Web). Of course, some embodiments of the invention may be implemented as a combination of both software (e.g., a computer program product) and hardware. Still other embodiments of the invention are implemented as entirely hardware, or entirely software (e.g., a computer program product).
As will be apparent to one of ordinary skill in the art from a reading of this disclosure, the present disclosure can be embodied in forms other than those specifically disclosed above. The particular embodiments described above are, therefore, to be considered as illustrative and not restrictive. Those skilled in the art will recognize, or be able to ascertain, using no more than routine experimentation, numerous equivalents to the specific embodiments described herein. Thus, it will be appreciated that the scope of the present invention is not limited to the above described embodiments, but rather is defined by the appended claims; and that these claims will encompass modifications of and improvements to what has been described.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the description herein. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
