A control method for reducing the performance requirements of OHT positioning hardware

Abstract

The application discloses a control method for reducing performance requirements of OHT positioning hardware. The method comprises the following steps: pasting bar codes on a driving path, the bar direction of the bar codes being consistent with the driving direction of the OHT; obtaining the values of the bar codes on the path in advance based on a planned path logic; verifying the values of the bar codes obtained based on the path logic by using the values of the bar codes obtained by a code reader during driving; if continuous verification abnormities occur, controlling the OHT to drive at a reduced speed, and reducing the speed of the OHT as a whole according to a detailed path planning; and adjusting the acceleration and deceleration of the OHT according to the planned path speed during the execution process. The application can reduce the difficulty of deploying track labels in an OHT project, reduce the electrical cost of the OHT project, prolong the service life of the code reader, and realize more smooth and intelligent acceleration and deceleration of the OHT by combining the detailed path with the acceleration and deceleration path.

Description

Technical Field

[0001] This invention relates to the field of conveying equipment technology, and specifically to a control method for reducing the hardware performance requirements of OHT positioning. Background Technology

[0002] "OHT" is an abbreviation for Overhead Hoist Transport. This system is widely recognized as the main transport system for 300mm FABs and the next generation of FABs. Currently, it is used not only for transport within process areas but also for transport between process areas or between factories. During high-speed travel, the OHT needs to accurately know its current location. The commonly used solution is to use high-speed cameras or high-speed barcode readers to provide position information during the OHT's high-speed movement.

[0003] Currently, commercially available high-speed barcode readers that meet the OHT walking speed (3.5m / s) have three major drawbacks.

[0004] Drawback 1: High price. The mainstream Keyence, Cognex and Honeywell are basically priced at 30,000+ RMB.

[0005] Second drawback: Large size. When used in OHT equipment, which has strict requirements on weight and size, it takes up a lot of space.

[0006] Defect 3: The required reading distance is usually over 100mm, making normal use and installation difficult. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a control method that reduces the performance requirements of OHT positioning hardware.

[0008] To achieve the above objectives, the present invention provides a control method for reducing the hardware performance requirements of OHT positioning, comprising:

[0009] A barcode is affixed along the driving route, with the bar shape of the barcode aligned with the driving direction of the OHT.

[0010] Based on the planned path logic, the barcode values ​​of each item on the path are obtained in advance. During the journey, the barcode values ​​obtained by the barcode reader are used to verify the barcode values ​​obtained based on the path logic.

[0011] If continuous verification anomalies occur, control the OHT to reduce speed and plan a deceleration path based on the detailed path plan.

[0012] Based on the planned path speed, fine-tune acceleration and deceleration during execution.

[0013] Furthermore, the barcode is stretched.

[0014] Furthermore, the barcode has a width of 56mm and a length of 176mm.

[0015] Furthermore, a sensing area is provided on the side of the barcode. The sensing area is used to trigger the barcode reader to read the barcode. If the barcode reading is abnormal and the barcode reader is still within the barcode area, the barcode reading will be retried until it moves out of the barcode reading area.

[0016] Furthermore, precise feedback of the OHT's walking position is achieved by combining the encoder values ​​fed back from the walking motor.

[0017] Furthermore, during the initial debugging phase, the sensing area is also used to trigger the detection of whether the barcode is within the detailed path. If it is not, it is determined that the driving path is abnormal, and the OHT operation is stopped. If it is, the theoretical barcode value is assigned to the current barcode, and then the barcode action is executed. In the subsequent debugging phase, after the barcode reader reads the barcode value, it is determined whether the returned barcode value is consistent with the current barcode value. If they are consistent, it is determined to be a normal situation, and no action is taken. If they are inconsistent, the actual barcode value is assigned to the current barcode, and then the barcode action is executed.

[0018] Furthermore, the path planning method is as follows:

[0019] Clear the detailed path list data, and determine whether the target location is equal to the current location. If so, OHT does not need to perform any movement action, and the path planning is complete. Otherwise, determine whether the number of paths with the same starting point is greater than 1. If so, retrieve the detailed data of the two paths with the same starting point. If the two paths find a path in the same direction, determine whether the current label is equal to the end label. If no path in the same direction is found, determine that the map information is incorrect.

[0020] If the number of paths with the same starting point is 1, then store the path data in a List, and then check if the current label is equal to the end label. If they are not equal, calculate the maximum speed of the found road segment, set the path's key point as the starting point of the next path, and then perform a loop check. If they are equal, then store the stop point data in a List, and the path planning is complete.

[0021] Furthermore, the deceleration path is planned as follows:

[0022] Get the starting label of the current path segment and the maximum speed of the current path segment. If the target speed is less than the current speed, or the current path is the last path, calculate the deceleration segment and store the point that caused the deceleration.

[0023] If the current path is not the last path, then search for the deceleration point in reverse from the current point. If the current position is found and passes the condition check, store the path and type deceleration starting point. If the condition check fails, return to continue the check. If the current position is not found, check if the maximum speed is 0. If it is 0, then pass the path speed limit to the maximum speed. If the maximum speed is not equal to 0 and the current label is a location label, then check if the cumulative distance is above the safe distance. If the current label is not a location label, then do not read data while moving.

[0024] If the current path is the last path, directly determine whether the current label is a location label. If it is, store the data in the possible deceleration section. Otherwise, determine whether the detailed path has only one segment. If it has only one segment, store the data in the possible deceleration section. The single-point deceleration section planning is complete.

[0025] If the detailed path is not a single segment, directly determine whether the cumulative distance is above the safe distance. If the cumulative distance is above the safe distance, store the path as a deceleration start point. If the cumulative distance is less than the safe distance, store the path as a deceleration waypoint, and then return to continue the judgment.

[0026] Furthermore, the method for fine-tuning acceleration and deceleration is as follows:

[0027] The system checks if the current label is equal to the previous label. If they are, it switches to the next segment and assigns the current label to the previous label. If they are not equal, it searches for the current label in the detailed path. If the label does not exist, the formal path is incorrect. If the label exists, it records the position of the label in the detailed path. Then, it checks if the label is a location label or the last path. If so, it checks if the label is in the deceleration map or cached commands. If it is in the deceleration map, it checks if the conditions are met. If they are met, it performs the deceleration action; otherwise, it does not decelerate. If it is in the cached commands, it executes the control commands according to priority. If the label is neither a location label nor the last path, it checks if it is the last cached command. If it is, it retrieves the last critical path control command; otherwise, it retrieves the next critical path control command, obtains the left and right turn actions from the control commands, and updates the target position of the guide wheel according to the command.

[0028] Beneficial effects: 1. This invention can reduce the difficulty of deploying track tags in OHT projects;

[0029] 2. This invention can reduce the electrical cost expenditure of OHT projects;

[0030] 3. This invention can extend the service life of the barcode reader;

[0031] 4. The combination of detailed paths and acceleration / deceleration paths makes the crane's acceleration and deceleration smoother and more intelligent. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the barcode used in an embodiment of the present invention;

[0033] Figure 2 This is a flowchart of a control method to reduce the hardware performance requirements for OHT positioning;

[0034] Figure 3 This is a flowchart illustrating the path planning in an embodiment of the present invention;

[0035] Figure 4 This is a flowchart of the deceleration path planning in an embodiment of the present invention;

[0036] Figure 5 This is a flowchart of the fine-tuning acceleration and deceleration in an embodiment of the present invention. Detailed Implementation

[0037] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. These embodiments are implemented based on the technical solutions of the present invention, and it should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0038] like Figures 1 to 5 As shown, this embodiment of the invention provides a control method for reducing the hardware performance requirements of OHT positioning, including:

[0039] Barcodes are affixed along the driving route, with the barcodes oriented in the same direction as the OHT's driving direction. See also Figure 1 The barcode has been elongated; specifically, its width is 56mm and its length is 176mm. This is to prevent afterimages from appearing during the photo-taking process or the vehicle from crossing the barcode area after the reader has triggered the reading.

[0040] Based on the planned path logic, the barcode values ​​of each item on the path are obtained in advance. During the journey, the barcode values ​​obtained by the barcode reader are used to verify the barcode values ​​obtained based on the path logic.

[0041] If continuous verification anomalies occur, the OHT will be controlled to reduce speed, and a deceleration path will be planned based on the detailed path.

[0042] Based on the planned path speed, fine-tune acceleration and deceleration during execution.

[0043] To prevent the barcode reader from being in reading mode for extended periods during operation, thus shortening its lifespan, a sensing area is provided on the side of the barcode. This sensing area triggers the barcode reader to read the code. If the reading is abnormal and the reader is still within the barcode area, the reading attempt is retried until the reader moves out of the reading area. Among various barcode sensing solutions, a specular reflection type photoelectric sensor combined with a reflective strip is selected.

[0044] The system uses a combination of labels and encoder values ​​fed back from the walking motor to achieve precise positional feedback for the OHT (Outer Handling Telephone) system. It also allows for increased barcode spacing, reducing the difficulty of barcode placement during project implementation.

[0045] See Figure 2 During the initial debugging phase, the sensing area is also used to trigger the detection of whether the barcode is within the detailed path. If it is not, it is determined that the driving path is abnormal and the OHT operation is stopped. If it is, the theoretical barcode value is assigned to the current barcode, and then the barcode action is executed. In the subsequent debugging phase, after the barcode reader reads the barcode value, it is determined whether the returned barcode value is consistent with the current barcode value. If they are consistent, it is determined to be a normal situation and no action is taken. If they are inconsistent, the actual barcode value is assigned to the current barcode, and then the barcode action is executed.

[0046] See Figure 3 The path planning method is as follows:

[0047] Clear the detailed path list data, and determine whether the target location is equal to the current location. If so, OHT does not need to perform any movement action, and the path planning is complete. Otherwise, determine whether the number of paths with the same starting point is greater than 1. If so, retrieve the detailed data of the two paths with the same starting point. If the two paths find a path in the same direction, determine whether the current label is equal to the end label. If no path in the same direction is found, determine that the map information is incorrect.

[0048] If the number of paths with the same starting point is 1, then store the path data in a List, and then check if the current label is equal to the end label. If they are not equal, calculate the maximum speed of the found road segment, set the path's key point as the starting point of the next path, and then perform a loop check. If they are equal, then store the stop point data in a List, and the path planning is complete.

[0049] See Figure 4 The deceleration path is planned as follows:

[0050] Get the starting label of the current path segment and the maximum speed of the current path segment. If the target speed is less than the current speed, or the current path is the last path, calculate the deceleration segment and store the point that caused the deceleration.

[0051] If the current path is not the last path, then search for the deceleration point in reverse from the current point. If the current position is found and passes the condition check, store the path and type deceleration starting point. If the condition check fails, return to continue the check. If the current position is not found, check if the maximum speed is 0. If it is 0, then pass the path speed limit to the maximum speed. If the maximum speed is not equal to 0 and the current label is a location label, then check if the cumulative distance is above the safe distance. If the current label is not a location label, then do not read data while moving.

[0052] If the current path is the last path, directly determine whether the current label is a location label. If it is, store the data in the possible deceleration section. Otherwise, determine whether the detailed path has only one segment. If it has only one segment, store the data in the possible deceleration section. The single-point deceleration section planning is complete.

[0053] If the detailed path is not a single segment, directly determine whether the cumulative distance is above the safe distance. If the cumulative distance is above the safe distance, store the path as a deceleration start point. If the cumulative distance is less than the safe distance, store the path as a deceleration waypoint, and then return to continue the judgment.

[0054] See Figure 5 The fine-tuning of acceleration and deceleration is as follows:

[0055] The system checks if the current label is equal to the previous label. If they are, it switches to the next segment and assigns the current label to the previous label. If they are not equal, it searches for the current label in the detailed path. If the label does not exist, the formal path is incorrect. If the label exists, it records the position of the label in the detailed path. Then, it checks if the label is a location label or the last path. If so, it checks if the label is in the deceleration map or cached commands. If it is in the deceleration map, it checks if the conditions are met. If they are met, it performs the deceleration action; otherwise, it does not decelerate. If it is in the cached commands, it executes the control commands according to priority. If the label is neither a location label nor the last path, it checks if it is the last cached command. If it is, it retrieves the last critical path control command; otherwise, it retrieves the next critical path control command, obtains the left and right turn actions from the control commands, and updates the target position of the guide wheel according to the command.

[0056] The above description is merely a preferred embodiment of the present invention. It should be noted that for those skilled in the art, other parts not specifically described are existing technology or common knowledge. Several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for reducing the hardware performance requirements of OHT positioning, characterized in that, include: A barcode is affixed along the driving route, with the bar shape of the barcode aligned with the driving direction of the OHT. Based on the planned path logic, the barcode values ​​of each item on the path are obtained in advance. During the journey, the barcode values ​​obtained by the barcode reader are used to verify the barcode values ​​obtained based on the path logic. If continuous verification anomalies occur, control the OHT to reduce speed and plan a deceleration path based on the detailed path plan. Based on the planned path speed, fine-tune acceleration and deceleration during execution; The barcode is stretched. The barcode has a sensing area on its side, which is used to trigger the barcode reader to read the barcode. If the barcode reading is abnormal and the barcode reader is still within the barcode area, the barcode reading will be retried until it moves out of the barcode reading area. The deceleration path is planned as follows: Get the starting label of the current path segment and the maximum speed of the current path segment. If the target speed is less than the current speed, or the current path is the last path, calculate the deceleration segment and store the point that caused the deceleration. If the current path is not the last path, then search for the deceleration point in reverse from the current point. If the current position is found and passes the condition check, store the path and type deceleration starting point. If the condition check fails, return to continue the check. If the current position is not found, check if the maximum speed is 0. If it is 0, then pass the path speed limit to the maximum speed. If the maximum speed is not equal to 0 and the current label is a location label, then check if the cumulative distance is above the safe distance. If the current label is not a location label, then do not read data while moving. If the current path is the last path, directly determine whether the current label is a location label. If it is, store the data in the possible deceleration section. Otherwise, determine whether the detailed path has only one segment. If it has only one segment, store the data in the possible deceleration section. The single-point deceleration section planning is complete. If the detailed path is not a single segment, directly determine whether the cumulative distance is above the safe distance. If the cumulative distance is above the safe distance, store the path as a deceleration start point. If the cumulative distance is less than the safe distance, store the path as a deceleration waypoint, and then return to continue the judgment.

2. The control method for reducing the hardware performance requirements of OHT positioning according to claim 1, characterized in that, The barcode is 56mm wide and 176mm long.

3. The control method for reducing the hardware performance requirements of OHT positioning according to claim 1, characterized in that, The OHT achieves accurate position feedback by combining encoder values ​​fed back from the walking motor.

4. The control method for reducing the hardware performance requirements of OHT positioning according to claim 1, characterized in that, During the initial debugging phase, the sensing area is also used to trigger the detection of whether the barcode is within the detailed path. If it is not, it is determined that the driving path is abnormal and the OHT operation is stopped. If it is, the theoretical barcode value is assigned to the current barcode, and then the barcode action is executed. In the subsequent debugging phase, after the barcode reader reads the barcode value, it is determined whether the returned barcode value is consistent with the current barcode value. If they are consistent, it is determined to be a normal situation and no action is taken. If they are inconsistent, the actual barcode value is assigned to the current barcode, and then the barcode action is executed.

5. The control method for reducing the hardware performance requirements of OHT positioning according to claim 1, characterized in that, The path planning method is as follows: Clear the detailed path list data, and determine whether the target location is equal to the current location. If so, OHT does not need to perform any movement action, and the path planning is complete. Otherwise, determine whether the number of paths with the same starting point is greater than 1. If so, retrieve the detailed data of the two paths with the same starting point. If the two paths find a path in the same direction, determine whether the current label is equal to the end label. If no path in the same direction is found, determine that the map information is incorrect. If the number of paths with the same starting point is 1, then store the path data in a List, and then check if the current label is equal to the end label. If they are not equal, calculate the maximum speed of the found road segment, set the path's key point as the starting point of the next path, and then perform a loop check. If they are equal, then store the stop point data in a List, and the path planning is complete.

6. The control method for reducing the hardware performance requirements of OHT positioning according to claim 1, characterized in that, The method for fine-tuning acceleration and deceleration is as follows: The system checks if the current label is equal to the previous label. If they are, it switches to the next segment and assigns the current label to the previous label. If they are not equal, it searches for the current label in the detailed path. If the label does not exist, the formal path is incorrect. If the label exists, it records the position of the label in the detailed path. Then, it checks if the label is a location label or the last path. If so, it checks if the label is in the deceleration map or cached commands. If it is in the deceleration map, it checks if the conditions are met. If they are met, it performs the deceleration action; otherwise, it does not decelerate. If it is in the cached commands, it executes the control commands according to priority. If the label is neither a location label nor the last path, it checks if it is the last cached command. If it is, it retrieves the last critical path control command; otherwise, it retrieves the next critical path control command, obtains the left and right turn actions from the control commands, and updates the target position of the guide wheel according to the command.

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