Signal handshake cooperative control method of automobile part coating robot

Abstract

The application relates to the technical field of industrial robot cooperative control, and discloses a signal handshake cooperative control method for an automobile part coating robot; according to the coating process sequence of primer, color paint and varnish, the method establishes a point-to-point handshake channel between adjacent coating robots, and establishes a shared workpiece identity file; a current coating robot sends spraying intention information before a workpiece arrives at a corresponding spraying station; adjacent downstream coating robots feed back relay confirmation information according to the workpiece identity, the state of a previous process, the state of the device and relay spraying conditions; the current coating robot sends spraying execution state information during spraying; when spraying execution state information is missing, abnormal state information is received or waiting is timed out, the adjacent downstream coating robots execute waiting, skip the current workpiece or a safe shutdown process; thus, the upstream spraying abnormality is feedforwardly blocked, and the workpiece coating process is continuously traced.

Description

Technical Field

[0001] This invention relates to the field of industrial robot collaborative control technology, specifically a signal handshake collaborative control method for an automotive parts painting robot. Background Technology

[0002] Automotive parts painting production lines typically employ a multi-spray booth, multi-robot serial operation to sequentially apply primer, color coat, and clear coat. In existing production lines, each painting robot operates independently according to a preset trajectory and fixed production rhythm. Adjacent robots usually lack direct communication mechanisms, making it difficult to promptly transmit information about the upstream robot's painting completion status, abnormal painting conditions, and workpiece passage status to the downstream robot. When the primer robot experiences a painting interruption due to spray gun blockage, abnormal air pressure, servo axis failure, or paint supply anomalies, the downstream color coat and clear coat robots may continue painting according to their original rhythm. This results in the direct application of color coat and clear coat onto parts that are not covered by primer or have incomplete primer coverage, leading to problems such as missed primer application, uneven coating thickness, reduced interlayer adhesion, and batch rework.

[0003] For example, Chinese invention patent application CN102371220B discloses a flexible, efficient, and automatic painting system and process for a large-wheeled tractor chassis. It uses a programmable logic controller (PLC), a robot control system, a paint booth control system, and an accumulation chain control system for interlocking control, enabling coordination between workpiece transport and robot painting. However, this solution relies heavily on centralized scheduling by a higher-level control system. Abnormal states require data collection, judgment, and forwarding before affecting subsequent painting actions. In high-frequency continuous painting scenarios, it is difficult to promptly interrupt the downstream robot's continued painting of abnormal workpieces. Chinese invention patent application CN107552289B discloses a visual recognition painting robot system and its operation method. It uses laser sensors, encoders, and an industrial control computer to identify workpiece contours and generate painting paths, primarily to improve the matching between the painting path and the workpiece shape. However, it does not address how the downstream robot should synchronously wait, skip, or stop when the upstream robot experiences painting abnormalities.

[0004] Therefore, the main problem with existing technologies is the lack of a direct, real-time signal handshake communication link between multiple painting robots. Upstream painting anomalies cannot promptly constrain downstream painting actions, causing a single workstation's painting interruption to further propagate into multi-stage coating defects. To solve this problem, it is necessary to establish a point-to-point signal handshake mechanism between adjacent painting robots. This mechanism would allow downstream robots to initiate painting based on upstream painting completion signals and wait, skip abnormal workpieces, or trigger a safety shutdown in case of upstream anomalies or handshake timeouts. This would reduce the formation of defective paint films and improve the real-time collaborative control and painting quality stability of the painting production line. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a signal handshake collaborative control method for automotive parts painting robots, which solves the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A signal handshake collaborative control method for an automotive parts painting robot includes:

[0008] S1: Establish a point-to-point handshake channel between adjacent painting robots according to the painting process sequence of primer, color paint and clear coat, and establish a workpiece identity file shared by each painting robot.

[0009] S2: Before the workpiece arrives at the spraying station corresponding to the current painting robot, the current painting robot sends the spraying intention information to the adjacent downstream painting robot according to the workpiece's identity file;

[0010] S3: The adjacent downstream painting robot sends relay confirmation information to the current painting robot based on the workpiece identity, the status of the previous process, the status of the machine equipment, and the relay spraying conditions;

[0011] S4: After receiving the relay confirmation information, the current painting robot starts the spraying action and sends the spraying execution status information to the adjacent downstream painting robot according to the predetermined cycle during the spraying process;

[0012] S5: When the adjacent downstream painting robot does not receive painting execution status information, receives abnormal status information, or waits for a timeout, it will execute the waiting, skip the current workpiece, or safety shutdown process according to the abnormality level.

[0013] Preferably, S1 includes:

[0014] When establishing a point-to-point handshake channel and generating a workpiece identity file, the node robots are configured according to the workstation sequence of each painting robot in the production line.

[0015] Set up a main link and a backup link between adjacent node robots;

[0016] The link status is determined based on the status message sending period, message loss rate, and transmission delay.

[0017] Synchronize the clocks of the robots at each node;

[0018] Before the workpiece enters the line, collect workpiece identity information, conveyor chain pulse, process parameter table version number and spray trajectory file identifier to generate a workpiece identity file;

[0019] Simultaneous verification is performed based on the file verification value.

[0020] Preferably, S2 includes:

[0021] When sending spraying intention information, the current painting robot determines the spraying intention trigger zone based on the conveyor chain pulse, conveyor chain linear speed, spraying station entrance position and spraying trajectory start position.

[0022] After the workpiece identity, equipment status, and process version are verified, spraying intention information is generated, which includes workpiece identity, process type, expected spraying start and end positions, trajectory identifier, message sequence number, and relay requirements.

[0023] The adjacent downstream painting robot verifies the core fields and check codes of the spraying intention information;

[0024] The painting robot updates the current process permission status based on valid relay confirmation, negotiated relay confirmation, rejected relay confirmation, or waiting timeout results.

[0025] Preferably, the adjacent downstream painting robot verifies the core fields and checksums of the painting intent information, including:

[0026] The adjacent downstream painting robot receives the painting intention information through a point-to-point handshake channel and performs consistency verification on the corresponding messages in the backup link or broadcast link;

[0027] The unique identification code of the workpiece, the message serial number, the expected spraying start pulse count value, the process parameter table version number, and the spraying trajectory file identifier are compared;

[0028] When there is a mismatch in field comparison, a message verification error, or a message sequence number rollback, an intent to retransmit is generated, carrying the sequence number of the most recently successfully received message and the error type code.

[0029] Preferably, S3 includes:

[0030] When receiving feedback confirmation information, the adjacent downstream painting robot retrieves the local workpiece identity file using the workpiece's unique identification code, and requests retransmission if the file is missing.

[0031] The status of the preceding process, controller, spray gun, servo axis, paint supply, atomizing air pressure, high voltage static electricity, task queue, safety interlock, spraying sequence, spraying coverage area connection, and process parameter version are verified sequentially.

[0032] Based on the verification results, a confirmation message for a confirmed relay, a confirmation message for a negotiated relay, or a confirmation message for a rejected relay will be generated.

[0033] Preferably, based on the verification result, a positive relay confirmation message, a negotiated relay confirmation message, or a rejection relay confirmation message is generated, including:

[0034] When the workpiece identity is consistent, the status of the preceding process meets the relay requirements, the machine is in a relayable state, the spraying sequence relationship and the coverage area connection relationship meet the relay requirements, and the process parameter versions are consistent, a positive relay confirmation message is generated.

[0035] Only when the versions of process parameters are inconsistent and both versions of the process parameter table are in the allowed parallel dwell period, a negotiation relay confirmation message is generated;

[0036] If there are discrepancies in identity, incomplete preceding processes, unusable equipment, no slots in the task queue, inadequate trajectory connection, or inadequate safety interlocking, a rejection confirmation message with a rejection reason code will be generated.

[0037] Preferably, S4 includes:

[0038] Before the spraying starts, the current painting robot verifies the workpiece identity, whether the relay confirmation information is within the validity period, the process parameter version, the loading status of the spraying trajectory file, and the executable status of the machine equipment;

[0039] After the review is approved, the spraying parameters are loaded, and the process package for this step is sent to the adjacent downstream painting robot.

[0040] According to the status message sending cycle, the end position, spray gun status, servo status, trajectory progress, conveyor chain pulse and process measured value are collected, the process measured value is normalized for deviation, spraying execution status information is generated and written into the workpiece identity file.

[0041] When the painting robot detects an anomaly, it sends an anomaly status message; when it completes the painting process, it sends an execution completion message.

[0042] Preferably, when the painting robot detects an anomaly, it sends an anomaly status message; when the painting is completed, it sends an execution completion message, including:

[0043] When the painting robot detects an anomaly, it writes the anomaly type code and the machine's health level into the painting execution status information within the same status message sending cycle, and sends the anomaly status information. The anomaly status information carries the workpiece's unique identification code, execution status sequence number, anomaly occurrence pulse count value, anomaly duration, anomaly level suggestion, and machine's handling status.

[0044] When the current process of spraying is completed and no abnormality occurs, an execution completion message is sent. The execution completion message carries the current process completion mark, the workpiece unique identification code, the completion pulse count value, the completion timestamp, and the workpiece identity file signature verification value.

[0045] Preferably, S5 includes:

[0046] The adjacent downstream painting robot verifies the painting execution status information based on the execution status sequence number, sending timestamp, receiving timestamp, process deviation, and progress ratio;

[0047] Based on the verification results, determine whether it is normal, slightly abnormal, workpiece abnormal, or safety abnormal;

[0048] When the spraying execution status information is missing, the process of requesting a replacement, cross-verification, and safety anomaly determination is executed in sequence.

[0049] Upon receiving abnormal status information, the system searches the abnormality handling table according to the abnormality type code and abnormality level code, and performs actions such as delaying and waiting, adding the current workpiece to the skip queue, or entering the safe shutdown process based on the search results.

[0050] Preferably, the verification results are used to determine whether the condition is normal, slightly abnormal, workpiece abnormal, or safety abnormal, including:

[0051] When all checks on the spraying execution status information pass, it is determined to be in a normal state.

[0052] When a single frame is lost, a single delay exceeds the limit, or a low-priority parameter exceeds the limit for a short time, it is judged as a minor abnormal state.

[0053] When there are continuous frame drops, continuous process deviations exceeding limits, abnormal progress rationality, or abnormal status information carrying a level 2 or level 3 abnormality code, it is determined to be an abnormal status of the workpiece.

[0054] When a servo axis failure occurs, a safety interlock is triggered, a status message is continuously interrupted, an abnormal status information carries a level 4 abnormal code, or a multi-source verification is inconsistent, it is determined to be a safety abnormal status.

[0055] When multiple states coexist, the final state is determined according to the priority of safety abnormality, workpiece abnormality, minor abnormality and normal state.

[0056] Compared with the prior art, the present invention provides a signal handshake collaborative control method for automotive parts painting robots, which has the following beneficial effects:

[0057] 1. This invention establishes a point-to-point handshake channel between adjacent coating robots according to the coating process sequence of primer, color paint, and clear coat. It associates spraying intent information, relay confirmation information, spraying execution status information, and abnormal status information with workpiece identity files. This allows downstream coating robots to confirm the execution status of upstream processes, machine relay conditions, and the abnormal handling status of the corresponding workpiece before starting spraying. Simultaneously, through message continuity verification, anomaly handling tables, skip queues, and safe shutdown procedures, it classifies and handles upstream spray gun blockages, air supply abnormalities, servo axis malfunctions, or paint supply abnormalities. This prevents downstream coating robots from continuing to spray color paint and clear coat on workpieces with incomplete primer coverage or incomplete primer coverage, ultimately reducing multi-process coating defects, lowering the risk of batch rework, and improving the real-time collaborative control and spraying quality stability of the coating production line.

[0058] 2. This invention establishes a workpiece identity file for each automotive component and associates and records information such as painting intention, relay confirmation, painting execution status, abnormal status, and completion with the workpiece's unique identification code, message sequence number, and timestamp. This creates a continuous correspondence between the execution status, abnormal nodes, handling actions, and process parameter versions of each process in the primer, color coat, and clear coat stages. When communication interruptions, equipment failures, inconsistent parameter versions, or abnormal workpiece identities occur during production, the cause of the abnormality and the scope of affected workpieces can be located based on the process annotation records. Ultimately, this improves the traceability of the painting process, the efficiency of abnormality investigation, and the accuracy of rework handling. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the signal handshake collaborative control method for an automotive parts painting robot according to the present invention;

[0060] Figure 2 This is a schematic diagram of the point-to-point handshake channel layout for the primer, color paint, and clear coat robots of this invention;

[0061] Figure 3 This is a schematic diagram illustrating the establishment and synchronous verification of the workpiece identity file in this invention;

[0062] Figure 4 This is a sequence diagram showing the spraying intent and relay confirmation handshake of the present invention;

[0063] Figure 5 This is a schematic diagram of the spraying execution status cycle reporting and anomaly feedforward of the present invention;

[0064] Figure 6 This is a flowchart illustrating the anomaly level determination and downstream processing of the present invention. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Example 1: Figure 1 - Figure 6 A signal handshake collaborative control method for an automotive parts painting robot is presented, including:

[0067] S1: Establish a point-to-point handshake channel between adjacent painting robots according to the painting process sequence of primer, color paint and clear coat, and establish a workpiece identity file shared by each painting robot.

[0068] S2: Before the workpiece arrives at the spraying station corresponding to the current painting robot, the current painting robot sends the spraying intention information to the adjacent downstream painting robot according to the workpiece's identity file;

[0069] S3: The adjacent downstream painting robot sends relay confirmation information to the current painting robot based on the workpiece identity, the status of the previous process, the status of the machine equipment, and the relay spraying conditions;

[0070] S4: After receiving the relay confirmation information, the current painting robot starts the spraying action and sends the spraying execution status information to the adjacent downstream painting robot according to the predetermined cycle during the spraying process;

[0071] S5: When the adjacent downstream painting robot does not receive painting execution status information, receives abnormal status information, or waits for a timeout, it will execute the waiting, skip the current workpiece, or safety shutdown process according to the abnormality level.

[0072] This method is applied to an automated painting production line for automotive parts such as bumpers, door panels (inner and outer), fenders, hoods, trunk lids, rearview mirror housings, and wheel arch trims. The automated painting production line is equipped with a primer spray booth, a color paint spray booth, and a clear coat spray booth sequentially along the workpiece flow direction. A primer coating robot is installed in the primer spray booth, at least one color paint coating robot is installed in the color paint spray booth, and at least one clear coat coating robot is installed in the clear coat spray booth. In one optional configuration, the automated painting production line adopts a three-spray-booth, five-robot tandem structure, where the first node robot performs primer spraying, the second and third node robots perform color paint spraying, and the fourth and fifth node robots perform clear coat spraying. Workpieces are transported via a suspended conveyor chain or skid. The conveyor belt passes through each painting station sequentially, and each painting robot executes the corresponding painting action according to the taught trajectory, painting parameter table, and workpiece arrival information. The input information of this method includes at least the workpiece identity information, conveyor belt encoder pulses, the operating status of each painting robot, the spray gun status, paint flow rate, atomizing air pressure, high voltage electrostatic voltage, process parameter table version, painting trajectory file, spray booth temperature, spray booth humidity, spray booth exhaust status, paint supply equipment status, compressed air supply equipment status, high voltage electrostatic equipment status, and conveyor equipment operating status. The output information includes at least the painting start command, painting stop command, downstream waiting command, current workpiece skip mark, safety stop command, abnormal reporting record, and process annotation record of workpiece identity file.

[0073] Specifically, such as Figure 2 and Figure 3 As shown: In S1, the process position of each coating robot in the production line is used as the node sequence. The primer coating robot, color paint coating robot, and clear coat coating robot are configured as node robots in sequence. Adjacent node robots establish a point-to-point handshake channel through industrial real-time Ethernet. The point-to-point handshake channel is used to transmit spraying intention information, relay confirmation information, and spraying execution status information bound to a single workpiece. The point-to-point handshake channel can be established using industrial real-time Ethernet, which is used to transmit spraying intention information, relay confirmation information, and spraying execution status information between adjacent coating robots, and enables the above information to be transmitted according to a fixed communication cycle. Other industrial Ethernet links can also be used if the requirements of fixed-cycle communication and real-time transmission of status messages are met. To reduce the impact of single-link synchronization failure on the cooperative control of adjacent robots, a main link and a backup link are configured between adjacent node robots. The main link is used for regular handshake message transmission, and the backup link is used to transmit retransmitted messages of the same message sequence when the main link loses synchronization or becomes unstable.

[0074] Link status is determined based on the continuity of handshake message arrival, statistical frame loss rate, and transmission delay. If no valid message is received from the peer in two consecutive status message transmission cycles, the current link is marked as out-of-synchronization. If the message loss rate within the statistical window of the most recent 100 handshake messages is greater than 1%, or the median transmission delay of the most recent 10 handshake messages is greater than 2ms, the current link is marked as unstable. 100 frames are used as the frame loss rate statistical window because a small number of message samples cannot reflect a 1% frame loss ratio; 100 frames can form a calculable statistical basis without significantly increasing buffer overhead. The median transmission delay of the most recent 10 handshake messages is used to reduce the impact of occasional jitter in a single frame on link status judgment. The median transmission delay threshold can be selected as 2ms, which can be determined during the production line debugging phase by adding 3 times the jitter margin to the measured median transmission delay of normal links. When the field network topology is long, there are many switching nodes, or the controller communication refresh cycle is long, the transmission delay threshold can be adjusted according to the field measurement results.

[0075] The status message sending period is the basic period for each node robot to send handshake status messages or execution status messages. It can be selected as 5ms and adjusted between 3ms and 10ms according to the real-time task cycle of the painting robot controller. When the external communication refresh cycle of the robot controller is greater than 5ms, the status message sending period can be set to 1 to 2 times the controller's communication refresh cycle. This range is determined with reference to the common external event processing cycle of 4ms to 8ms for painting robot controllers. 5ms allows for a handshake status refresh to be completed near a single controller scheduling cycle, while also taking into account industrial communication bandwidth usage. After establishing a point-to-point handshake channel, each painting robot performs unified clock synchronization, which can use IEEE 1588 precision... The clock protocol enables each node robot to record the message sending time, message receiving time, workpiece arrival time, and abnormal occurrence time under the same time reference. The clock synchronization accuracy can be selected to be no greater than 1μs. Under normal painting conditions where the end tool center point speed is no greater than 500mm / s, the position error corresponding to a 1μs synchronization error is no greater than 0.5μm. This error is less than the position deviation allowed for spray trajectory execution and spray width control. If the field controller does not support microsecond-level synchronization, a millisecond-level unified clock can also be used, and the status message sending period and timeout window can be increased accordingly. For example, the status message sending period can be adjusted to 10ms, and the first-level timeout window can be adjusted to 20ms to maintain the judgment hierarchy between timeout windows.

[0076] Workpiece identity files are established before the workpiece enters the first spray booth. After the workpiece is loaded onto the conveyor, the RFID reader at the preparatory station reads or writes the workpiece's unique identification code, vehicle model code, and component category code. Simultaneously, it reads the current pulse count value of the conveyor chain encoder and records the workpiece's entry timestamp. The conversion relationship between the conveyor chain pulse count value and the workpiece displacement is determined by the number of pulses per revolution of the conveyor chain encoder, the sprocket circumference, and the transmission reduction ratio. The workpiece travel distance is calculated based on the pulse increment, and the workpiece travel time is determined by the ratio of the workpiece travel distance to the current conveyor chain linear speed. Through this process, each node robot can associate subsequent handshake messages based on the same workpiece identity and the same conveyor position reference.

[0077] The unique identification code for a workpiece can be a 16-byte code, where the first 6 bytes are the date, workshop, and shift code, the middle 6 bytes are the serial number, and the last 4 bytes are the combination code of vehicle model and part category. The above code length and field allocation are suitable for automotive parts painting production scenarios with tens of thousands of pieces per day and millions of pieces per year. Automotive parts painting lines are usually produced continuously by shift, with a daily processing volume of thousands to tens of thousands of pieces and an annual cumulative output of millions of pieces. The 16-byte code capacity can cover this production scale and reserve coding space for vehicle model information, part category information, and quality traceability information.

[0078] The workpiece identity file includes at least the following fields: unique workpiece identifier, vehicle model code, component category code, entry timestamp, initial pulse count of the conveyor chain, current workstation position, primer process permission status, primer process execution status, color coat process permission status, color coat process execution status, clear coat process permission status, clear coat process execution status, abnormal event code, abnormality level, processing flag, process parameter table version number, spray trajectory file identifier, and the most recent file update time. After the workpiece identity file is generated, it is synchronized to each painting robot via a point-to-point handshake channel. Each painting robot uses the same unique workpiece identifier as spraying intention information, relay confirmation information, and spraying execution status. The system establishes an associated index for status information. To prevent inconsistencies in workpiece identity files among different robots, each painting robot calculates a file verification value based on the workpiece's unique identifier, vehicle model code, process parameter table version number, current workstation position, and the most recent file update time. When any painting robot detects an inconsistency between its local file verification value and that of an adjacent robot, it temporarily suspends subsequent painting actions on the workpiece and requests a file retransmission from the robot with the latest file update time. This creates a handshake channel status, conveyor chain position conversion relationship, and workpiece identity file that can be referenced by all node robots, providing a data foundation for the generation and transmission of subsequent painting intent information.

[0079] Specifically, such as Figure 4As shown: In S2, the current painting robot continuously receives pulses from the conveyor encoder and, combined with the entry position of the painting station, the length of the workpiece carrier, the conveyor speed, and the starting position of the painting trajectory, determines whether the workpiece has entered the painting intention trigger zone. The painting intention trigger zone is set upstream of the actual painting start zone and can be selected as the conveyor distance corresponding to 100ms to 300ms in advance. For example, when the conveyor speed is 0.2m / s, the painting intention trigger zone can be set 20mm to 60mm upstream of the painting start point. This range is determined based on the painting intention transmission, message verification, and relay. The required time for confirmation is determined, with more than 100ms covering a complete handshake interaction and less than 300ms avoiding premature generation of a large number of undelivered workpiece tasks that would occupy the controller queue. The painting robot generates the painting intention information when the workpiece's unique identification code matches the local workpiece identity file, the pulse count value of the corresponding conveyor chain falls into the spraying intention trigger area, the machine's equipment is ready and available, the machine's spray gun, paint supply, atomizing air, high voltage electrostatic discharge, and servo axis are not in an abnormal isolation state, and the current process parameter table version matches the workpiece identity file record version.

[0080] The painting intent information is generated by the current painting robot based on the workpiece identity file, the machine's process parameter table, and the machine's painting trajectory file. The painting intent information includes at least the current painting robot node number, the target workpiece unique identifier, the vehicle model code, the part category code, the current process type, the expected painting start pulse count, the expected painting end pulse count, the expected painting start timestamp, the expected painting end timestamp, the version number of the process parameter table to be called, the identifier of the painting trajectory file to be called, the machine's health level, the painting coverage area boundary, the connection area identifier, and the relay requirements for adjacent downstream painting robots. The current process type can be marked as primer, color paint, or clear coat. The health level can be set to executable, restricted executable, and non-executable; relay requirements can be recorded as downstream waiting, process parameter version confirmation, connection area confirmation, skip queue confirmation, etc.; the spraying intention information is also written with message sequence number, sending timestamp, link identifier, and message check code; the message sequence number is incremented according to the workpiece unique identification code and robot node number respectively to distinguish message sequences of different workpieces and different node robots; the message check code can use CRC-32 to detect common burst bit errors in industrial fields; to improve the credibility of message source, an identity authentication label can also be appended to the end of the message, which is generated by the key negotiated by each painting robot in the production batch and the message body content;

[0081] The spraying intention information is sent to the adjacent downstream painting robot via a point-to-point handshake channel and can be simultaneously copied to a backup link or broadcast link. Upon receiving the spraying intention information from different paths, the adjacent downstream painting robot first compares the workpiece unique identifier, message sequence number, expected spraying start pulse count, process parameter table version number, and spraying trajectory file identifier. When the core fields match and the message checksum is correct, the spraying intention information is marked as valid. When the core fields do not match, the message checksum is incorrect, or the message sequence number is rolled back, the spraying intention information is marked as pending verification and sent to the current painting robot. Intent retransmission request; The intent retransmission request includes at least the sequence number of the most recently successfully received message and the error type code. The current painting robot retransmits the painting intent information corresponding to the sequence number according to the error type code. The number of intent retransmissions can be selected to be no more than 2 times. This number is determined based on the fact that instantaneous electromagnetic interference and short-term link jitter in the industrial field can usually be recovered by 1 to 2 retransmissions. If a valid reception confirmation is not obtained after 2 retransmissions, continuing to retransmit will compress the subsequent painting control window. Therefore, the current painting robot marks the workpiece as an intent transmission failure workpiece, does not start the painting action, and sends a handshake failure record to the central control system.

[0082] After the current painting robot sends its painting intention information, it starts an intention response waiting timer. The threshold of the intention response waiting timer can be selected as 20ms, and can be adjusted between 10ms and 40ms according to the on-site communication cycle. This threshold is determined based on the 5ms to 8ms normal external event response time of the adjacent downstream painting robot, the communication time of message round-trip transmission and verification usually not exceeding 5ms, and the jitter margin of the controller task scheduling. When the external communication refresh cycle of the on-site controller is slow, this threshold can be set to 4 to 6 times the status message sending cycle. The current painting robot receives a response from the adjacent downstream painting robot before the timer expires. When a valid relay confirmation is received, this confirmation is used as input for subsequent spraying start judgment. If a relay rejection or negotiation message is received before the timer expires, the workpiece identity file is updated to a pending negotiation state, and the process enters the waiting, parameter adjustment, or reporting process according to the reason for rejection or the content of negotiation. If no valid response is received before the timer expires, the spraying action is not started, and the current process permission status in the workpiece identity file is marked as unpermitted. Valid spraying intent information is written to the local cache of the current painting robot and the adjacent downstream painting robot for subsequent judgment of workpiece identity, previous process status, machine equipment status, and relay spraying conditions.

[0083] Specifically, such as Figure 4As shown: In S3, after confirming the validity of the spraying intention information, the adjacent downstream painting robot retrieves the local workpiece identity file using the unique identification code of the workpiece in the spraying intention information, and determines whether there is a record in the local workpiece identity file corresponding to the unique identification code of the workpiece; when the local workpiece identity file lacks a corresponding record, the adjacent downstream painting robot sends a file retransmission request to the current painting robot, and does not generate a positive relay confirmation message before the file retransmission is completed; when the same workpiece identity cannot be established after file retransmission, the workpiece is marked as an inconsistent identity workpiece, and a rejection relay confirmation message is fed back to the current painting robot; when the local workpiece identity file has a corresponding record, the adjacent downstream painting robot... Downstream painting robots read the status of the preceding process of the workpiece; for color paint painting robots, the status of the preceding process includes at least the primer process permission status, primer process execution status, and primer process exception flag; for clear varnish painting robots, the status of the preceding process includes at least the primer process execution status, color paint process execution status, and corresponding exception flags; when the preceding process execution status is completed and the exception flag is empty, the adjacent downstream painting robot continues to judge the status of its own equipment; when the preceding process status is incomplete, skipped, pending exception, or unknown, the adjacent downstream painting robot sends a rejection confirmation message or a delayed confirmation message to the current painting robot.

[0084] The status of this machine is determined by the robot controller status, spray gun status, servo axis status, paint supply status, atomized air pressure status, high-voltage electrostatic status, task queue status, and safety interlock status as inputs. When the robot controller is running and there is no emergency stop signal, the spray gun shut-off control is available, the servo axis has no alarm, the paint supply pressure is within the allowable range of the target pressure given in the process parameter table, the atomized air pressure is within the allowable range of the target pressure, the high-voltage electrostatic output is controllable, there are available slots in the task queue, and the spray booth safety door and spray booth interlock status meet production conditions, the adjacent downstream painting robot will determine the machine's status as ready to take over. The allowable range of paint supply pressure can be ±10% of the target pressure, and the atomized air... The allowable pressure range can be ±10% of the target pressure, and the allowable high-voltage electrostatic voltage range can be ±8% of the target voltage. These ranges are determined based on the requirements for paint atomization stability, wet film thickness control, and electrostatic adsorption stability in the coating process. Among these, the paint supply pressure and atomizing air pressure directly affect the atomization state and film thickness uniformity, and ±10% can cover normal pipeline fluctuations and identify obvious anomalies. The high-voltage electrostatic voltage is affected by the workpiece shape, spray distance, and grounding status, which will cause certain feedback fluctuations. ±8% can balance electrostatic adsorption stability and false alarm control. The task queue capacity can be set according to the number of workpieces that the local controller can cache at the same time, and can be selected as at least 3, to simultaneously save the relay information of the current workpiece, the next workpiece, and the abnormal workpiece to be processed.

[0085] The relay spraying condition determination is based on the expected spraying start pulse count, expected spraying end pulse count, spraying coverage area boundary, connection area identifier, process parameter table version number, and spraying trajectory file identifier from the spraying intention information. The adjacent downstream painting robot compares the current process spraying end point with the machine's relay spraying start point in time sequence, and converts the difference in the corresponding conveyor chain pulse count into the workpiece travel time difference. When the workpiece travel time difference is between the machine's minimum preparation time and maximum waiting time, the timing relay condition is determined to be met. The machine's minimum preparation time can be 50ms to 150ms, and can be selected as 100ms. This range is determined based on the time required for the downstream painting robot to enter the spraying start position from the standby posture, complete the spray gun pre-trigger verification, and load the process parameters. The maximum waiting time can be 500ms to 1500ms. This range is determined based on the workpiece passage time and workpiece cycle time between two adjacent spraying stations, and can be selected to not exceed half of the interval between adjacent workpiece arrivals to reduce the risk of cross-workpiece confusion in the downstream task queue.

[0086] The spatial relay condition is determined based on the boundary of the spraying coverage area. The workpiece surface coordinate system is established using tooling positioning pins, carrier reference holes, vehicle model reference surfaces, or teaching trajectory reference points. The trajectory points in the spraying trajectory files of each painting robot are transformed to the same workpiece surface coordinate system according to the calibration relationship between the robot base coordinate system and the workpiece surface coordinate system. The boundary of the spraying coverage area is jointly determined by the trajectory points, the spray gun width, and the spraying distance. Adjacent downstream painting robots map the end of the current process coverage area and the beginning of the machine's coverage area to the same workpiece surface coordinate system. When there is no uncovered gap between the two and the overlapping area does not exceed the allowable connection band width, the spatial relay condition is deemed to be met. The connection band width can be set according to the spray width and the curvature of the parts, and can be selected as 5% to 15% of the spray width. This range is determined based on the risk of missed spraying and re-spraying at the spraying boundary. When it is less than 5% of the spray width, robot trajectory errors or workpiece positioning deviations are likely to form missed spraying boundaries. When it is more than 15% of the spray width, it is likely to increase the risk of re-spraying, sagging, or local film thickness being too high.

[0087] In the case of two paint coating robots or two varnish coating robots spraying in parallel, the adjacent downstream coating robots also confirm the yielding relationship based on the boundary of the area they are responsible for and the identification of the connecting area. When the time windows for spraying the connecting strip of the two robots overlap, the robot with the higher process priority is the master controller, and the other robot shifts the spraying time of the connecting strip to one status message sending cycle. The shift time is determined according to the periodic instruction refresh method of the robot controller, which is used to enable the slave controller to perform yielding adjustment in the next control cycle, while reducing the impact of excessive waiting time for the connecting strip on the continuity of the wet film.

[0088] The relay confirmation information is generated based on the results of workpiece identity determination, preceding process status determination, machine equipment status determination, timing relay condition determination, and spatial relay condition determination. When the workpiece identity is consistent, the preceding process status meets the relay requirements, the machine equipment status is relayable, the timing relay conditions are met, the spatial relay conditions are met, and the process parameter table version is consistent, the adjacent downstream painting robot sends a positive relay confirmation message to the current painting robot. The positive relay confirmation message includes at least the downstream robot node number, the target workpiece unique identifier, the relay confirmation flag, the task slot number, the expected downstream spraying start pulse count value, the expected downstream spraying end pulse count value, the machine process parameter table version number, the machine spraying trajectory file identifier, the machine equipment health level, and the receipt timestamp. When only the process parameter table versions are inconsistent and both versions are in the allowed parallel dwell period, the adjacent downstream painting robot sends a negotiated relay confirmation message, carrying the suggested process parameter table version. After receiving the negotiated relay confirmation message, the current painting robot checks whether it has the correct version locally. The corresponding version is retained. If the corresponding version is retained locally, the painting intention information is regenerated according to the corresponding version. If the corresponding version is not retained locally, the workpiece is marked as a workpiece with inconsistent parameter versions. When there are situations such as incomplete preceding processes, unusable equipment, no slots in the task queue, unmet spatial relay conditions in the connection area, or unmet safety interlock conditions, the adjacent downstream painting robot sends back a rejection confirmation message and writes the rejection reason code. The rejection reason code can be set to 01 for identity inconsistency, 02 for incomplete preceding processes, 03 for unusable equipment, 04 for no slots in the task queue, 05 for inconsistent process parameter versions, 06 for unmet trajectory connection conditions, and 07 for unmet safety interlock conditions. After receiving a positive relay confirmation message, the current painting robot updates the current process permission status in the workpiece identity file to permission and writes the relay confirmation message to the local cache. When the current painting robot receives a negotiated relay confirmation message or a rejection relay confirmation message, it does not start the painting action until the negotiation is completed or the central control system issues a processing instruction.

[0089] Specifically, such as Figure 5As shown: In S4, before starting the painting process, the current painting robot verifies the workpiece identity file, relay confirmation information, and the robot's real-time status. The verification includes at least: whether the unique workpiece identification code in the relay confirmation information matches the unique workpiece identification code currently entering the painting window; whether the relay confirmation information is valid; whether the version of the robot's process parameter table matches the version in the painting intent information; whether the robot's painting trajectory file has been successfully loaded; and whether the spray gun, servo axis, paint supply, atomizing air, and high-voltage electrostatic discharge are all in an executable state. The validity period of the relay confirmation information can be from 100ms to 500ms, and can be selected as 200ms. This range is based on the distance the workpiece travels from the painting intent trigger area to the painting start area at a stable line speed on a conventional painting line. The required time (in milliseconds) must be determined, and the validity period of the relay confirmation information must not exceed the estimated remaining time from the workpiece's spraying intention trigger area to the spraying start point. If the relay confirmation information remains unused for more than 500ms, the workpiece position, task queue status, or equipment status may have changed, and the current painting robot will re-initiate the relay confirmation. After verification, the current painting robot will switch the status of its internal task slot from pending to executing, open the corresponding spraying trajectory file, and load the target values ​​for paint flow rate, atomized air pressure, high-voltage electrostatic voltage, spraying speed, spray width control parameters, and color-changing valve status according to the vehicle model and part category. When the workpiece reaches the spraying start pulse count value, the current painting robot will trigger the spraying action.

[0090] The spraying execution status information is generated and sent according to a predetermined status message sending cycle. The data collected for the spraying execution status information includes at least the end-effector center point position fed back by the robot controller, the spray gun trigger status, the servo axis running status, the trajectory execution progress, the conveyor encoder pulses, the measured value of the paint flow meter, the measured value of the atomizing air pressure sensor, the high-voltage electrostatic feedback value, the spray booth temperature and humidity status, and the machine's fault register. The end-effector center point position is fed back in real time by the robot controller; the spray gun trigger status is confirmed by both the spray gun valve control signal and the spray gun feedback signal; and the paint flow rate is measured by the gear pump flow meter. Alternatively, mass flow meters can be used to collect data; atomized air pressure can be collected by a spray gun inlet pressure sensor; and high-voltage electrostatic voltage can be collected by the feedback channel of an electrostatic generator. The collected measured values ​​are then normalized according to the target values ​​in the process parameter table. Specifically, the paint flow rate deviation is the difference between the measured flow rate and the target flow rate divided by the target flow rate; the atomized air pressure deviation is the difference between the measured pressure and the target pressure divided by the target pressure; and the high-voltage electrostatic voltage deviation is the difference between the measured voltage and the target voltage divided by the target voltage. When the target value is zero or the spray gun is currently in the closed section, the corresponding parameters are not included in the deviation judgment to prevent the dry spray section from being mistakenly judged as a process abnormality.

[0091] The spraying execution status information includes at least the following fields: current coating robot node number, target workpiece unique identifier, execution status sequence number, current conveyor chain pulse count value, current end effector center point coordinates, current spray gun trigger status, current trajectory segment number, completed spraying stroke percentage, cumulative spraying time percentage, paint flow deviation, atomized air pressure deviation, high voltage electrostatic voltage deviation, servo axis status, spray booth environment status, machine health level, anomaly type code, and sending timestamp. The completed spraying stroke percentage is determined by the ratio of the current trajectory segment's cumulative length to the total trajectory length of this process, and the cumulative spraying time percentage is determined by the ratio of the current spraying time to the process setting. The ratio of the fixed spraying time to the actual spraying time is determined, and the difference between the two is used to determine whether the trajectory execution speed is abnormal. The current painting robot generates an execution status sequence number and writes it into the spraying execution status information within each status message sending cycle. The execution status sequence number increases in chronological order. After receiving the data, the adjacent downstream painting robot determines whether there is any message loss based on the continuity of the execution status sequence number. The current painting robot also writes the spraying execution status information into the local workpiece identity file and annotates the current process execution status. The annotation content includes at least the fields of current execution progress, the timestamp of the most recent normal message, the timestamp of the most recent abnormal message, and the current health level.

[0092] To reduce response delays caused by re-looking up tables during the handshake phase between adjacent downstream painting robots, the current painting robot sends its process package to the adjacent downstream painting robot before starting spraying. The process package includes at least the following fields: a unique identifier for the target workpiece, a version number of the process parameter table, a summary of the spraying trajectory file, target values ​​and allowable deviation bands for paint flow rate, target values ​​and allowable deviation bands for atomized air pressure, target values ​​and allowable deviation bands for high-voltage electrostatic voltage, an anomaly type coding table, and an anomaly level handling table. Upon receiving the process package, the adjacent downstream painting robot establishes an upstream process buffer. When parsing the spraying execution status information, it directly references the target values ​​and deviation thresholds in this buffer without accessing the central control database or remote parameter table. After the current workpiece completes all painting processes, the adjacent downstream painting robot releases the corresponding upstream process buffer. If the adjacent downstream painting robot finds that the process package version is inconsistent with the version number in the spraying execution status information, it initiates a process package retransmission request to the current painting robot. If the inconsistency persists after retransmission, the workpiece is placed into a waiting state, and subsequent spraying actions are suspended.

[0093] When a painting robot detects an anomaly during the painting process, it writes the anomaly type code and its own health level into the painting execution status information within the same status message sending cycle, and simultaneously sends the anomaly status information. The anomaly status information shares the workpiece unique identification code and execution status sequence number with the normal painting execution status information, and additionally carries fields such as the anomaly occurrence pulse count value, anomaly duration, anomaly level suggestion, and the machine's handling status. When the current painting robot completes the painting process without generating an anomaly, it sends execution completion information to the adjacent downstream painting robot. The execution completion information includes at least the current process completion flag, workpiece unique identification code, completion pulse count value, completion timestamp, and workpiece identity file signature verification value. The adjacent downstream painting robot determines whether to continue waiting, skip the current workpiece, or enter the safe shutdown process based on the continuous painting execution status information, anomaly status information, or execution completion information.

[0094] Specifically, such as Figure 6 As shown: In S5, after the adjacent downstream painting robot enters the relay preparation state, it performs continuity verification, delay verification, process deviation verification, and progress rationality verification on the painting execution status information sent by the current painting robot. Continuity verification is based on the execution status sequence number. The most recently received execution status sequence number should be incremented by 1 relative to the previous valid execution status sequence number. When the execution status sequence number jumps, the corresponding number of lost frames is recorded. Delay verification is based on the sending timestamp and the local receiving timestamp in the painting execution status information. The upper limit of transmission delay can be selected as 5ms. When the receiving timestamp is earlier than the sending timestamp, or the transmission delay deviates significantly from the minimum transmission delay calibrated during the link debugging phase, it is determined that the timestamp is abnormal. When the transmission delay is greater than 5ms, it is determined that there is an abnormality in the communication path or controller task scheduling. This value is determined based on the millisecond-level handshake control requirements between adjacent robots and the 5ms-level status message sending cycle, so that the adjacent downstream painting robot can determine whether the previous frame of status information is reliable before the next execution status refresh.

[0095] Process deviation verification uses paint flow rate deviation, atomized air pressure deviation, and high-voltage electrostatic voltage deviation as inputs. The paint flow rate deviation threshold can be ±5%, the atomized air pressure deviation threshold can be ±10%, and the high-voltage electrostatic voltage deviation threshold can be ±8%. These ranges are determined based on the control requirements of the coating process for wet film thickness, atomization stability, and electrostatic adsorption stability. Among these, paint flow rate directly affects wet film thickness, and the allowable deviation range should be small. Atomized air pressure is significantly affected by instantaneous fluctuations in the pipeline, and the allowable deviation range can be appropriately widened. High-voltage electrostatic voltage is affected by workpiece shape, spray distance, and grounding status, which will produce certain feedback fluctuations. ±8% can balance electrostatic adsorption stability and false alarm control. Progress rationality verification uses the proportion of completed spraying stroke and the proportion of cumulative spraying time as inputs. When the absolute value of the difference between the two is greater than 10%, it is determined that the current coating robot has abnormal acceleration, abnormal deceleration, or trajectory execution stagnation. The 10% threshold is determined based on the normal speed transition range between robot spraying trajectory segments, and is used to cover reasonable trajectory speed changes and identify obvious execution progress mismatches.

[0096] Based on the results of continuity verification, delay verification, process deviation verification, and schedule rationality verification, adjacent downstream painting robots generate four status levels: normal, minor anomaly, workpiece anomaly, and safety anomaly. When all the above verifications pass, the status level is normal, and the adjacent downstream painting robots continue to maintain the relay preparation state. When only a single frame loss, a single delay exceeding the limit, or a low-priority parameter briefly exceeds the limit occurs, the status level is minor anomaly, and a short-term waiting window is initiated. When continuous frame loss, continuous process deviation exceeding the limit, schedule rationality anomaly, or the anomaly status information carries a level 2 or level 3 anomaly code, the status level is workpiece anomaly, and... The current workpiece is either waited for or skipped based on the type of anomaly. When a servo axis failure, safety interlock trigger, status message transmission is completely interrupted, the anomaly status information carries a level 4 anomaly code, or multiple source verification results are inconsistent, the status level is designated as a safety anomaly. When multiple verification results exist simultaneously, the final status level is determined according to the priority of safety anomaly, workpiece anomaly, minor anomaly, and normal. Any safety interlock anomaly, servo axis failure, level 4 anomaly, or complete interruption of status message transmission overrides other verification results and is classified as a safety anomaly. During waiting, retransmission, cross-verification, and delayed recovery, adjacent downstream painting robots keep their spray guns closed.

[0097] The safe shutdown procedure includes shutting down the spray gun, high-voltage electrostatic discharge, and paint supply valve; retracting the center point of the end effector to a position no less than 200mm from the workpiece surface; and deviating the spray gun direction from the normal to the workpiece surface by no less than 30°. Simultaneously, a safe shutdown alarm is reported to the central control system. The 200mm retraction distance and 30° deviation angle are determined based on the risk of paint dripping from the spray gun, the size of the robot's end effector, the workpiece shape, and the workspace of adjacent robots. These measures are used to reduce the risk of paint dripping onto the workpiece surface and motion interference between robots during shutdown. During actual debugging, the above distances and angles can be verified based on the spray gun structure, the curved surface shape of the components, and the robot's safety envelope.

[0098] When an adjacent downstream painting robot fails to receive painting execution status information, a three-level timeout escalation process is implemented. The first-level timeout window can take two status message transmission cycles; when the status message transmission cycle is 5ms, the first-level timeout window is 10ms. After the first-level timeout is triggered, the adjacent downstream painting robot sends a retransmission request to the current painting robot. The retransmission request includes at least the most recently successfully received execution status sequence number and the unique identification code of the target workpiece. The current painting robot retransmits the painting execution status information after the missing sequence number based on its local transmission cache. The second-level timeout window can take six status message transmission cycles; when the status message transmission cycle is 5ms, the second-level timeout window is 30ms, which is determined based on the communication time required for one retransmission and one status verification. After the second-level timeout is triggered, the adjacent downstream painting robot initiates a cross-verification request to other adjacent robots or the broadcast link. The cross-verification request is used to obtain the current painting robot's... The system records the message observations and workpiece identification file annotations within the most recent second-level timeout window. When most return results indicate that the current painting robot is still in normal execution, the adjacent downstream painting robot continues to wait. When most return results indicate that the current painting robot is abnormal or cannot be confirmed, it enters the third-level timeout process. The third-level timeout window can take 10 status message sending cycles. When the status message sending cycle is 5ms, the third-level timeout window is 50ms. This window is determined based on the safety handling time after desynchronization and is used to allow the adjacent downstream painting robot to complete the shutdown or skip the judgment before starting its own painting. The above three-level timeout windows can be adjusted within 6ms to 20ms, 20ms to 60ms, and 40ms to 100ms respectively, but the later-level timeout window is larger than the earlier-level timeout window to maintain the response hierarchy between retransmission, verification, and safety handling. After the third-level timeout is triggered, the adjacent downstream painting robot executes the safety shutdown procedure.

[0099] When an adjacent downstream painting robot receives an abnormal status message, it looks up the abnormal handling table according to the abnormality type code and abnormality level code, and generates a corresponding control action. The abnormality type code can be set to 01 for spray gun blockage, 02 for abnormal atomizing air pressure, 03 for servo axis failure, 04 for abnormal paint supply pressure, 05 for abnormal high-voltage static electricity, 06 for color-changing valve malfunction, 07 for unexpected pause in the spraying stroke, 08 for workpiece tracking loss, 09 for controller restart, and 10 for communication link desynchronization. The abnormality level code includes levels one to four, where level one corresponds to instantaneous disturbances, such as those experienced by adjacent downstream painting robots. The first level corresponds to a short-term recoverable anomaly, where the adjacent downstream painting robot initiates a delayed waiting window; the second level corresponds to a situation where the current workpiece cannot continue to be processed, where the adjacent downstream painting robot adds the current workpiece to the skip queue; the third level corresponds to a safety anomaly, where the adjacent downstream painting robot executes a safety shutdown procedure; the anomaly handling table uses anomaly type codes as rows and anomaly level codes as columns. Each entry records at least the following fields for the adjacent downstream painting robot: action type, waiting window, whether it has been added to the skip queue, whether the spray gun has been turned off, whether the high-voltage static electricity has been turned off, whether it has entered a safe parking posture, and whether it has reported to the central control system.

[0100] The delay waiting window can be set to 200ms, and can be adjusted between 100ms and 500ms based on the workshop compressed air recovery time, paint supply stabilization time, or robot controller reset time. This range is determined based on the common recovery time of short-term air pressure fluctuations, material supply fluctuations, and short-term communication synchronization loss in the coating production line. It is only applicable to recoverable anomalies such as air pressure fluctuations, short-term material supply fluctuations, and short-term communication synchronization loss, and not applicable to safety anomalies such as servo axis failures and safety interlock disconnection. The skipping process corresponding to the level 3 anomaly is to add the unique identification code of the current workpiece to the skip queue. When the workpiece arrives at the downstream station, the adjacent downstream coating robot does not open the spray gun, only performs idle tracking, and transfers the workpiece to the rejection or rework process.

[0101] For typical anomalies, spray gun clogging is identified when the measured paint flow rate is consistently below 70% of the target value. When the flow feedback sampling period is no more than 5ms, two consecutive status message sending cycles (10ms) are used to determine a clogging anomaly. When the flow feedback sampling period is greater than 5ms, two consecutive valid sampling cycles are used for determination. The 70% threshold is determined based on the need to distinguish between slight flow fluctuations and obvious clogging, and two consecutive sampling cycles are used to filter out single-sample jitter. Atomized air pressure anomalies are identified when the pressure feedback value deviates from the target value by more than 15%. When the pressure sensor feedback period is no more than 5ms, one consecutive status message sending cycle is used to determine an anomaly. When the pressure feedback period is greater than 5ms, one to two valid sampling cycles are used for confirmation. The 15% threshold is based on the atomization pressure and the spray particle size distribution. The impact of particle state is determined; excessive atomization pressure deviation will quickly cause uneven atomization, therefore its confirmation window is shorter than that of spray gun blockage anomaly. When servo axis failure, safety door interlock disconnection, or controller emergency stop signal is triggered, multi-cycle confirmation is no longer waited for, and a level four anomaly is generated directly. When the current painting robot sends recovery status information within the delay waiting window, and the workpiece unique identification code, execution status sequence number, and health level in the recovery status information are all valid, the adjacent downstream painting robot clears the waiting state and resumes relay preparation. When the waiting window expires and no recovery status information is received, the adjacent downstream painting robot switches the current workpiece to skip processing. When the current workpiece has passed the downstream spraying start position during the waiting period, the adjacent downstream painting robot does not perform follow-up spraying and marks the workpiece as an unrelayed part to avoid incorrect spraying due to missed position.

[0102] In boundary scenarios, when an RFID tag reading fails, the adjacent downstream painting robot uses the temporary identification code passed from the upstream to maintain the handshake process and marks the workpiece as an identity verification item, which is then transferred to manual verification after the final process. When the conveyor encoder signal is lost, the adjacent downstream painting robot uses the most recent valid pulse count as a starting point, estimates the workpiece position based on the conveyor rated linear speed and local synchronization clock, and realigns it using the file verification value after the encoder recovers. When the current painting robot controller restarts, the adjacent downstream painting robot pauses the relay and requests the current painting robot to resend the most recent workpiece identity file annotation. If the reconstruction is successful, the relay resumes; if the reconstruction fails, the affected workpiece is added to the skip queue. When a human takes over through the central control system, the adjacent downstream painting robot pauses its automatic handling logic and executes the human takeover command with the highest priority.

[0103] In addition to the specific numerical descriptions mentioned above, each threshold can also be calibrated during the production line debugging phase based on the controller communication refresh cycle, conveyor chain speed, workpiece transit time, spray gun response time, process parameter stabilization time, and actual measurement results of on-site communication delay. After calibration, the values ​​are written into the process parameter table and called according to the vehicle model or part category. Through the above processing, a closed-loop process is formed between the current painting robot and the adjacent downstream painting robot, from workpiece identity sharing, spraying intention transmission, relay condition confirmation, spraying execution status notification to abnormal classification and handling. This allows upstream spraying abnormalities to be identified and blocked before downstream spraying starts, thereby improving the synchronization, reliability, and safety of the multi-robot painting production line.

[0104] Example 2: Based on Example 1, the specific application process of a signal handshake collaborative control method for an automotive parts painting robot is further explained:

[0105] In a specific operational scenario, the workpiece to be painted is a front bumper of a certain vehicle model. The front bumper passes through a primer spray booth, a color paint spray booth, and a clear coat spray booth sequentially via a suspended conveyor chain. A first node robot is installed in the primer spray booth, a second and a third node robot are installed in the color paint spray booth, and a fourth and a fifth node robot are installed in the clear coat spray booth. The second and third node robots are responsible for painting the color paint on the left side, right side, and central transition area of ​​the front bumper, respectively, while the fourth and fifth node robots are responsible for painting the clear coat on their respective areas. Before production begins, each node robot completes point-to-point handshake channel connectivity detection, clock synchronization, loading of process parameter tables, and loading of painting trajectory files. The status message sending period can be 5ms. When the field controller communication refresh period is greater than 5ms, the status message sending period can be set to 1 to 2 times the controller communication refresh period so that each node robot can record the workpiece arrival time, message sending time, message receiving time, and abnormal occurrence time under a unified time reference.

[0106] After the front bumper is loaded onto the suspension conveyor, the RFID reader at the preparatory station reads the carrier tag and writes the workpiece unique identifier, vehicle model code, and component category code. For example, the workpiece unique identifier can be set to A20260101B010001, where A20260101 represents the production date and workshop code, B01 represents the shift, and 0001 represents the current shift sequence number. The RFID reader simultaneously reads the current pulse count value of the conveyor encoder and writes the entry timestamp, vehicle model code, component category code, process parameter table version number, and painting trajectory file identifier into the workpiece identity file. After the workpiece identity file is synchronized to the five node robots, each node robot uses the same workpiece unique identifier as the associated index for subsequent painting intention information, relay confirmation information, painting execution status information, and abnormal status information, and confirms the consistency between the local file and the files of adjacent robots through the file verification value.

[0107] When the front bumper approaches the primer spraying station corresponding to the first node robot via the conveyor chain, the first node robot determines whether the front bumper has entered the spraying intention trigger zone based on the conveyor chain encoder pulse, conveyor chain linear speed, primer spraying start position, and the machine's spraying trajectory start point. The conveyor chain linear speed can be 0.2 m / s, and the spraying intention trigger zone can be set 40 mm upstream of the primer spraying start point, corresponding to an advance of approximately 200 ms. This advance is within the range of 100 ms to 300 ms. This range is determined based on the time required for spraying intention transmission, message verification, and relay confirmation. It can reserve a complete handshake interaction time before the workpiece reaches the spraying start position and reduce the occupation of the controller queue by prematurely generating workpiece tasks that have not yet arrived. After the first node robot confirms that the workpiece identity file has been matched, the machine is ready, the spray gun is in normal condition, the paint supply pressure and atomizing air pressure are within the process allowable range, and there are no alarms on the servo axis, it generates spraying intention information for the front bumper.

[0108] The painting intent information includes at least the following fields: first node robot number, unique workpiece identification code for the front bumper, vehicle model code, component category code, current process type, expected primer spraying start pulse count, expected primer spraying end pulse count, process parameter table version number, primer spraying trajectory file identifier, machine health level, and relay requirements for the second node robot. The first node robot sends the painting intent information to the second node robot via a point-to-point handshake channel and can simultaneously copy it to a backup link. After receiving the painting intent information from different paths, the second node robot compares the workpiece unique identification code, message sequence number, expected spraying start pulse count, process parameter table version number, and spraying trajectory file identifier. When the above core fields are consistent and the message checksum is correct, the painting intent information is marked as valid intent information.

[0109] After the second node robot confirms the validity of the painting intention information, it reads the local workpiece identity file, confirms the existence of the front bumper's identity record, and checks the primer process permission status, primer process execution status, primer process abnormality mark, machine equipment status, task queue status, and color paint relay painting conditions. At this time, the primer process is not yet completed, so the second node robot does not start color paint painting. Instead, it creates a relay task slot for the front bumper locally and sends relay confirmation information back to the first node robot. The relay confirmation information indicates that the second node robot has recognized the front bumper and has the ability to enter the color paint painting preparation stage after receiving the primer execution completion information. After receiving the relay confirmation information before the intention response waiting timer expires, the first node robot updates the primer process permission status in the workpiece identity file to permission and enters the pre-painting start review.

[0110] When the bumper reaches the primer spraying start pulse count value, the first node robot initiates the primer spraying action and sends spraying execution status information to the second node robot according to the status message sending cycle. The spraying execution status information includes at least the workpiece unique identification code, execution status sequence number, current conveyor chain pulse count value, end tool center point coordinates, spray gun trigger status, current trajectory segment number, completed spraying stroke percentage, cumulative spraying time percentage, paint flow deviation, atomized air pressure deviation, high voltage electrostatic voltage deviation, machine health level, and sending timestamp. The second node robot confirms the message continuity based on the execution status sequence number, confirms the transmission delay based on the sending and receiving timestamps, and judges whether the primer spraying process is stable based on the paint flow deviation, atomized air pressure deviation, and high voltage electrostatic voltage deviation. When the spraying execution status information continuously sent by the first node robot meets the corresponding threshold requirements, the second node robot maintains the relay preparation state and continuously updates the process annotations for the primer process in the local workpiece identity file.

[0111] When the first node robot completes the primer spraying without any abnormalities, it sends an execution completion message to the second node robot. This completion message includes at least the following fields: current process completion flag, workpiece unique identifier, completion pulse count, completion timestamp, and workpiece identity file verification value. After confirming that the primer process is complete and the abnormality flag is empty, the second node robot moves the front bumper from the waiting queue to the paint spraying queue. The second and third node robots then perform parallel relay confirmation based on their respective paint coverage areas. The two paint robots convert the trajectory points in their respective paint trajectory files to the same workpiece surface coordinate system and compare the left and right paint areas to ensure they are in the middle. Check for uncovered gaps or excessive overlap at the joint. When the overlap width of the central joint is within 5% to 15% of the spray width, the spatial relay condition is deemed met. This range is determined based on the risk of missed spraying and respraying at the spraying boundary. If it is less than 5% of the spray width, it is easy to form a missed spray boundary due to trajectory error or workpiece positioning deviation. If it is more than 15% of the spray width, it is easy to increase the risk of respraying, sagging, or local film thickness being too high. If the time windows for the two paint robots to enter the joint overlap, the second node robot with higher process priority will be the master controller, and the third node robot will postpone the spraying time of the joint by one status message sending cycle to reduce respraying or missed spraying at the joint.

[0112] During the paint spraying stage, the second and third node robots execute the spraying according to their own spraying trajectories and continuously send spraying execution status information to adjacent node robots. When the spraying execution status of the two paint robots is continuous, the process deviation is within the allowable range, and the progress ratio is matched, the fourth and fifth node robots receive the paint process completion signatures before the clear coat spraying and enter the clear coat relay preparation. During the clear coat spraying stage, the same identity confirmation, relay confirmation, and execution status notification logic as the paint spraying stage is followed until the front bumper completes all painting processes. After the front bumper completes the clear coat spraying, the workpiece identity file records the completion timestamps, execution status, abnormal markers, process parameter table version numbers, and process signature verification values ​​of the primer, paint, and clear coat processes for subsequent quality traceability and process analysis.

[0113] In an abnormal operating scenario, the first node robot experiences a spray gun blockage during primer spraying. The first node robot continuously reads the measured value of the paint flow meter. When the measured paint flow rate is consistently lower than 70% of the target flow rate, and the flow feedback sampling period is no more than 5ms, the first node robot confirms the abnormality within two consecutive status message sending cycles, encodes the abnormality type as spray gun blockage, and determines the abnormality level as the level at which the current workpiece cannot continue to be processed. The 70% threshold is determined based on the need to distinguish between slight flow fluctuations and obvious blockages, and the two consecutive sampling cycles are used to filter out single sampling jitter. Within the same status message sending cycle, the first node robot writes the abnormality type code, abnormality level suggestion, abnormality occurrence pulse count value, and its own handling status into the abnormality status information and sends it to the second node robot, while simultaneously notifying subsequent node robots via a broadcast link.

[0114] After receiving the abnormal status information, the second node robot queries the abnormal handling table according to the abnormality type code and abnormality level code. Since the current workpiece cannot continue to be processed due to the abnormality, the second node robot adds the unique identification code of the front bumper to the skip queue and keeps the spray gun closed. When the front bumper arrives at the second node robot's painting station, the second node robot only performs idle tracking, does not open the spray gun, and does not spray paint on the workpiece. The third, fourth, and fifth node robots synchronously update their local skip queues based on the same unique identification code of the workpiece, and do not perform actual painting actions when the front bumper enters their respective stations. The central control system marks the front bumper as a workpiece to be rejected or returned according to the abnormality reporting record, and transfers it to the rework process at the subsequent rejection station. Thus, the upstream primer spraying abnormality will not continue to spread to the paint and clear coat processes.

[0115] In another abnormal operating scenario, the first node robot detects a short-term fluctuation in atomized air pressure. When the atomized air pressure deviates from the target pressure by more than 15%, but is not accompanied by servo axis failure, safety interlock triggering, or controller emergency stop signal, the first node robot generates a secondary abnormal status information. The 15% threshold is determined based on the degree of influence of atomized pressure on the spray particle state. Excessive atomized pressure deviation will lead to uneven atomization, so it needs to be identified within a short time. After receiving the secondary abnormal status information, the second node robot does not immediately add the workpiece to the skip queue, but instead starts a delayed waiting window. The delayed waiting window can be 200ms, and can be adjusted within the range of 100ms to 500ms according to the workshop compressed air recovery time. This range is used to cover the recovery process of common short-term air pressure fluctuations and material supply fluctuations. If the first node robot sends recovery status information within 200ms, and the workpiece unique identification code, execution status sequence number, and health level in the recovery status information are all valid, then the second node robot clears the waiting state and continues to maintain relay preparation. If the delayed waiting window expires and no recovery status information is received, the second node robot switches the front bumper to skip processing.

[0116] In another abnormal operating scenario, the second node robot briefly fails to receive the painting execution status information from the first node robot. If the second node robot fails to receive valid execution status information from the first node robot for two consecutive status message transmission cycles, it triggers a first-level timeout and sends a retransmission request to the first node robot. The retransmission request includes at least the most recently successfully received execution status sequence number and the unique identifier of the target workpiece. The first node robot retransmits the painting execution status information after the missing sequence number based on its local transmission cache. If the second node robot still fails to receive valid information within the second-level timeout window, it initiates a cross-verification request to other node robots or the broadcast link to obtain the message observation record and workpiece information from the first node robot within the most recent second-level timeout window. The document records the signatures; when most return results show that the first node robot is still in normal execution, the second node robot continues to wait and keeps the spray gun closed; when most return results show that the first node robot is abnormal or cannot be confirmed, it enters the third-level timeout process and executes the safety shutdown procedure; the safety shutdown procedure includes shutting down the spray gun, high voltage electrostatic discharge and paint supply valve, moving the center point of the end tool to a position no less than 200mm away from the workpiece surface, and deviating the spray gun direction from the normal of the workpiece surface by no less than 30°, while reporting a safety shutdown alarm to the central control system; the 200mm withdrawal distance and 30° deviation angle are determined based on the risk of paint dripping from the spray gun, the size of the robot end tool, the shape of the workpiece, and the workspace of adjacent robots, and are used to reduce the risk of paint dripping contamination and motion interference during the shutdown process;

[0117] During continuous operation of the production line, when the RFID tag of a workpiece fails to be read, the corresponding node robot uses the temporary identification code transmitted from upstream to maintain the handshake process and marks the workpiece as an identity verification item. This workpiece is then transferred to manual verification after the final process. When the encoder signal of the conveyor chain is briefly lost, each node robot uses the most recent valid pulse count value as a starting point, combined with the rated line speed of the conveyor chain and the local synchronization clock to estimate the workpiece position, and realigns it using the workpiece identity file verification value after the encoder recovers. When the controller of a node robot restarts, the adjacent downstream painting robot pauses the relay and requests the node robot to resend the most recent workpiece identity file annotation. The relay resumes after successful reconstruction, and if reconstruction fails, the affected workpiece is added to the skip queue.

[0118] During the above operation, each automotive component uses a unique identification code as the main thread. After entering the painting line, it sequentially completes identity registration, painting intention transmission, relay confirmation, painting execution status notification, abnormal status judgment, and workpiece handling record. Before starting painting, the current painting robot obtains relay confirmation from the adjacent downstream painting robot and continuously sends execution status information during the painting process. The adjacent downstream painting robot decides to wait, relay, skip, or safely stop based on the upstream painting execution status, abnormal level, and workpiece identity file. Thus, in scenarios such as primer painting abnormalities, short-term air pressure fluctuations, loss of execution status, or abnormal identity information, the downstream painting robot can obtain the basis for handling before its own painting starts, reducing the situation where workpieces without primer coverage or with incomplete primer coverage continue to enter the color paint and clear coat processes, and improving the collaborative control stability and quality traceability integrity of the multi-robot painting production line.

[0119] It should be noted that this invention can be deployed on the device itself to realize embedded applications, or it can run on a PC or other terminal with a user interface, thereby meeting various hardware environments and usage requirements.

[0120] The above embodiments can be implemented in whole or in part by software, hardware, firmware, or any other combination. When implemented in software, the above embodiments can be implemented in whole or in part by a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, the processes or functions of the embodiments of this application are implemented in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted wirelessly or wiredly from one website, computer, server, or data center to another website, computer, server, or data center. Wired methods include optical fiber, twisted pair, coaxial cable, etc. Wireless methods include infrared, microwave, etc. Available media include any available media that can be accessed by a computer or data storage devices such as servers and data centers that contain one or more sets of available media. Available media can be magnetic media (floppy disks, hard disks, magnetic tapes), optical media (DVDs), or semiconductor media. Semiconductor media can be solid-state drives.

[0121] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0122] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A signal handshake collaborative control method for an automotive parts painting robot, characterized in that, include: S1: Establish a point-to-point handshake channel between adjacent painting robots according to the painting process sequence of primer, color paint and clear coat, and establish a workpiece identity file shared by each painting robot. S2: Before the workpiece arrives at the spraying station corresponding to the current painting robot, the current painting robot sends the spraying intention information to the adjacent downstream painting robot according to the workpiece's identity file; S3: The adjacent downstream painting robot sends relay confirmation information to the current painting robot based on the workpiece identity, the status of the previous process, the status of the machine equipment, and the relay spraying conditions; S4: After receiving the relay confirmation information, the current painting robot starts the spraying action and sends the spraying execution status information to the adjacent downstream painting robot according to the predetermined cycle during the spraying process; S5: When the adjacent downstream painting robot does not receive painting execution status information, receives abnormal status information, or waits for a timeout, it will execute the waiting, skip the current workpiece, or safety shutdown process according to the abnormality level.

2. The signal handshake collaborative control method for an automotive parts painting robot according to claim 1, characterized in that, S1 includes: When establishing a point-to-point handshake channel and generating a workpiece identity file, the node robots are configured according to the workstation sequence of each painting robot in the production line. Set up a main link and a backup link between adjacent node robots; The link status is determined based on the status message sending period, message loss rate, and transmission delay. Synchronize the clocks of the robots at each node; Before the workpiece enters the line, collect workpiece identity information, conveyor chain pulse, process parameter table version number and spray trajectory file identifier to generate a workpiece identity file; Simultaneous verification is performed based on the file verification value.

3. The signal handshake collaborative control method for an automotive parts painting robot according to claim 1, characterized in that, S2 includes: When sending spraying intent information, the current painting robot determines the spraying intent trigger zone based on the conveyor chain pulse, conveyor chain linear speed, spraying station entrance position, and spraying trajectory start position. After the workpiece identity, equipment status, and process version are verified, spraying intention information is generated, which includes workpiece identity, process type, expected spraying start and end positions, trajectory identifier, message sequence number, and relay requirements. The adjacent downstream painting robot verifies the core fields and check codes of the spraying intention information; The painting robot updates the current process permission status based on valid relay confirmation, negotiated relay confirmation, rejected relay confirmation, or waiting timeout results.

4. The signal handshake collaborative control method for an automotive parts painting robot according to claim 3, characterized in that, The adjacent downstream painting robot verifies the core fields and checksums of the painting intent information, including: The adjacent downstream painting robot receives the painting intention information through a point-to-point handshake channel and performs consistency verification on the corresponding messages in the backup link or broadcast link; The unique identification code of the workpiece, the message serial number, the expected spraying start pulse count value, the process parameter table version number, and the spraying trajectory file identifier are compared; When there is a mismatch in field comparison, a message verification error, or a message sequence number rollback, an intent to retransmit is generated, carrying the sequence number of the most recently successfully received message and the error type code.

5. The signal handshake collaborative control method for an automotive parts painting robot according to claim 1, characterized in that, S3 includes: When receiving feedback confirmation information, the adjacent downstream painting robot retrieves the local workpiece identity file using the workpiece's unique identification code and requests retransmission if the file is missing. The status of the preceding process, controller, spray gun, servo axis, paint supply, atomizing air pressure, high voltage static electricity, task queue, safety interlock, spraying sequence, spraying coverage area connection, and process parameter version are verified sequentially. Based on the verification results, a confirmation message for a confirmed relay, a confirmation message for a negotiated relay, or a confirmation message for a rejected relay will be generated.

6. The signal handshake collaborative control method for an automotive parts painting robot according to claim 5, characterized in that, Based on the verification results, a positive relay confirmation message, a negotiated relay confirmation message, or a rejection relay confirmation message is generated, including: When the workpiece identity is consistent, the status of the preceding process meets the relay requirements, the machine is in a relayable state, the spraying sequence relationship and the coverage area connection relationship meet the relay requirements, and the process parameter versions are consistent, a positive relay confirmation message is generated. Only when the versions of process parameters are inconsistent and both versions of the process parameter table are in the allowed parallel dwell period, a negotiation relay confirmation message is generated; If there are discrepancies in identity, incomplete preceding processes, unusable equipment, no slots in the task queue, inadequate trajectory connection, or inadequate safety interlocking, a rejection confirmation message with a rejection reason code will be generated.

7. The signal handshake collaborative control method for an automotive parts painting robot according to claim 1, characterized in that, S4 includes: Before the spraying starts, the current painting robot verifies the workpiece identity, whether the relay confirmation information is within the validity period, the process parameter version, the loading status of the spraying trajectory file, and the executable status of the machine equipment; After the review is approved, the spraying parameters are loaded, and the process package for this step is sent to the adjacent downstream painting robot. According to the status message sending cycle, the end position, spray gun status, servo status, trajectory progress, conveyor chain pulse and process measured value are collected, the process measured value is normalized for deviation, spraying execution status information is generated and written into the workpiece identity file. When the painting robot detects an anomaly, it sends an anomaly status message; when it completes the painting process, it sends an execution completion message.

8. The signal handshake collaborative control method for an automotive parts painting robot according to claim 7, characterized in that, When the painting robot detects an anomaly, it sends an anomaly status message; when it completes painting, it sends an execution completion message, including: When the painting robot detects an anomaly, it writes the anomaly type code and the machine's health level into the painting execution status information within the same status message sending cycle, and sends the anomaly status information. The anomaly status information carries the workpiece's unique identification code, execution status sequence number, anomaly occurrence pulse count value, anomaly duration, anomaly level suggestion, and machine's handling status. When the current process of spraying is completed and no abnormality occurs, an execution completion message is sent. The execution completion message carries the current process completion mark, the workpiece unique identification code, the completion pulse count value, the completion timestamp, and the workpiece identity file signature verification value.

9. The signal handshake collaborative control method for an automotive parts painting robot according to claim 1, characterized in that, S5 includes: The adjacent downstream painting robot verifies the painting execution status information based on the execution status sequence number, sending timestamp, receiving timestamp, process deviation, and progress ratio; Based on the verification results, determine whether it is normal, slightly abnormal, workpiece abnormal, or safety abnormal; When the spraying execution status information is missing, the process of requesting a replacement, cross-verification, and safety anomaly determination is executed in sequence. Upon receiving abnormal status information, the system searches the abnormality handling table according to the abnormality type code and abnormality level code, and performs actions such as delaying and waiting, adding the current workpiece to the skip queue, or entering the safe shutdown process based on the search results.

10. The signal handshake collaborative control method for an automotive parts painting robot according to claim 9, characterized in that, Based on the verification results, determine whether it is normal, slightly abnormal, workpiece abnormal, or safety abnormal, including: When all checks on the spraying execution status information pass, it is determined to be in a normal state. When a single frame is lost, a single delay exceeds the limit, or a low-priority parameter exceeds the limit for a short time, it is judged as a minor abnormal state. When there are continuous frame drops, continuous process deviations exceeding limits, abnormal progress rationality, or abnormal status information carrying a level 2 or level 3 abnormality code, it is determined to be an abnormal status of the workpiece. When a servo axis failure occurs, a safety interlock is triggered, a status message is continuously interrupted, an abnormal status information carries a level 4 abnormal code, or a multi-source verification is inconsistent, it is determined to be a safety abnormal status. When multiple states coexist, the final state is determined according to the priority of safety abnormality, workpiece abnormality, minor abnormality and normal state.

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