A lifting limiting device, a limiting method and an automatic guided vehicle

Abstract

The application relates to the field of limiting, and discloses a lifting limiting device, a lifting limiting method and an automatic guided vehicle. A lifting limiting method comprises the following steps: judging whether a limiting sensor is in a triggered state; wherein the limiting sensor comprises an upper limiting sensor and / or a lower limiting sensor; if the limiting sensor is in an untriggered state, an output current value of a driver is acquired and recorded; if the output current value is smaller than a threshold value, an actual load current curve is fitted according to the recorded output current value; whether a curvature value change of the actual load current curve satisfies a preset condition is judged; and if the curvature value change of the actual load current curve satisfies the preset condition, the working state of a lifting motor is adjusted. Therefore, the lifting limiting method can protect the overall mechanism when the limiting sensor fails, and prolong the service life of the mechanism.

Description

Technical Field

[0001] This invention relates to the field of limiting technology, and in particular to a lifting limiting device, a limiting method, and an automated guided vehicle. Background Technology

[0002] When using mechanical limit switches, the lifting mechanism of existing Automated Guided Vehicles (AGVs) uses mechanical structures to prevent the movement of moving parts. When the limit switch is triggered, it will generate an impact load on the overall mechanism, which can easily cause the mechanism to jam and damage key components. Summary of the Invention

[0003] This invention discloses a lifting limit device, a limit method, and an automatic guide vehicle, which are used to steadily detect overload current and promptly cut off the drive when the limit sensor fails, thereby protecting the overall mechanism.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] In a first aspect, the present invention provides a lifting and limiting method, comprising:

[0006] Determine whether the limit sensor is in a triggered state; wherein the limit sensor includes an upper limit sensor and / or a lower limit sensor;

[0007] If the limit sensor is in an untriggered state, acquire the output current value of the driver and record it;

[0008] If the output current value is less than the threshold, the actual load current curve is fitted based on the recorded output current value;

[0009] Determine whether the curvature value change of the actual load current curve meets the preset conditions;

[0010] If the curvature value of the actual load current curve changes to meet the preset conditions, the working state of the lifting motor is adjusted.

[0011] In the lifting limit method provided in this invention, when the limit sensor is in an untriggered state, it may be due to two reasons: firstly, the lifting mechanism may not have reached the limit position, thus the limit sensor is not triggered; secondly, the limit sensor may be malfunctioning and unable to send a trigger signal back to the lifting motor. However, the lifting mechanism may have already reached or exceeded the limit position, requiring mechanical limiting. In this case, the lifting limit method acquires and records the driver's output current value in real time. When the output current value is less than a threshold, the recorded real-time output current value is fitted to an actual load current curve. The curvature value change on the actual load current curve is used to determine whether the preset conditions for adjusting the lifting motor have been met. When the curvature value change meets the preset conditions, the operating state of the lifting motor is adjusted, such as shutting it off. Therefore, the lifting limit method has high responsiveness and sensitivity, allowing for more timely shutdown of the lifting motor when the limit sensor fails, effectively reducing the damage to the overall mechanism caused by mechanical limiting, thereby protecting the overall mechanism and extending its service life.

[0012] In some embodiments, determining whether the limit sensor is in a triggered state specifically includes:

[0013] The photoelectric signal of the limit sensor is detected. If the photoelectric signal is detected, the limit sensor is determined to be in a triggered state.

[0014] In some embodiments, the method further includes:

[0015] If the limit sensor is in a triggered state, determine whether the current control command is a self-test command;

[0016] If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

[0017] In some embodiments, the method further includes:

[0018] If the output current value is greater than or equal to the threshold, determine whether the current control command is a self-test command;

[0019] If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

[0020] In some embodiments, if the curvature value change of the actual load current curve meets a preset condition, adjusting the operating state of the lifting motor includes:

[0021] If the curvature value change of the actual load current curve meets the preset conditions, determine whether the current control command is a self-test command;

[0022] If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

[0023] In some embodiments, determining whether the curvature change of the actual load current curve meets a preset condition includes:

[0024] Calculate the first slope k1 and the second slope k2 in the actual load current curve, and the first slope k1 and the second slope k2 satisfy: k2-k1<Δk. If t2-t1>t, then the curvature value of the actual load current curve is determined to meet the preset condition; where t1 is the time corresponding to k1 and t2 is the time corresponding to k2; t, Δk, k2 and k1 are all positive numbers.

[0025] In a second aspect, embodiments of the present invention provide a lifting limit device, comprising: a processor and a memory, wherein the memory stores program code, and when the program code is executed by the processor, the processor performs the method as described in any one of the first aspects.

[0026] Thirdly, the present invention also provides a lifting limiting device, comprising: a lifting mechanism, a lifting drive mechanism, a transmission mechanism, a limiting mechanism, and a driver;

[0027] The lifting drive mechanism is connected to the lifting mechanism via the transmission mechanism and is used to drive the lifting mechanism to move up and down;

[0028] The transmission mechanism includes a swing arm, and the input shaft of the swing arm is connected to the output shaft of the lifting drive mechanism.

[0029] The limiting mechanism includes a limiting block, a first limiting sensor, and a second limiting sensor. The limiting block includes a limiting groove for limiting the swing range of the swing arm. The limiting groove includes a first limiting wall and a second limiting wall. When the swing arm approaches the first limiting wall and is in a first trigger position, the first limiting sensor is triggered. When the swing arm approaches the second limiting wall and is in a second trigger position, the second limiting sensor is triggered.

[0030] The driver is signal-connected to the lifting drive mechanism and is used to adjust the working state of the lifting drive mechanism according to the trigger state of the limit mechanism.

[0031] In some embodiments, the first trigger position is when the gap between the swing arm and the first limiting wall is less than or equal to a first preset value; and / or

[0032] The second trigger position is when the gap between the swing arm and the second limiting wall is less than or equal to a second preset value.

[0033] In some embodiments, a trigger plate is mounted on the output shaft of the swing arm to trigger the first limit sensor or the second limit sensor.

[0034] In some embodiments, the transmission mechanism further includes a pull rod, the output shaft of the swing arm is rotatably connected to the pull rod, and the end of the pull rod away from the swing arm is drively connected to the lifting mechanism;

[0035] Alternatively, the lifting drive mechanism includes a lifting motor and a lifting reducer, wherein the lifting motor is connected to the swing arm via the lifting reducer.

[0036] Fourthly, the present invention also provides an automated guided vehicle, including a chassis and a lifting limit device as described in any of the second aspects.

[0037] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, it implements the steps of any of the lifting limit methods described in the first aspect.

[0038] In a sixth aspect, embodiments of the present invention provide a computer program product comprising: computer program code, which, when executed on a computer, causes the computer to perform the method described in any one of the first aspects. Attached Figure Description

[0039] Figure 1 A three-dimensional representation of a lifting and limiting device provided in an embodiment of the present invention. Figure 1 ;

[0040] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0041] Figure 3 A three-dimensional representation of a lifting and limiting device provided in an embodiment of the present invention. Figure 2 ;

[0042] Figure 4 This is a schematic diagram of one side structure of a lifting and limiting device provided in an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the other side of a lifting and limiting device provided in an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the other side of a lifting and limiting device provided in an embodiment of the present invention;

[0045] Figure 7 This is a schematic diagram of the other side of a lifting and limiting device provided in an embodiment of the present invention;

[0046] Figure 8 A schematic diagram showing the position of the limit block in its normal state;

[0047] Figure 9 This is a schematic diagram showing the position of the limit block in an overloaded state.

[0048] Figure 10 A schematic diagram illustrating the force analysis of a traditional mechanical limit switch;

[0049] Figure 11 This is a schematic diagram of the limiting force analysis of the limiting block provided in an embodiment of the present invention;

[0050] Figure 12 A control principle diagram of a lifting limit device provided in an embodiment of the present invention;

[0051] Figure 13 A flowchart illustrating a lifting and limiting method provided in an embodiment of the present invention;

[0052] Figure 14 A flowchart illustrating the judgment process of a lifting limit method provided in an embodiment of the present invention;

[0053] Figure 15 A flowchart illustrating the determination of another lifting limit method provided in an embodiment of the present invention;

[0054] Figure 16 A flowchart illustrating the determination of another lifting limit method provided in an embodiment of the present invention;

[0055] Figure 17 A flowchart illustrating the determination of another lifting limit method provided in an embodiment of the present invention;

[0056] Figure 18 A flowchart illustrating the determination of another lifting limit method provided in an embodiment of the present invention;

[0057] Icons: 100-Lifting mechanism; 200-Lifting drive mechanism; 300-Transmission mechanism; 400-Limiting mechanism; 500-Driver; 110-First optical axis; 120-Second optical axis; 210-Lifting motor; 220-Lifting reducer; 310-Swing arm; 320-Tie rod; 410-Limiting block; 420-First limit sensor; 430-Second limit sensor; 440-Trigger plate; 411-Limiting groove; 421-First trigger groove; 431-Second trigger groove; 411a-First limiting wall; 411b-Second limiting wall. Detailed Implementation

[0058] First, let me introduce the application scenario of this application: In the design of moving parts, limit devices are often designed to limit the travel of the mechanism or protect the mechanism body. Limit mechanisms can be divided into soft limits, hard limits, and mechanical limits based on their working principle. A soft limit refers to setting the movement range of the mechanism by adjusting the parameters of the control program; a soft limit is merely a control program without an actual mechanism. A hard limit refers to controlling the travel through external electrical components such as limit switches. The function of a hard limit is to reliably connect or disconnect the power supply to the motor; it is its core control unit and has a more complex structure and is more difficult to design than a mechanical limit device. Electrical limit devices consist of two parts: an electrical limit-mechanical conversion device and a power supply connection and disconnection device. Mechanical limits prevent the movement of moving parts through mechanical structures. Mechanical limits restrict collisions between mechanisms and can cause impact or damage, thus their normal usage probability is low. In the design process, soft limits, hard limits, and mechanical limits are generally designed in the order of soft limits first, then hard limits, and finally mechanical limits, meaning the limit travel size is, in order, soft limits, hard limits, and then mechanical limits. Traditional limit methods, after electrical limit failure, can only rely on mechanical limits to stop the mechanism's movement. However, this is problematic because the overload current to the driver requires a certain accumulation time, and the resulting impact can damage the mechanism itself. Furthermore, a single error value can easily trigger driver overload, resulting in a high probability of false triggering. When a mechanical limit is triggered, it generates an impact load on the entire mechanism, easily causing jamming and damage to critical components.

[0059] Based on the above application scenarios, this application provides a lifting limit device, a limit method, and an automatic guide vehicle, which are used to steadily detect overload current and promptly cut off the drive to protect the overall mechanism when the limit sensor fails.

[0060] 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. In the description of the embodiments of this application, unless otherwise stated, " / " means "or", for example, A / B can mean A or B; "and / or" in the text is only a description of the relationship between related objects, indicating that there can be three relationships, for example, A and / or B can mean: A alone, A and B at the same time, and B alone. In addition, in the description of the embodiments of this application, "multiple" means two or more.

[0061] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0062] Firstly, such as Figures 1 to 7 As shown, this embodiment of the invention provides a lifting and limiting device, including: a lifting mechanism 100, a lifting drive mechanism 200, a transmission mechanism 300, a limiting mechanism 400, and a driver 500; the lifting drive mechanism 200 is connected to the lifting mechanism 100 via the transmission mechanism 300, and is used to drive the lifting mechanism 100 to lift and lower; the transmission mechanism 300 includes a swing arm 310, and the input shaft of the swing arm 310 is connected to the output shaft of the lifting drive mechanism 200; the limiting mechanism 400 includes a limiting block 410, a first limiting sensor 420, and a second limiting sensor 430, for limiting... Block 410 includes a limiting groove 411 for limiting the swing range of the swing arm 310; the limiting groove 411 includes a first limiting wall 411a and a second limiting wall 411b. When the swing arm 310 approaches the first limiting wall 411a and is in the first trigger position, the first limiting sensor 420 is triggered, and when the swing arm 310 approaches the second limiting wall 411b and is in the second trigger position, the second limiting sensor 430 is triggered; the driver 500 is signal-connected to the lifting drive mechanism 200 and is used to adjust the working state of the lifting drive mechanism 200 according to the trigger state of the limiting mechanism 400.

[0063] In the aforementioned lifting and limiting device, the lifting drive mechanism 200 drives the lifting mechanism 100 to rise or fall via the transmission mechanism 300. During the lifting and lowering process, the limiting mechanism 400 limits the lifting and lowering extreme positions. The driver 500 is signal-connected to the lifting drive mechanism 200 and the limiting mechanism 400 to achieve the function of automatic stop and limiting. Specifically, the power output shaft of the lifting drive mechanism 200 is coaxially driven with the input shaft of the swing arm 310 of the transmission mechanism 300, such as by a spline connection. The limiting mechanism 400 includes a limiting block 410 with a limiting groove 411 for mechanically limiting the swing arm 310. The limiting mechanism 400 also includes a first limiting sensor 420 and a second limiting sensor 430. The first limiting sensor 420 is used to limit the highest position of the lifting mechanism 100 driven by the swing arm 310, and can be defined as an upper limiting sensor. The second limiting sensor 430 is used to limit the lowest position of the lifting mechanism 100 driven by the swing arm 310, and can be defined as a lower limiting sensor. In one possible implementation, the limiting groove 411 includes a first limiting wall 411a and a second limiting wall 411b. When the swing arm 310 approaches the first limiting wall 411a and is in a first trigger position, the first limiting sensor 420 is triggered, i.e., the upper limiting sensor is triggered, and the lifting mechanism 100 reaches its highest position. When the swing arm 310 approaches the second limiting wall 411b and is in a second trigger position, the second limiting sensor 430 is triggered, i.e., the lower limiting sensor is triggered, and the lifting mechanism 100 reaches its lowest position. The driver 500 adjusts the working state of the lifting drive mechanism 200, such as stopping, according to the triggering state of the first limit sensor 420 and the second limit sensor 430.

[0064] The lifting limit device provided in this embodiment of the invention uses a combination of electrical and mechanical limits. When the electrical limit switches, which act as proximity switches (i.e., the first limit sensor 420 and the second limit sensor 430), fail or the trigger signal cannot be fed back to the driver 500 of the pusher, mechanical limits are applied by the limit block 410. This not only protects the electrical limit switches but also effectively protects the reliability and safety of the transmission mechanism 300, and accurately positions the upper and lower limits of the lifting mechanism 100.

[0065] It should be noted that, in order to protect the transmission mechanism 300, the limit block 410 is made of an elastic material, such as rubber or polyurethane.

[0066] In some embodiments, the lifting drive mechanism 200 includes a lifting motor 210 and a lifting reducer 220, wherein the lifting motor 210 is connected to the swing arm 310 via the lifting reducer 220.

[0067] One possible way to achieve this is, such as Figure 1 As shown, the lifting drive mechanism 200 includes a lifting motor 210 and a lifting reducer 220. The lifting motor 210 is fixed to the lifting reducer 220 with four screws, and the output shaft of the lifting motor 210 is connected to the input gear of the lifting reducer 220 via a key for outputting power. The lifting reducer 220 is fixed to the chassis of the automated guided vehicle with six screws, mainly used to convert the small torque of the lifting motor 210 into a large torque output. The first limit sensor 420, i.e., the upper limit sensor, is installed on the sheet metal on the side of the chassis to limit the highest position of the lifting mechanism 100. The limit block 410 is installed on the chassis with two screws for the swing arm 310. Mechanical limiters; the swing arm 310 is mounted on the output side of the lifting reducer 220 via a spline, used to output rotational motion and drive the lifting mechanism 100 to move; the second limit sensor 430, i.e., the lower limit sensor, is mounted on the sheet metal on the side of the chassis, used to limit the lowest position of the lifting mechanism 100; one end of the transmission mechanism 300 is connected to the output shaft of the lifting reducer 220, and the other end is connected to the first optical shaft 110 in the lifting mechanism 100, which drives the lifting mechanism 100 to rise or fall when the lifting reducer 220 moves; the lifting mechanism 100 is fixed to the chassis via four second optical shafts 120, and is used to lift the load under the drive of the lifting reducer 220.

[0068] In some embodiments, a trigger plate 440 is mounted on the output shaft of the swing arm 310 for triggering the first limit sensor 420 or the second limit sensor 430.

[0069] In one possible implementation, the first limit sensor 420 and the second limit sensor 430 are photoelectric sensors, and a trigger plate 440 for triggering the photoelectric sensors is mounted on the output shaft of the swing arm 310. For example, the trigger plate 440 is a circular sheet metal part, fixed to the output shaft of the swing arm 310 by screws, used to trigger the on / off signals of the upper and lower limit sensors. Figure 2 As shown, the first limit sensor 420 has a first trigger groove 421 on the side facing the trigger piece 440. The first trigger groove 421 is a U-shaped groove, and the opening of the U-shaped groove faces the trigger piece 440. When the trigger piece 440 is inserted into the first trigger groove 421 under the drive of the swing arm 310, the first limit sensor 420 is triggered. The second limit sensor 430 has a second trigger groove 431 on the side facing the trigger piece 440. The second trigger groove 431 is a U-shaped groove, and the opening of the U-shaped groove faces the trigger piece 440. When the trigger piece 440 is inserted into the second trigger groove 431 under the drive of the swing arm 310, the second limit sensor 430 is triggered.

[0070] In some embodiments, the transmission mechanism 300 further includes a pull rod 320, the output shaft of the swing arm 310 is rotatably connected to the pull rod 320, and the end of the pull rod 320 away from the swing arm 310 is connected to the lifting mechanism 100 in a transmission manner.

[0071] One possible way to achieve this is, such as Figure 1 and Figure 3 As shown, the transmission mechanism 300 also includes a pull rod 320. One end of the pull rod 320 is connected to the output shaft of the swing arm 310, and the other end is connected to the first optical shaft 110 of the lifting mechanism 100. When the lifting motor 210 drives the lifting reducer 220 to move, the swing arm 310 and the pull rod 320 drive the lifting mechanism 100 to rise or fall.

[0072] In some embodiments, the first trigger position is when the gap between the swing arm 310 and the first limiting wall 411a is less than or equal to a first preset value; and / or, the second trigger position is when the gap between the swing arm 310 and the second limiting wall 411b is less than or equal to a second preset value.

[0073] In one possible implementation, refer to Figure 8 The limiting groove 411 of the limiting block 410 has a first limiting wall 411a and a second limiting wall 411b. When the gap between the swing arm 310 and the first limiting wall 411a is less than or equal to a first preset value, the swing arm 310 drives the trigger piece 440 to insert into the first trigger groove 421, and the first limiting sensor 420 is triggered. It is worth noting that the first preset value can be a value greater than or equal to 0. When the gap between the swing arm 310 and the second limiting wall 411b is less than or equal to a second preset value, the swing arm 310 drives the trigger piece 440 to insert into the second trigger groove 431, and the second limiting sensor 430 is triggered. It is worth noting that the second preset value can be a value greater than or equal to 0. Figure 8 Only a schematic diagram of the swing arm 310 in the first trigger position is shown. The shape and size of the limiting groove 411 are adapted to the shape and size of the swing arm 310.

[0074] To address the drawback of conventional AGV lifting mechanisms, where the 100 limit switch triggering generates impact loads on the entire mechanism, potentially causing jamming and damage to critical components, this invention proposes a lifting limit device. Based on the motion pattern of the lifting motor 210's output end, a conical limit block 410 is designed. During the limit switch's activation, the resistance at the lifting motor 210's output end gradually increases. This avoids impact loads on the mechanism and allows for stable detection of overload current, enabling timely cut-off and protection of the entire mechanism. Ordinary limit methods, after electrical limit switch failure, rely solely on mechanical limit switches to stop the mechanism's movement. However, the accumulation of overload current to the driver 500 takes time, during which the resulting impact can damage the mechanism. Furthermore, a single error value can easily trigger the driver 500 overload, resulting in a high probability of false triggering. This invention, through force analysis of the limit block 410 and referencing... Figure 8 and Figure 9 By establishing a load current variation model and performing real-time load current monitoring based on the model, the accuracy of limit triggering can be improved, and the lifting mechanism 100 can be protected in advance.

[0075] from Figure 10 and Figure 11 There is a significant difference in the working principle between ordinary limiting blocks and the limiting block of this invention. The resistance exerted by an ordinary mechanical limiting block on the mechanism is related to the compression of the limiting block: f = k·Δh, where f represents the resistance of the limiting block on the mechanism, k represents the stiffness coefficient within the elastic deformation of the limiting block, and Δh represents the compression. The compression of an ordinary mechanical limiting mechanism is usually designed to be linearly related to time, expressed as: Δh = v·t, where v represents the speed of the mechanism and t represents time. Therefore, the reaction force exerted by the limiting block on the entire mechanism is the integral of the resistance per unit length per unit time, expressed as: Where T represents the time from contact to stopping, and L represents the total length of the cross section. The resistance exerted by the mechanical limiting block on the mechanism in this embodiment is also related to the compression of the limiting block: f = k·Δh. However, the compression of the limiting block is not linearly variable, but rather: Δh = h2 - h1, where h1 represents the initial contact height, and h2 represents the contact height at time point t2. h2 is expressed as h2 = l·tanθ2, where l represents the length direction coordinate, and θ2 represents the angle between the lifting reducer arm and the limiting block at time point t2. h2 is also expressed as h1 = l·tanθ1 + d, where d represents the height difference between the center of the limiting block and the center of the arm, and θ1 represents the angle between the lifting reducer arm and the limiting block at time point t1. The relationship between θ1 and θ2 is as follows: θ 1＝ θ2-wt, where w represents the angular velocity of the swing arm. Therefore, the reaction force of the limiting mechanism as a whole on the limiting block is expressed as: Where L1 represents the x-coordinate of the closest contact point between the swing arm and the limit block, and L1 can be expressed as This invention alters the compression trend of the limiting mechanism by designing the external dimensions of the limiting block, thereby changing the load current curve of the lifting motor. It also monitors the load current curve in real time and sets an alarm threshold to cut off the lifting motor. Conventional limiting methods, when electrical limiting fails, rely solely on mechanical limiting to stop the mechanism's movement. This is problematic because the overload current to the driver requires a certain accumulation time, during which the resulting impact can damage the mechanism. Furthermore, a single error value can easily trigger driver overload, resulting in a high probability of false triggering. In contrast, this invention's embodiment gradually increases the resistance at the lifting motor output during the limiting process. This avoids impact loads on the mechanism and allows for stable overload current detection, timely cut-off, and protection of the overall mechanism.

[0076] In one possible implementation, the control principle diagram of the lifting limit device in the automated guided vehicle is as follows: Figure 12 As shown, the main control board of the automated guided vehicle is connected to the driver 500 of the lifting motor 210 via signal connection. The main control board adjusts the operating state of the lifting motor 210, such as starting, stopping, or reversing, through the driver 500. The load current of the lifting motor 210 is fed back to the driver 500 to generate a load current curve. The lifting motor 210 drives the trigger plate 440 via the swing arm 310 to trigger either the first limit sensor 420 or the second limit sensor 430. The main control board monitors the photoelectric signals of the first limit sensor 420 and the second limit sensor 430, and sends control signals to the driver 500 based on these signals to adjust the operating state of the lifting motor 210.

[0077] Secondly, embodiments of the present invention also provide a lifting and limiting method, such as... Figure 13 As shown, the method includes the following steps:

[0078] S1301. Determine whether the limit sensor is in the triggered state; wherein the limit sensor includes an upper limit sensor and / or a lower limit sensor.

[0079] S1302. If the limit sensor is in an untriggered state, obtain the output current value of the driver and record it;

[0080] S1303. If the output current value is less than the threshold, fit the actual load current curve based on the recorded output current value.

[0081] S1304. Determine whether the curvature value change of the actual load current curve meets the preset conditions.

[0082] S1305. If the curvature value of the actual load current curve meets the preset conditions, adjust the working state of the lifting motor.

[0083] In the lifting limit method provided in this embodiment of the invention, when the limit sensor is in an untriggered state, it may be due to two reasons: firstly, the lifting mechanism has not reached the limit position, and the limit sensor has not been triggered; secondly, the limit sensor may be malfunctioning and unable to feed back the trigger signal to the lifting motor. However, the lifting mechanism may have already reached or exceeded the limit position, requiring mechanical limiting. In the above lifting limit method, the output current value of the driver is acquired and recorded in real time. When the output current value is less than a threshold, the recorded real-time output current value is fitted to an actual load current curve. The curvature value change on the actual load current curve is used to determine whether the preset conditions for adjusting the lifting motor have been met. When the curvature value change meets the preset conditions, the operating state of the lifting motor is adjusted, such as turning off the lifting motor.

[0084] Therefore, the above-mentioned lifting limit method has high responsiveness and high sensitivity, and can shut down the lifting motor more promptly when the limit sensor fails, effectively reducing the damage of mechanical limit to the overall mechanism, thereby protecting the overall mechanism and extending its service life.

[0085] In some embodiments, determining whether the limit sensor is in a triggered state specifically includes:

[0086] The photoelectric signal of the limit sensor is detected. If the photoelectric signal is detected, the limit sensor is determined to be in the triggered state.

[0087] It should be noted that the limit sensor is a photoelectric sensor. The triggering of the limit sensor is determined by detecting its photoelectric signal. For example, the limit sensor is a slot-type photoelectric sensor, where a light emitter and a receiver are mounted face-to-face on opposite sides of a slot. The emitter emits infrared or visible light, which the receiver receives when unobstructed. However, when the trigger plate passes through the slot, the light is blocked, triggering the photoelectric switch to output a control signal that cuts off or connects the load current, thus completing a control action. The detection distance of the slot-type switch is typically only a few centimeters due to the limitations of the overall structure. If the lifting mechanism is moving upwards, it may trigger the upper limit sensor signal; if it is moving downwards, it may trigger the lower limit sensor signal.

[0088] In some embodiments, a lifting limit method, such as Figure 14 As shown, the method includes the following steps:

[0089] S1401. Determine whether the limit sensor is in the triggered state; if yes, execute S1402; otherwise, execute S1405.

[0090] S1402. Determine whether the current control command is a self-test command; if yes, execute S1403; otherwise, execute S1404.

[0091] S1403, Control the lifting motor to reverse;

[0092] S1404, Control the lifting motor to stop moving; and execute S1401;

[0093] S1405. Obtain the output current value of the driver and record it.

[0094] It should be noted that in S1401 above, if the limit sensor is in the triggered state, it indicates that the lifting mechanism has reached the set hard limit and successfully detected the photoelectric signal, requiring the lifting mechanism to be stopped. This is specifically achieved by reversing or stopping the lifting motor. In S1402 above, the self-test command is the power-on self-test command executed by the automated guided vehicle. This step is mainly used to confirm whether the automated guided vehicle is in the power-on self-test state and also to determine whether a lifting operation is currently in progress. If it is not a self-test command, then the lifting mechanism is performing a lifting action.

[0095] In some embodiments, a lifting limit method, such as Figure 15 As shown, the method includes the following steps:

[0096] S1501. Obtain the output current value of the driver and record it;

[0097] S1502. Determine whether the output current value of the driver is less than the threshold. If yes, execute S1506; otherwise, execute S1503.

[0098] S1503. Determine whether the current control command is a self-test command; if yes, execute S1504; otherwise, execute S1505.

[0099] S1504, Control the lifting motor to reverse;

[0100] S1505, Control the lifting motor to stop moving;

[0101] S1506. Fit the actual load current curve based on the recorded output current value.

[0102] It should be noted that obtaining the driver's output current value is mainly used to determine the change of load current over time, and to steadily detect overload current so as to cut off the lifting motor in time and protect the overall mechanism. By analyzing the driver load, the operating status of the lifting motor and lifting mechanism is analyzed. If the load current exceeds the threshold, it indicates that the lifting mechanism may be stuck, requiring the lifting mechanism to be stopped. This is specifically achieved by reversing or stopping the lifting motor. In S1506 above, curve fitting is mainly performed based on the recorded output current value and recording time. Compared with the traditional method of directly comparing the output current value and the threshold, this embodiment can effectively eliminate the error introduced by a single error value and reduce the probability of false triggering. For example, this embodiment uses the previously sampled load current value, i.e., the output current value, to fit the actual load current curve based on the plotting method.

[0103] In some embodiments, a lifting limit method, such as Figure 16 As shown, the method includes the following steps:

[0104] S1601. Fit the actual load current curve based on the recorded output current value;

[0105] S1602. Determine whether the curvature value change of the actual load current curve meets the preset conditions; if yes, execute S1603; if no, execute S1606.

[0106] S1603. Determine whether the current control command is a self-test command; if yes, execute S1604; otherwise, execute S1605.

[0107] S1604, Control the lifting motor to reverse;

[0108] S1605, Control the lifting motor to stop moving;

[0109] S1606, Control the lifting motor to continue rotating.

[0110] It should be noted that the above method analyzes the operation of the lifting motor and lifting mechanism by judging the change in the curvature value of the actual load current curve, calculates the slope (curvature value) of the load current curve at various points, and judges that the curvature change is in an upward state. At this time, the lifting mechanism may be stuck and needs to be stopped. Otherwise, S1606 can be executed to control the lifting motor to continue rotating.

[0111] In some embodiments, determining whether the curvature change of the actual load current curve meets a preset condition includes:

[0112] Calculate the first slope k1 and the second slope k2 in the actual load current curve, and the first slope k1 and the second slope k2 satisfy: k2-k1<Δk. If t2-t1>t, then the curvature value of the actual load current curve is determined to meet the preset condition; where t1 is the time corresponding to k1 and t2 is the time corresponding to k2; t, Δk, k2 and k1 are all positive numbers.

[0113] It should be noted that if the difference satisfies two slopes k1 and k2 within a specific range, and the corresponding time satisfies t2-t1>t, then it is determined that the alarm threshold has been reached and the lifting motor needs to be cut off.

[0114] To make the solutions provided in the embodiments of the present invention easier to understand, the lifting limit control process provided in the embodiments of the present invention will be described in detail below through a specific embodiment. For example... Figure 17 As shown, the process includes the following steps:

[0115] S1701, Detect the photoelectric signal of the upper limit sensor;

[0116] S1702. Determine whether the upper limit sensor is in the triggered state; if yes, execute S1703; if no, execute S1706.

[0117] S1703. Determine whether the current control command is a self-test command; if yes, execute S1704; otherwise, execute S1705.

[0118] S1704, Control the lifting motor to reverse;

[0119] S1705, Control the lifting motor to stop moving; and execute S1701;

[0120] S1706. Obtain the output current value of the driver and record it;

[0121] S1707. Determine whether the output current value of the driver is less than the threshold. If yes, execute S1708; otherwise, execute S1703.

[0122] S1708. Fit the actual load current curve based on the recorded output current value;

[0123] S1709. Determine whether the curvature value change of the actual load current curve meets the preset conditions; if yes, execute S1703; if no, execute S1710.

[0124] S1710, Control the lifting motor to continue rotating.

[0125] One possible way to achieve this is, such as Figure 18 As shown, the lifting and limiting method includes the following steps:

[0126] S1801, Detect the photoelectric signal of the upper limit sensor;

[0127] S1802. Determine whether the upper limit sensor is in the triggered state; if yes, execute S1805; if no, execute S1806.

[0128] S1803, Detect the photoelectric signal of the lower limit sensor;

[0129] S1804. Determine whether the lower limit sensor is in the triggered state; if yes, execute S1805; if no, execute S1806.

[0130] S1805. Determine whether the current control command is a self-test command; if yes, execute S1807; otherwise, execute S1808.

[0131] S1807, Control the lifting motor to reverse;

[0132] S1808, Control the lifting motor to stop moving; and execute S1801 and S1803;

[0133] S1806. Obtain the output current value of the driver and record it;

[0134] S1809. Determine whether the output current value of the driver is less than the threshold. If yes, execute S1810; otherwise, execute S1805.

[0135] S1810. Fit the actual load current curve based on the recorded output current value;

[0136] S1811. Determine whether the curvature value change of the actual load current curve meets the preset conditions; if yes, execute S1805; if no, execute S1812.

[0137] S1812, Control the lifting motor to continue rotating.

[0138] It should be noted that S1801 and S1803 can be performed simultaneously or sequentially. The order is not limited to executing S1801 first and then S1803; it is also possible to execute S1803 first and then S1801.

[0139] Thirdly, embodiments of the present invention provide a lifting limit device, including: a processor and a memory, wherein the memory stores program code, and when the program code is executed by the processor, the processor implements any of the methods in the second aspect embodiment.

[0140] Fourthly, embodiments of the present invention also provide an automated guided vehicle, including a chassis and a lifting and limiting device as described in any of the embodiments of the first aspect.

[0141] In one possible implementation, the lifting reducer in the lifting limit device is fixed to the chassis of the automated guided vehicle, the first limit sensor, i.e. the upper limit sensor, is installed on the sheet metal on the side of the chassis, the second limit sensor, i.e. the lower limit sensor, is installed on the sheet metal on the side of the chassis, and the lifting mechanism is fixed to the chassis by four second optical shafts.

[0142] Fifthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of any of the lifting limit methods described in the first aspect.

[0143] In a sixth aspect, embodiments of the present invention provide a computer program product comprising: computer program code, which, when executed on a computer, causes the computer to perform any of the methods in the first aspect.

[0144] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0145] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0146] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0147] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0148] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A lifting and limiting method, characterized in that, include: Determine whether the limit sensor is in a triggered state; wherein the limit sensor includes an upper limit sensor and / or a lower limit sensor; If the limit sensor is in an untriggered state, obtain the output current value of the driver and record it; If the output current value is less than the threshold, the actual load current curve is fitted based on the recorded output current value; Determine whether the curvature value change of the actual load current curve meets the preset conditions; If the curvature value change of the actual load current curve meets the preset conditions, adjust the working state of the lifting motor; Determining whether the curvature change of the actual load current curve meets preset conditions includes: Calculate the first slope in the actual load current curve. Second slope And the first slope Second slope satisfy: ,like If the curvature value of the actual load current curve satisfies a preset condition, then it is determined that the curvature value of the curve satisfies the preset condition. for At the corresponding time, for The corresponding time; All are positive numbers, and All are constants.

2. The lifting and limiting method according to claim 1, characterized in that, Determining whether the limit sensor is in a triggered state includes: The photoelectric signal of the limit sensor is detected. If the photoelectric signal is detected, the limit sensor is determined to be in a triggered state.

3. The lifting and limiting method according to claim 2, characterized in that, Also includes: If the limit sensor is in a triggered state, determine whether the current control command is a self-test command; If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

4. The lifting and limiting method according to claim 1, characterized in that, Also includes: If the output current value is greater than or equal to the threshold, determine whether the current control command is a self-test command; If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

5. The lifting and limiting method according to claim 1, characterized in that, If the curvature value change of the actual load current curve meets the preset conditions, adjust the working state of the lifting motor, including: If the curvature value change of the actual load current curve meets the preset conditions, determine whether the current control command is a self-test command; If the current control command is a self-test command, control the lifting motor to reverse; if the current control command is not a self-test command, control the lifting motor to stop moving.

6. A lifting and limiting device for implementing the lifting and limiting method as described in any one of claims 1-5, characterized in that, include: Lifting mechanism, lifting drive mechanism, transmission mechanism, limit mechanism, and drive unit; The lifting drive mechanism is connected to the lifting mechanism via the transmission mechanism and is used to drive the lifting mechanism to move up and down; The transmission mechanism includes a swing arm, and the input shaft of the swing arm is connected to the output shaft of the lifting drive mechanism. The limiting mechanism includes a limiting block, a first limiting sensor, and a second limiting sensor. The limiting block includes a limiting groove for limiting the swing range of the swing arm. The limiting groove includes a first limiting wall and a second limiting wall. When the swing arm approaches the first limiting wall and is in a first trigger position, the first limiting sensor is triggered. When the swing arm approaches the second limiting wall and is in a second trigger position, the second limiting sensor is triggered. The driver is signal-connected to the lifting drive mechanism and is used to adjust the working state of the lifting drive mechanism according to the trigger state of the limit mechanism.

7. The lifting and limiting device according to claim 6, characterized in that, The first trigger position is when the gap between the swing arm and the first limiting wall is less than or equal to a first preset value; and / or, The second trigger position is when the gap between the swing arm and the second limiting wall is less than or equal to a second preset value.

8. The lifting and limiting device according to claim 6, characterized in that, A trigger plate is installed on the output shaft of the swing arm to trigger either the first limit sensor or the second limit sensor.

9. The lifting limiting device according to any one of claims 6-8, characterized in that, The transmission mechanism also includes a pull rod, the output shaft of the swing arm is rotatably connected to the pull rod, and the end of the pull rod away from the swing arm is connected to the lifting mechanism in a transmission manner; Alternatively, the lifting drive mechanism includes a lifting motor and a lifting reducer, wherein the lifting motor is connected to the swing arm via the lifting reducer.

10. An automated guided vehicle, characterized in that, Includes a chassis and a lifting limit device as described in any one of claims 6-9.

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