An adaptive electromagnetic driven manipulator for stable transportation and its gripping method

Abstract

The present invention discloses an adaptive electromagnetic driven manipulator for stable transportation and a clamping method thereof. The manipulator includes a base, a main body cover, clamping fingers and a detection component. The four clamping fingers are all mounted on the base and arranged in sequence along the circumference of the central axis of the base. The clamping fingers include a slider, a push-pull electromagnet, a force transmission rod, a clamping rod and a clamping claw. The slider is slidably connected to the side of the base; one end of the force transmission rod is rotatably connected to the slider. The inner end of the clamping rod is rotatably connected to the base. The middle part of the clamping rod is rotatably connected to the other end of the force transmission rod. The slider is driven by a push-pull electromagnet to slide back and forth. The present invention utilizes a camera, an oblique distance measuring sensor and a vertical distance measuring sensor to cooperate to realize the recognition of the contour size and height of complex arc-shaped objects, thereby judging whether the object can be clamped and selecting the best clamping method.

Description

Background Art

[0001] In recent years, with the rapid development of robotics and artificial intelligence technologies, robots and intelligent devices have gradually become part of everyday life. Simultaneously, with the emergence of issues such as an aging population, the demand for companion and household robots is also growing. However, current robotic arms are still in their infancy. Existing robotic arms on the market are generally expensive and complex to control. Most are designed for specific scenarios and are not suitable for gripping other objects. Real-world robotic arms need to grip a wide range of objects of varying sizes and shapes. Most commercially available robotic arms for these diverse situations use designs that mimic human fingers. However, finger-like arms are complex, costly to manufacture, and lack stability, raising the bar for use and reducing their practicality. Simpler claw-shaped arms are also difficult to use due to their limited claw shape, resulting in easy drops and difficulty controlling gripping force. Most commercially available robotic arms use hydraulic, pneumatic, or electric motors for drive. The present invention utilizes electromagnetic and spring drives, which are easier to control and further reduce cost and accessibility. The robot is equipped with two sets of distance sensors and cameras. After calculating the positioning using contour extraction analysis and center of mass estimation algorithms, the robot can be moved to the top of the object to scan and grasp it. In the control of traditional finger-type robots, knowing the center of mass alone is far from enough. Many calculations must be performed based on the shape and size of the object before it can be grasped. The design of this robot can avoid such complex calculations. The two sets of distance sensors can find the appropriate height and use different gripping methods according to the shape of the object. The design principle solves the problem of gripping and robot positioning of objects with complex shapes such as spheres, cylinders, and cones based on arcs. The robot design has added auxiliary fingers and pressure fingers to prevent objects from falling out of the robot when using direct gripping or specific shoveling actions, greatly increasing the stability of the robot during transportation. Summary of the Invention

[0002] The present invention aims to provide a self-adaptive electromagnetic driven manipulator for stable transportation and a gripping method thereof.

[0003] An adaptive electromagnetically driven manipulator for stable transportation comprises a base, a main body cover, gripping fingers, and a detection assembly. Four gripping fingers are mounted on the base and arranged in sequence along the circumference of the central axis of the base. The gripping fingers comprise a slider, a push-pull electromagnet, a force transmission rod, a gripping rod, and a clamping claw. The slider is slidably connected to the side of the base; one end of the force transmission rod is rotationally connected to the slider. The inner end of the gripping rod is rotationally connected to the base. The middle portion of the gripping rod is rotationally connected to the other end of the force transmission rod. The slider is driven by the push-pull electromagnet to slide back and forth.

[0004] When the four gripping fingers flip inward to their extreme position of approaching each other, the manipulator enters a clamping state. When the four gripping fingers flip outward to their extreme position of separation, the manipulator enters a released state. The gripping jaws are fixed to the bottom end of the gripping rod. The gripping jaws consist of a main body and a gripping point at the end of the main body. In the clamping state, the inner sides of the gripping points at the bottom of the four gripping jaws can be combined to form a square pyramid-shaped load-bearing concave surface.

[0005] The four jaws have an arcuate groove on one side of their main body. The grooves on adjacent jaws are located on opposite sides. The four arcuate grooves are divided into two groups of two. When clamping, the two arcuate grooves in the same group join together to form a U-shaped support groove.

[0006] The detection assembly includes an oblique distance sensor, a vertical distance sensor, and a camera. The camera and vertical distance sensor are fixed to the bottom of the base. The axes of the camera and vertical distance sensor are parallel to the central axis of the base. The center of the camera lens is on the central axis of the base. The distance between the detection portion of the vertical distance sensor and the central axis of the base is equal to the distance between the clamping jaws and the central axis of the base when the clamp is in the released state.

[0007] An oblique distance measuring sensor is fixed on one of the clamping fingers or on the clamping fingers of two clamping fingers facing each other. In a released state, the detection direction of the oblique distance measuring sensor is tilted toward the side away from the base.

[0008] Preferably, the adaptive electromagnetically driven manipulator for stable transport further includes two first auxiliary assemblies and two second auxiliary assemblies. A first auxiliary assembly or a second auxiliary assembly is disposed between each of two adjacent gripping fingers. Two first auxiliary assemblies and two second auxiliary assemblies are provided, and the two first auxiliary assemblies and the two second auxiliary assemblies are alternately arranged along the circumference of the base. The positions of the two second auxiliary assemblies correspond to the positions of the two sets of arc-shaped grooves, respectively.

[0009] The first auxiliary component includes a first telescopic bracket and an auxiliary finger. The first telescopic bracket includes two first connecting cylinders and a first V-shaped rod. The opposite ends of the two first connecting cylinders and the two ends of the first V-shaped rod respectively form a cylindrical pair. The opposite ends of the two first connecting cylinders and the middle parts of the clamping rods in the two adjacent clamping fingers respectively form a rotating pair. The common axis of the rotating pair formed by the first connecting cylinder and the clamping rod (7) is perpendicular to the common axis of the rotating pair formed by the clamping rod and the base. The top of the auxiliary finger is fixed to the middle part of the first V-shaped rod. The bottom end of the auxiliary finger is provided with an auxiliary support plate; in the clamping state, the two side edges of the auxiliary support plate are spliced ​​with the adjacent side edges of the two adjacent clamping claws.

[0010] The second auxiliary assembly includes a second telescopic bracket and a pressure finger. The second telescopic bracket includes two second connecting cylinders and a second V-shaped rod. The opposing ends of the two second connecting cylinders form cylindrical pairs with the ends of the second V-shaped rod. The opposing ends of the two second connecting cylinders form spherical pairs with the middle portions of the clamping rods of two adjacent clamping fingers. The pressure finger is fixed to the middle portion of the second V-shaped rod.

[0011] Preferably, the base is provided with four chute grooves, evenly distributed along the circumference of the base's central axis. The length of the chute grooves is arranged along the base's central axis. The four chute grooves correspond to the four gripping fingers, respectively; the sliders are slidably connected within the corresponding chute grooves.

[0012] Preferably, the clamping rod is L-shaped.

[0013] Preferably, the electromagnet body of the push-pull electromagnet is fixed in the corresponding slide slot. The outer end of the push rod of the push-pull electromagnet 4 is fixed to the slider. A spring is sleeved on the outer side of the push rod; the two ends of the spring respectively press against the electromagnet body and the slider.

[0014] Preferably, two side edges of the main body of the clamping jaw are parallel to each other.

[0015] The clamping method of the adaptive electromagnetic driven manipulator for stable transportation includes the following steps:

[0016] Step 1: The robot moves to a position above the target object; the vertical ranging sensor measures the distance Z0 from itself to the table where the target object is placed; then, the robot moves horizontally to the top of the target object.

[0017] Step 2: The camera captures an image of the target object; based on the position of the target object in the image, the robot moves horizontally so that the robot moves directly above the target object.

[0018] Step 3: Determine whether the shape of the target object exceeds the standard.

[0019] 3-1. Determine whether the outline size of the target object exceeds the standard.

[0020] The mobile platform drives the manipulator to rotate around the central axis of the base; during the rotation of the manipulator, the vertical ranging sensor continuously detects the distance value.

[0021] During the manipulator's rotation, if the distance value measured by the vertical ranging sensor remains within the permissible error range (Z0), the target object's outline size is considered within the specified range. Otherwise, the target object's outline size is considered to be exceeded, and the manipulator's rotation angle range S is recorded when the distance value measured by the vertical ranging sensor exceeds the permissible error range (Z0). If two 45° angle intervals, 180° apart, exist around the central axis of the base that completely cover the rotation angle range S, the target object is considered to be a horizontally placed, elongated object.

[0022] 3-2. Determine whether the height of the target object exceeds the standard.

[0023] The robot is controlled to descend intermittently, with each descent distance defined as ΔZ. After each descent, the difference ΔX between the distance X measured before and the distance X' measured after the descent is calculated. If ΔX·sinα-ΔZ < s, the robot continues descending. s is the preset tolerance. If ΔX·sinα-ΔZ ≥ s, the object's height is calculated as H = ΔX·sinα-ΔZ. α is the angle between the oblique ranging sensor and the horizontal plane when the sensor is released. If the height H exceeds the preset maximum height, the target object is considered to be out of range.

[0024] Step 4: For the following three situations, give up gripping or grip the target object in a corresponding way.

[0025] Case 1: The target object's outline size exceeds the standard and is not judged as a horizontally placed long object, or the target object's height exceeds the standard; the target object is judged to be unable to be gripped.

[0026] Case 2: The target object's outline size and height do not exceed the standard, and it is determined that the target object can be grasped, and the robot arm grasps the target object.

[0027] Case 3: The target object's outline size exceeds the standard and is judged to be a horizontally placed long object. The height of the target object does not exceed the standard. It is judged that the target object can be gripped. The gripping method is as follows: the robot arm rotates around the central axis of the base so that the arrangement direction of the two sets of arc-shaped grooves is parallel to the length direction of the target object; the four gripping fingers lift the target object so that the target object falls into the U-shaped support groove formed by the two sets of arc-shaped grooves.

[0028] As a preference, the specific process of step 2 is as follows:

[0029] 2-1. The camera captures an image of the target object.

[0030] 2-2. Convert the image obtained in step 2-1 into a grayscale image.

[0031] 2-3. Convert the grayscale image obtained in step 2-2 into a binary image.

[0032] 2-4. Perform contour extraction on the binary image obtained in step 2-3 to obtain a contour image;

[0033] 2-5. Extract the centroid coordinates of the contour in the contour image obtained in step 2-4

[0034] 2-6. If the image offset distance D is greater than the allowable error σ, move the robot along The direction of the vector moves by a preset distance ε. The expression of the image offset distance D is as follows

[0035]

[0036] 2-7. Repeat steps 2-1 to 2-6 until the image offset distance D is greater than or equal to the allowable error σ.

[0037] Preferably, in step 4, if condition 2 is met, the clamping method is as follows:

[0038] The manipulator continues to move downward, and when the oblique ranging sensor detects the side of the target object, the manipulator descends intermittently;

[0039] Each time the manipulator descends, the mobile platform drives the manipulator to rotate around the central axis of the base, and the oblique distance sensor continuously detects the distance value x i ; Calculate the average distance S x as follows:

[0040]

[0041] Where n is the number of sampling times of the oblique ranging sensor during the rotation of the manipulator.

[0042] If the robot is intermittently descending, the average distance S x If it continues to increase, it is judged that the target object has a pointed cone structure;

[0043] If the robot is intermittently descending, the average distance S x If it continues to decrease, the target object is judged to have a funnel-shaped structure;

[0044] If the robot is intermittently descending, the average distance S x If it decreases first and then increases, the target object is judged to have a waist-shaped structure;

[0045] Otherwise, it is judged that the target object has a common structure;

[0046] For target objects with pointed cone structures and ordinary structures, the robot grips the target object by scooping it up from the bottom.

[0047] For funnel-shaped target objects, the robot grips the target object from the top edge of the target object.

[0048] For target objects with a waisted structure, the robot grips the target object from the narrowest part of the target object.

[0049] Preferably, in step four, if condition 3 is met, the manipulator lifts the target object by scooping, and the specific process is: first, the two gripping fingers located on one side of the target object rotate inward to a gripping state and move to the bottom edge of the target object; then, the bottom of the manipulator tilts toward the target object; finally, the two gripping fingers in the released state rotate inward to a gripping state, so that the target object leaves the table, thereby achieving gripping of the target object.

[0050] The beneficial effects of the present invention are:

[0051] 1. The four gripping fingers of the present invention can be controlled individually, and objects that are difficult to grip, such as spherical or long objects, can be gripped by scooping.

[0052] 2. The present invention utilizes a camera, an oblique distance measuring sensor and a vertical distance measuring sensor in combination to realize the recognition of the outline size and height of an object, thereby determining whether the object can be clamped and selecting the best clamping method.

[0053] 3. The present invention has auxiliary finger and pressure finger structures, which can prevent spherical objects and long objects from falling during movement.

[0054] 4. The present invention utilizes a spring to further increase the clamping force, and the spring itself does not consume electrical energy and does not require a hydraulic or pneumatic device to provide pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a structural schematic diagram of the present invention.

[0056] Figure 2a It is a structural schematic diagram of the base in the present invention.

[0057] Figure 2b Schematic diagram of the installation position of the slider and the push-pull electromagnet in the present invention.

[0058] Figure 3a This is the first schematic diagram of the clamping rod and the clamping jaw in the present invention (a schematic diagram showing the arc-shaped groove located on one side of the clamping jaw).

[0059] Figure 3b This is the second schematic diagram of the clamping rod and the clamping jaw in the present invention (a schematic diagram showing the arc-shaped groove on the other side of the clamping jaw).

[0060] Figure 4It is a schematic diagram of the process of scooping up the sphere according to the present invention.

[0061] Figure 5 Schematic diagram of clamping an object with a waist-tightening structure according to the present invention.

[0062] Figure 6 This is a flow chart of the present invention for detecting the shape of an object and clamping the object.

[0063] Figure 7 This is a schematic diagram of the present invention when detecting the height of an object.

[0064] Figure 8a This is a relationship diagram between the object outline and the motion trajectory of the vertical ranging sensor when the present invention detects an object whose outline size does not exceed the standard.

[0065] Figure 8b This is a diagram showing the relationship between the object outline and the motion trajectory of the vertical ranging sensor when the present invention detects a horizontally placed long object.

[0066] Figure 8c This is a relationship diagram between the object outline and the motion trajectory of the vertical ranging sensor when the present invention detects an object whose outline size exceeds the standard and is not an elongated object.

[0067] Among them, 1. Slider; 2. Base; 3. Oblique distance measuring sensor; 4. Push-pull electromagnet; 5. Main body cover; 6. Force transmission rod; 7. Clamping rod; 8. First hinge axis; 9. Second hinge axis; 10. Third hinge axis; 11 Fixed pin; 12. Main body pin; 13. Vertical distance measuring sensor; 14. Camera; 15. Clamping claw; 16. First telescopic bracket; 17. Second telescopic bracket; 18. Auxiliary finger; 19. Pressing finger; 20. Spring. Specific implementation methods

[0068] The present invention will be further described below with reference to the accompanying drawings.

[0069] like Figure 1 As shown, an adaptive electromagnetically driven manipulator for stable transport includes a base 2, a main body cover 5, gripping fingers, a first auxiliary component, a second auxiliary component, and a detection component. The four gripping fingers are mounted on the base 2 and are evenly distributed along the circumference of the base 2. The side of the base 2 is provided with four chute grooves 2-1, evenly distributed along the circumference of the central axis of the base 2. The main body cover 5 is fixed to the bottom end of the base 2 by a main body pin 12. The length of the chute grooves 2-1 is arranged along the central axis of the base 2.

[0070] The clamping finger includes a slider 1, a push-pull electromagnet 4, a first hinge shaft 8, a second hinge shaft 9, a third hinge shaft 10, a force transmission rod 6, a clamping rod 7 and a clamping claw 15. The slider 1 is slidably connected in the slide groove 2-1. One end of the force transmission rod 6 is rotationally connected to the slider 1 via the third hinge shaft 10. The clamping rod 7 is L-shaped, and the inner end is rotationally connected to the main body cover 5 via the second hinge shaft 9. The middle part of the clamping rod 7 is rotationally connected to the other end of the force transmission rod 6 via the first hinge shaft 8. The main body of the push-pull electromagnet 4 is fixed to the top of the corresponding slide groove 2-1 by a fixing pin 11. The outer end of the push rod of the push-pull electromagnet 4 is fixed to the slider 1. The expansion and contraction of the push-pull electromagnet 4 can drive the clamping rod 7 to flip and realize the clamping action. The spring 20 is placed on the outside of the push rod, and its two ends respectively press against the main body of the push-pull electromagnet 4 and the slider 1.

[0071] When the clamping claws 15 in the four clamping fingers are turned inward to the extreme position of being close to each other, the manipulator is in a clamping state. When the clamping claws 15 in the four clamping fingers are turned outward to the extreme state of being separated from each other, the manipulator is in a released state.

[0072] A clamping jaw 15 is fixed to the bottom end of the clamping rod 7. The jaw 15 consists of a main body and a clamping point 15-1 at the end of the main body. The two sides of the main body of the jaw 15 are parallel to each other. In the clamping state, the inner sides of the clamping points 15-1 at the bottom of the four jaws 15 form a square pyramid-shaped support concave surface, which can provide stable positioning and support for spherical objects.

[0073] The main body of each of the four gripping jaws 15 is provided with an arcuate groove 15-2 on one side; the arcuate grooves 15-2 on two adjacent gripping jaws 15 are located on opposite sides. In this configuration, the four arcuate grooves 15-2 are divided into two groups of two. In the clamping state, the two arcuate grooves 15-2 in the same group can be joined together to form a U-shaped support groove capable of supporting a long rod-shaped object. The two U-shaped support grooves provide stable positioning and support for the long rod-shaped object. Therefore, the robot arm provided by this application can stably grasp both spherical and long rod-shaped objects by lifting them.

[0074] A first auxiliary assembly or two second auxiliary assemblies are positioned between each pair of adjacent gripping fingers. Two first and two second auxiliary assemblies are provided, alternating along the circumference of the base 2. The positions of the two second auxiliary assemblies correspond to the positions of the two sets of arcuate grooves 15-2. The first auxiliary assembly is located between the sides of the main body of two adjacent gripping jaws 15 where no arcuate grooves 15-2 are located.

[0075] The first auxiliary assembly includes a first telescopic bracket 16 and an auxiliary finger 18. The first telescopic bracket 16 comprises two first connecting cylinders and a first V-shaped rod. The opposing ends of the two first connecting cylinders and the ends of the first V-shaped rod respectively form a cylindrical pair. The opposing ends of the two first connecting cylinders and the middle portions of the clamping rods 7 of two adjacent clamping fingers respectively form a revolute pair via a ball joint. The common axis of the revolute pair formed by the first connecting cylinder and the clamping rod 7 is perpendicular to the common axis of the revolute pair formed by the clamping rod 7 and the main body cover 5. The top of the auxiliary finger 18 is fixed to the middle portion of the first V-shaped rod. The bottom end of the auxiliary finger 18 is provided with an auxiliary support plate. The auxiliary support plate is triangular in shape, with two sides corresponding to the relative positions of the sides of the main body of two adjacent clamping jaws 15 in the clamping state without the arc-shaped groove 15-2. This plate can compensate for the gap formed between the two adjacent clamping jaws 15 and improve the support stability of spherical objects during movement of the manipulator (the movement direction must be consistent with the arrangement direction of the two first auxiliary assemblies during movement).

[0076] The second auxiliary component includes a second telescopic bracket 17 and a pressure finger 19. The second telescopic bracket 17 includes two second connecting cylinders and a second V-shaped rod. The opposite ends of the two second connecting cylinders and the two ends of the second V-shaped rod respectively form a cylindrical pair. The opposite ends of the two second connecting cylinders and the middle parts of the clamping rods 7 in the two adjacent clamping fingers respectively form a spherical pair through ball joints. The pressure finger 19 is fixed to the middle part of the second V-shaped rod. The pressure finger 19 is used to provide auxiliary fixation to the two sides of the long rod-shaped object when the manipulator clamps the long rod-shaped object, thereby improving the clamping stability of the long rod-shaped object.

[0077] Since the four gripping fingers can be controlled independently, for long rod-shaped objects, one of the gripping fingers can be controlled to flip downward first, and then the long rod-shaped object can be grabbed on a plane in a "scooping" manner.

[0078] During the clamping process of the clamping jaws 15, the spring 20 can resist the slider 1, providing a large enough spring force so that the four clamping fingers can close and clamp the object. The process of loosening the clamping jaws 15 is the opposite of the process of clamping the clamping jaws 15.

[0079] This embodiment has two gripping methods: the first gripping method is to grip after scooping, which divides the four grippers 15 into two groups, with two adjacent grippers 15 in one group. First, tilt the mechanical grippers 15, and then tighten the grippers 15 on the tilted side (if the object is too long but there is enough space to use the scooping action, the manipulator will first rotate to align the gap between the two groups of grippers 15 of the object with the long side of the object). Since the distance between the grippers 15 and the bottom becomes longer after tightening, the manipulator moves downward to contact the surface where the object is located, such as Figure 4 Finally, tighten the other side clamp 15, return the robot to the center position, and move downward to make up the height difference after the clamp 15 is retracted. Figure 4 As shown in part b of the figure, the object is ultimately scooped up at its short side. This scooping action is suitable for situations where the long side exceeds the standard, or where direct gripping can cause slippage, such as cylinders, or objects with the shortest side at the top, which is difficult to grip, such as triangular pyramids.

[0080] The second clamping method is direct clamping, which is suitable for the case where the object does not exceed the standard and the clamping jaws 15 have a suitable position for direct clamping (not conical or cylindrical). Figure 5 When directly gripping, the robot's Z axis moves to the scanned most suitable gripping height, and the four grippers 15 simultaneously retract to grip the object.

[0081] The detection component includes an oblique ranging sensor 3, a vertical ranging sensor 13 and a camera 14. The camera 14 is fixed to the middle of the outer side surface of the main body cover 5. The vertical ranging sensor 13 is fixed to the edge of the outer side surface of the main body cover 5. The axes of the camera 14 and the vertical ranging sensor 13 are parallel to the central axis of the base 2. The center of the lens of the camera 14 is on the central axis of the base 2; the distance between the detection part of the vertical ranging sensor and the central axis of the base 2 is equal to the distance between the clamping claw in the loose state and the central axis of the base 2. The vertical ranging sensor cooperates with the rotation of the manipulator to detect whether the target object exceeds the allowable range that can be clamped.

[0082] Two oblique distance measuring sensors 3 are respectively fixed to the inner side surfaces of two opposing gripping fingers' jaws 15. When released, the detection direction of the oblique distance measuring sensors 3 is tilted away from the base 2. The detection direction lines of the two oblique distance measuring sensors 3 intersect and form an equal angle with the normal plane to the central axis of the base 2 (which is horizontal when the robot arm is in a vertical position).

[0083] The clamping method of the adaptive electromagnetic driven manipulator for stable transportation includes the following steps:

[0084] Step 1: Mount the manipulator on the end effector of a mobile platform capable of three degrees of freedom (3DFO) movement and three degrees of freedom rotation. The mobile platform is an industrial robot. The mobile platform drives the manipulator to a position above the target object. The vertical ranging sensor 13 measures the distance Z0 between itself and the surface where the target object is placed. The mobile platform then moves the manipulator above the target object, maintaining the distance to ensure the camera can capture a complete image of the target object.

[0085] Step 2: Accurately position the robot arm directly above the target object.

[0086] 2-1. A camera, located at the center of the robot arm, captures an image of the target object and sends it to a host computer. The host computer reads the image and stores information about each pixel in a three-dimensional array [RGB]. The color of a pixel in the image is composed of the values ​​of red (R), green (G), and blue (B). The three elements in the array correspond to the components of the three primary colors in the pixel.

[0087] 2-2. Convert the image to grayscale to facilitate the next step of binarization. The grayscale calculation formula is shown in Equation 1:

[0088] Gray=(R*0.3+G*0.59+B*0.11) Formula (1)

[0089] Among them, R, G, and B are the three elements corresponding to a pixel point in the three-dimensional array (i.e., the values ​​of red R, green G, and blue B).

[0090] 2-3. Binarization: Use the histogram binarization method. The grayscale image obtained in step 2-2 is plotted as a histogram, with the grayscale value on the horizontal axis and the number of pixels corresponding to that grayscale on the vertical axis. When the background and object grayscale differ, two peaks form in the histogram. The grayscale value at the lowest point between the two peaks is used as the threshold. When the value is above the threshold, it is considered white; when it is below the threshold, it is considered black, resulting in a binary image.

[0091] 2-4. Perform contour extraction on the binary image obtained in step 2-3 to obtain a contour map. This step is used to remove points inside the contour. If a pixel in the binary image is black and all pixels within the 3*3 neighborhood of the pixel are black, the pixel is considered to be inside the object and is replaced with white. Otherwise, the pixel is considered to be at the edge of the image and needs to be retained. Finally, non-edge points are removed, leaving only the contour.

[0092] 2-5. The contour obtained in step 2-4 is a series of points; let the coordinates of the i-th point in the contour be (x i ,y i ), i=1,2,...,n; n is the number of points on the contour; the coordinates of the centroid of the contour The expression of is shown in formula (2):

[0093]

[0094] 2-6. If the image offset distance D is greater than the allowable error σ, move the robot along The direction of the vector moves by a preset distance ε. The expression of the image offset distance D is shown in formula (3):

[0095]

[0096] 2-7. Repeat steps 2-1 to 2-6 until the image offset distance D is greater than or equal to the allowable error σ, and the robot is considered to have moved directly above the target object.

[0097] During the subsequent downward movement of the manipulator, the image offset distance D is recalculated; when the image offset distance D is greater than 2σ, the horizontal position of the manipulator needs to be corrected again according to steps 2-1 to 2-7.

[0098] Step 3: Determine whether the shape of the target object exceeds the standard.

[0099] 3-1. Determine whether the outline size of the target object exceeds the standard.

[0100] The mobile platform drives the manipulator to rotate around the central axis of the base (2) for one circle; during the rotation of the manipulator, the path of the vertical distance measuring sensor 13 is a circular track; the size of the circular track corresponds to the moving range of the clamping claw; during the rotation of the manipulator, the vertical distance measuring sensor 13 continuously detects the distance value.

[0101] During the manipulator's rotation, if the distance value measured by the vertical ranging sensor 13 remains within the permissible error range centered on Z0, the target object's outline size is determined to be within the specified range. Otherwise, the target object's outline size is determined to be within the specified range, and the manipulator's rotation angle range S is recorded when the distance value measured by the vertical ranging sensor 13 is less than the permissible error range centered on Z0. Within the manipulator's 360° rotation range, if two 45° angle intervals separated by 180° exist that completely cover the rotation angle range S, then, based on the target object's outline size exceeding the specified range, the target object is further determined to be a horizontally placed elongated object. If only two ends of the elongated object exceed the gripping range, gripping is achieved using the two sets of arc-shaped grooves 15-2.

[0102] When the target object's outline size does not exceed the standard, the relative relationship between the circular trajectory of the vertical distance measuring sensor 13 and the target object is as follows: Figure 8a As shown;

[0103] When the target object exceeds the size limit and is judged to be a horizontally placed long object, the relative relationship between the circular trajectory of the vertical distance measuring sensor 13 and the target object is as follows: Figure 8b As shown;

[0104] When the target object's outline size exceeds the standard and is not determined to be a horizontally placed long object, the relative relationship between the circular trajectory of the vertical ranging sensor 13 and the target object is as follows: Figure 8c As shown;

[0105] 3-2. Determine whether the height of the target object exceeds the standard.

[0106] The robot is controlled to descend intermittently, with each descent distance being defined as ΔZ. After each descent, the difference ΔX between the distance X measured before and the distance X' measured after the descent is calculated. If ΔX·sinα-ΔZ < s, the robot continues descending. s is the allowable error. If ΔX·sinα-ΔZ ≥ s, the object's height is calculated as H = ΔX·sinα-ΔZ. α is the angle between the oblique ranging sensor 3 and the horizontal plane when the sensor is released. If the height H is greater than the preset maximum height, the target object is considered to be above the specified height.

[0107] Step 4: For the following three situations, give up gripping or grip the target object in a corresponding way.

[0108] Case 1: The target object's outline size exceeds the standard and is not judged as a horizontally placed long object, or the target object's height exceeds the standard; the target object is judged to be unable to be gripped.

[0109] Case 2: The target object's outline size and height do not exceed the standard. It is determined that the target object can be gripped. The gripping method is as follows:

[0110] The manipulator continues to move downward, and when the oblique distance measuring sensor 3 detects the side of the target object (whether the side is detected is determined by the height of the target object), the manipulator intermittently descends;

[0111] Each time the manipulator descends, the mobile platform drives the manipulator to rotate around the central axis of the base (2) for one circle, and the oblique distance sensor 3 continuously detects the distance value x i ; Calculate the average distance S x As shown in formula (6).

[0112]

[0113] Wherein, n is the sampling times of the oblique distance measuring sensor 3 during the rotation of the manipulator.

[0114] If the robot is intermittently descending, the average distance S x If it continues to increase, it is judged that the target object has a pointed cone structure;

[0115] If the robot is intermittently descending, the average distance S x If it continues to decrease, the target object is judged to have a funnel-shaped structure;

[0116] If the robot is intermittently descending, the average distance S x If it decreases first and then increases, the target object is judged to have a waist-shaped structure;

[0117] Otherwise, it is judged that the target object has a common structure;

[0118] For target objects with pointed cone structures and ordinary structures, the robot grips the target object by scooping it up from the bottom.

[0119] For funnel-shaped target objects, the robot grips the target object from the top edge of the target object.

[0120] For the target object with waisted structure, the manipulator grabs the target object from the narrowest part of the target object (the average distance S is measured). x The smallest position is the narrowest part of the target object).

[0121] Case 3: The target object's outline size exceeds the standard and is judged to be a horizontally placed long object. The height of the target object does not exceed the standard. The target object is judged to be able to be gripped. The gripping method is as follows:

[0122] The manipulator rotates around the central axis of the base so that the arrangement direction of the two sets of arc grooves 15-2 is parallel to the length direction of the target object; the manipulator scoops up the target object so that it falls into the U-shaped support groove formed by the two sets of arc grooves 15-2 to complete the gripping.

[0123] The specific process of the robot arm scooping up the target object is as follows: first, the two gripping fingers on one side of the target object rotate inward to a gripping state and move to the bottom edge of the target object; then, the bottom of the robot arm tilts toward the target object; finally, the two gripping fingers in the released state rotate inward to a gripping state, allowing the target object to leave the table and achieve gripping of the target object.

Claims

1. An adaptive electromagnetic driven manipulator for stable transportation, comprising a base (2), a main body cover (5), gripping fingers and a detection component; characterized in that: The four clamping fingers are all mounted on the base (2) and are arranged in sequence along the circumferential direction of the central axis of the base (2); the clamping fingers include a slider (1), a push-pull electromagnet (4), a force transmission rod (6), a clamping rod and a clamping claw; the slider (1) is slidably connected to the side of the base (2); one end of the force transmission rod (6) is rotatably connected to the slider (1); the inner end of the clamping rod is rotatably connected to the base (2); the middle of the clamping rod is rotatably connected to the other end of the force transmission rod (6); the slider (1) is driven by the push-pull electromagnet (4) to slide back and forth; When the four gripping fingers are turned inward to the extreme position of being close to each other, the manipulator is in a clamping state; when the four gripping fingers are turned outward to the extreme state of being separated from each other, the manipulator is in a loose state. The bottom end of the gripping rod is fixed with a gripping claw; the gripping claw consists of a main body and a gripping sharp corner at the end of the main body; in the clamping state, the inner sides of the gripping sharp corners at the bottom of the four gripping claws can be assembled into a quadrangular pyramid-shaped load-bearing concave surface; An arc-shaped groove is formed on one side of the main body of each of the four clamping jaws; the arc-shaped grooves formed on two adjacent clamping jaws are located on opposite sides; the four arc-shaped grooves are divided into two groups of two; in the clamping state, the two arc-shaped grooves in the same group are joined together to form a U-shaped support groove; The detection assembly comprises an oblique distance measuring sensor, a vertical distance measuring sensor and a camera (14); the camera (14) and the vertical distance measuring sensor are fixed to the bottom of the base (2); the axes of the camera (14) and the vertical distance measuring sensor are parallel to the central axis of the base (2); the center of the lens of the camera (14) is on the central axis of the base (2); the distance between the detection part of the vertical distance measuring sensor and the central axis of the base (2) is equal to the distance between the clamping claw in the loose state and the central axis of the base (2); An oblique distance measuring sensor is fixed on the clamping claw of one of the clamping fingers, or on the clamping claws of two clamping fingers facing each other; in a released state, the detection direction of the oblique distance measuring sensor is tilted toward the side away from the base (2); The adaptive electromagnetic driven manipulator further comprises two first auxiliary components and two second auxiliary components; a first auxiliary component or a second auxiliary component is provided between two adjacent gripping fingers; there are two first auxiliary components and two second auxiliary components; the two first auxiliary components and the two second auxiliary components are alternately arranged along the circumference of the base (2); the positions of the two second auxiliary components correspond to the positions of the two groups of arc-shaped grooves respectively; The first auxiliary component includes a first telescopic bracket (16) and an auxiliary finger (18); the first telescopic bracket (16) includes two first connecting tubes and a first V-shaped rod; the opposite ends of the two first connecting tubes and the two ends of the first V-shaped rod respectively form a cylindrical pair; the opposite ends of the two first connecting tubes and the middle of the clamping rods in the two adjacent clamping fingers respectively form a rotation pair; the common axis of the rotation pair formed by the first connecting tube and the clamping rod (7) is perpendicular to the common axis of the rotation pair formed by the clamping rod (7) and the base (2); the top end of the auxiliary finger (18) is fixed to the middle of the first V-shaped rod; the bottom end of the auxiliary finger (18) is provided with an auxiliary support plate; in the clamping state, the two side edges of the auxiliary support plate are spliced ​​with the adjacent side edges of the two adjacent clamping claws; The second auxiliary component includes a second telescopic bracket (17) and a pressing finger (19); the second telescopic bracket (17) includes two second connecting tubes and a second V-shaped rod; the opposite ends of the two second connecting tubes and the two ends of the second V-shaped rod respectively form a cylindrical pair; the opposite ends of the two second connecting tubes and the middle parts of the clamping rods in two adjacent clamping fingers respectively form a spherical pair; the pressing finger (19) is fixed to the middle part of the second V-shaped rod.

2. The adaptive electromagnetic driven manipulator for stable transportation according to claim 1, characterized in that: The side of the base (2) is provided with four slide grooves evenly distributed along the circumference of the central axis of the base (2); the length direction of the slide groove is arranged along the central axis direction of the base (2); the four slide grooves correspond to the four clamping fingers respectively; the slider (1) is slidably connected in the corresponding slide groove.

3. The adaptive electromagnetic driven manipulator for stable transportation according to claim 1, characterized in that: The clamping rod is L-shaped.

4. The adaptive electromagnetic driven manipulator for stable transportation according to claim 1, characterized in that: The push-pull electromagnet (4) is fixed in the corresponding slide groove; the outer end of the push rod of the push-pull electromagnet (4) is fixed to the slider (1); a spring (20) is sleeved on the outer side of the push rod; the two ends of the spring (20) respectively press against the electromagnet body and the slider (1).

5. The adaptive electromagnetic driven manipulator for stable transportation according to claim 1, characterized in that: The two side edges of the main body of the clamping jaw are parallel to each other.

6. The method for gripping with an adaptive electromagnetically driven manipulator for stable transportation according to claim 1, characterized in that: The following steps are involved: Step 1: The manipulator moves to a position above the target object; the vertical distance sensor (13) measures the distance Z0 between itself and the table where the target object is placed; then, the manipulator moves horizontally to the top of the target object; Step 2: The camera captures the image of the target object; According to the position of the target object in the image, the manipulator moves horizontally so that the manipulator moves directly above the target object; Step 3: Determine whether the shape of the target object exceeds the standard; 3-1. Determine whether the outline size of the target object exceeds the standard; The mobile platform drives the manipulator to rotate around the central axis of the base (2) for one circle; during the rotation of the manipulator, the vertical distance sensor (13) continuously detects the distance value; During the rotation of the manipulator, if the distance value measured by the vertical distance measuring sensor (13) is always maintained within the error tolerance range including Z0, it is judged that the outline size of the target object does not exceed the standard; otherwise, it is judged that the outline size of the target object exceeds the standard, and the rotation angle range S of the manipulator when the distance value measured by the vertical distance measuring sensor (13) exceeds the error tolerance range including Z0 is recorded; in the circumferential direction of the central axis of the base, if there are two 45° angle intervals separated by an angle of 180° that can completely cover the rotation angle range S, then it is judged that the target object is a horizontally placed long strip object; 3-2. Determine whether the height of the target object exceeds the standard; Control the intermittent descent of the manipulator, and the distance of each descent is the descent distance. ; Each time the manipulator descends, the difference between the distance value X measured before the descent and the distance X' measured after the descent is calculated X; if X· - <s, the manipulator continues to descend; s is the preset allowable error; if X· - ≥s, then calculate the height of the object H= X· - ; is the angle between the oblique distance measuring sensor (3) and the horizontal plane in the released state; if the height value H is greater than the preset maximum height, it is determined that the height of the target object exceeds the standard; Step 4: For the following three situations, give up gripping or grip the target object in a corresponding way; Case 1: The target object's outline size exceeds the standard and is not judged as a horizontally placed long object, or the target object's height exceeds the standard; the target object is judged to be ungrabable; Case 2: The target object's outline size and height do not exceed the standard, so the robot arm determines that the target object can be grasped, and grasps the target object; Case 3: The target object's outline size exceeds the standard and is judged to be a horizontally placed long object. The height of the target object does not exceed the standard. It is judged that the target object can be gripped. The gripping method is as follows: the robot arm rotates around the central axis of the base so that the arrangement direction of the two sets of arc-shaped grooves is parallel to the length direction of the target object; the four gripping fingers lift the target object so that the target object falls into the U-shaped support groove formed by the two sets of arc-shaped grooves.

7. The clamping method according to claim 6, characterized in that: The specific process of step 2 is as follows: 2-1. The camera captures an image of the target object; 2-2. Convert the image obtained in step 2-1 into a grayscale image; 2-3. Convert the grayscale image obtained in step 2-2 into a binary image; 2-4. Perform contour extraction on the binary image obtained in step 2-3 to obtain a contour image; 2-5. Extract the centroid coordinates of the contour in the contour image obtained in step 2-4 , ; 2-6. If the image offset distance D is greater than the allowable error , move the robot along Move the vector in the direction of the preset distance ; The expression of image offset distance D is as follows D= ； Repeat steps 2-1 to 2-6 until the image offset distance D is greater than or equal to the allowable error. .

8. The clamping method according to claim 6, characterized in that: In step 4, if condition 2 is met, the clamping method is as follows: The manipulator continues to move downward, and when the oblique distance measuring sensor (3) detects the side of the target object, the manipulator descends intermittently; Each time the manipulator descends, the mobile platform drives the manipulator to rotate around the central axis of the base (2) for one circle, and the oblique distance sensor (3) continuously detects the distance value x i ; Calculate the average distance as follows: ； Wherein, n is the number of sampling times of the oblique distance measuring sensor (3) during the rotation of the manipulator; If the robot is intermittently descending, the average distance If it continues to increase, it is judged that the target object has a pointed cone structure; If the robot is intermittently descending, the average distance If it continues to decrease, the target object is judged to have a funnel-shaped structure; If the robot is intermittently descending, the average distance If it decreases first and then increases, the target object is judged to have a waist-shaped structure; Otherwise, it is judged that the target object has a common structure; For target objects with pointed cone structures and ordinary structures, the manipulator grabs the target object by scooping it up from the bottom of the target object. For funnel-shaped target objects, the robot grips the target object from the top edge of the target object; For target objects with a waisted structure, the robot grips the target object from the narrowest part of the target object.

9. The clamping method according to claim 6, characterized in that: In step 4, if condition 3 is met, the manipulator lifts the target object by scooping it up. The specific process is as follows: first, the two gripping fingers on one side of the target object rotate inward to a gripping state and move to the bottom edge of the target object; then, the bottom of the manipulator tilts toward the side close to the target object; finally, the two gripping fingers in the released state rotate inward to a gripping state, so that the target object leaves the table, thereby achieving gripping of the target object.

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