CN102040072B - Method for regulating speed of high-speed stocker by adopting wireless indoor positioning technique - Google Patents

Abstract

The invention relates to a high-speed stacker positioning and speed regulation method applied to a fully automatic three-dimensional storage system, using wireless indoor positioning technology, address code positioning technology, and address chip photoelectric positioning technology to perform three-level positioning on the stacker, and according to Select the high-speed/low-speed motion mode for the length of the moving distance, and perform three-stage optimal speed regulation on the stacker. This method has the advantages of low cost, high throughput, low power consumption, high reliability, and flexible application. It can be widely used in Logistics warehousing centers, modern distribution centers and other fields have broad market application prospects.

Description

A speed regulation method of high-speed stacker using wireless indoor positioning technology

technical field

The present invention relates to a high-speed stacker positioning and speed regulation method applied to a fully automatic three-dimensional storage system, in particular to a three-stage stacking machine using wireless indoor positioning technology, address code positioning technology, and address chip photoelectric positioning technology. The invention relates to a method for positioning, selecting a high-speed/low-speed motion mode according to the length of the moving distance, and performing three-stage optimal speed regulation on the stacker. The method can be widely used in logistics storage centers, modern distribution centers, etc., and belongs to the technical field of storage and transportation devices.

Background technique

The fully automatic three-dimensional storage system is a storage system that automatically stores and retrieves materials on shelves in the form of units (such as pallets) without direct manual processing. A comprehensive facility integrating control and computer technologies, which has the advantages of high land utilization rate, high access efficiency, and high accuracy rate, and has been widely used in logistics in machinery manufacturing, food, clothing, chemical, pharmaceutical, metallurgy and other industries In the system, it is an important part of logistics modernization.

The stacker is the core equipment and main handling equipment of the fully automatic three-dimensional storage system. It shuttles back and forth in the lanes of the three-dimensional storage system to complete operations such as storage, storage, transfer, warehouse transfer, and inventory. The operation of the stacker Speed and efficiency determine the throughput and turnover rate of the entire fully automatic three-dimensional storage system.

Optimizing the stacker involves two aspects, one is to increase the running speed of the stacker while reducing energy consumption; the other is to optimize the operation process and reduce the distance of the invalid path of the stacker. For the second optimization, currently, it can be realized by classifying material positions, adjusting the sequence of inbound and outbound orders, optimizing the inbound and outbound transmission device, and adopting a shelf structure that can be inbound and outbound at both ends; while for the first optimization, currently it is mainly The method of increasing the running speed of the horizontal walking motor and optimizing the speed curve of the variable frequency motor is realized.

Since the distance in the horizontal direction of the roadway of the three-dimensional storage system is often much greater than the vertical direction, such as a general standard warehouse, the height of the warehouse is 9 meters to 12 meters, while the width of the warehouse can reach 100 meters, and some warehouses can reach 250 meters, so the horizontal direction speed adjustment Optimization is more practical to optimize the stacker.

To improve the operating efficiency of the stacker, the main bottleneck lies in the precise positioning of the stacker. The horizontal positioning in the traditional stacker roadway adopts the address sheet photoelectric positioning relative addressing method, and two photoelectric sensors are installed on the stacker. , and the distance is exactly equal to the length of an address sheet. When the stacker is running horizontally, when one of the photoelectric sensors is blocked by the address sheet, it sends a logic signal to the programmable logic controller (Programmable Logic Control, PLC), and the frequency conversion motor Slow down, and the stacker slides slowly. When the other photoelectric sensor is blocked by the address sheet, the two photoelectric sensors send logic signals at the same time, and the frequency conversion motor stops, so as to realize the horizontal positioning of the stacker. This positioning method only It is necessary to adjust the position of the address sheet to adjust the positioning position of the stacker, and the addressing of the cargo location is realized by relative addressing, that is, according to the difference between the address of the docking column and the address of the target column, the counting of the stacker It is realized by the number of address chips, which has the advantages of simple installation, low cost, and stable and reliable work. The disadvantage is that it cannot increase the speed, which is generally below 120 meters per minute.

In the relative addressing mode, before the stacker detects the next address card, it cannot know its absolute position and how far away it is from the target position, and is limited by the response speed of the photoelectric sensor. In order to work reliably, only It can run at a lower speed, which limits the improvement of the operating efficiency of the stacker.

The absolute position addressing of the stacker is an improved method in recent years. There are two main methods of measuring the absolute position. One is the encoder method, which encodes the cargo position through various coding methods. When the stacker passes by, it passes through the photoelectric , radio frequency, etc. to read the coded data, so as to know the current position of the stacker, such as the barcode positioning system (Barcode Positioning System, BPS) launched by Leyi Electronics Company in Germany in 2005, by placing the barcode tape on the travel route, The photoelectric barcode reading head is installed on the stacker. During the operation of the stacker, the barcode information is continuously scanned and converted into distance information through the built-in encoder to achieve precise positioning. The advantages are high precision, good reliability, and installation adjustment It is simple and can be used in the application scenarios of multiple vehicles on one track or curved tracks. The disadvantage is that it is expensive, the barcode pollution will affect the scanning results, and the scanning response speed of the photoelectric barcode reading head cannot keep up with high-speed movement;

The second is to use the laser distance measurement method. The Chinese patent "A method for fast and precise positioning and stepless speed regulation of the stacker" (patent number: ZL 200710045397.6) discloses this idea, that is, on the side of the stacker roadway Install a laser rangefinder, and install a large-area laser reflector on the stacker to accurately measure the absolute distance of the stacker. The distance measurement accuracy can reach ± 3 mm. The measured absolute distance is compared with the address of the cargo column to obtain Determining the column address of the stacker, because the absolute position is measured, creates conditions for the optimization of the speed regulation of the stacker. After optimization, the operating speed of the stacker can reach 200-280 m/min.

Laser ranging is a high-precision ranging method. For this reason, Banner Corporation of the United States has developed the L-GAGE LT7 series long-distance diffuse reflection laser sensor specially designed for stacker ranging. The working distance of the sensor is It can reach 250 meters, and the distance measurement accuracy is high, up to ±2mm. It is modularized and easy to install.

However, the disadvantage of the laser ranging method is that it can only be applied in a straight track, and the optical path is easily disturbed by foreign objects, etc., and the levelness and straightness errors of the track and the installation angle of the reflector will cause measurement errors, so the installation and use requirements are relatively high. High, expensive, on the other hand, because the laser has a certain degree of danger, even if the infrared II laser is used, it will cause some discomfort to the human eye and bring harm to the maintenance, maintenance and use personnel.

Compared with laser ranging technology, the cost of wireless ranging technology is greatly reduced, and the risk is relatively smaller, but the disadvantage is that the ranging accuracy is low, and often can only reach meter-level accuracy. According to different wireless ranging technical methods, Accuracy is also different, generally speaking, such as ultra-wideband (Ultrawide Band, UWB) technology can achieve decimeter-level accuracy; radio frequency tag (RFID) technology, WiFi technology can only achieve meter-level accuracy; ZigBee technology is even lower, often only 3 to 5 meter accuracy.

Ranging range is also a problem. For example, ZigBee technology can only reach 64 meters in distance without power amplification, but ZigBee technology is the cheapest in terms of implementation cost.

At present, the principle of wireless ranging is mainly realized by Received Signal Strength Indication (RSSI). Since the signal strength between two wireless communication nodes decreases with the increase of distance, RSSI can be used to determine The distance between the two, but the transmission of wireless signals in space is affected by space media, obstacles and other conditions and presents different properties. Therefore, in actual ranging applications, the accuracy is often low. The advantage is that For wireless positioning applications, some chips with wireless radio frequency RF functions, such as the ZigBee chip CC2430 of Texas Instruments TI, have integrated modules for measuring RSSI and positioning, which are easy to use and low in power consumption. The response speed is fast, and the channel access delay is only 15 milliseconds.

From the perspective of the actual application of the stacker, the stacker does not always work at high speed. The stacker needs to go through the process of acceleration, high speed and deceleration when moving from one cargo location to another. The additional braking mechanism may It can prolong the high-speed operation time of the stacker to improve efficiency, but it also increases the energy consumption of the stacker. Therefore, under normal circumstances, the stacker is driven by a frequency conversion motor, and the motor speed is adjusted in real time according to the speed optimization curve.

Therefore, although the response speed of the traditional address chip photoelectric positioning relative addressing mode and encoder absolute addressing mode is slow, it can also provide high-precision and reliable positioning during the deceleration and parking phase of the stacker and at an appropriate speed setting. addressability. Accordingly, the present invention provides a three-level positioning of the stacker using wireless indoor positioning technology, address code positioning technology, and address chip photoelectric positioning technology, and selects high-speed/low-speed motion modes according to the length of the movement distance, and the stacker The method of three-stage optimized speed regulation has the advantages of low cost, high efficiency, low power consumption, stability and reliability, and can be widely used in various automatic three-dimensional storage systems, with good economic benefits and market prospects.

Contents of the invention

The purpose of the present invention is to provide a speed control method for high-speed stackers using wireless indoor positioning technology, specifically a method for three-dimensional stacker cranes using wireless indoor positioning technology, address code positioning technology, and address chip photoelectric positioning technology Level positioning, and select the high-speed/low-speed movement mode according to the length of the moving distance, and perform three-stage optimal speed regulation on the stacker to reduce the turnover cycle of the stacker and reduce the energy consumption of the stacker.

In order to achieve the above-mentioned technical purpose, the present invention is accomplished through the following technical devices:

Fully automatic three-dimensional storage system, consisting of: three-dimensional storage shelves, outbound transmission chain, inbound transmission chain, anti-collision stopper at the inbound end, anti-collision stopper at the outbound end, stacker, address sheet, double photoelectric sensor, column Composed of address code tags, column address code readers, wireless reference nodes, wireless mobile nodes, and roadways.

The stacker moves horizontally in the roadway, and an address sheet is installed every other width of the cargo space on the roadway floor. The address sheet is an opaque metal sheet with a certain width, and double photoelectric sensors are installed at the bottom of the stacker. Fork-type photoelectric sensor, the distance between them is exactly equal to the width of the address sheet, which can provide four logic state combinations of "front side blocking", "full blocking", "rear side blocking" and "all non-blocking" to precisely adjust the position of the address sheet. Make the stacker just stop at the position of each cargo space.

Install the column address coding label on the bottom of the three-dimensional storage shelf on one side. The content of the label is the column address of the cargo position. The installation position should not affect the operation of entering and exiting the warehouse. Install a column address code reader at the label position, leave a certain distance between the two, and use a non-contact reading method, so a certain distance will not affect the reading accuracy and response speed, and it will also prevent the stacker from shaking left and right when it is running. Errors leave room for redundancy.

Install a wireless reference node at one end of the roadway and a wireless mobile node on the stacker. There should be an open space between the two to avoid other objects to ensure that the communication will not be affected. Generally, it can be installed on the ceiling, or Close to the ground of the roadway, the two should be on the same level as possible, and aligned and parallel to the roadway.

The wireless reference node and the wireless mobile node provide wireless distance measurement for positioning and addressing when the stacker moves at a high speed and at a constant speed; the column address code reader and the column address code label provide column address absolute addressing for the stacking mechanism Positioning and addressing during deceleration movement; address sheet and dual photoelectric sensors provide address sheet photoelectric positioning and relative addressing, which is used for positioning and addressing when the stacker is parked.

Combining the three positioning methods, the specific steps of the technical solution provided by the present invention are as follows:

(1) Decompose the operation, determine the starting column address and target column address of the stacker movement;

(2) detect wireless state, activate wireless mobile node and wireless reference node, measure the received signal strength indication RSSI ₀ between the two once;

(3) Determine whether the communication is normal? Normal (Y), then RSSI ₀ and the initial distance d ₀ of two wireless nodes are written into the wireless mobile node;

(4) Abnormal (N), then there is a fault, alarm, and end;

(5) The programmable logic controller PLC loads the target column address, compares it with the starting column address, and calculates the horizontal distance to be moved;

(6) Determine whether the horizontal distance is greater than the short-range threshold? If it is greater than (Y), then adopt high-speed operation mode, otherwise (N) adopt low-speed operation mode;

(7) PLC starts the stacker, in the high-speed operation mode, the frequency conversion motor increases the speed at the set acceleration rate, and when it reaches the set high speed, it runs at a constant speed; in the low-speed operation mode, the frequency conversion motor increases the speed at the set acceleration rate to reach the set value At low speed, run at a constant speed;

(8) The wireless mobile node regularly measures the distance, calculates the distance between the wireless reference node, and measures the RSSI between the two wireless nodes. According to the formula RSSI-RSSI ₀ =10nlg(d ₀ /d), the current distance d can be calculated;

(9) Determine whether it is greater than the deceleration distance? Y (greater than), then start deceleration process, wireless mobile node sends deceleration logic state to PLC, otherwise (N) returns to (8);

(10) During the deceleration process, the variable frequency motor reduces the speed at the set deceleration rate, and the set value of the deceleration rate in the high-speed operation mode and the low-speed operation mode is different;

(11) Start the column address code reader, and read the column address code when the stacker passes the column address code label;

(12) Compared with the target column address, determine whether it is the address before the target column address? Yes (Y), then send the docking logic state to the PLC, start the double light point sensor, otherwise (N), continue to execute (11);

(13) The double photoelectric sensor detects the logical state of "front side shielding", the variable frequency motor switches to the parking speed, detects the logical state of "full shielding", stops the variable frequency motor, and ends.

After the wireless mobile node and the column address code reader complete the distance measurement and positioning, they all communicate with the PLC through the corresponding logic state, so the system reliability is good.

Description of drawings

Fig. 1 is a structural diagram of a fully automatic three-dimensional storage system embodiment of a high-speed stacker speed regulating method using wireless indoor positioning technology according to the present invention;

Fig. 2 is a flow chart of a method for speed regulation of a high-speed stacker using wireless indoor positioning technology in the present invention;

Fig. 3 is a schematic diagram of wireless ranging of a high-speed stacker speed regulation method using wireless indoor positioning technology according to the present invention;

Fig. 4 is a long-distance wireless ranging principle diagram of a high-speed stacker speed regulation method using wireless indoor positioning technology according to the present invention;

Fig. 5 is a schematic diagram of track bending wireless positioning of a high-speed stacker speed control method using wireless indoor positioning technology according to the present invention;

Fig. 6 is a schematic diagram of a column address code positioning embodiment of a high-speed stacker speed regulation method using wireless indoor positioning technology according to the present invention;

Fig. 7 is a schematic diagram of address chip photoelectric positioning of a high-speed stacker speed regulating method using wireless indoor positioning technology according to the present invention;

Fig. 8 is a force analysis diagram of the stacker in a high-speed stacker speed regulation method using wireless indoor positioning technology according to the present invention;

Fig. 9 is a frequency conversion motor speed optimization curve of a high-speed stacker speed control method using wireless indoor positioning technology according to the present invention;

Fig. 10 is a schematic diagram of speed-power consumption-throughput comparison of a high-speed stacker speed regulation method using wireless indoor positioning technology according to the present invention.

Detailed ways

Referring to the accompanying drawings, the present invention will be described in detail below.

As shown in Figure 1, the embodiment of a kind of fully automatic three-dimensional storage system applied by the present invention is composed of: three-dimensional storage shelf (100), outbound transmission chain (101), inbound transmission chain (102), storage terminal anti- Collision block (103), anti-collision block at outbound end (104), stacker (105), address sheet (106), double photoelectric sensor (107), column address code label (108), column address code reader It consists of a fetcher (109), a wireless reference node (110), a wireless mobile node (111), and a roadway (112).

The stacker (105) moves horizontally in the roadway (112), and an address sheet (106) is installed every other width of the cargo space on the ground of the roadway (112). The address sheet (106) is an opaque metal with a certain width. Sheet, the width is generally determined by the width of a single cargo space, such as the cargo space width of 520 mm, the width of its address sheet (106) is preferably 100 mm.

Dual photoelectric sensors (107) are installed at the bottom of the stacker (105), adopting the fork-type photoelectric sensors of the opposite beam, and the distance is just equal to the width of the address sheet (106), which can provide "front side shielding", "full shielding", " The combination of the four logical states of "blocking on the rear side" and "not covering all" accurately adjusts the position of the address sheet (106), so that the stacker (105) just stops at the position of each cargo row.

Install the column address coding label (108) below the three-dimensional storage shelf (100) on one side, preferably a 13.56M radio frequency RFID label, the content of the label is the column address of the cargo location, and the installation position is not to affect the operation of entering and leaving the warehouse. All labels are installed On the same horizontal line, a column address code reader (109) is installed at the position of the stacker (105) facing the column address code label (108), preferably a 13.56M wireless radio frequency RFID tag reader, leaving a space between the two A certain distance is adopted as a non-contact reading method, so a certain distance does not affect the reading accuracy and response speed, and also leaves a redundant space for the left and right shaking errors of the stacker (105) during operation.

A wireless reference node (110) is installed at one end of the roadway (112), and a wireless mobile node (111) is installed on the stacker (105), preferably ZigBee wireless module CC2430, should be an open space between the two, avoiding the existence of other In order to ensure that the communication is not affected, it can generally be installed on the ceiling or close to the ground of the roadway. The two should be on the same horizontal line as possible and aligned and parallel to the roadway.

The wireless reference node (110) and the wireless mobile node (111) provide wireless distance measurement for positioning and addressing when the stacker (105) moves at a high speed and at a constant speed; the column address code reader (109) and the column address code label (108) provides column address absolute addressing, and is used for positioning and addressing when the stacker (105) brakes and decelerates; address sheet (106) and double photoelectric sensors (107) provide address sheet photoelectric positioning relative addressing, It is used for positioning and addressing when the stacker (105) stops.

As shown in Figure 2, in combination with three positioning methods, the specific steps of the technical solution provided by the present invention are as follows:

(1) START(200). Job decomposition (201). Determine the starting column address and the target column address that stacker (105) moves, any operation can finally be decomposed into each movement of stacker (105), as storage operation can be decomposed into two moves, namely: Move to the storage dock -> pick up the goods -> move to the target storage location, moving to the storage dock is actually moving from the current docked storage location to the storage dock, the starting column address is the current storage location column address, and the destination column address is the storage station; and moving to the target location is to move from the storage station to the target location, the starting column address is the storage platform, and the destination column address is the target location column address;

(2) detect wireless status (202), activate wireless mobile node (111) and wireless reference node (110), measure the received signal strength indicator RSSI ₀ between the two once;

(3) Determine whether the communication is normal? (203) normal (Y), then RSSI ₀ and two wireless nodes initial distance d ₀ are written into wireless mobile node (111);

(4) Abnormal (N), then there is fault (210), reports to the police (211), ends (224);

(5) programmable logic controller PLC loads target column address (204), compares with initial column address, calculates the horizontal distance (205) that needs to move;

(6) Determine whether the horizontal distance is greater than the short-range threshold (206)? Greater than (Y), then adopt the high-speed operation mode (208), otherwise (N) adopt the low-speed operation mode (207);

(7) PLC starts the stacker (209), high-speed operation mode, the frequency conversion motor increases the speed with the set acceleration rate, and when reaching the set high speed, it runs at a constant speed; the low speed operation mode, the frequency conversion motor increases the speed with the set acceleration rate, When the set low speed is reached, it runs at a constant speed;

(8) _The wireless mobile node (111) regularly calculates the distance between the wireless reference node (110), measures _the RSSI between the two wireless nodes, and can calculate the current distance d;

(9) Determine whether the distance is greater than the deceleration distance (213)? Greater than (Y), then start deceleration process (214), wireless mobile node (111) sends deceleration logic state to PLC, otherwise (N) gets back to (8); [0066] (10) deceleration process (214), variable frequency motor Decrease the speed with the set deceleration rate, and the deceleration rate setting values are different between the high-speed operation mode and the low-speed operation mode;

(11) Start column address code reader (215), read column address code (216) when stacker (105) passes column address code label (108);

(12) Compared with the target column address, determine whether it is the previous address of the target column address (217)? Yes (Y), then send the docking logic state (218) to the PLC, start the double light point sensor (219), otherwise (N), continue to execute (11);

(13) double photoelectric sensor detects " front side is blocked " logical state (220), and variable frequency motor is switched to parking speed (221), detects " all blocking " logical state (222), variable frequency motor stops (223), finishes ( 224).

As shown in Figure 3 (a), the wireless node A (300) and the wireless node B (301) are installed horizontally (303), then the measured distance between the two is the distance of the horizontal movement of the stacker; Node C (302) is installed obliquely (304), and the measured distance between the two is greater than the distance of the horizontal movement of the stacker. In practical applications, it should be installed on the same horizontal line as much as possible and parallel to the roadway. Do the conversion.

Wireless node A ( 300 ) and wireless node B ( 301 ) can be realized by selecting ultra-high frequency UWB wireless module, radio frequency tag RFID wireless module, wireless local area network WiFi module, wireless sensor network ZigBee module, etc. An embodiment of the present invention is to select the ZigBee chip CC2430 of TI Company for use, the operating frequency is 2.4GHz free of application fee and free of use fee, the transmission distance is between 10 meters to 75 meters, and the transmission rate is 20 to 250 kilobits per second. In order to improve the wireless signal strength, there should be an unobstructed free space in the middle.

As shown in Figure 3(b), the relationship between the initial distance d ₀ (313) between the wireless reference node position (310) and the wireless mobile node position A (311) and the received signal strength indicator RSSI ₀ is: RSSI ₀ =-(10nlgd ₀ +A), where n represents the signal propagation constant, and A represents the received signal strength at a distance of 1 meter, which is also a constant.

The relationship between the current distance d (314) between the wireless reference node location (310) and the wireless mobile node location B (312) and RSSI is: RSSI=-(10nlgd+A).

Knowing RSSI ₀ , d ₀ , and RSSI, RSSI-RSSI ₀ =10nlg(d ₀ /d) can be deduced from the two formulas, and the current distance d (314) can be calculated accordingly.

The CC2430 chip has a built-in function of positioning through RSSI. Only one RSSI value is filled in the 8 RSSI registers to realize the above-mentioned ranging function. Due to the existence of errors, the error obtained by this ranging method is between 3 meters and 5 meters. The effective working distance is within 64 meters, which is more suitable for medium-distance three-dimensional shelves.

As shown in Figure 4(a), for long-distance three-dimensional shelves (400), the method of increasing the radio frequency transmission power can be adopted, such as adding TI’s power amplifier chip CC2591, and the working distance can reach 500 meters; or using a small directional antenna, then The enhanced wireless node A (401) and the enhanced wireless node B (402) can implement long-distance applications.

As shown in Figure 4(b), it can be positioned in sections. The long-distance three-dimensional shelf (400) is divided into several sections, such as section A (406) and section B (407). For ZigBee wireless with a working distance of 64 meters technology, the distance between section A (406) and section B (407) can reach 128 meters, and the total length can reach 256 meters, which is suitable for the application of long-distance three-dimensional shelves (400).

Deploy three wireless anchor nodes of wireless anchor node A (403), wireless anchor node B (404), and wireless anchor node C (405), and the section A wireless mobile node (408) in section A (406) is based on the wireless Determine the strength of the signal and the wireless anchor node A (403) or the wireless anchor node B (404) to achieve ranging positioning. Determine the strength of the wireless anchor node B (404) or wireless anchor node C (405) to achieve ranging positioning.

As shown in Figure 5, for the track curved three-dimensional shelf (500), using wireless network technology, integrated wireless network node 1-1 (501), wireless network node 2-1 (502), wireless network node 1-2 (503) , wireless network node 2-2 (504), wireless network node 1-3 (505), wireless network node 2-3 (506) locate the wireless mobile node 1 (507) in each lane, and there are many related algorithms , such as weighted centroid positioning algorithm, RSSI similarity positioning algorithm, quadrilateral ranging positioning algorithm, etc.

The wireless network positioning technology can also use the method of time-division multiplexing to realize the positioning of multiple mobile nodes. For example, in the embodiment of ZigBee wireless technology, under normal circumstances, about 100 mobile nodes can be tracked at the same time. Multi-vehicle applications are also suitable.

For the sake of positioning accuracy, since the wireless positioning accuracy can only reach 3 meters to 5 meters, of course there is an algorithm to improve the accuracy, but it will increase the complexity of the system. In the application of stacker positioning, wireless positioning is only used in stacking Positioning when the machine moves at a constant speed, such accuracy can already meet the requirements, so when calculating the deceleration distance, the speed and error can be integrated, obtained by the formula d _deceleration =d _target -0.5*v _{uniform speed} *t _deceleration -d _error , stacking When the machine reaches the deceleration distance d _{and decelerates} , most of the target distance d has been _completed . In order to ensure the reliability of the stacker, there is an upper limit for the deceleration rate of the safe stop when the stacker itself has a certain frictional resistance. , it can be concluded that half of the product of the safest deceleration time t _deceleration and the speed v _constant speed of the stacker in the constant speed operation stage is the theoretical distance for the stacker to stop safely, and the error d _error also needs to be taken into account, so in After subtracting these factors, the deceleration distance is obtained.

Assuming d _target =50 meters, v _{uniform speed} =240 meters/minute, t _deceleration =3 seconds, d _error =5 meters, then can calculate, d _deceleration =39 meters.

As shown in Figure 6, a row address coding positioning embodiment corresponds to each shelf row (600) and deploys a row address passive RFID tag (601), and a row address passive RFID reader is installed at the corresponding position of the stacker (602), after reading the column address code (603), judge whether it is the previous address of the target column address, and in the process of moving to the left, the previous address of the target column address (605) is the one on the right side of the target column address Column address (606), and in the process of moving to the right, the previous address of the target column address (605) is a column address (607) on the left side of the target column address. After arriving, the logic state of docking is sent to the PLC (604) .

This part of the function can also be realized by using barcode labels and barcode photoelectric scanners.

As shown in Figure 7(a), in the process of moving to the right, the right photoelectric sensor (702) is blocked, and the logic state of "front side blocking" is sent, the frequency conversion motor is switched to the parking speed, and the left photoelectric sensor (701) is blocked, Send the logic state of "full cover", and the frequency conversion motor stops.

As shown in Figure 7(b), in the process of moving to the left, the left photoelectric sensor (701) is blocked, and the logic state of "front side blocking" is sent, the frequency conversion motor is switched to the parking speed, and the right photoelectric sensor (702) is blocked, Send the logic state of "full cover", and the frequency conversion motor stops.

As shown in Figure 8, when the stacker is running to the right, the cargo (800) is subjected to an upward force (801) and a forward frictional force (802). Only when the forward frictional force (802) is large enough can it be The goods follow the movement of the stacker during the start-up acceleration phase, and are related to the weight of the goods and the magnitude of the upward force (801). Therefore, during the start-up acceleration phase, if the target cargo position is at the upper right, the forward friction force (802 ), is also conducive to the increase of the acceleration rate, and in the deceleration and docking stage, the reverse forward friction force (802) is also one of the limiting conditions for the deceleration rate; at the same time, the stacker resistance (803) It is also one of the parameters for calculating the safe deceleration time t deceleration during the deceleration and parking phase of the stacker.

As shown in Figure 9, the high-speed operation mode speed regulation curve (900) enters the high-speed uniform speed operation after completing the high-speed operation mode startup acceleration time (904), and after the operation is greater than the deceleration distance, enters the high-speed operation mode stop deceleration time (905), The area enclosed by the polyline and the abscissa is the moving distance;

The speed regulation curve (902) of the low-speed operation mode enters the low-speed uniform-speed operation after completing the start-up acceleration time (903) of the low-speed operation mode. The area of is the moving distance;

For the speed regulation curve (901) of the short-distance high-speed operation mode, it enters the deceleration process when reaching a high speed, and the speed regulation curve (902) of the low-speed operation mode is also adopted, as long as the high-speed operation mode distance (908) shaded area and the low-speed operation mode If the shaded areas of the distance (909) are equal, the total moving distance is also equal, and the time difference (907) of the high-speed/low-speed operation mode is also similar. Therefore, for short-distance movement, the use of the low-speed operation mode improves safety and reduces energy consumption. consumption.

Therefore, the short-range threshold is used to distinguish between the high-speed operation mode and the low-speed operation mode, and is obtained by using the formula _dthreshold =0.5* _vhigh-speed * _{tacceleration} .

Assuming v _{high speed} = 240 m/min, t _acceleration = 3 seconds, then it can be calculated that d _threshold = 6 meters.

As shown in Figure 10, the three-dimensional storage system using high-speed stacker, its high-speed stacker speed regulation curve (1000), under normal circumstances, in the process of starting acceleration and stopping deceleration, it is necessary to overcome the inertia to do work, the power of the frequency conversion motor It will increase correspondingly, and during the period of constant speed operation, as long as the power overcomes the resistance of the stacker to do work, the power will be lower, as shown in the shaded interval of the horizontal stripes of the power curve (1002) of the high-speed stacker;

Compared with the current three-dimensional storage system using low-speed stackers, its low-speed stacker speed control curve (1001) and the low-speed stacker power curve (1003) oblique shaded interval, it can be seen that for the same moving distance, In terms of time, the low-speed stacker is far longer than the high-speed stacker, and the total power consumption of the low-speed stacker is higher than that of the high-speed stacker. The specific situation depends on the operating parameters of the stacker.

For the throughput of three-dimensional storage per unit time, the throughput curve (1004) of the high-speed stacker is higher than the throughput curve (1005) of the low-speed stacker.

In addition, in terms of implementation cost, at present, the implementation cost of laser ranging technology is 10,000 yuan, while the cost of the distance measurement and positioning technology realized by the present invention is 1,000 yuan. Therefore, the present invention has the advantages of low cost, high throughput, and low power consumption. , high reliability, and flexible application advantages, it has a broad market application prospect.

Claims (2)

1. high-speed buck stacker speed regulating method that uses the wireless indoor location technology; Be applied to the fully automatic stereo warehousing system; It is characterized in that: utilization wireless indoor location technology, geocoding location technology, address slice photoelectricity location technology are carried out three grades of location and are selected high low speed mode of motion according to miles of relative movement length piler; Piler is carried out three sections methods of optimizing speed governing, and concrete steps are following:

(1) operation is decomposed, and confirms initial column address and target column address that piler moves;

(2) detect wireless status, activate wireless mobile node and wireless datum node, measure once reception signal strength indication RSSI between the two ₀

(3) do you judge whether communication normal? Normally, then with RSSI ₀With two radio node initial distance d ₀Write wireless mobile node; Then there is fault in mal, reports to the police, and finishes;

(4) pack the target column address into programmable logic controller (PLC) PLC and initial column address relatively, calculating needs the horizontal throw that moves;

Does (5) judgement need mobile horizontal throw greater than the short distance threshold value? Greater than, then adopt the high-speed cruising pattern, otherwise adopt low-speed operation mode;

(6) programmable logic controller (PLC) PLC starts piler, and under the high-speed cruising pattern, variable-frequency motor to be to set the rate of acceleration rev up, reaches when setting high rotating speed, travels at the uniform speed; Under low-speed operation mode, variable-frequency motor reaches when setting slow speed of revolution to set the rate of acceleration rev up, travels at the uniform speed;

(7) distance between wireless mobile node and the wireless datum node is calculated in wireless mobile node periodic ranging, measures the reception signal strength indication RSSI between two radio nodes, according to formula RSSI-RSSI ₀=10nlg (d ₀/ d) can calculate current distance d, n representation signal propagation constant wherein;

(8) do you judge that current distance is greater than deceleration distance? Greater than, then starting moderating process, wireless mobile node sends the deceleration logic state to programmable logic controller (PLC) PLC, otherwise gets back to step (7);

(9) moderating process, variable-frequency motor is to set the moderating ratio rev down, and the high-speed cruising pattern is different with low-speed operation mode moderating ratio setting value;

(10) start the column address code reader, when piler process column address code tag, read the column address coding;

(11) the column address coding and the target column address of reading are compared, judge whether to be previous address, target column address? Be, then send and stop logic state, start double-photoelectric-sensor to programmable logic controller (PLC) PLC, otherwise, execution in step (10) continued;

(12) in piler moves right process; When right side opto-electronic pickup (702) is blocked; Double-photoelectric-sensor sends " block the front side " logic state, and variable-frequency motor switches to the stop rotating speed, when left side opto-electronic pickup (701) is blocked; Double-photoelectric-sensor sends " all blocking " logic state, and variable-frequency motor stops; Be moved to the left in the process at piler; When left side opto-electronic pickup (701) is blocked; Double-photoelectric-sensor sends " block the front side " logic state, and variable-frequency motor switches to the stop rotating speed, when right side opto-electronic pickup (702) is blocked; Double-photoelectric-sensor sends " all blocking " logic state, and variable-frequency motor stops.

2. a kind of high-speed buck stacker speed regulating method that uses the wireless indoor location technology as claimed in claim 1; It is characterized in that: three grades of location comprise location and addressing when the wireless distance finding location is used for piler high speed uniform movement, select for use ultra broadband UWB wireless technology, RF tag RFID technology, WLAN WiFi technology, wireless sensor network ZigBee technology to realize; The column address coding provides the column address absolute addressing, and location and addressing when being used for piler braking decelerated movement select for use bar code photo electric scanning, passive RF label RFID technology to realize; Address slice and double-photoelectric-sensor provide the location relative addressing of address slice photoelectricity, location and addressing when being used for the piler stop.

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