CN110465928B - Storage commodity taking and placing mobile platform and path planning method of mobile platform - Google Patents
Storage commodity taking and placing mobile platform and path planning method of mobile platform Download PDFInfo
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- CN110465928B CN110465928B CN201910781253.XA CN201910781253A CN110465928B CN 110465928 B CN110465928 B CN 110465928B CN 201910781253 A CN201910781253 A CN 201910781253A CN 110465928 B CN110465928 B CN 110465928B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J15/00—Gripping heads and other end effectors
- B25J15/08—Gripping heads and other end effectors having finger members
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/02—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type
- B25J9/04—Programme-controlled manipulators characterised by movement of the arms, e.g. cartesian coordinate type by rotating at least one arm, excluding the head movement itself, e.g. cylindrical coordinate type or polar coordinate type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/08—Programme-controlled manipulators characterised by modular constructions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/16—Programme controls
- B25J9/1656—Programme controls characterised by programming, planning systems for manipulators
- B25J9/1664—Programme controls characterised by programming, planning systems for manipulators characterised by motion, path, trajectory planning
- B25J9/1666—Avoiding collision or forbidden zones
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
- B60P1/00—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
- B60P1/00—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading
- B60P1/04—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading with a tipping movement of load-transporting element
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- Mechanical Engineering (AREA)
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Abstract
The invention discloses a storage commodity taking and placing mobile platform and a path planning method of the mobile platform, wherein the mobile platform comprises a mobile platform body, an obstacle avoidance device, a mechanical arm device, a commodity placing device, a commodity identification device and a commodity grabbing device; the obstacle avoidance device, the mechanical arm device and the commodity placing device are arranged on the moving platform body, the commodity grabbing device is arranged at the tail end of the mechanical arm device, and the commodity identification device is arranged on the commodity grabbing device; the mechanical arm device comprises a rotating mechanism and a plurality of mechanical arms, the mechanical arms are connected in a rotating mode, the mechanical arms form a modular mechanical arm, one end of the first mechanical arm is fixed to the rotating mechanism, and the tail end of the last mechanical arm is fixed to the commodity grabbing device. The method adopts an improved dynamic window method to adjust the three weights of the evaluation function in real time, improves the adaptability of the mobile platform to the environment, and ensures the success rate of the mobile platform reaching the specified position point.
Description
Technical Field
The invention relates to the field of mobile robots, in particular to a mobile platform for taking and placing stored commodities and a path planning method of the mobile platform.
Background
With the rapid development of the internet, online shopping has become one of the shopping methods that people often adopt. The online shopping promotes the high-speed development of the logistics industry, unmanned factories and unmanned sorting gradually appear, and the mobile robot can bring great convenience for storage, transportation, distribution and the like.
At present, a lot of mobile robots for picking and placing stored commodities exist, but most of mobile robots can easily pick and place commodities with large volumes, and pick and place commodities with small volumes are not easily achieved.
Chinese patent No. 201520955138.7 discloses a transfer robot for small articles, which uses a worm gear mechanism to clamp and separate two grippers by two articulated arms, and since the grippers are arranged at the ends of the articulated arms, the distance between the worm gear and the two grippers is large, resulting in a large distance between a force application point and a force bearing point, and reducing the reliability of gripping articles; in addition, as the worm drive has larger relative sliding between tooth surfaces, heat is generated, so that the worm drive fails due to gluing; and the worm gear is installed in the mount pad, and the mount pad wraps the worm gear completely, and the worm gear is because can not in time dispel the heat and the veneer, influences worm drive's bearing capacity, has further reduceed the reliability of snatching the article.
Chinese patent application No. 201811183053.6 discloses a mobile robot for picking and placing goods on a shelf, which realizes the picking of goods by a picking plate of a goods picking device; because the grabbing plate is of a C-like shape, the goods are grabbed in an encircling mode, the grabbing plate is suitable for grabbing large-size goods, and grabbing of small-size goods is difficult to achieve.
In addition, currently, a method combining an a-algorithm and a dynamic window method is commonly used to implement path planning of a mobile robot, see document "global dynamic path planning fusing an improved a-algorithm and a dynamic window method"; however, the three weights of the evaluation functions of most dynamic window methods are constant values all the time in the whole process of path planning and cannot be changed due to the change of the environment, so that the self-adaptive capacity of the mobile robot to the environment is poor, and the obstacle avoidance capacity is also poor.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a moving platform for taking and placing stored commodities and a path planning method of the moving platform.
The technical scheme adopted by the invention for solving the problem of the mobile platform is as follows:
a storage commodity taking and placing moving platform comprises a moving platform body, an obstacle avoidance device, a mechanical arm device, a commodity placing device, a commodity identification device and a commodity grabbing device; the obstacle avoidance device, the mechanical arm device and the commodity placing device are arranged on the moving platform body, the commodity grabbing device is arranged at the tail end of the mechanical arm device, and the commodity identification device is arranged on the commodity grabbing device;
the mechanical arm device comprises a rotating mechanism and a plurality of mechanical arms, the mechanical arms are mutually and rotatably connected, the mechanical arms form a modular mechanical arm, one end of the first mechanical arm is fixed with the rotating mechanism, and the tail end of the last mechanical arm is fixed with the commodity grabbing device; the rotating mechanism is arranged on the moving platform body, and the modular mechanical arm is arranged on the rotating mechanism;
the commodity grabbing device comprises a connecting frame, a lead screw support, a lead screw nut, two finger pushing rods, two fingers and a fourth motor; one side of the connecting frame is fixedly connected with one side of the tail end of the modular mechanical arm, and the other side of the connecting frame is provided with a lead screw support; a screw is rotatably arranged on the screw support, a screw nut is sleeved on the screw and can slide on the screw, and one end of the screw is connected with an output shaft of a fourth motor arranged on the other side of the tail end of the modular mechanical arm through a coupler; one end of each finger is hinged to the connecting frame, and an opening formed at the other end of each finger is used for grabbing a commodity; one end of each of the two finger pushing rods is fixed on the corresponding finger, and the other end of each finger pushing rod is hinged to the screw nut.
The commodity placing device comprises a fifth motor, a motor bracket, a turnover table shifting piece, two turnover table brackets and a turnover table; the two turning platform supports and the motor support are fixed on the moving platform body, an arc-shaped groove is formed in one end of the turning platform, connecting columns are arranged on two sides of the other end of the turning platform, the two connecting columns are respectively matched with notches of the corresponding turning platform supports, and the turning platform can rotate relative to the turning platform supports; the fifth motor is fixed on the motor support, a turnover table shifting piece is installed on an output shaft of the fifth motor, and the turnover table shifting piece is always clamped in a groove of the turnover table.
The rotating mechanism comprises a base, a mounting seat, a first output flange and a first motor; the base is installed on the moving platform body, and first motor is installed on the base, installs first output flange on the output shaft of first motor, and the mount pad is installed on first output flange.
The mechanical arm comprises a second motor, a second output flange and a mechanical arm body; the mechanical arm body comprises a No. 1 arm plate support, a first arm plate, a U-shaped No. 2 arm plate support and a second arm plate; one side of the No. 1 armboard bracket is connected with the second output flange and one end of the second armboard; the opposite side of No. 1 arm board support links to each other with the one end of first arm board, and the end of first arm board and second arm board all links to each other with No. 2 arm board support.
The obstacle avoidance device comprises a radar support, a laser radar scanning range finder and a plurality of ultrasonic sensors; the laser radar scanning range finder is arranged on the radar support; a plurality of ultrasonic sensor install around the moving platform body.
The mobile platform also comprises a control system, wherein the control system comprises a motion control panel and an upper computer, the motion control panel and the upper computer are both arranged on the mobile platform body, the upper computer is in communication connection with the motion control panel, the motion control panel is electrically connected with a motor, and the upper computer is in communication connection with the laser radar scanning range finder and the plurality of ultrasonic sensors respectively; the motion control plate adopts an STM32F429 chip; the upper computer adopts the association thinpapadx 260.
The commodity grabbing device further comprises a spring, and two ends of the spring are fixedly connected with one end, close to the connecting frame, of each finger respectively.
The finger is provided with a plurality of anti-slip grooves.
The technical scheme adopted by the invention for solving the problems of the method is as follows:
a path planning method for a storage commodity taking and placing mobile platform comprises the following steps:
1) constructing a global map: before work, scanning a working environment through a laser radar scanning range finder to complete construction of a global map, and storing the global map in an upper computer;
the working environment comprises commodity classification position information and barrier information;
2) and (3) global path planning: the upper computer issues a goods taking instruction, retrieves the commodity classification position, and performs global path planning on a traveling path from the starting point of the mobile platform to the commodity classification position by adopting an A-x algorithm; if a new obstacle appears on the global map, the upper computer judges the position relation between the new obstacle and the global path; if the new obstacle is not on the global path, the mobile platform continues to travel; if the new obstacle is located on the global path, executing step 3), and enabling the mobile platform to bypass the new obstacle and return to the global path;
3) local path optimization: and performing local path optimization on a path between the current position of the mobile platform and a path which bypasses a new obstacle and returns to the global path by adopting an improved dynamic window method, and adjusting three weights of an evaluation function of the improved dynamic window method in real time.
Wherein, the improved dynamic window method in the step 3) comprises the following steps:
s1, building working environments with different numbers of obstacles through matlab, and obtaining a plurality of feasible speed spaces with different sizes;
s2, performing multiple path planning on each working environment by using a dynamic window method to obtain an optimal weight combination under each working environment; sequentially obtaining a set of optimal weight combinations of all working environments according to the steps, and constructing a fuzzy logic controller;
and S3, taking the real-time feasible speed space of the mobile platform and the distance between the current position of the mobile platform and the commodity classification position as the input of the fuzzy logic controller, and obtaining three weights of alpha, beta and gamma of the improved dynamic window method evaluation function in real time, so that the function of automatically searching the optimal weight combination by the mobile platform, further adjusting the path in real time and reaching the target point is realized.
Compared with the prior art, the invention has the beneficial effects that:
1) the commodity grabbing device provided by the invention has the advantages that the commodity grabbing is realized through the two fingers of the commodity grabbing device, the two fingers are similar to the clamp heads of the pliers, the commodity taking and placing reliability is improved, and the moving platform is particularly suitable for displaying and placing commodities with the maximum volume equivalent to the size of the pop-top can on the goods shelf.
2) According to the invention, the opening and closing of the two fingers are realized through the transmission of the screw rod, so that the commodity is grabbed, and the transmission efficiency can reach 97% due to the small friction force between the screw rod and the screw rod nut, so that the reliability of grabbing the commodity by the mobile platform is further improved; and the lead screw transmission can realize the micro-feeding, can reduce the feed amount of the lead screw transmission when the goods are denser, and guarantee the accuracy of grabbing.
3) The invention adopts a mode of combining the commodity grabbing device and the mechanical arm, so that the commodity grabbing device is more flexible to extend out and retract, and is particularly suitable for goods shelves with smaller layer distance; and the volume of the commodity grabbing device is small (240 × 80 × 40mm), and the commodity grabbing device can be better suitable for the conditions of more commodities and more dense placement.
4) The two mechanical arm bodies are designed in a light weight mode and are composed of the arm plate and the arm plate support, and the arm plate is provided with a plurality of hollowed holes, so that the weight of the arm is effectively reduced, the load of the mobile platform is reduced, and the rotation of the mechanical arm device and the walking of the mobile platform are more flexible; in addition, the hollow holes in the arm plate can be used for bundling and fixing cables of equipment such as motors on the arm device by using a binding belt and the like, so that messy routing of the mobile platform is avoided.
5) The camera is arranged at the tail end of the second mechanical arm body by adopting an eye-on-hand structural strategy, so that the camera is identified at the near end of a commodity, the commodity identification accuracy is improved, and the camera is convenient to grab.
6) The path planning method of the mobile platform adopts an improved dynamic window method to adjust the three weights of the evaluation function in real time, so that the mobile platform can better adapt to the working environment with violent change of the number of obstacles, the adaptability of the mobile platform to the environment is improved, and the success rate of the mobile platform reaching the specified position point is ensured.
7) The four arm plates are all the arm plates with the same specification, so that the replacement and maintenance of the arms at the later stage are facilitated, and the maintenance cost is reduced.
8) The mobile platform can automatically finish goods taking and goods transferring, greatly improves the sorting automation degree and improves the working efficiency.
Drawings
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic structural diagram of a mobile platform body and a control system according to the present invention;
FIG. 3 is a schematic structural view of the rotating mechanism of the present invention;
FIG. 4 is a schematic diagram of a first robot according to the present invention;
FIG. 5 is a schematic view of a second robot arm according to the present invention;
FIG. 6 is a schematic view of the structure of the merchandise gripping device of the present invention;
FIG. 7 is a schematic structural diagram of a merchandise identification device according to the present invention;
FIG. 8 is a schematic view of the merchandise placement device according to the present invention;
FIG. 9 is a schematic view of the engagement between the flipping table pick of the present invention and the flipping table;
fig. 10 is a schematic structural diagram of an obstacle avoidance apparatus according to the present invention;
FIG. 11 is a diagram showing simulation results of experiment 1 according to the present invention;
FIG. 12 is a diagram showing simulation results of experiment 2 of the present invention;
FIG. 13 is a diagram showing simulation results of experiment 3 according to the present invention;
in the figure: 1-moving a platform body; 2-a control system; 3-obstacle avoidance device; 4-a mechanical arm device; 5-a commodity placing device; 6-a goods identification device; 7-a goods grasping device;
21-a motion control panel; 22-an upper computer; 31-a radar mount; 32-lidar scanning rangefinder; 33-an ultrasonic sensor; 41-a rotation mechanism; 42-a first robot arm; 43-a second robotic arm; 51-a fifth stepper motor; 52-motor support; 53-a turn-over plectrum; 54-a roll-over stand; 55-overturning the platform; 61-a camera; 62-a camera mount; 71-a connecting frame; 72-lead screw support; 73-lead screw; 74-lead screw nut; 75-a spring; 76-push fingers; 77-finger; 78-a fourth stepper motor;
411-a base; 412-a mount; 413-a first output flange; 414-first stepper motor; 421-a second stepper motor; 422-a second output flange; 423-1 armboard support; 424-first arm board; 425-2 armboard support; 426-a second arm plate; 431-a third stepper motor; 432-a third output flange; 433-3 armboard support; no. 434-4 armboard support; 435-a third arm board; 436-fourth arm board.
Detailed Description
Specific examples of the present invention are given below. The specific examples are only intended to illustrate the invention in further detail and do not limit the scope of protection of the claims of the present application.
The invention provides a storage commodity taking and placing moving platform (a moving platform for short, see fig. 1-13), which comprises a moving platform body 1, a control system 2, an obstacle avoidance device 3, a mechanical arm device 4, a commodity placing device 5, a commodity identification device 6 and a commodity grabbing device 7; the control system 2, the obstacle avoidance device 3, the mechanical arm device 4 and the commodity placing device 5 are installed on the moving platform body 1, the obstacle avoidance device 3 is located at the front end of the moving platform body 1, and the commodity placing device 5 is located in an area which can be touched by a mechanical arm of the mechanical arm device 4; the commodity grabbing device 7 is arranged on the mechanical arm device 4, and the commodity identification device 6 is arranged on the commodity grabbing device 7;
the mechanical arm of the mechanical arm device 4 reaches the position of the commodity through rotary motion; the commodity placing device 5 is used for containing the sorted commodities and transferring the commodities; the commodity identification device 6 is used for identifying the target commodity and calculating a commodity coordinate value to realize the positioning of the commodity; the commodity grabbing device 7 realizes grabbing of commodities;
the robot arm device 4 includes a rotation mechanism 41, a first robot arm 42, and a second robot arm 43; the rotating mechanism 41 is installed on the moving platform body 1, the first mechanical arm 42 is installed on the rotating mechanism 41, and the second mechanical arm 43 is installed on the first mechanical arm 42;
the rotating mechanism 41 comprises a base 411, a mounting seat 412, a first output flange 413 and a first stepping motor 414; the base 411 is installed on the mobile platform body 1, the first stepping motor 414 is installed on the base 411, the output shaft of the first stepping motor 414 is installed with a first output flange 413, the installation base 412 is installed on the first output flange 413, and the first stepping motor 414 drives the first output flange 413 to rotate; the output shaft of the first stepping motor 414 passes through the upper plane of the base 411 and is provided with a first output flange 413, and the first output flange 413 is not contacted with the base 411;
the first robot arm 42 includes a second stepping motor 421, a second output flange 422, and a first robot arm body; the second stepping motor 421 is mounted on the mounting base 412, a second output flange 422 is mounted on an output shaft of the second stepping motor 421, the first stepping motor 414 is perpendicular to the output shaft of the second stepping motor 421, and the second output flange 422 is not in contact with the mounting base 412; the second output flange 422 is provided with a first mechanical arm body, the tail end of the first mechanical arm body is connected with the second mechanical arm 43, the first mechanical arm 42 can rotate around the output shaft of the first stepping motor 414 under the action of the first stepping motor 414, and can rotate around the output shaft of the second stepping motor 421 under the action of the second stepping motor 421;
the first mechanical arm body comprises a No. 1 arm plate support 423, a first arm plate 424, a U-shaped No. 2 arm plate support 425 and a second arm plate 426; one side of the arm plate support 423 of No. 1 is fixedly connected with the second output flange 422 and one end of the second arm plate 426; the other side of the No. 1 arm plate support 423 is fixedly connected with one end of a first arm plate 424, the tail ends of the first arm plate 424 and a second arm plate 426 are fixedly connected with a No. 2 arm plate support 425, and the two arm plates are positioned on the two sides of the No. 2 arm plate support 425;
the second robot arm 43 includes a third stepping motor 431, a third output flange 432, and a second robot arm body; the third stepping motor 431 is arranged on the inner side of the No. 2 arm plate bracket 425, the output end of the third stepping motor 431 penetrates through one side of the second arm plate bracket 425 and the second arm plate 426, and a third output flange 432 is arranged on the output end of the third stepping motor 431; a second mechanical arm body is arranged on the third output flange 432, the third output flange 432 is not in contact with the second mechanical arm plate 426, and the output shaft of the third stepping motor 431 is parallel to the output shaft of the second stepping motor 421; the end of the second mechanical arm body is provided with a commodity identification device 6 and a commodity grabbing device 7, and a third stepping motor 431 drives a third output flange 432 to rotate so as to enable the second mechanical arm body to rotate around an output shaft of the third stepping motor 431;
the second mechanical arm body comprises a No. 3 arm plate bracket 433, a U-shaped No. 4 arm plate bracket 434, a third arm plate 435 and a fourth arm plate 436; one side of the arm plate bracket 433 of No. 3 is connected with one end of the second output flange 432 and the fourth arm plate 436, the other side of the arm plate bracket 433 of No. 3 is fixedly connected with one end of the third arm plate 435, the tail ends of the third arm plate 435 and the fourth arm plate 436 are both connected with the arm plate bracket 434 of No. 4, and the two arm plates are positioned at two sides of the arm plate bracket 434 of No. 4;
preferably, the first arm board 424, the second arm board 426, the third arm board 435 and the fourth arm board 436 have the same structure and are provided with a plurality of hollow holes, so that the load of the mobile platform is reduced;
the commodity grabbing device 7 comprises a connecting frame 71, a lead screw support 72, a lead screw 73, a lead screw nut 74, two finger pushing rods 76, two fingers 77 and a fourth stepping motor 78; the connecting frame 71 is in an L shape, one side of the connecting frame is fixedly connected with the end part of the arm plate bracket 434 No. 4, and the other side of the connecting frame is provided with a screw rod support 72; the screw support 72 is provided with two end lugs, two ends of the screw 73 respectively penetrate through the corresponding end lugs to be installed on the screw support 72, and the screw 73 can rotate relative to the screw support 72; the screw 73 is sleeved with a screw nut 74, and the screw nut 74 can slide on the screw 73; one end of the screw 73 is connected with an output shaft of the fourth stepping motor 78 through a coupler, and the fourth stepping motor 78 is installed on the inner side of the arm plate bracket 434 No. 4; the positions of the two fingers 77 close to the end parts are respectively hinged on the connecting frame 71 through pin shafts, and an opening formed at one end of the two fingers 77 far away from the connecting frame 71 is used for grabbing commodities; one end of each of the two pushing finger rods 76 is fixed at a position close to the middle of the corresponding finger 77, and the other end of each of the two pushing finger rods 76 is hinged on the screw nut 74; the fourth stepping motor 78 drives the screw rod 73 to rotate, the screw rod 73 drives the screw rod nut 74 to slide on the screw rod 73, and further drives the finger pushing rod to move back and forth, and the two fingers 77 are driven to open or grasp through the finger pushing rod;
each finger 77 is a rhomboid irregular profile body, and the middle parts of the two sides of the finger 77 are used as starting positions to respectively extend towards the two ends in a concave manner and terminate at the two ends, so that four side surfaces of the finger 77 are formed; anti-slip grooves are formed in the fingers 77, so that the grabbing stability is improved; the finger 77 can also be covered with a layer of anti-slip film to prevent the goods from slipping; when in use, the two fingers 77 are in surface contact or line contact with the grabbed commodities, so that the hand-held type hand-held device is suitable for grabbing commodities which are displayed and placed on a goods shelf and have the volume equivalent to the size of a pop can, small bottle shampoo or potato chips and the like; the opposite clamping surfaces of the two fingers are provided with semicircular grooves at intervals, the front ends of the fingers are in arc surface transition, the objects to be clamped are prevented from being scratched by tips, and the semicircular grooves are easier to clamp stably.
The commodity grabbing device 7 further comprises a spring 75, two ends of the spring 75 are fixedly connected with one end, close to the connecting frame 71, of each finger 77 respectively, the spring 75 plays a role in assisting the fingers 77, and when the opening between the two fingers 77 is closed, the spring 75 is in a compressed state;
the control system 2 comprises a motion control panel 21 and an upper computer 22, and the motion control panel 21 and the upper computer 22 are both arranged on the mobile platform body 1; the motion control panel 21 is in communication connection with the upper computer 22, and the upper computer 22 issues instructions to the motion control panel 21; the motion control plate 21 is respectively in communication connection with a first stepping motor 414, a second stepping motor 421, a third stepping motor 431, a fourth stepping motor 78 and a fifth stepping motor 51, so that rotation of the first mechanical arm and the second mechanical arm, grabbing of commodities and dumping of the commodities are realized; the upper computer 22 is respectively in communication connection with the laser radar scanning range finder 32, the ultrasonic sensors 33 and the camera 61, so that path planning, emergency obstacle avoidance and commodity identification of the mobile platform are realized; the motion control plate 21 adopts an STM32F429 chip; the upper computer 22 adopts the associative thinpadx 260; the upper computer 22 is loaded with a path planning algorithm and a commodity identification algorithm, which can all adopt the prior art.
The article recognition device 6 includes a camera 61 and a camera mount 62; the lower part of the camera mounting frame 62 and the upper end of the connecting frame 71 are fixedly connected with the end part of the arm plate bracket 434 No. 4, and the camera 61 is fixed on the camera mounting frame 62; the camera 61 collects the characteristics of the commodities in the visual area and transmits the characteristic information to the upper computer 22, the upper computer 22 matches the characteristic information collected by the camera 61 with the characteristics of the commodities in a preset commodity database, the highest matching degree is selected as a final result of the identification, the instruction information is transmitted to the motion control panel, the motion control panel controls the fourth stepping motor to act, and then the commodity grabbing device 7 is controlled to act, and then the grabbing of the commodities is completed; the camera 61 is an RGB-D camera;
the commodity placing device 5 comprises a fifth stepping motor 51, a motor bracket 52, a turn-over shifting sheet 53, two turn-over brackets 54 and a turn-over table 55; the two turning platform brackets 54 and the motor bracket 52 are both fixed on the moving platform body 1, one end of the turning platform 55 is provided with an arc-shaped groove 552, two sides of the other end of the turning platform 55 are provided with connecting columns 551, the two connecting columns 551 are respectively matched with the notches 541 of the corresponding turning platform brackets 54, and the turning platform 55 can rotate relative to the turning platform brackets 54; the fifth stepping motor 51 is fixed on the motor support 52, the table-turning shifting piece 53 is installed on an output shaft of the fifth stepping motor 51, the table-turning shifting piece 53 is always clamped in the groove 552 of the table-turning 55, the fifth stepping motor 51 drives the table-turning shifting piece 53 to rotate, and the table-turning shifting piece 53 pushes against the table-turning 55 to rotate, so that goods can be poured;
the obstacle avoidance device 3 comprises a radar support 31, a laser radar scanning range finder 32 and a plurality of ultrasonic sensors 33; the radar support 31 is arranged at the front end of the top of the mobile platform body 1, and the laser radar scanning range finder 32 is arranged on the radar support 31; the laser radar scanning range finder 32 scans the working environment, completes the construction of a two-dimensional map and marks obstacles; the ultrasonic sensors 13 are arranged on the periphery of the mobile platform body 1, the ultrasonic sensors 13 can emit high-frequency mechanical waves, echoes can be generated when the ultrasonic sensors meet obstacles, and the echoes are used for marking the suddenly appearing obstacles, so that the mobile platform can be stopped suddenly when the ultrasonic sensors meet the suddenly appearing obstacles to avoid the obstacles in an emergency;
the moving platform body 1 belongs to the prior art and comprises a storage battery, a driving wheel, a driven wheel, a walking motor and a chassis, wherein the walking motor is connected with the driving wheel to drive the driving wheel to rotate so as to realize walking of the moving platform body 1; the walking motor is in communication connection with the motion control plate 21 to realize the rotation of the walking motor; the storage battery is electrically connected with each electric component and supplies power to each electric component;
the lidar scanning rangefinder 32 is of the model RPLIDAR-a 1.
The size of the moving platform is 800 x 600 mm.
The working principle and the working process of the invention are as follows:
after the working instruction is sent out, the mobile platform body 1 moves to a position point where the commodity to be grabbed is located according to a preset path; the motion control board 21 controls the first stepping motor 414, the second stepping motor 421 and the third stepping motor 431 respectively to rotate the first mechanical arm 42 and the second mechanical arm 43, so that the commodity grasping device 7 approaches to the commodity to be grasped; the upper computer 22 issues an instruction to make the commodity recognition device 6 recognize the commodity to be grabbed, and make the commodity grabbing device 7 grab the recognized commodity; meanwhile, the motion control panel 21 controls the first mechanical arm 42 and the second mechanical arm 43 to rotate, and the grabbed commodity is placed on the turnover table 55; the mobile platform body 1 is started again to move to a next position point, and the commodity taking and placing process is repeated to complete the taking and placing of the next commodity; after all the commodities in the instruction are taken and placed, the mobile platform moves to the position of the transfer box according to a set path, and the motion control board 21 controls the fifth stepping motor 51 to rotate the turnover table 55 so as to dump the commodities into the transfer box.
The invention also provides a path planning method (method for short) of the storage commodity taking and placing mobile platform, which comprises the following steps:
1) constructing a global map: before work, the mobile platform walks, the working environment is scanned through the laser radar scanning range finder 32 to complete the construction of a global map, and the global map is stored in an upper computer;
the working environment comprises commodity classification position information and barrier information;
2) and (3) global path planning: the upper computer issues a goods taking instruction to the mobile platform, retrieves the commodity classification position, and performs global path planning on a traveling path from the starting point of the mobile platform to the commodity classification position by adopting an A-x algorithm; if a new obstacle appears on the global map, the upper computer judges the position relation between the new obstacle and the global path; if the new obstacle is not on the global path, the mobile platform continues to travel; if the new obstacle is located on the global path, executing step 3), and enabling the mobile platform to bypass the new obstacle and return to the global path;
3) local path optimization: the method comprises the steps that a local path optimization is carried out on a path between the current position of a mobile platform and a path which returns to a global path by bypassing a new obstacle by adopting an improved dynamic window method (DWA), the adaptability of the mobile platform to a working environment is improved by adjusting three weights of an evaluation function of the improved dynamic window method in real time, and the autonomous optimization of the mobile platform to the three weights of the evaluation function is realized;
wherein, the evaluation function of the improved dynamic window method is as follows:
G(v,w)=σ(α*heading(v,w)+β*dist(v,w)+γ*velocity(v,w))
wherein, the heading (v, w) is a course angle evaluation function of the mobile platform and represents an included angle between the orientation of the tail end of the simulation track of the mobile platform and a target point; dist (v, w) is the distance between the mobile platform and the new obstacle; velocity (v, w) is a speed evaluation function of the mobile platform; alpha, beta and gamma are the weights of the three components; σ is a smoothing function; v and w are respectively the linear velocity and the angular velocity of the mobile platform;
the improved dynamic window method comprises the following steps:
s1, building working environments with different numbers of obstacles through matlab, and obtaining a plurality of feasible speed spaces with different sizes;
s2, performing multiple path planning on each working environment by using a dynamic window method to obtain an optimal weight combination under each working environment; sequentially obtaining a set of optimal weight combinations of all working environments according to the steps, and constructing a fuzzy logic controller;
and S3, taking the real-time feasible speed space of the mobile platform and the distance between the current position of the mobile platform and the commodity classification position as the input of the fuzzy logic controller, obtaining three weights of alpha, beta and gamma in real time, and realizing the function of automatically searching the optimal weight combination of the mobile platform so as to adjust the path of the mobile platform in real time and reach a target point.
In order to verify the effectiveness of the improved dynamic window method, a grid map scene with 16 circular obstacles is established based on matlab 2016 to carry out simulation path planning of a mobile platform, and three groups of experiments are carried out in total; in the experiment, the starting point of the mobile robot is set as (0,0), and the target point is set as (7, 6); the three weights of experiment 1 are constant values, α ═ 0.1, β ═ 0.9, and γ ═ 0.5, respectively, and the simulation result is shown in fig. 11; the three weights of experiment 2 are always constant values, α is 0.5, β is 0.9, γ is 0.5, and unlike experiment 1, the value of α is different, and the simulation result is shown in fig. 12; experiment 3 adopts an improved dynamic window method, the initial values of three weights are set to be alpha-0.5, beta-0.9 and gamma-0.5, and the simulation result is shown in fig. 13;
the simulation results show that two kinds of situations that the target is inaccessible occur in experiment 1 and experiment 2, the course angle weight alpha of experiment 1 is 0.1, and the mobile platform cannot be motivated to reach the target point even if the mobile platform reaches the vicinity of the target point due to the fact that the weight is too low and the heuristic performance of the mobile platform is not enough; the course angle weight alpha of the experiment 2 is 0.5, and the heuristic property that the mobile platform reaches a target point is strong due to the over-high weight setting, so that the obstacle avoidance capability of the mobile platform is weakened, and the problem that the target cannot be reached due to the shielding of an obstacle occurs; experiment 3 adopts an improved dynamic window method, and the mobile platform obtains the optimal weight combination in real time according to fuzzy logic reasoning, can accurately reach a target position point, obviously improves the adaptability to the working environment, and further verifies the effectiveness of the improved dynamic window method.
Nothing in this specification is said to apply to the prior art.
Claims (8)
1. A storage commodity taking and placing moving platform comprises a moving platform body, an obstacle avoidance device, a mechanical arm device, a commodity placing device, a commodity identification device and a commodity grabbing device; the obstacle avoidance device, the mechanical arm device and the commodity placing device are arranged on the moving platform body, the commodity grabbing device is arranged at the tail end of the mechanical arm device, and the commodity identification device is arranged on the commodity grabbing device; it is characterized in that the preparation method is characterized in that,
the mechanical arm device comprises a rotating mechanism and a plurality of mechanical arms, the mechanical arms are mutually and rotatably connected, the mechanical arms form a modular mechanical arm, one end of the first mechanical arm is fixed with the rotating mechanism, and the tail end of the last mechanical arm is fixed with the commodity grabbing device; the rotating mechanism is arranged on the moving platform body, and the modular mechanical arm is arranged on the rotating mechanism;
the commodity grabbing device comprises a connecting frame, a lead screw support, a lead screw nut, two finger pushing rods, two fingers and a fourth motor; one side of the connecting frame is fixedly connected with one side of the tail end of the modular mechanical arm, and the other side of the connecting frame is provided with a lead screw support; a screw is rotatably arranged on the screw support, a screw nut is sleeved on the screw and can slide on the screw, and one end of the screw is connected with an output shaft of a fourth motor arranged on the other side of the tail end of the modular mechanical arm through a coupler; one end of each finger is hinged to the connecting frame, and an opening formed at the other end of each finger is used for grabbing a commodity; one end of each of the two finger pushing rods is fixed on the corresponding finger, and the other end of each finger pushing rod is hinged to the screw nut;
the path planning method of the warehousing commodity taking and placing mobile platform comprises the following steps:
1) constructing a global map: before work, scanning a working environment through a laser radar scanning range finder to complete construction of a global map, and storing the global map in an upper computer;
the working environment comprises commodity classification position information and barrier information;
2) and (3) global path planning: the upper computer issues a goods taking instruction, retrieves the commodity classification position, and performs global path planning on a traveling path from the starting point of the mobile platform to the commodity classification position by adopting an A-x algorithm; if a new obstacle appears on the global map, the upper computer judges the position relation between the new obstacle and the global path; if the new obstacle is not on the global path, the mobile platform continues to travel; if the new obstacle is located on the global path, executing step 3), and enabling the mobile platform to bypass the new obstacle and return to the global path;
3) local path optimization: performing local path optimization on a path between the current position of the mobile platform and a path which bypasses a new obstacle and returns to the global path by adopting a dynamic window method, and adjusting three weights of an evaluation function of the dynamic window method in real time;
the dynamic window method in the step 3) comprises the following steps:
s1, building working environments with different numbers of obstacles through matlab, and obtaining a plurality of feasible speed spaces with different sizes;
s2, performing multiple path planning on each working environment by using a dynamic window method to obtain an optimal weight combination under each working environment; sequentially obtaining a set of optimal weight combinations of all working environments according to the steps, and constructing a fuzzy logic controller;
and S3, taking the real-time feasible speed space of the mobile platform and the distance between the current position of the mobile platform and the commodity classification position as the input of the fuzzy logic controller, and acquiring three weights of alpha, beta and gamma of the evaluation function of the dynamic window method in real time, so that the function of automatically searching the optimal weight combination by the mobile platform to adjust the path in real time and reach a target point is realized.
2. The mobile platform of claim 1, wherein the item placement device comprises a fifth motor, a motor bracket, a flipping table paddle, two flipping table brackets, and a flipping table; the two turning platform supports and the motor support are fixed on the moving platform body, an arc-shaped groove is formed in one end of the turning platform, connecting columns are arranged on two sides of the other end of the turning platform, the two connecting columns are respectively matched with notches of the corresponding turning platform supports, and the turning platform can rotate relative to the turning platform supports; the fifth motor is fixed on the motor support, a turnover table shifting piece is installed on an output shaft of the fifth motor, and the turnover table shifting piece is always clamped in a groove of the turnover table.
3. The mobile platform of claim 1, wherein the rotation mechanism comprises a base, a mount, a first output flange, and a first motor; the base is installed on the moving platform body, and first motor is installed on the base, installs first output flange on the output shaft of first motor, and the mount pad is installed on first output flange.
4. The mobile platform of claim 3, wherein the robotic arm comprises a second motor, a second output flange, and a robotic arm body; the mechanical arm body comprises a No. 1 arm plate support, a first arm plate, a U-shaped No. 2 arm plate support and a second arm plate; one side of the No. 1 armboard bracket is connected with the second output flange and one end of the second armboard; the opposite side of No. 1 arm board support links to each other with the one end of first arm board, and the end of first arm board and second arm board all links to each other with No. 2 arm board support.
5. The mobile platform of claim 1, wherein the obstacle avoidance device comprises a radar support, a lidar scanning range finder, and a plurality of ultrasonic sensors; the laser radar scanning range finder is arranged on the radar support; a plurality of ultrasonic sensor install around the moving platform body.
6. The mobile platform of claim 5, further comprising a control system, wherein the control system comprises a motion control board and an upper computer, the motion control board and the upper computer are both mounted on the mobile platform body, the upper computer is in communication connection with the motion control board, the motion control board is electrically connected with the motor, and the upper computer is in communication connection with the laser radar scanning range finder and the plurality of ultrasonic sensors respectively; the motion control plate adopts an STM32F429 chip; the upper computer adopts the association thinpapadx 260.
7. The mobile platform of claim 1, wherein the article grasping device further comprises a spring, and two ends of the spring are respectively fixedly connected to one end of the two fingers close to the connecting frame.
8. The mobile platform of claim 1, wherein the finger has a plurality of anti-slip grooves thereon.
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