Tea picking device adopting redundant degree-of-freedom series-parallel mechanical arm and tea picking method thereof

Abstract

The invention discloses a tea picking device adopting a redundant degree-of-freedom series-parallel mechanical arm and a tea picking method of the tea picking device. The rack is driven by the two movable chassis to move, the translation device is driven by the two lifting devices on the rack to ascend and descend, and a static platform of the series-parallel mechanical arm is driven to drive the picking tail end and the whole series-parallel mechanical arm to translate. Two first joint motors at the two ends of a static platform in the series-parallel mechanical arm drive two first driving arms to drive a movable platform support to move through two driven connecting rod sets, a second joint motor drives a second driving arm to drive the movable platform support to move through a second driven connecting rod, and a third joint motor on the movable platform support in the picking tail end drives a steering engine frame to rotate. A steering engine on the steering engine frame drives a steering engine arm to drive the two blades to move oppositely or oppositely through the two connecting rods and the two clamping blocks; a belt conveying mechanism is arranged on the rack and located behind the translation device, and a material box is arranged at the output end of the belt conveying mechanism. The tea bud picking and collecting device can achieve accurate picking and low-loss collection of tea buds.

Description

Technical Field

[0001] The present invention belongs to the technical field of agricultural machinery, and particularly relates to a tea picking device using a redundant degree-of-freedom serial-parallel robotic arm and a tea picking method thereof. Background Art

[0002] In the field of existing automated harvesting equipment for famous and high-quality tea, industrial robotic arms, as the core picking devices, have obvious technical defects. Specifically, for traditional serial robotic arms, due to the long transmission chain, problems such as excessive inertia moment of the end effector, attenuation of positioning accuracy, and hysteresis of dynamic response occur; although conventional parallel robotic arms (such as Delta structures) have the characteristics of high motion accuracy and good running stability, they are limited by their inherent structural characteristics and have the defect of a small effective working space. If the operation range is forcibly expanded through a magnifying mechanism, not only will the floor area of the equipment be greatly increased, but also the force balance state of the mechanical system will be damaged, and the risk of equipment overturning is extremely likely to be caused by the center-of-gravity shift in the tea garden operation environment with complex terrain features, seriously restricting the reliability and continuity of the harvesting operation. In addition, most traditional tea bud collection devices adopt the negative pressure adsorption method, which has problems such as low collection efficiency and damage to the integrity of tea buds, and it is difficult to meet the continuous harvesting requirements of high-density tea buds, and the energy consumption is high. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and propose a tea picking device using a redundant degree-of-freedom serial-parallel robotic arm and a tea picking method thereof.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] The tea picking device of the present invention using a redundant degree-of-freedom serial-parallel robotic arm includes a mobile chassis, a frame, a serial-parallel picking robotic arm, a lifting device, a translation device, a binocular camera, and a belt conveyor. The frame is driven by two symmetrically arranged mobile chassis to move, and a binocular camera and two symmetrically arranged lifting devices are provided on the frame. The two lifting devices drive the translation device to lift; the belt conveyor is arranged on the frame and is located behind the translation device, and a material box is detachably fixed at the output end of the belt conveyor on the frame; a first baffle is fixed on the frame on the side of the belt conveyor away from the translation device.

[0006] The series-parallel picking robotic arm includes a series-parallel robotic arm and a picking end; the series-parallel robotic arm includes a stationary platform, a first active arm, a first driven link, a second active arm, a second driven link, and a moving platform; the stationary platform is driven to translate by a translation device, and the direction in which the translation device drives the stationary platform to translate is perpendicular to the direction in which the two mobile chassis drive the frame to move forward, and parallel to the conveying direction of the belt conveyor mechanism; one ends of the two first active arms respectively form a revolute pair with the two ends of the stationary platform, and are respectively driven to rotate by two first joint motors, and the other ends are both fixed with n parallel arranged first rotating shafts, n≥3; the moving platform includes a moving platform bracket and a rotary member, the moving platform bracket is located below the stationary platform, and both ends of the moving platform bracket are fixed with n parallel arranged second rotating shafts, and the middle forms a revolute pair with the rotary member; there are two groups of driven link groups composed of n parallel arranged first driven links, and both ends of each first driven link in the driven link group respectively form a spherical hinge with a first rotating shaft and a second rotating shaft on the same side; the first motor bracket forms a revolute pair with the stationary platform; one end of the second active arm forms a revolute pair with the first motor bracket and is driven to rotate by a second joint motor, and both ends of the second driven link are respectively hinged to the other end of the second active arm and the rotary member. Among them, the rotation center axes between the two first active arms and the stationary platform, the rotation center axis between the first motor bracket and the stationary platform, the rotation center axis between the rotary member and the moving platform bracket, each first rotating shaft and each second rotating shaft are horizontal and parallel, the rotation center axis between the second active arm and the first motor bracket and the rotation center axes at both ends of the second driven link are horizontal and parallel, perpendicular to the first rotating shaft, and perpendicular to the direction in which the translation device drives the series-parallel picking robotic arm to translate; the picking end is installed on the moving platform bracket.

[0007] Preferably, the lifting device includes a handwheel, a fixed housing, a nut block, a screw rod, and a worm. The fixed housing is fixed to the frame. The horizontally arranged worm forms a revolute pair with the fixed housing. The handwheel is fixed to the worm. The vertically arranged screw rod forms a revolute pair with the fixed housing and forms a ball screw pair with the nut block through balls; the worm meshes with the turbine fixed on the screw rod.

[0008] Preferably, the translation device includes a bottom plate, a synchronous wheel bracket, synchronous wheels, tensioning wheels, and a synchronous belt; both ends of the horizontally arranged bottom plate are fixed to the nut blocks of the two lifting devices; the synchronous wheel bracket forms a sliding pair with the bottom plate; the synchronous wheel bracket is hinged with a synchronous wheel, and tensioning wheels are hinged on both sides of the synchronous wheel; both ends of the synchronous belt are fixed to the bottom plate, and the synchronous wheel and the two tensioning wheels all form rolling friction pairs with the synchronous belt, and the synchronous wheel is driven to rotate by a servo motor.

[0009] Preferably, the picking end includes a rudder machine frame and two blades that can be opened and closed. The rudder machine frame is driven by the third joint motor to rotate, and the third joint motor is fixed to the moving platform bracket; a second baffle is fixed on the rudder machine frame in front of the two blades. In the picking end, the middle of the rudder machine arm forms a rotational pair in the horizontal direction with the rudder machine frame and is driven by a steering gear to rotate. The two ends are respectively hinged to one ends of two connecting linkages arranged in central symmetry, and the other ends of the two connecting linkages are hinged to the middle parts of two clamping blocks arranged in axial symmetry. The upper ends of the two clamping blocks are hinged to the rudder machine frame, and the lower ends are fixed with two blades arranged in axial symmetry.

[0010] The tea picking method of the tea picking device using the redundant degree-of-freedom series-parallel manipulator of the present invention is as follows:

[0011] The two mobile chassis drive the frame to move onto the tea ridge. The two lifting devices drive the translation device and the series-parallel picking manipulator to rise or fall, so that the height of the blade end reaches the preset initial height; the two mobile chassis drive the frame to intermittently advance along the tea ridge. And whenever the two mobile chassis stop driving the frame, the series-parallel picking manipulator and the translation device work to carry out the tea picking work in the current working area; the process of the tea picking work is as follows: First, the binocular camera acquires the image of the current working area and transmits the image of the current working area to the upper computer. The upper computer identifies the positions of the tea buds in the working area and generates a set of spatial coordinates of the tea bud positions. Among them, the spatial coordinate system takes a corner point on the side of the working area close to the series-parallel picking manipulator as the origin O, the advancing direction of the two mobile chassis driving the frame is the Y-axis direction, the translation direction of the translation device driving the series-parallel picking manipulator is the X-axis direction, and the vertical direction is the Z-axis direction; then according to the generated set of spatial coordinates of the tea bud positions, the overall optimal picking path of the working area is obtained through the improved ant colony algorithm; then the tea buds on the optimal picking path in the current working area are harvested according to the overall optimal picking path of the working area.

[0012] Preferably, the process of optimizing the picking path by using the improved ant colony algorithm is as follows:

[0013] (1) The working area is divided into two low-density areas and a high-density area located between the two low-density areas along the X-axis direction, and transition areas are divided on one side of the two low-density areas adjacent to the high-density area; let the speed of the static platform when it is located in other areas of the low-density area except the transition area be , the speed when it is located in the high-density area be , the speed when it is located in the transition area be , and , is the X-axis coordinate of the static platform when it is located in the transition area, is the X-axis coordinate of the farthest point from the high-density area in the transition area; the speed of the static platform when it is located in other areas except the transition area in the low-density area and the speed when it is located in the high-density area are taken from their respective candidate sets.

[0014] (2) Parameter initialization: Set the initial value of pheromone on the path from node i to node j at the t-th iteration, the number of ants, the pheromone weight , the heuristic weight , the evaporation coefficient , the speed influence coefficient , the cross-interval penalty factor , the pheromone increment adjustment coefficient ; Define the time window: , , is the offset of the redundant degree of freedom control picking end in the X-axis direction provided by the redundant degree of freedom expansion mechanism composed of joint motor two, active arm two and driven link two, represents the X-axis coordinate of node i, represents the static platform at the speed at that point.

[0015] (3) Considering the time cost and the speed of the static platform comprehensively, define the heuristic information , and considering the position area difference between node i and node j and the difference in the translational speed of the static platform at node i and node j, define the modified heuristic information ;

[0016] The path selection probability is

[0017]

[0018] In the formula, represents the set of unvisited nodes on the path from node i to node j;

[0019] (4) Select and , calculate the speed of the static platform when it is located in the transition area, execute steps (2) and (3), and obtain the path selection probabilities of various paths from node i to node j;

[0020] (5) Update the global pheromone:

[0021]

[0022] In the formula, represents the pheromone increment left by ant q on the path from node i to node j, and , is the number of nodes successfully picked by ant q, is the time cost of ant q on the path from node i to node j, and the benchmark speed Take the speed The maximum speed in the candidate set;

[0023] After each update of the global pheromone, recalculate the path selection probability of various paths from node i to node j;

[0024] (6) When the iteration times are reached, use the path from node i to node j with the maximum path selection probability as the selected and corresponding optimal picking path;

[0025] (7) Repeat steps (4) to (6), and update and when repeating, until all and combinations are traversed, use the path from node i to node j with the maximum among all calculated path selection probabilities as the final picking path from node i to node j, and obtain the corresponding and combination;

[0026] (8) The ant starts from the starting point of the operation area until the node with the largest X-axis coordinate in the operation area. Each time a path from node i to node j is generated, node j is used as the new node i, so as to generate the overall optimal picking path of the operation area.

[0027] More preferably, the heuristic information is

[0028]

[0029] In the formula, represents the maximum value that can be obtained from the candidate set, the time difference of the ant from node i to node j is the time cost of ant q on the path from node i to node j , represents the distance in the X-axis direction of the constant-speed section part in the path from node i to node j, and the speed of the static platform when the path from node i to node j is in the constant-speed section part , and respectively represent the starting X-axis coordinate and the ending X-axis coordinate of the variable-speed section part in the path from node i to node j, and the speed of the static platform when the path from node i to node j is in the variable-speed section part , the total harvesting time of each node in the path from node i to node j , n is the total number of nodes in the path from node i to node j, is the harvesting time at node p, including picking and throwing times.

[0030] More preferably, the modified heuristic information is

[0031]

[0032] where is the velocity difference weight, is the area difference, and , represents the minimum value that can be obtained from the candidate set.

[0033] Preferably, the process of harvesting each tea bud on the overall optimal harvesting path in the current working area according to the overall optimal harvesting path of the working area is as follows: The translation device drives the static platform to drive the entire series-parallel picking manipulator to translate along the X-axis direction, so that the midpoint of the two blade ends at the picking end is translated to the X-axis coordinate position of each tea bud position on the overall optimal harvesting path of the working area in sequence, and the series-parallel picking manipulator translates along the X-axis direction at the corresponding speed calculated in step (7) on each final picking path; while the series-parallel picking manipulator translates along the X-axis direction, two joint motors 1 drive the corresponding active arms 1 to rotate, and each active arm 1 drives the moving platform bracket and the picking end to move in the vertical plane parallel to the YOZ plane through the corresponding driven link group, so that the midpoint of the two blade ends at the picking end is translated to the Y-axis coordinate position of each tea bud position on the overall optimal harvesting path of the working area in sequence, and the distance deviation between the midpoint of the two blade ends at the picking end and the tea bud position in the X-axis direction and the Y-axis direction is calculated in real time. When the distance deviation in the Y-axis direction is not within the preset deviation range, joint motor 2 drives the active arm 2 to drive the driven link 2 to rotate, and the driven link 2 drives the picking end to adjust along the X-axis direction through the moving platform bracket, so that the distance deviation in the X-axis direction is within the preset deviation range. If the distance deviation in the Y-axis direction is not within the preset deviation range, two joint motors 1 drive the corresponding active arms 1 to rotate for adjustment; when the midpoint of the two blade ends at the picking end reaches the tea bud position, the servo motor drives the servo arm to rotate forward, and the servo arm drives the lower ends of the two clamping blocks to move towards each other through the two connecting links, thereby driving the two blade ends to close for tea bud shearing to complete the picking of the tea bud; then joint motor 3 drives the tea bud holder to rotate the tea bud towards the direction close to the belt conveyor mechanism, and the tea bud is thrown onto the conveyor belt of the belt conveyor mechanism by centrifugal force, and the belt conveyor mechanism transports the tea bud into the material box to complete the collection of the tea bud; then the controller controls joint motor 3 to drive the tea bud holder to rotate the tea bud away from the belt conveyor mechanism to the original position, and at the same time controls the servo motor to drive the servo arm to rotate in reverse, and the servo arm drives the two clamping blocks and the two blades to move away from each other to the original position through the two connecting links.

[0034] The present invention has the following beneficial effects:

[0035] The present invention can realize accurate picking and low-loss collection of tea buds; specifically, the present invention adopts the combination of a translation device and a serial-parallel robot arm with redundant degrees of freedom, and on the basis of the picking path optimized by the improved ant colony algorithm, the translation device drives the serial-parallel robot arm to drive the picking end to translate along the X-axis direction, and two joint motors one at both ends of the static platform in the serial-parallel robot arm drive two active arms one to drive the moving platform bracket and the picking end to move in a vertical plane parallel to the YOZ plane through two driven connecting rod groups, so that the picking end moves to the tea bud position on the picking path, and joint motor two in the serial-parallel robot arm drives active arm two to drive the moving platform bracket and the picking end to perform real-time fine-tuning along the X-axis direction through driven connecting rod two, thereby realizing dynamic compensation of the position of the picking end in the X-axis direction, and the translation device can maintain continuous driving in one direction, thereby avoiding frequent changes in the translation device. The picking end position is adjusted by rapid or repeated start and stop, which reduces the inertial impact of the translation device, improves the overall operation stability, and eliminates the positioning jitter caused by emergency stop. Through this "main frame (composed of a translation device, a static platform, a dynamic platform bracket, two joint motors, two active arms and two driven connecting rod groups) coarse positioning + redundant degree of freedom expansion mechanism (composed of a motor bracket one, an active arm two, a driven connecting rod two and a rotating part) fine adjustment" collaborative motion mode, the translation device can maintain continuous driving in one direction to improve efficiency while also achieving precise positioning of the tea bud position, thereby enabling accurate picking of the tea buds; among them, in the picking path planning optimized by the improved ant colony algorithm, the time window constraint and the real-time feedback mechanism are combined, so that the path for picking according to the optimal path takes into account both time and success rate, further improving the picking efficiency. Furthermore, the present invention collects tea buds by throwing tea buds. When the picking end completes the picking of tea buds, the controller controls the three-drive servo frame of the joint motor to drive the tea buds to rotate in the direction close to the belt conveyor mechanism, and throws the tea buds onto the conveyor belt of the belt conveyor mechanism through centrifugal force. The tea buds are transported to the material box through the belt conveyor mechanism to collect the tea buds. Compared with the existing negative pressure adsorption method, the method avoids the breakage and abrasion of the tea buds caused by collision and friction with the tube wall (the centrifugal force size is pre-debugged and designed, and the collision force received by the tea buds when they are thrown onto the conveyor belt of the belt conveyor mechanism can be very small), there is no need to maintain continuous airflow pressure, the power consumption is low, and the structure is simple and easy to maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0037] Figure 2 It is a structural schematic diagram of the lifting device in the present invention.

[0038] Figure 3This is a schematic structural diagram of the translation device in the present invention.

[0039] Figure 4 This is a schematic structural diagram of the series-parallel picking manipulator in the present invention.

[0040] Figure 5 This is a schematic structural diagram of the moving platform and the picking end in the present invention.

[0041] Figure 6 This is a schematic structural diagram of the picking end when the blade is closed in the present invention.

[0042] Figure 7 This is a schematic structural diagram of the picking end when the blade is opened in the present invention.

[0043] Figure 8 This is a flowchart of the improved ant colony algorithm for optimizing the picking path in the present invention.

[0044] Figure 9 This is a schematic diagram of the division of the operation area in the present invention.

[0045] Figure 10 This is a schematic diagram of the structure of the series-parallel picking manipulator when performing X-axis direction compensation during the operation of the present invention Figure 1 。

[0046] Figure 11 This is a schematic diagram of the structure of the series-parallel picking manipulator when performing X-axis direction compensation during the operation of the present invention Figure 2 。 Detailed implementation manners

[0047] The present invention will be further described below with reference to the accompanying drawings.

[0048] As Figure 1 shown, the tea picking device of the present invention using a redundant degree-of-freedom series-parallel manipulator includes a mobile chassis 1, a frame 2, a material box 3, a series-parallel picking manipulator 4, a lifting device 5, a translation device 6, a binocular camera 7, and a belt conveyor 8. The frame 2 is driven by two symmetrically arranged mobile chassis 1, and two symmetrically arranged lifting devices 5 are provided on the frame 2. The two lifting devices 5 drive the translation device 6 to lift and lower, and the translation device 6 drives the series-parallel picking manipulator 4 to translate; the belt conveyor 8 is provided on the frame 2 and is located behind the translation device 6, and a material box 3 is detachably fixed at the output end of the belt conveyor 8 on the frame 2; a first baffle 9 is fixed on the frame 2 on the side of the belt conveyor 8 away from the translation device 6, and the first baffle 9 is used to prevent tea buds from falling outside the belt conveyor 8 when the series-parallel picking manipulator 4 throws tea buds towards the belt conveyor 8; the binocular camera 7 is provided on the frame 2 for collecting images of the tea row operation area. Among them, the direction in which the translation device 6 drives the series-parallel picking manipulator 4 to translate is perpendicular to the direction in which the two mobile chassis 1 drive the frame 2 to move forward and parallel to the conveying direction of the belt conveyor 8.

[0049] As Figure 2 shown, the lifting device 5 includes a handwheel 5-1, a fixed housing 5-2, a nut block 5-3, a screw rod 5-4 and a worm 5-5. The fixed housing 5-2 is fixed to the frame 2. The horizontally arranged worm 5-5 and the fixed housing 5-2 form a rotating pair, and the handwheel 5-1 is fixed to the worm 5-5. The vertically arranged screw rod 5-4 and the fixed housing 5-2 form a rotating pair and form a ball screw pair with the nut block 5-3 through balls. The worm 5-5 meshes with the turbine fixed on the screw rod 5-4.

[0050] As Figure 3 shown, the translation device 6 includes a bottom plate 6-1, a synchronous wheel bracket 6-4, synchronous wheels 6-6, tension wheels 6-7 and a synchronous belt 6-8. The two ends of the horizontally arranged bottom plate 6-1 are fixed to the nut blocks 5-3 of the two lifting devices 5. The synchronous wheel bracket 6-4 and the bottom plate 6-1 form a sliding pair. The synchronous wheel bracket 6-4 is hinged with a synchronous wheel 6-6, and tension wheels 6-7 are hinged on both sides of the synchronous wheel 6-6. One end of the synchronous belt 6-8 is fixed to a fixed base 6-2, and the other end bypasses the bottom end of one of the tension wheels 6-7, the top end of the synchronous wheel 6-6 and the bottom end of the other tension wheel 6-7 in sequence and is fixed to the other fixed base 6-2. The two fixed bases 6-2 are both fixed on the bottom plate 6-1. The synchronous wheel 6-6 and the two tension wheels 6-7 all form rolling friction pairs with the synchronous belt 6-8, and the synchronous wheel 6-6 is driven to rotate by a servo motor 6-5.

[0051] As Figure 4 and Figure 5As shown, the series-parallel picking manipulator 4 includes a series-parallel manipulator and a picking end 4-11; the series-parallel manipulator includes a static platform 4-1, a first active arm 4-2, a first driven link 4-3, a first motor bracket 4-6, a second active arm 4-8, a second driven link 4-9, and a moving platform 4-10; the static platform 4-1 is fixed on the synchronous pulley bracket 6-4; one ends of the two first active arms 4-2 respectively form a rotating pair with the two ends of the static platform 4-1, and are respectively driven to rotate by two first joint motors 4-4, and three first rotating shafts arranged in parallel are fixed at the other ends; the moving platform 4-10 includes a moving platform bracket 4-10-1 and a rotating member 4-10-3, the moving platform bracket 4-10-1 is located below the static platform 4-1, and three second rotating shafts 4-10-5 arranged in parallel are fixed at both ends of the moving platform bracket 4-10-1, and the middle forms a rotating pair with the rotating member 4-10-3; there are two groups of driven link groups composed of three first driven links 4-3 arranged in parallel, and both ends of each first driven link in the driven link group respectively form a spherical hinge with a first rotating shaft and a second rotating shaft 4-10-5 on the same side through two fish-eye bearings; the first motor bracket 4-6 forms a rotating pair with the static platform 4-1; one end of the second active arm 4-8 forms a rotating pair with the first motor bracket 4-6 and is driven to rotate by the second joint motor 4-7, and both ends of the second driven link 4-9 are respectively hinged to the other end of the second active arm 4-8 and the rotating member 4-10-3. Among them, the rotation center axes between the two first active arms 4-2 and the static platform 4-1, the rotation center axis between the first motor bracket 4-6 and the static platform 4-1, the rotation center axis between the rotating member 4-10-3 and the moving platform bracket 4-10-1, each first rotating shaft and each second rotating shaft 4-10-5 are horizontal and arranged in parallel, the rotation center axis between the second active arm 4-8 and the first motor bracket 4-6 and the rotation center axes at both ends of the second driven link 4-9 are horizontal and arranged in parallel, and are perpendicular to the first rotating shaft and perpendicular to the direction in which the translation device 6 drives the static platform 4-1 to translate.

[0052] As Figure 6 and Figure 7As shown, the picking end 4-11 includes a rudder machine frame 4-11-4, a rudder machine arm 4-11-6, a connecting link 4-11-7, a clamping block 4-11-8, a second baffle 4-11-9 and a blade 4-11-10. The rudder machine frame 4-11-4 is driven to rotate by a joint motor three 4-11-2, and the joint motor three 4-11-2 is fixed to the moving platform bracket 4-10-1; the middle part of the rudder machine arm 4-11-6 forms a rotating pair in the horizontal direction with the rudder machine frame 4-11-4 and is driven to rotate by a steering gear 4-11-5. The two ends are respectively hinged to one end of two connecting links 4-11-7 arranged in central symmetry. The other ends of the two connecting links 4-11-7 are hinged to the middle parts of two clamping blocks 4-11-8 arranged in axial symmetry. The upper ends of the two clamping blocks 4-11-8 are both hinged to the rudder machine frame 4-11-4, and the lower ends are fixed with two blades 4-11-10 arranged in axial symmetry. A second baffle 4-11-9 is fixed on one side of the two blades 4-11-10 on the rudder machine frame 4-11-4, and the second baffle is located on the side of the two blades 4-11-10 away from the belt conveyor 8.

[0053] As a preferred embodiment, the fixed shell 5-2 is fixed to the frame 2 through the chassis 5-6.

[0054] As a preferred embodiment, two guide rails 6-9 arranged in parallel and at intervals are fixed on the bottom plate 6-1. The two guide rails 6-9 respectively form a sliding pair with two sliders 6-10, and the synchronous pulley bracket 6-4 is fixed to both sliders 6-10.

[0055] As a preferred embodiment, both ends of the synchronous belt 6-8 are respectively fixed to two fixed bases 6-2 through two synchronous belt pressing plates 6-3.

[0056] As a preferred embodiment, the motor bracket one 4-6 is supported on the static platform 4-1 through a rotary bearing one 4-5.

[0057] As a preferred embodiment, the rotating part 4-10-3 is supported on the moving platform bracket 4-10-1 through a rotary bearing two 4-10-2.

[0058] More preferably, the outer ring of the rotary bearing two 4-10-2 is embedded in the bearing hole opened on the moving platform bracket 4-10-1 and is axially limited by the bearing end cover 4-10-4 fixed to the moving platform bracket 4-10-1 and the transition step surface in the bearing hole. The inner ring is fixed to the optical axis section at one end of the threaded rod, and the threaded section at the other end of the threaded rod is threadedly connected to the rotating part 4-10-3.

[0059] As a preferred embodiment, the housing of the third joint motor 4-11-2 is fixed to the moving platform bracket 4-10-1 through the second motor bracket 4-11-1, and the output shaft of the third joint motor 4-11-2 is fixed to the rudder machine bracket 4-11-4 through the motor flange 4-11-3.

[0060] Among them, the servo motor 6-5, the second joint motor 4-7, the third joint motor 4-11-2, the steering gear 4-11-5 and the two first joint motors 4-4 are all controlled by the controller. The signal output end of the binocular camera 7 is connected to the controller, and the controller communicates with the upper computer.

[0061] The tea picking method of the tea picking device using the redundant degree-of-freedom series-parallel manipulator of the present invention is as follows:

[0062] The two mobile chassis 1 drive the frame 2 to move onto the tea ridge. Manually rotate the two handwheels 5-1 synchronously forward or backward (by two workers). Each handwheel 5-1 drives the nut block 5-3 to rise or fall through the corresponding worm 5-5, worm gear and screw 5-4, and then drives the translation device 6 and the series-parallel picking manipulator 4 to rise or fall through the two nut blocks 5-3, so that the height of the end of the blade 4-11-10 reaches the preset initial height. The two mobile chassis 1 drive the frame 2 to intermittently advance along the tea ridge. And whenever the two mobile chassis 1 stop driving the frame 2, the series-parallel picking manipulator 4 and the translation device 6 work to perform the tea picking work in the current working area. The tea picking work process is as follows: First, the binocular camera 7 acquires the image of the current working area and transmits the image of the current working area to the upper computer. The upper computer identifies the positions of the tea buds in the working area and generates a set of spatial coordinates of the tea bud positions. Among them, the spatial coordinate system takes a corner point on the side of the working area close to the series-parallel picking manipulator 4 as the origin O, the direction in which the two mobile chassis 1 drive the frame 2 to advance is the Y-axis direction, the direction in which the translation device 6 drives the series-parallel picking manipulator 4 to translate is the X-axis direction, and the vertical direction is the Z-axis direction. Then, according to the generated set of spatial coordinates of the tea bud positions, the overall optimal picking path of the working area is obtained through the improved ant colony algorithm. Then, the tea buds on the overall optimal picking path in the current working area are harvested according to the overall optimal picking path of the working area (after harvesting, the translation device 6 drives the series-parallel picking manipulator 4 back to the initial position).

[0063] Among them, as Figure 8 shown, the process of obtaining the optimal picking path by using the improved ant colony algorithm is as follows:

[0064] (1) As Figure 9As shown in the figure, the working area is divided into two low-density regions and a high-density region located between the two low-density regions along the X-axis direction according to the distribution characteristics of tea buds (high density in the middle and low density on both sides). A transition region is demarcated on one side of each of the two low-density regions adjacent to the high-density region. Let the size ranges of the two low-density regions be [0, 0.4m] and [1.1m, 1.5m] respectively, where m is the unit of meter. The size ranges of the transition regions in the two low-density regions are [0.3m, 0.4m] and [1.1m, 1.2m] respectively, and the size range of the high-density region is (0.4m, 1.1m). When the static platform 4-1 is located in other regions of the low-density region except the transition region, the speed is , when it is located in the high-density region, the speed is , when it is located in the transition region, the speed is , and , is the X-axis coordinate of the static platform 4-1 when it is located in the transition region, is the X-axis coordinate of the farthest point of the transition region from the high-density region, that is, or ; the speed of the static platform 4-1 when it is located in other regions of the low-density region except the transition region is taken from the candidate set {0.1m / s, 0.12m / s, 0.14m / s}, where m / s is the unit of meter per second. When it is located in the high-density region, the speed is taken from the candidate set {0.05m / s, 0.07m / s, 0.09m / s}.

[0065] (2) Parameter initialization: Let the pheromone on the path from node i to node j at the t-th iteration be , set the initial value of , the number of ants m = 20, the pheromone weight in the weight parameter, the heuristic weight , the evaporation coefficient , the speed influence coefficient in the dynamic parameter, the cross-interval penalty factor , the pheromone increment adjustment coefficient ; define the time window: , which is used to restrict the time for the ant to reach node i from the previous node at node i (the i-th tea bud), ensuring that the path selection meets the time limit. is the offset of the redundant degree of freedom control of the picking end 4-11 in the X-axis direction provided by the redundant degree of freedom expansion mechanism composed of the joint motor two, the active arm two 4-8 and the driven link two 4-9, and , represents the X-axis coordinate of node i, Represent the velocity of the static platform 4-1 at at this point.

[0066] (3) Considering both the time cost and the velocity of the static platform 4-1, define the heuristic information as

[0067]

[0068] In the formula, define the heuristic information to represent the attraction from node i to node j, denote the maximum value that can be obtained from the candidate set. In this embodiment, , represent the time cost from node i to node j, represent the time difference of the ant from node i to node j, and , represent the distance in the X-axis direction of the constant-velocity segment part in the path from node i to node j, represent the velocity of the static platform 4-1 when it is in the constant-velocity segment part in the path from node i to node j, and , and respectively represent the X-axis coordinates of the starting point (starting node) and the ending point (ending node) of the variable-velocity segment part in the path from node i to node j, represent the velocity of the static platform 4-1 when it is in the variable-velocity segment part in the path from node i to node j, and , n is the total number of nodes in the path from node i to node j, is the harvesting time at node p, including the picking and throwing times, and ;

[0069] Considering the position area difference between node i and node j and the difference in the translational velocity of the static platform 4-1 at node i and node j, the heuristic information is corrected to be

[0070]

[0071] In the formula, is the velocity difference weight, and = 0.2, is the area difference, and , denote the minimum value that can be obtained from the candidate set. In this embodiment, ;

[0072] The path selection probability is

[0073]

[0074] In the formula, represents the set of unvisited nodes on the path from node i to node j.

[0075] (4) Select and , calculate the speed when the static platform is in the transition region, and execute steps (2) and (3) to obtain the path selection probabilities of various paths from node i to node j.

[0076] (5) Update the global pheromone

[0077]

[0078] In the formula, represents the increment of pheromone left by ant q on the path from node i to node j, and , is the number of nodes successfully picked by ant q (i.e., the number of nodes passed by the path from node i to node j where ant q is located), and the time cost of ant q on the path from node i to node j , is the reference speed, and the maximum speed of 0.14 m / s during the translation of the static platform 4 - 1 is taken.

[0079] After each update of the global pheromone, recalculate the path selection probabilities of various paths from node i to node j.

[0080] (6) When the iteration number is reached, use the path from node i to node j with the maximum path selection probability as the selected and corresponding optimal picking path.

[0081] (7) Repeat steps (4) to (6), and update and when repeating, until all and combinations are traversed, use the path from node i to node j with the maximum path selection probability among all calculated path selection probabilities as the final picking path from node i to node j, and obtain the corresponding and combination.

[0082] (8) The ant starts from the starting point (i.e., initially node i is at the position of ), and until it reaches the node with the maximum X - axis coordinate in the working area, each time a path from node i to node j is generated, node j is used as the new node i, thus generating the overall optimal picking path of the working area.

[0083] The process of harvesting each tea bud on the overall optimal picking path within the current working area according to the overall optimal picking path of the working area is as follows: The controller controls the servo motor 6-5 to drive the synchronous pulley 6-6 to rotate. The synchronous pulley 6-6 and the synchronous belt 6-8 form a rolling friction pair, thereby driving the synchronous pulley bracket 6-4 to translate along the X-axis direction. The synchronous pulley bracket 6-4 drives the entire series-parallel picking robotic arm 4 to translate along the X-axis direction through the static platform 4-1, so that the midpoint of the ends of the two blades 4-11-10 of the picking end 4-11 is sequentially translated to the X-axis coordinate positions of the positions of each tea bud (node positions) on the overall optimal picking path of the working area, and the series-parallel picking robotic arm 4 translates along the X-axis direction at the corresponding speed calculated in step (7) on each final picking path; while the series-parallel picking robotic arm 4 is translating along the X-axis direction, the controller controls the two joint motors one 4-4 to drive the corresponding active arms one 4-2 to rotate. Each active arm one 4-2 drives the moving platform bracket 4-10-1 and the picking end 4-11 to move in the vertical plane parallel to the YOZ plane through the corresponding driven link groups, so that the midpoint of the ends of the two blades 4-11-10 of the picking end 4-11 is sequentially translated to the Y-axis coordinate positions of the positions of each tea bud on the overall optimal picking path of the working area, and the distance deviation between the midpoint of the ends of the two blades 4-11-10 of the picking end 4-11 (the image of the midpoint position of the ends of the two blades 4-11-10 of the picking end 4-11 can be obtained in real time through the binocular camera 7) and the position of this tea bud in the X-axis direction and the Y-axis direction is calculated in real time. If the distance deviation in the X-axis direction is not within the preset deviation range, the controller controls the joint motor two to drive the active arm two 4-8 to drive the driven link two 4-9 to rotate. The driven link two 4-9 drives the picking end 4-11 to adjust along the X-axis direction through the moving platform bracket 4-10-1, so that the distance deviation in the X-axis direction is within the preset deviation range. If the distance deviation in the Y-axis direction is not within the preset deviation range, the two joint motors one 4-4 drive the corresponding active arms one 4-2 to rotate for adjustment, such as Figure 10 and Figure 11As shown; when the midpoints of the ends of the two blades 4-11-10 at the picking end 4-11 reach the position of the tea bud, the controller controls the servo motor 4-11-5 to drive the servo arm 4-11-6 to rotate forward. The servo arm 4-11-6 drives the lower ends of the two clamping blocks 4-11-8 to move towards each other through the two connecting linkages 4-11-7, thereby driving the ends of the two blades 4-11-10 to close for shearing the tea bud, completing the picking of the tea bud. At the same time, the two closed blades 4-11-10 and the baffle two 4-11-9 form a three-sided enclosed accommodation cavity for temporarily storing the tea bud. Then, the controller controls the joint motor three 4-11-2 to drive the servo frame 4-11-4 to drive the tea bud to rotate towards the direction close to the belt conveyor 8, and the tea bud is thrown onto the conveyor belt of the belt conveyor 8 by centrifugal force. The belt conveyor 8 transports the tea bud into the material box to complete the collection of the tea bud. Then, the controller controls the joint motor three 4-11-2 to drive the servo frame 4-11-4 to drive the tea bud to rotate away from the belt conveyor 8 to the original position, and at the same time controls the servo motor 4-11-5 to drive the servo arm 4-11-6 to rotate in reverse. The servo arm 4-11-6 drives the two clamping blocks 4-11-8 and the two blades 4-11-10 to move away from each other to the original position.

Claims

1. A tea picking device using a redundant degree of freedom series-parallel robotic arm, comprising a lifting device, a translation device and a belt transmission mechanism, characterized in that: It further includes a series-parallel picking robotic arm; two lifting devices for driving the lifting of the translation device are provided on the frame; the belt conveyor mechanism is located behind the translation device; a first baffle is fixed on the frame on the side of the belt conveyor mechanism away from the translation device; The series-parallel picking robotic arm includes a series-parallel robotic arm and a picking end; the series-parallel robotic arm includes a static platform and a moving platform; the static platform is driven to translate by the translation device, and the direction is perpendicular to the advancing direction of the frame; one end of each of the two first active arms forms a rotational pair with both ends of the static platform respectively, and is driven to rotate by two first joint motors respectively, and the other end of each is fixed with n first rotating shafts arranged in parallel, where n≥3; the moving platform includes a moving platform bracket, the moving platform bracket is located below the static platform, and both ends of the moving platform bracket are fixed with n second rotating shafts arranged in parallel, and the middle forms a rotational pair with a rotating member; there are two sets of driven link groups composed of n first driven links arranged in parallel, and both ends of each first driven link in the driven link group form spherical hinges with one first rotating shaft and one second rotating shaft on the same side respectively; a first motor bracket forms a rotational pair with the static platform; one end of the second active arm forms a rotational pair with the first motor bracket and is driven to rotate by a second joint motor, and both ends of the second driven link are hinged to the other end of the second active arm and the rotating member respectively; among them, the rotational center axes between the two first active arms and the static platform, the rotational center axis between the first motor bracket and the static platform, the rotational center axis between the rotating member and the moving platform bracket, each first rotating shaft and each second rotating shaft are horizontal and parallel, the rotational center axis between the second active arm and the first motor bracket and the rotational center axes at both ends of the second driven link are horizontal and parallel, perpendicular to the first rotating shaft, and perpendicular to the direction in which the translation device drives the series-parallel picking robotic arm to translate; the picking end is installed on the moving platform bracket.

2. The tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 1, characterized in that: The lifting device includes a handwheel, a fixed housing, a nut block, a screw rod and a worm; the fixed housing is fixed on the frame, the horizontally arranged worm forms a rotational pair with the fixed housing, the handwheel is fixed on the worm, the vertically arranged screw rod forms a rotational pair with the fixed housing, and forms a ball screw pair with the nut block through balls; the worm meshes with the turbine fixed on the screw rod.

3. The tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 1, characterized in that: The translation device includes a bottom plate, a synchronous wheel bracket, a synchronous wheel, a tensioning wheel and a synchronous belt; both ends of the horizontally arranged bottom plate are fixed to the nut blocks of the two lifting devices; the synchronous wheel bracket forms a sliding pair with the bottom plate; the synchronous wheel is hinged on the synchronous wheel bracket, and tensioning wheels are hinged on both sides of the synchronous wheel; both ends of the synchronous belt are fixed on the bottom plate, the synchronous wheel and the two tensioning wheels form rolling friction pairs with the synchronous belt respectively, and the synchronous wheel is driven to rotate by a servo motor.

4. The tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 1, characterized in that: The picking end includes a steering gear frame and two blades that can be opened and closed; the steering gear frame is driven by a joint motor three to rotate, and the joint motor three is fixed to the moving platform bracket; a second baffle is fixed on the steering gear frame in front of the two blades; in the picking end, the middle of the steering gear arm forms a rotational pair with the steering gear frame in the horizontal direction and is driven by a steering gear to rotate. The two ends are respectively hinged to one ends of two connecting linkages arranged centrosymmetrically, and the other ends of the two connecting linkages are hinged to the middle parts of two clamping blocks arranged axially symmetrically. The upper ends of the two clamping blocks are hinged to the steering gear frame, and the lower ends are fixed with two blades arranged axially symmetrically.

5. The tea picking method of the tea picking device using a redundant degree-of-freedom series-parallel robotic arm as described in claim 4, characterized in that: Specifically as follows: Two mobile chassis drive the frame to move onto the tea ridge. The translation device and the serial-parallel picking robotic arm are driven to rise or fall by two lifting devices, so that the height of the blade end reaches the preset initial height. Two mobile chassis drive the frame to intermittently advance along the tea ridge. And whenever the two mobile chassis stop driving the frame, the serial-parallel picking robotic arm and the translation device work to pick tea in the current working area. The process of picking tea is as follows: First, the binocular camera acquires the image of the current working area and transmits the image of the current working area to the upper computer. The upper computer identifies the positions of the tea buds in the working area and generates a set of spatial coordinates of the tea bud positions. Among them, the spatial coordinate system takes a corner point on the side of the working area close to the serial-parallel picking robotic arm as the origin O, the advancing direction of the two mobile chassis drive the frame as the Y-axis direction, the translation direction of the translation device driving the serial-parallel picking robotic arm as the X-axis direction, and the vertical direction as the Z-axis direction. Then, according to the generated set of spatial coordinates of the tea bud positions, the overall optimal picking path of the working area is obtained through the improved ant colony algorithm. Then, each tea bud on the optimal picking path in the current working area is harvested according to the overall optimal picking path of the working area.

6. The tea picking method of the tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 5, characterized in that: The process of obtaining the optimal picking path by using the improved ant colony algorithm is as follows: (1) The working area is divided into two low-density regions and a high-density region located between the two low-density regions along the X-axis direction, and a transition region is defined; assume that the speed of the static platform in the low-density region except the transition region is , the speed in the high-density region is , and the speed in the transition region is ; (2)Set the pheromone on the path from node i to node j at the t-th iteration initial value, the number of ants, pheromone weight , heuristic weight , evaporation coefficient , speed influence coefficient , cross-interval penalty factor , pheromone increment adjustment coefficient , time window; (3) Define heuristic information and modified heuristic information ; Calculate the path selection probability; (4) Selection and Calculate the velocity when the static platform is in the transition region, execute steps (2) and (3), and obtain the path selection probabilities of various paths from node i to node j; (5) Update the global pheromone. After each update of the global pheromone, recalculate the path selection probabilities of various paths from node i to node j. (6) When the number of iterations is reached, the path from node i with the highest path selection probability to node j is used as the selected and corresponding optimal picking path; (7) Repeat steps (4) to (6), and update and until all combinations of and are traversed. Take the path from node i to node j with the maximum path selection probability among all calculated path selection probabilities as the final picking path from node i to node j, and obtain the and combinations corresponding to the final picking path; (8) The ant starts from the starting point of the working area until it reaches the node with the largest X-axis coordinate in the working area. Each time a path from node i to node j is generated, node j is taken as the new node i, so as to generate the overall optimal picking path of the working area.

7. The tea picking method of the tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 6, characterized in that: The heuristic information is wherein, represents the maximum value that can be obtained from the candidate set, the time difference between the ant from node i to node j and the time cost of ant q on the path from node i to node j , represents the distance in the X-axis direction of the constant-speed section part in the path from node i to node j, and the speed of the static platform when it is in the constant-speed section part in the path from node i to node j , and respectively represent the starting X-axis coordinate and the ending X-axis coordinate of the variable-speed section part in the path from node i to node j, and the speed of the static platform when it is in the variable-speed section part in the path from node i to node j is the total harvesting time of each node in the path from node i to node j , n is the total number of nodes in the path from node i to node j, is the harvesting time at node p, including the picking and throwing times.

8. The tea picking method of the tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 7, characterized in that: The corrected heuristic information is In the formula, is the speed difference weight, is the regional difference, and , represents the minimum value that can be obtained from the candidate set.

9. The tea picking method of the tea picking device using a serial-parallel robotic arm with redundant degrees of freedom according to claim 8, characterized in that: The path selection probability is Wherein, represents the set of unvisited nodes on the path from node i to node j; The update of the global pheromone is Wherein, represents the increment of pheromone left by ant q on the path from node i to node j, and , is the number of nodes successfully picked by ant q, is the time cost of ant q on the path from node i to node j, and the reference speed takes the speed the maximum speed in the candidate set, represents the X-axis coordinate of node i, represents the static platform at the speed at.

10. The tea picking method of the tea picking device using a redundant degree-of-freedom series-parallel robotic arm according to claim 6, characterized in that: The process of harvesting tea buds on the overall optimal picking path in the current working area according to the overall optimal picking path of the working area is as follows: The translation device drives the static platform to drive the entire serial-parallel picking robotic arm to translate along the X-axis direction, so that the midpoint of the two blade ends at the picking end is sequentially translated to the X-axis coordinate positions of each tea bud position on the overall optimal picking path of the working area, and the serial-parallel picking robotic arm translates along the X-axis direction at the corresponding speed calculated in step (7) on each final picking path; while the serial-parallel picking robotic arm translates along the X-axis direction, two joint motors 1 drive the corresponding active arms 1 to rotate, and each active arm 1 drives the moving platform support and the picking end to move in a vertical plane parallel to the YOZ plane through the corresponding driven link group, so that the midpoint of the two blade ends at the picking end is sequentially translated to the Y-axis coordinate positions of each tea bud position on the overall optimal picking path of the working area, and the distance deviation between the midpoint of the two blade ends at the picking end and the tea bud position in the X-axis direction and the Y-axis direction is calculated in real time. When the distance deviation in the Y-axis direction is not within the preset deviation range, joint motor 2 drives the active arm 2 to drive the driven link 2 to rotate, and the driven link 2 drives the picking end to adjust along the X-axis direction through the moving platform support, so that the distance deviation in the X-axis direction is within the preset deviation range. If the distance deviation in the Y-axis direction is not within the preset deviation range, two joint motors 1 drive the corresponding active arms 1 to rotate for adjustment; when the midpoint of the two blade ends at the picking end reaches the tea bud position, the servo motor drives the servo arm to rotate forward, and the servo arm drives the lower ends of the two clamping blocks to move towards each other through two connecting links, thereby driving the two blade ends to close for tea bud shearing; then joint motor 3 drives the tea bud rack to rotate the tea bud towards the direction close to the belt conveyor mechanism, and throws the tea bud onto the conveyor belt of the belt conveyor mechanism by centrifugal force, and the belt conveyor mechanism transports the tea bud into the material box; then joint motor 3 drives the tea bud rack to rotate the tea bud away from the belt conveyor mechanism to the original position, and at the same time the servo motor drives the servo arm to rotate in reverse, and the servo arm drives the two clamping blocks and the two blades to move away from each other to the original position.

Images