Control method and system for electric forklift

Abstract

Provided are a control method and system for an electric forklift. The control system first determines by means of a danger monitoring value whether a vehicle is in danger, and sends a braking command to a standard electric-motor controller (2), wherein only relevant components brake, without affecting the overall power system; and the control system then determines for the second time by means of the movement trend value of a moving component whether the vehicle is in danger, and the control system shuts down a power source when necessary, thereby eliminating a hidden danger. The system uses a double-layer determination path, and reduces, by using the high safety integrity of a safety controller (1), the overall failure rate of a control system including a standard electric-motor controller, and reduces the cost of a main unit; and the use of two determination links improves the flexibility and robustness of the system, and avoid power-source shutdown caused by erroneous determination.

Description

A control method and control system for an electric forklift Technical Field

[0001] This invention relates to a control method and control system for an electric forklift, belonging to the field of forklift safety control technology. Background Technology

[0002] Electric forklifts are used in various industries in different countries, but they pose a risk of unintended behavior, meaning the machine's response may not match the driver's intended action, which generally increases the risk of injury to the driver. Examples include unexpected movements, the machine continuing to move while the driver is off the seat, and gear control failure. To effectively brake electric forklifts in the event of unintended behavior, existing electric forklifts are equipped with control systems. These systems determine when a hazard is detected by vehicle movement signals and then issue a braking command.

[0003] Control systems are classified into different levels based on their failure rate. Electric forklift control systems must meet the corresponding safety integrity standards to enter the market. For example, one of the requirements for high safety integrity is that the electric forklift control system must achieve a sufficiently low failure rate to meet safety objectives. Existing control systems rely on vehicle motor controllers, such as drive motor controllers and pump motor controllers, to meet the safety integrity requirements. Therefore, high-safety-level forklift motor controllers must be used when manufacturing electric forklifts to meet safety integrity compliance requirements. However, the significant cost difference between compliant safety-grade motor controllers and standard motor controllers makes it difficult to reduce the cost of existing functional safety-compliant electric forklift control systems. Summary of the Invention

[0004] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a control method and control system for an electric forklift that takes into account low cost, low failure rate, and easy operation after braking.

[0005] To achieve the above objectives, this disclosure employs the following technical solution:

[0006] Firstly, this disclosure provides a control method for an electric forklift, wherein the control method is executed by a high-safety-level safety controller, and the control method includes...

[0007] Acquire vehicle motion signals, and obtain hazard monitoring values ​​based on the vehicle motion signals;

[0008] In response to the danger monitoring value reaching the first intervention threshold, a corresponding braking command is output, which is used to control the standard vehicle motor controller to perform braking;

[0009] Obtain the motion parameters of the braked moving part, and obtain the motion trend value of the moving part based on the motion parameters;

[0010] In response to the motion trend value of the moving component reaching the second intervention threshold, a power source shutdown command corresponding to the moving component is output.

[0011] In some embodiments of the first aspect,

[0012] The step of acquiring vehicle motion signals and acquiring hazard monitoring values ​​based on vehicle motion signals includes acquiring a driver leaving the seat signal and acquiring the signal duration based on the driver leaving the seat signal.

[0013] The step of responding to the danger monitoring value reaching a first intervention threshold by outputting a corresponding braking command, the braking command being used to control the standard vehicle motor controller to perform braking, including responding to the signal duration reaching a first time threshold by outputting a drive motor braking command, the drive motor braking command being used to control the standard drive motor controller to perform braking;

[0014] The step of obtaining motion parameters of the braked moving part and obtaining motion trend value of the moving part based on the motion parameters includes setting a first cycle interval, obtaining the rotation speed of two drive motors in adjacent first time cycles, and obtaining the difference in drive motor rotation speed based on the two drive motor rotation speeds in adjacent first time cycles.

[0015] The step of responding to the motion trend value of the moving component reaching the second intervention threshold and outputting a power source shutdown command corresponding to the moving component includes, in response to the speed difference of the drive motor being within the first deceleration threshold, outputting a drive motor shutdown command.

[0016] In some embodiments of the first aspect,

[0017] The step of acquiring vehicle motion signals and acquiring hazard monitoring values ​​based on vehicle motion signals includes acquiring a driver leaving the seat signal and acquiring the signal duration based on the driver leaving the seat signal.

[0018] The method of responding to the danger monitoring value reaching a first intervention threshold and outputting a corresponding braking command, the braking command being used to control the standard vehicle motor controller to perform braking, including responding to the signal duration reaching a second time threshold and outputting a fork pump motor braking command, the fork pump motor braking command being used to control the standard fork pump motor controller to perform braking;

[0019] The step of obtaining motion parameters of the braked moving part and obtaining motion trend value of the moving part based on the motion parameters includes setting a second cycle interval, obtaining the speed of two fork pump motors in adjacent second time cycles, and obtaining the speed difference of the fork pump motors based on the speed of the two fork pump motors in adjacent second time cycles.

[0020] The step of responding to the motion trend value of the moving component reaching the second intervention threshold and outputting a power source shutdown command corresponding to the moving component includes, in response to the fork pump motor speed difference being within the second deceleration threshold, outputting a fork pump motor shutdown command.

[0021] Secondly, this disclosure also provides a control system for an electric forklift, including,

[0022] A safety controller is configured to: acquire vehicle motion signals, acquire hazard monitoring values ​​based on the vehicle motion signals; output a corresponding braking command in response to the hazard monitoring value reaching a first intervention threshold; acquire motion parameters of the braked moving parts, acquire motion trend values ​​of the moving parts based on the motion parameters; and output a power source shutdown command corresponding to the moving parts in response to the motion trend value of the moving parts reaching a second intervention threshold.

[0023] The vehicle motor controller is configured to perform braking according to the braking command;

[0024] A vehicle hazard action monitor is configured to monitor the vehicle's action signals and monitor the motion parameters of the braked moving parts.

[0025] A contactor is used to respond to a power source shutdown command and execute a power source shutdown action.

[0026] The failure rate of the safety controller is lower than that of the vehicle motor controller, and it meets compliance requirements;

[0027] The safety controller is connected to the vehicle motor controller and the vehicle dangerous action monitor via signals. The vehicle motor controller is connected to the moving parts via electrical signals. The safety controller is connected to the contactor via electrical signals. The contactor is connected to the power source via electrical signals.

[0028] In some embodiments of the second aspect,

[0029] The vehicle hazardous action monitor includes a seat detector switch, which is used to output a signal indicating that the driver has left the seat.

[0030] The safety controller is also configured to: obtain the duration of the signal based on the driver leaving the seat signal; output a drive motor braking command in response to the signal duration reaching a first time threshold; set a first cycle interval, obtain the rotational speeds of two drive motors in adjacent first time cycles, obtain the drive motor speed difference based on the rotational speeds of the two drive motors in adjacent first time cycles; and output a drive motor stop command in response to the drive motor speed difference being within a first deceleration threshold.

[0031] The moving component includes a drive motor, and the vehicle motor controller includes a drive motor controller configured to brake the drive motor according to the drive motor braking command;

[0032] The vehicle dangerous action monitor also includes a first encoder, which is used to monitor the rotational speed of the drive motor;

[0033] The contactor includes a first contactor electrically connected to the drive motor, the first contactor being used to respond to a drive motor stop command and execute the drive motor stop action.

[0034] In some embodiments of the second aspect,

[0035] The vehicle hazardous action monitor includes a seat detector switch, which is used to output a signal indicating that the driver has left the seat.

[0036] The safety controller is also configured to: acquire the duration of the signal based on the driver leaving the seat signal; output a fork pump motor braking command in response to the signal duration reaching a second time threshold; set a second cycle interval, acquire the fork pump motor speeds of two adjacent second time cycles, acquire the fork pump motor speed difference based on the two fork pump motor speeds of the two adjacent second time cycles; and output a fork pump motor stop command in response to the fork pump motor speed difference being within a second deceleration threshold.

[0037] The moving component includes a fork pump motor, and the vehicle motor controller includes a fork pump motor controller, which is configured to brake the fork pump motor according to a braking command from the fork pump motor.

[0038] The vehicle hazardous action monitor also includes a second encoder, which is used to monitor the rotational speed of the fork pump motor;

[0039] The contactor includes a second contactor electrically connected to the fork pump motor, the second contactor being used to respond to a fork pump motor stop command and execute a fork pump motor stop action.

[0040] Thirdly, this disclosure also provides a safety controller, including a processor and a memory connected to the processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, it performs the steps of the control method for an electric forklift as described in any embodiment of the first aspect.

[0041] Fourthly, this disclosure also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the control method for the electric forklift described in any embodiment of the first aspect.

[0042] Fifthly, this disclosure also provides a computer program product, including a computer program / instructions, characterized in that, when the computer program / instructions are executed by a processor, they implement the steps of the control method for the electric forklift described in any embodiment of the first aspect.

[0043] In a sixth aspect, this disclosure also provides an electric forklift, including the control system of the electric forklift described in any embodiment of the second aspect.

[0044] Compared with the prior art, the beneficial effects achieved by this disclosure are as follows:

[0045] The electric forklift control method and control system disclosed herein first determines whether the vehicle is in danger by checking whether a hazard monitoring value reaches a first intervention threshold, and then outputs a braking command to a standard vehicle motor controller. The standard vehicle motor controller only brakes the relevant power components and does not cause the entire power system to stop; therefore, normal operation can be restored after braking by manual operation. In contrast to the method of obtaining hazard monitoring values, this method uses the motion trend value of moving components to make a secondary judgment on whether the danger of the electric forklift still exists, and eliminates the safety hazard by stopping the power source. Therefore, the electric forklift control method and control system uses a two-layer judgment path to safely control the vehicle, fully utilizing the low failure rate mechanism of a high-safety-integrity safety controller to compensate for vehicle hazard. The motor controller failure rate meets the requirement of achieving overall low failure rate in control systems that include standard vehicle motor controllers, satisfies the safety compliance requirements of the control system safety level, and saves on the procurement cost of vehicle motor controllers. Simultaneously, by employing two different vehicle hazard judgment links, it improves operational flexibility and robustness, preventing power source shutdown due to control system overreaction. Therefore, the electric forklift control system can simultaneously meet the requirements of high safety level, low failure rate, and low cost. Furthermore, the electric forklift control method satisfies the requirement of improving safety level and reducing failure rate on control systems using standard forklift motor controllers, meeting safety compliance design requirements, and reducing main unit costs, achieving an overall failure rate level close to that of control systems using safety-type forklift motor controllers. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 is a flowchart of the steps of the control method for the electric forklift provided in this embodiment;

[0048] Figure 2 is a schematic diagram of the control system of the electric forklift provided in this embodiment;

[0049] Figure 3 is a logical diagram of the two-layer protection link in this embodiment;

[0050] Figure 4 is a schematic diagram of the internal program logic of the security controller in this embodiment;

[0051] Figure 5 is a schematic block diagram of the safety controller provided in this embodiment;

[0052] Figure 6 is a supplementary structural diagram of the vehicle motor controller in Figure 2;

[0053] Figure 7 is a schematic diagram of the supplementary structure of the contactor in Figure 2;

[0054] In the diagram: 1 - Safety controller;

[0055] 2-Vehicle motor controller; 2.1-Drive motor controller; 2.2-Fork pump motor controller;

[0056] 3-Vehicle hazardous action monitoring unit; 3.0-Seat detector switch; 3.1-First encoder; 3.2-Second encoder;

[0057] 4-Contactor; 4.1-First contactor; 4.2-Second contactor;

[0058] 5.1-Drive motor; 5.2-Fork pump motor. Detailed Implementation

[0059] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments and specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations thereof. In the absence of conflict, the embodiments and technical features in the embodiments can be combined with each other.

[0060] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0061] Example 1:

[0062] Figure 1 is a flowchart of a control method for an electric forklift according to Embodiment 1 of the present invention. This flowchart only shows the logical sequence of the method described in this embodiment. Under the premise of no conflict, in other possible embodiments of the present invention, the steps shown or described may be performed in a different order than that shown in Figure 1.

[0063] The control method for the electric forklift provided in this embodiment can be executed by a high-safety-integrity (hereinafter referred to as a safety-type) safety controller 1. This controller can be implemented in software and / or hardware and can be integrated into the vehicle's control system. Referring to Figure 1, the method of this embodiment specifically includes the following steps:

[0064] Safety controller 1 acquires vehicle motion signals and obtains hazard monitoring values ​​based on these signals. Vehicle motion signals include at least the driver's acceleration needs, passenger position information, gear shifting information, or steering information, which can be obtained by safety controller 1 from input components such as vehicle sensors and the driving system. Some vehicle motion signals can be directly converted into hazard monitoring values, such as slope information obtained from tilt sensors or speeding information obtained from speed sensors. Other vehicle motion signals need to be indirectly converted into hazard monitoring values, such as calculating the duration of passenger position information as a hazard monitoring value to determine whether the driver has left their seat.

[0065] In response to the danger monitoring value reaching the first intervention threshold, a corresponding braking command is output. The braking command is used to control the standard vehicle motor controller 2 to perform braking. Although the failure rate of the standard forklift motor controller 2 is higher than that of the safety forklift motor controller in the prior art, the failure probability of the standard forklift motor controller 2 during actual forklift operation is still very low. Therefore, the safety controller 1 outputs a braking command that the vehicle motor controller 2 can read. Upon receiving the braking command, the vehicle motor controller 2 performs corresponding braking actions, such as controlling the brake pads, restoring the dangerous gear to neutral, or electric braking. The braking actions that the vehicle motor controller 2 can control are proactive and targeted, avoiding the complete shutdown of the power source of the component to be braked.

[0066] The method acquires the motion parameters of the braked moving component and obtains the motion trend value of the moving component based on these parameters. Since a safety controller 1 is used, this method also utilizes the low failure rate of the safety controller 1 to acquire the motion parameters of the moving component, which have a different nature than the hazard monitoring value, through a different acquisition channel. This aims to determine whether the previously issued braking command was effectively executed. The motion trend value of the moving component mainly refers to the change of motion parameters measured in time. For example, if the braking command is used to control the vehicle motor controller 2 to perform electric braking, then in this step, the rotor's steering speed and direction are acquired. When the rotor's rotational speed decreases as commanded, the previously issued braking command has achieved an active braking effect. When the rotor's rotational speed reaches the second intervention threshold, the control of the vehicle motor controller 2 has not achieved a braking effect.

[0067] In response to the motion trend value of the moving component reaching the second intervention threshold, a power source shutdown command corresponding to the moving component is output. The safety controller 1 outputs the power source shutdown command corresponding to the moving component, independently of the braking command. Unlike the braking command, although the power source shutdown command will stop the component and its power source along with the brake failure, it can prevent dangerous situations from occurring to the greatest extent. Furthermore, unlike the failure rate of the braking command, the execution of the power source shutdown command has a low failure rate, thereby meeting the safety level requirements of the control system using the control method for the electric forklift provided in this embodiment.

[0068] Therefore, the electric forklift control method provided in this embodiment uses a two-layer decision path to perform safe vehicle control. It makes full use of the low failure rate of the high safety integrity safety controller to compensate for the failure rate of the vehicle motor controller, meeting the requirement of achieving overall low failure rate in a control system that includes a standard vehicle motor controller. This satisfies safety compliance design and reduces host cost, thereby saving the procurement cost of the vehicle motor controller. At the same time, by using two different vehicle hazard judgment links, the flexibility and robustness of use are improved, preventing the power source from shutting down due to control system overreaction.

[0069] Example 2:

[0070] This embodiment provides a control method for an electric forklift. This embodiment is an optimization based on Embodiment 1 to improve the technical effect and refine the technical solution. For details not described in this embodiment, please refer to Embodiment 1.

[0071] Taking an electric forklift as an example, when operating an electric forklift, the driver may leave the seat due to a sudden danger or unintentionally. However, unlike the above situations, the driver may also adjust their posture by briefly lifting their buttocks off the seat. Optionally, in a further but non-limiting embodiment of this application, the vehicle action signal includes a driver leaving the seat signal, and the duration of the driver leaving the seat signal can be used as a hazard monitoring value. For example, using a seat detector switch 3.0 that meets the safety level, when the seat detector switch 3.0 monitors whether a person is in the seat, the safety controller 1 obtains a driver leaving the seat signal OPC_Valid = 1. "OPC_Valid = 1" indicates that the person is in the seat; otherwise, OPC_Valid = 0.

[0072] The first intervention threshold includes a first time threshold. When the driver leaves the seat signal changes from OPC_Valid=1 to OPC_Valid=0, the duration of OPC_Valid=0 is counted. If the duration of OPC_Valid=0 is less than the first time threshold, it is considered that the driver has only briefly left the seat; however, if the duration of OPC_Valid=0 reaches the first time threshold, it is considered that the driver has left the seat.

[0073] Optionally, the calculation of the duration from the acquisition of the driver leaving the seat signal is a low-error-rate calculation with a high safety level.

[0074] The electric forklift is driven by the drive motor 5.1; therefore, in response to the signal duration reaching a first time threshold, the safety controller 1 outputs a drive motor braking command; optionally, the vehicle motor controller 2 may include a drive motor controller 2.1, which has no certification level and has a higher failure rate than the safety controller 1; the drive motor braking command may be executed by the drive motor controller 2.1, which controls the rotor of the drive motor 5.1 to stop according to the drive motor braking command, so that the electric forklift stops after the driver leaves the seat; optionally, in other non-limiting embodiments of this application, the vehicle motor controller 2 may also include a brake pad control unit, which controls the brake pads to brake according to the braking command; optionally, the drive motor 5.1 has a model with a high safety level and low failure rate certification.

[0075] In most cases, the drive motor controller 2.1 can brake the drive motor 5.1, stopping the electric forklift. However, if the drive motor controller 2.1 fails, the safety controller 1 uses another set of information acquisition logic to detect whether the drive motor controller 2.1 is effectively braked. Optionally, in a further, but non-limiting, embodiment of this application, a first periodic interval is set, and the drive motor speed is periodically acquired according to the set first periodic interval to obtain the drive motor speed of two or more consecutive adjacent periods. The drive motor speed difference is obtained from the two drive motor speeds of adjacent first time periods. A first deceleration threshold is preset. If the drive motor speed difference is within the first deceleration threshold, it means that the drive motor braking command in the first-layer vehicle hazard judgment link has not achieved the braking effect, that is, the drive motor controller 2.1 may have failed. Therefore, in response to the drive motor speed difference being within the first deceleration threshold, the safety controller 1 outputs a drive motor stop command.

[0076] For example, the drive motor speed n between two adjacent first cycle intervals is obtained. 1_t1 and n 1_t0 The speed difference of the drive motor |n is calculated. 1_t1 -n 1_t0 |, set the first deceleration threshold α, when |n 1_t1 -n 1_t0 When |≤α, it means that the braking command of the drive motor in the first-level vehicle hazard judgment link did not achieve the braking effect, and the drive motor controller 2.1 failed. 1_t1 -n 1_t0 When |>α, it means that the drive motor 5.1 has been successfully braked.

[0077] When drive motor 5.1 stops, the electric forklift loses power and coasts freely. The drive motor stop command is output through the high safety integrity controller 1. The output link of the drive motor stop command avoids the low failure rate drive motor controller 2.1. Therefore, compared with the drive motor braking command, the execution failure rate of the drive motor stop command is lower. This satisfies the safety requirement of the control system using the electric forklift control method provided in this embodiment to prevent the vehicle from continuing to drive with low failure rate when the driver leaves the seat. It also meets the cost requirement of replacing the high safety integrity drive motor controller in the prior art with a standard drive motor controller 2.1 in the control system.

[0078] The above content only meets the safety requirement of preventing the vehicle from continuing to drive with low failure rate when the driver leaves the seat. For industrial electric vehicles, the control system also needs to have a safety function that stops the forks after the driver leaves the seat. Optionally, in a further but non-limiting embodiment of this application, the safety controller 1 acquires the signal duration and, in response to the signal duration reaching a second time threshold, outputs a fork pump motor braking command. The fork pump motor braking command is used to control the standard fork pump motor controller 2.2 to perform braking. The fork pump motor controller 2.2 performs braking on the fork pump motor 5.2 according to the fork pump motor braking command, thereby stopping the forks.

[0079] A second period interval is set, and the speeds of two fork pump motors in adjacent second time periods are obtained. The speed difference between the two fork pump motors in adjacent second time periods is then calculated. Specifically, the speed n of the two fork pump motors in adjacent second time periods is obtained. 2_t1 and n 2_t0 The difference in speed of the forklift pump motor, |n, was calculated. 2_t1 -n 2_t0 |, set the second deceleration threshold β, when |n 2_t1 -n 2_t0 When |≤β, it means that the braking command of the fork pump motor in the first-level vehicle hazard judgment link has not achieved the braking effect, and the fork pump motor controller 2.2 has failed. 2_t1 -n 2_t0 When |>β, it means that the fork pump motor 5.2 has been successfully braked.

[0080] If the fork pump motor speed difference is within the second deceleration threshold, it indicates that the fork pump motor controller 2.2 failed to execute the fork pump motor braking command. In response to the fork pump motor speed difference being within the second deceleration threshold, a fork pump motor stop command is output. The fork pump motor stop command is output through the high safety integrity safety controller 1. The output link of the fork pump motor stop command avoids the standard fork pump motor controller 2.2. Therefore, compared with the fork pump motor braking command, the execution failure rate of the fork pump motor stop command is lower. This satisfies the safety requirement of the control system of the electric forklift using the control method provided in this embodiment to prevent the forks from continuing to move with low failure rate when the driver leaves the seat. It also meets the cost requirement of replacing the high safety integrity fork pump motor controller in the prior art with the standard fork pump motor controller 2.1 in the control system.

[0081] This embodiment describes a method for safety control of an electric forklift using a drive motor controller 2.1 and a fork pump motor controller 2.2, respectively. In other embodiments, those skilled in the art can also use the control method of the electric forklift provided in this embodiment for control systems that include other standard vehicle motor controllers 2. Given the same principle, it will not be described again here.

[0082] The electric forklift control method provided in this embodiment satisfies the cost reduction requirement of using standard drive motor controller 2.1 and fork pump motor controller 2.2 in the control system, while also meeting the safety level index of low failure rate of the overall control system.

[0083] Example 3:

[0084] This embodiment provides a control system for an electric forklift, referring to Figures 2, 3, 6, and 7, including:

[0085] Safety controller 1 is configured to: acquire vehicle motion signals, acquire hazard monitoring values ​​based on vehicle motion signals; output a corresponding braking command in response to the hazard monitoring value reaching a first intervention threshold; acquire motion parameters of the braked moving parts, acquire motion trend values ​​of the moving parts based on the motion parameters; and output a power source shutdown command corresponding to the moving parts in response to the motion trend values ​​of the moving parts reaching a second intervention threshold.

[0086] The vehicle motor controller 2 is configured to perform braking according to a braking command.

[0087] The vehicle hazard action monitor 3 is configured to monitor vehicle action signals and monitor the motion parameters of braked moving parts.

[0088] Contactor 4 is used to respond to a power source shutdown command and execute the power source shutdown action. Contactor 4 achieves power source shutdown by quickly cutting off the power supply to the power source.

[0089] Safety controller 1 has higher safety integrity than vehicle motor controller 2, therefore safety controller 1 has a lower failure rate than vehicle motor controller 2.

[0090] Safety controller 1 is connected to vehicle motor controller 2 and vehicle dangerous action monitor 3 respectively. Vehicle motor controller 2 is connected to moving parts. Safety controller 1 is connected to contactor 4. Contactor 4 is connected to power source.

[0091] The control system of the electric forklift provided in this embodiment can be controlled using the control method of the electric forklift provided in Embodiment 1 or 2. The specific technical effects are based on the same principle and will not be described in detail here.

[0092] Optionally, the vehicle dangerous action monitoring unit 3 mainly consists of some output function components and sensor components on the electric forklift, such as the seat detector switch 3.0, valve control switch, relay, combination handle, accelerator pedal, and angle sensor.

[0093] Scenario 1: In existing electric forklift control systems, to meet the requirement of a high overall failure rate and safety level, low-failure-rate vehicle motor controllers and high-safety-integrity safety controllers are used, both possessing low execution failure rates. Other components are primarily procured to meet low failure rate requirements. During operation, output function components and sensor components acquire hazard signals. The safety controller processes these signals and sends control commands to the vehicle motor controller, which then performs safety operations such as braking, thereby meeting the overall failure rate requirements of the control system. However, electric forklifts use corresponding vehicle motor controllers for different moving parts, and the procurement cost of low-failure-rate vehicle motor controllers is significantly higher than that of ordinary, standard vehicle motor controllers, although the cost difference for other components is not substantial.

[0094] Scenario 2: In the existing control system of electric forklifts, if there are no requirements for low failure rate and high safety level, the vehicle motor controller, safety controller, and other components are basically standard components, or some of them are components that achieve high safety integrity. For safety requirements, the control system does not meet the requirements for low failure rate, but the procurement cost is low.

[0095] Compared to the prior art in case 1, the electric forklift control system provided in this embodiment replaces the vehicle motor controller 2 with a standard component with a higher failure rate than the safety controller 1, significantly reducing costs. The safety controller 1 and other important components use safety-type components that meet high safety integrity requirements, resulting in an overall cost slightly higher than case 2 but significantly lower than case 1. Referring to Figures 1 and 4, in use, the safety controller 1 safely and with low failure rate outputs braking commands based on vehicle action signals, while the standard vehicle motor controller 2 performs conventional braking control based on the braking commands. This embodiment introduces motion parameters of the braked moving parts, and the safety controller 1 obtains the motion trend value of the moving parts through these motion parameters. It then performs high-safety, low-failure-rate analysis based on these motion trend values ​​to determine the braking failure status of the vehicle motor controller 2. If the vehicle motor controller 2 fails to brake, the safety controller 1 outputs a power source shutdown command, causing the moving parts to lose power and preventing continued operation. The entire process from the safety controller 1 acquiring motion parameters to the contactor 4 executing the power source shutdown action meets the low failure rate requirement, compensating for the failure rate of the vehicle motor controller 2 and thus meeting the stringent requirement of overall low failure rate.

[0096] Example 4:

[0097] This embodiment provides a control system for an electric forklift. This embodiment is an improvement on Embodiment 3; for details not covered herein, please refer to Embodiment 3. The control system for the electric forklift provided in this embodiment can be controlled using the control method for the electric forklift provided in Embodiment 2. Specific technical effects are based on the same principle and will not be elaborated further here.

[0098] Optionally, in a further but non-limiting embodiment of this application, referring to FIG2, the vehicle dangerous action monitor 3 includes a seat detector switch 3.0, which detects the driver's position information and outputs a signal that the driver leaves the seat;

[0099] The seat detector switch 3.0 can be connected to the safety controller 1 via a signal. The safety controller 1 is also configured to: obtain the duration of a signal based on a driver leaving the seat signal; and, in response to the signal duration reaching a first time threshold, output a drive motor braking command to the drive motor controller 2.1. The drive motor braking command can be executed by the drive motor controller 2.1, thereby controlling the drive motor 5.1 to brake. The safety controller 1 is also configured to: set a first cycle interval; obtain the speeds of two drive motors in adjacent first time cycles; obtain the speed difference between the two drive motors in adjacent first time cycles; and, in response to the speed difference being within a first deceleration threshold, output a drive motor stop command to the contactor 4. The contactor 4 cuts off the power to the drive motor 5.1 according to the drive motor stop command, allowing the drive motor 5.1 to stop and idle freely.

[0100] Optionally, the moving part includes a drive motor 5.1, and the vehicle motor controller 2 includes a drive motor controller 2.1, which is configured to brake the drive motor 5.1 according to a drive motor braking command;

[0101] The vehicle hazardous action monitor 3 also includes a first encoder 3.1, which is used to monitor the rotational speed of the drive motor 5.1 and output it in the form of message data n1;

[0102] The contactor 4 includes a first contactor 4.1 electrically connected to the drive motor 5.1. The first contactor 4.1 is used to respond to the drive motor stop command and perform the drive motor 5.1 stop action.

[0103] In use, the driver sits in the seat. When the driver begins to leave the seat, the seat detector switch 3.0 outputs a signal indicating that the driver has left the seat. The safety controller 1 receives this signal and calculates its duration. When the signal duration reaches a first time threshold, indicating that the driver has left the driver's seat, the safety controller 1 outputs a drive motor braking command to the drive motor controller 2.1. The drive motor controller 2.1 controls the drive motor 5.1 to brake according to the drive motor braking command. Ideally, the drive motor 5.1 will stop rotating or come to a slow stop, completing the standard braking of the first layer of protection. Since the drive motor controller 2.1 is a low-cost, common component, if the drive motor controller 2.1 fails unexpectedly, the safety controller 1 can determine the speed difference of the drive motor 5.1 by detecting the speed of the drive motor 5.1 through the first encoder 3.1. The speed difference is within the first speed reduction threshold. Then, the safety controller 1 outputs a drive motor stop command to the first contactor 4.1. The first contactor 4.1 responds to the drive motor stop command by cutting off the power to the drive motor 5.1, releasing the power, and allowing the drive motor 5.1 to idle freely, completing the safety braking of the second layer of protection.

[0104] The electric forklift control system provided in this embodiment can meet the requirements of using a more economical standard type drive motor controller 2.1, while enabling the control system to brake the drive motor 5.1 or release the drive motor 5.1 with low failure rate when the driver leaves the driver's seat.

[0105] For electric forklifts, when the driver leaves the driver's seat, in addition to the drive motor 5.1 requiring a cost-effective safety solution for braking or releasing power, the fork pump motor 5.2 also needs the same safety measures.

[0106] Optionally, in a further but non-limiting embodiment of this application, the safety controller 1 is further configured to: obtain the duration of a signal based on a driver leaving the seat signal; output a fork pump motor braking command in response to the signal duration reaching a second time threshold; set a second period interval, obtain the speeds of two fork pump motors in adjacent second time periods, obtain the speed difference of the fork pump motors based on the speeds of the two fork pump motors in adjacent second time periods; and output a fork pump motor stop command in response to the speed difference of the fork pump motors being within a second deceleration threshold.

[0107] The moving parts include a fork pump motor 5.2, and the vehicle motor controller 2 includes a fork pump motor controller 2.2, which is configured to brake the fork pump motor 5.2 according to a fork pump motor braking command.

[0108] The vehicle hazardous action monitor 3 also includes a second encoder 3.2, which monitors the rotational speed of the fork pump motor 5.2 and outputs it in the form of message data n2.

[0109] Contactor 4 includes a second contactor 4.2 electrically connected to the fork pump motor 5.2. The second contactor 4.2 is used to respond to the fork pump motor stop command and execute the stop action of the fork pump motor 5.2.

[0110] In use, the driver sits in the seat. When the driver begins to leave the seat, the seat detector switch 3.0 outputs a driver leaving the seat signal. The safety controller 1 receives the signal and calculates the signal duration based on the driver leaving the seat signal. In response to the signal duration reaching a second time threshold, indicating that the driver has left the driver's seat, the safety controller 1 outputs a fork pump motor braking command to the fork pump motor controller 2.2. The fork pump motor controller 2.2 controls the fork pump motor 5.2 to brake according to the fork pump motor braking command. Ideally, the fork pump motor 5.2 will stop rotating or slowly stop, thus closing the fork hydraulic system and stopping the forks from moving, completing the first layer of protection. The standard braking of the link; since the fork pump motor controller 2.2 is a low-cost, common component, when the fork pump motor controller 2.2 fails unexpectedly, the safety controller 1 can know that the speed difference of the fork pump motor 5.2 is within the second deceleration threshold by detecting the speed of the fork pump motor 5.2 through the second encoder 3.2; then the safety controller 1 outputs a fork pump motor stop command to the second contactor 4.2; the second contactor 4.2 responds to the fork pump motor stop command, cuts off the power to the fork pump motor 5.2, releases the power, and allows the fork pump motor 5.2 to run freely without power, depressurizes the fork hydraulic system, and completes the safety braking of the second layer of protection link.

[0111] Optionally, the second time threshold is the same as the first time threshold, or the second time threshold is different from the first time threshold according to the response speed of the fork pump motor 5.2 and the drive motor 5.1.

[0112] The electric forklift control system provided in this embodiment can meet the requirements of using a more economical standard fork pump motor controller 2.2, while enabling the control system to perform safety measures such as braking the fork pump motor 5.2 or releasing the power of the fork pump motor 5.2 with low failure rate when the driver leaves the driver's seat.

[0113] Referring to Figure 2, in one embodiment, the safety controller 1, the drive motor controller 2.1, and the first encoder 3.1 are all connected via CAN1 bus signals, and the safety controller 1, the fork pump motor controller 2.2, and the second encoder 3.2 are all connected via CAN2 bus signals.

[0114] Referring to Figure 3, it is not difficult for those skilled in the art to see that the first-layer protection link and the second-layer protection link are independent of each other when braking and releasing power, but the execution of the second-layer protection link is based on the failure of the first-layer protection link.

[0115] Optionally, as a more specific embodiment, the high safety level with low failure rate meets CE requirements and PLr performance level; the safety controller 1 conforms to Class 3 architecture and uses the CANopenSafety communication protocol to connect with other components via electrical signals; the first encoder 3.1 and the second encoder 3.2 use the CANopenSafety communication protocol to connect with other components via electrical signals; all vehicle hazardous action monitoring units 3 are low-failure-rate safety components that meet the requirements of EU standard Class 1 architecture; the combination handle, including N, D, R full interface input type (3 signal lines), forms a safety control system with the safety controller 1, and the safety controller 1 diagnoses the authenticity of the signals, with a diagnostic coverage rate of 99%.

[0116] The electric forklift control system provided by this implementation replaces expensive high-safety-level components with ordinary parts, significantly reducing procurement costs and even eliminating the anxiety of not being able to find compatible and compliant components. It uses a simple second-layer protection link and an easily implemented safety mechanism that is compliant. The safety functions are simple to implement, the safety software is easily decoupled from the standard software, the safety software is solidified and easy to certify, and changes in overall machine requirements will not affect the safety components, eliminating duplicate safety certification costs.

[0117] The first layer of protection uses the vehicle motor controller 2 as the execution unit. It controls the motor to brake autonomously and slow down slowly to ensure safety, reliability and smoothness. Although its failure rate does not meet the functional safety certification requirements, it is inexpensive. The second layer of protection uses a simple, compliant contactor as the execution unit to cut off the power source and put the electric forklift into a safe state. Its failure rate meets the functional safety certification requirements. The cost of a high-safety-level contactor that meets the functional safety certification requirements is not high.

[0118] Example 5:

[0119] This embodiment provides a safety controller, including a processor and a memory connected to the processor. The memory stores a computer program, and when the computer program is executed by the processor, it performs the steps of the control method for an electric forklift as provided in Embodiment 1 or 2.

[0120] The safety controller can be a server or an electronic terminal. Referring to Figure 5, as one embodiment, the safety controller includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor of the safety controller provides computing and control capabilities. The memory of the safety controller includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database of the safety controller stores data acquired and generated in the control method of the electric forklift. The I / O interfaces of the safety controller are used for exchanging information between the processor and external devices. The communication interface of the safety controller is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the control method of the electric forklift provided in Embodiment 1 or 2.

[0121] Those skilled in the art will understand that the structure shown in Figure 5 is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the safety controller to which the present application is applied. A specific safety controller may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0122] The safety controller provided in this embodiment has the same technical effects as that in Embodiment 1 or 2, and will not be described again here.

[0123] The safety controller provided in this embodiment can be used in the control system of the electric forklift provided in Embodiment 3 or 4.

[0124] Optionally, in a further but non-limiting embodiment of this application, referring to Figure 4, the logic layer of the safety controller can be divided into a high-safety-integrity safety side and a quality-management-based standard side. The safety side of the safety controller is used to handle safety-related tasks of the control system, and all safety component signals undergo safety processing. The standard side is used to handle non-safety tasks of the control system. In Figure 4, "D1", "AI", "PWM", etc., represent the signal input forms of different vehicle hazardous action monitors 3.

[0125] Example 6:

[0126] This embodiment provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the control method for an electric forklift provided in Embodiment 1 or Embodiment 2.

[0127] The computer-readable storage medium provided in this embodiment has the same technical effects as that in Embodiment 1 or 2, and will not be described again here.

[0128] Example 7:

[0129] This embodiment provides a computer program product storing a computer program that, when executed by a processor, implements the steps of the control method for the electric forklift provided in Embodiment 1 or Embodiment 2. The computer program product provided in this embodiment can be transmitted, distributed, and downloaded via the Internet in the form of signals.

[0130] The computer program product provided in this embodiment has the same technical effects as that in Embodiment 1 or 2, and will not be described again here.

[0131] 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.

[0132] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will 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, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0133] 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 that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0134] 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, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0135] Example 8:

[0136] This embodiment provides an electric forklift, including the control system of the electric forklift provided in embodiment three or four. The electric forklift provided in this embodiment has the same technical effects as that in embodiment three or four, and will not be described again here.

[0137] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0138] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0139] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A control method for an electric forklift, characterized in that, The control method of the electric forklift is executed by a high-safety-integrity safety controller (1), and the control method of the electric forklift includes, Acquire vehicle motion signals, and obtain hazard monitoring values ​​based on the vehicle motion signals; In response to the danger monitoring value reaching the first intervention threshold, a corresponding braking command is output, which is used to control the standard vehicle motor controller (2) to perform braking; Obtain the motion parameters of the braked moving part, and obtain the motion trend value of the moving part based on the motion parameters; In response to the motion trend value of the moving component reaching the second intervention threshold, a power source shutdown command corresponding to the moving component is output.

2. The control method for the electric forklift according to claim 1, characterized in that, The step of acquiring vehicle motion signals and acquiring hazard monitoring values ​​based on vehicle motion signals includes acquiring a driver leaving the seat signal and acquiring the signal duration based on the driver leaving the seat signal. In response to the danger monitoring value reaching the first intervention threshold, a corresponding braking command is output. The braking command is used to control the standard vehicle motor controller (2) to perform braking, including, in response to the signal duration reaching the first time threshold, outputting a drive motor braking command. The drive motor braking command is used to control the standard drive motor controller (2.1) to perform braking. The step of obtaining motion parameters of the braked moving part and obtaining motion trend value of the moving part based on the motion parameters includes setting a first cycle interval, obtaining the rotation speed of two drive motors in adjacent first time cycles, and obtaining the difference in drive motor rotation speed based on the two drive motor rotation speeds in adjacent first time cycles. In response to the motion trend value of the moving component reaching a second intervention threshold, a power source shutdown command corresponding to the moving component is output. This includes outputting a drive motor stop command in response to the drive motor speed difference being within a first deceleration threshold.

3. The control method for the electric forklift according to claim 1, characterized in that, The step of acquiring vehicle motion signals and acquiring hazard monitoring values ​​based on vehicle motion signals includes acquiring a driver leaving the seat signal and acquiring the signal duration based on the driver leaving the seat signal. In response to the danger monitoring value reaching the first intervention threshold, a corresponding braking command is output. The braking command is used to control the standard vehicle motor controller (2) to perform braking, including, in response to the signal duration reaching the second time threshold, outputting a fork pump motor braking command. The fork pump motor braking command is used to control the standard fork pump motor controller (2.2) to perform braking. The step of obtaining motion parameters of the braked moving part and obtaining motion trend value of the moving part based on the motion parameters includes setting a second cycle interval, obtaining the speed of two fork pump motors in adjacent second time cycles, and obtaining the speed difference of the fork pump motors based on the speed of the two fork pump motors in adjacent second time cycles. In response to the motion trend value of the moving component reaching a second intervention threshold, a power source shutdown command corresponding to the moving component is output. This includes outputting a fork pump motor stop command in response to the fork pump motor speed difference being within a second deceleration threshold.

4. A safety controller, characterized in that, The device includes a processor and a memory connected to the processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the control method for the electric forklift as described in any one of claims 1 to 3 are performed.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the program implements the steps of the control method for the electric forklift as described in any one of claims 1 to 3.

6. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the steps of the control method for the electric forklift as described in any one of claims 1 to 3.

7. A control system for an electric forklift, characterized in that, include, The safety controller (1) is configured to: acquire vehicle motion signals, acquire hazard monitoring values ​​based on the vehicle motion signals; output a corresponding braking command in response to the hazard monitoring values ​​reaching a first intervention threshold; acquire motion parameters of the braked moving parts, and acquire motion trend values ​​of the moving parts based on the motion parameters; In response to the motion trend value of the moving component reaching the second intervention threshold, a power source shutdown command corresponding to the moving component is output; The vehicle motor controller (2) is configured to perform braking according to the braking command; A vehicle dangerous action monitor (3) is configured to monitor the vehicle action signal and monitor the motion parameters of the braked moving parts; Contactor (4) is used to respond to a power source shutdown command and execute a power source shutdown action; The safety controller (1) has higher safety integrity than the vehicle motor controller (2) and meets compliance requirements; The safety controller (1) is connected to the vehicle motor controller (2) and the vehicle dangerous action monitor (3) respectively. The vehicle motor controller (2) is connected to the moving parts. The safety controller (1) is connected to the contactor (4) and the contactor (4) is connected to the power source.

8. The control system of the electric forklift according to claim 7, characterized in that, The vehicle dangerous action monitor (3) includes a seat detector switch (3.0), which is used to output a signal that the driver leaves the seat; The safety controller (1) is further configured to: obtain the duration of the signal based on the driver leaving the seat signal; output a drive motor braking command in response to the signal duration reaching a first time threshold; set a first cycle interval, obtain the rotational speeds of two drive motors in adjacent first time cycles, obtain the difference in drive motor rotational speeds based on the rotational speeds of the two drive motors in adjacent first time cycles; and output a drive motor stop command in response to the difference in drive motor rotational speeds being within a first deceleration threshold. The moving component includes a drive motor (5.1), and the vehicle motor controller (2) includes a drive motor controller (2.1), which is configured to brake the drive motor (5.1) according to the drive motor braking command; The vehicle dangerous action monitor (3) further includes a first encoder (3.1), which is used to monitor the rotational speed of the drive motor (5.1); The contactor (4) includes a first contactor (4.1) electrically connected to the drive motor (5.1), the first contactor (4.1) being used to respond to a drive motor stop command and execute a stop action of the drive motor (5.1).

9. The control system of the electric forklift according to claim 7, characterized in that, The vehicle dangerous action monitor (3) includes a seat detector switch (3.0), which is used to output a signal that the driver leaves the seat; The safety controller (1) is further configured to: acquire the duration of the signal based on the driver leaving the seat signal; output a fork pump motor braking command in response to the signal duration reaching a second time threshold; set a second cycle interval, acquire the speeds of two fork pump motors in adjacent second time cycles, acquire the speed difference of the fork pump motors based on the speeds of the two fork pump motors in adjacent second time cycles; and output a fork pump motor stop command in response to the speed difference of the fork pump motors being within a second deceleration threshold. The moving component includes a fork pump motor (5.2), and the vehicle motor controller (2) includes a fork pump motor controller (2.2), which is configured to brake the fork pump motor (5.2) according to the braking command of the fork pump motor; The vehicle dangerous action monitor (3) also includes a second encoder (3.2), which is used to monitor the rotational speed of the fork pump motor (5.2); The contactor (4) includes a second contactor (4.2) electrically connected to the fork pump motor (5.2), the second contactor (4.2) being used to respond to the fork pump motor stop command and execute the fork pump motor (5.2) stop action.

10. An electric forklift, characterized in that, The control system of the electric forklift as described in any one of claims 7 to 9 is included.

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