Computing load-based industrial vehicle maximum vehicle speed control system and method

Abstract

The present invention relates to controlling the maximum vehicle speed of an industrial vehicle (10), comprising: determining, by means of a processor (216) of the industrial vehicle, a torque applied to a traction wheel (20) of the industrial vehicle; converting the torque into an equivalent force value; and determining the acceleration of the industrial vehicle when the torque is applied to the traction wheel. Additional steps include: calculating a load on the movement of the industrial vehicle based at least in part on the acceleration and the equivalent force value; and controlling the maximum speed of the industrial vehicle based on the calculated load on the movement of the industrial vehicle.

Description

[0001] This application is a divisional application of Chinese patent application No. PCT / US2019 / 049882, National Application No. 201980057542.3, filed on September 6, 2019, entitled "Control System and Method for Maximum Vehicle Speed ​​of Industrial Vehicles Based on Computational Load". Technical Field

[0002] This invention relates generally to material handling vehicles, and more specifically to controlling the traction speed of vehicles. Background Technology

[0003] Forklifts and other types of industrial vehicles are expected to operate under a wide variety of conditions. Furthermore, such vehicles typically include many different functional systems, such as a traction system for controlling the vehicle's speed and a steering system for controlling its direction of travel.

[0004] Controlling the maximum vehicle speed can be beneficial under various vehicle operating conditions, such as when the vehicle is moving a load. Summary of the Invention

[0005] Various aspects of the present invention relate to a method for controlling a maximum vehicle speed of an industrial vehicle. The method includes: determining, by a processor of the industrial vehicle, a torque applied to a traction wheel of the industrial vehicle; and determining, by the processor of the industrial vehicle, the acceleration of the industrial vehicle when the torque is applied to the traction wheel. The method also includes calculating, by the processor of the industrial vehicle, a load moved by the industrial vehicle, based at least in part on the acceleration and the torque applied to the traction wheel. The method further includes controlling the maximum speed of the industrial vehicle by the processor of the industrial vehicle based on the calculated load moved by the industrial vehicle. As an example, the load may include one or more trailers towed by the industrial vehicle. As another example, the industrial vehicle may include a fork assembly for carrying the load.

[0006] Other aspects of the invention relate to a processor of an industrial vehicle determining whether the industrial vehicle has traveled more than a predetermined distance after a previous stop, wherein the calculation of the load moved by the industrial vehicle is delayed until it is determined that the industrial vehicle has traveled more than the predetermined distance.

[0007] Other aspects of the invention relate to determining the maximum speed of an industrial vehicle by a processor based on a calculated load and the gradient of the path the industrial vehicle is traveling on.

[0008] Other aspects of the invention relate to determining the rolling resistance of an industrial vehicle when moving a load using a processor of the industrial vehicle, wherein the load moved by the industrial vehicle is calculated based at least in part on the rolling resistance.

[0009] Other aspects of the invention relate to a processor of an industrial vehicle determining the gradient of the path traveled by the industrial vehicle while moving a load, wherein the load moved by the industrial vehicle is calculated based at least in part on the gradient.

[0010] Other aspects of the computational load according to the principles of the present invention involve: calculating a set of at least a minimum number of individual values ​​comprising the load moved by the industrial vehicle; and averaging the at least minimum number of individual values ​​to determine a corresponding value for the set. Other aspects of the present invention involve: a processor of the industrial vehicle collecting multiple sets of individual load values ​​of the load moved by the industrial vehicle; and averaging the corresponding values ​​of the multiple sets to determine the calculated load.

[0011] Another aspect of the invention relates to limiting the initial value of the calculated load to the maximum load for which the industrial vehicle is designed to move, by the processor of the industrial vehicle.

[0012] Another aspect of the invention relates to a processor of an industrial vehicle determining when a lifting mechanism of the industrial vehicle is raised or lowered, wherein when the lifting mechanism is raised or lowered, calculations of the load moved by the industrial vehicle based on acceleration and torque are not performed. Additionally, another aspect of the invention relates to, in response to determining when the lifting mechanism of the industrial vehicle is raised or lowered, the processor of the industrial vehicle limiting the calculated load to the maximum load for which the industrial vehicle is designed to move.

[0013] Other aspects of the invention relate to: in response to an industrial vehicle accelerating above a first predetermined value and traveling at least a predetermined distance, calculating a set of individual values ​​comprising a predetermined number of loads moved by the industrial vehicle; and averaging the predetermined number of individual values ​​to determine a corresponding value for the set. The predetermined number of individual values ​​of the load may be equal to or less than 200.

[0014] Another aspect of calculating the load according to the principles of the present invention involves: detecting a first operating condition by a processor of an industrial vehicle, the first operating condition including: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value; after the first operating condition, determining a second operating condition by the processor of the industrial vehicle, the second operating condition including the industrial vehicle, within a predetermined time period after the first operating condition: a) starting to accelerate again to exceed the first predetermined value, and b) having traveled a predetermined distance; in response to the occurrence of the first operating condition and the occurrence of the second operating condition within the predetermined time period after the first operating condition, collecting another set of individual load values ​​of the load moved by the industrial vehicle by the processor of the industrial vehicle; and averaging the corresponding values ​​of the plurality of sets to calculate the calculated load.

[0015] Another aspect of calculating the load according to the principles of the present invention involves: detecting a first operating condition by a processor of an industrial vehicle, the first operating condition including: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value; after the first operating condition, determining a third operating condition by the processor of the industrial vehicle, the third operating condition including the speed of the industrial vehicle not reaching or exceeding the second predetermined value within a predetermined time period after the first operating condition; in response to the occurrence of the first operating condition and the occurrence of the third operating condition within the predetermined time period after the first operating condition, limiting the calculated load by the processor of the industrial vehicle to the maximum load for which the industrial vehicle is designed to move.

[0016] Various aspects of the present invention relate to a system for controlling the maximum vehicle speed of an industrial vehicle. The system includes: a storage device storing executable instructions; and a processor communicating with the storage device. Specifically, when executing the executable instructions, the processor: a) determines a torque applied to a traction wheel of the industrial vehicle; b) determines the acceleration of the industrial vehicle when the torque is applied to the traction wheel; c) calculates a load moving by the industrial vehicle based at least in part on the acceleration and torque; and d) controls the maximum speed of the industrial vehicle based on the calculated load moving by the industrial vehicle. As an example, the load may include one or more trailers pulled by the industrial vehicle. As another example, the industrial vehicle may include a fork assembly for carrying the load.

[0017] Another aspect of the invention relates to a processor determining, when executing executable instructions, whether an industrial vehicle has traveled more than a predetermined distance after a previous stop; and wherein the calculation of the load moved by the industrial vehicle is delayed until it is determined that the industrial vehicle has traveled more than the predetermined distance.

[0018] Another aspect of the invention relates to a method in which, when the processor executes executable instructions, the processor determines the maximum speed of the industrial vehicle based on a calculated load and the gradient of the path along which the industrial vehicle travels.

[0019] Another aspect of the invention relates to a processor determining the rolling resistance of an industrial vehicle when moving a load, wherein the load moved by the industrial vehicle is calculated based at least in part on the rolling resistance.

[0020] Another aspect of the invention relates to a processor determining the gradient of a path traveled by an industrial vehicle while moving a load, wherein the load moved by the industrial vehicle is calculated based at least in part on the gradient.

[0021] Other aspects of the invention relate to a processor, when executing executable instructions, calculating a set of at least a minimum number of individual values ​​comprising a load moved by an industrial vehicle; and averaging the at least minimum number of individual values ​​to determine a corresponding value for the set. Furthermore, when executing executable instructions, the processor collects multiple sets of individual values ​​of a load moved by an industrial vehicle; and averages the corresponding values ​​of the multiple sets to determine a calculated load.

[0022] According to another aspect of the invention, when executing executable instructions, the processor limits the initial value of the calculated load to the maximum load that the industrial vehicle is designed to move.

[0023] According to another aspect of the invention, the processor determines when the lifting mechanism of the industrial vehicle is raised or lowered when executing executable instructions, wherein when the lifting mechanism is raised or lowered, no calculation of the load moved by the industrial vehicle based on acceleration and torque is performed. Furthermore, in response to determining whether the lifting mechanism of the industrial vehicle is raised or lowered, the processor may limit the calculated load to the maximum load for which the industrial vehicle is designed to move.

[0024] According to another aspect of the invention, when executing executable instructions, the processor, in response to the industrial vehicle accelerating to a level above a first predetermined value and traveling at least a predetermined distance, calculates a set of individual values ​​comprising a predetermined number of loads moved by the industrial vehicle; and averages the predetermined number of individual values ​​to determine a corresponding value for the set.

[0025] According to another aspect of the invention, when executing executable instructions, the processor: detects a first operating condition, the first operating condition comprising: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value; after the first operating condition, determines a second operating condition, the second operating condition comprising that, within a predetermined time period after the first operating condition, the industrial vehicle: a) begins to accelerate again to exceed the first predetermined value, and b) has traveled a predetermined distance; in response to the occurrence of the first operating condition and the occurrence of the second operating condition within the predetermined time period after the first operating condition, collects another set of individual values ​​of the load moved by the industrial vehicle; and averages the corresponding values ​​of the plurality of sets to calculate the calculated load.

[0026] According to another aspect of the invention, when the processor executes the executable instructions: detects a first operating condition, the first operating condition including: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value; after the first operating condition, determines a third operating condition, the third operating condition including that the speed of the industrial vehicle does not reach or exceed the second predetermined value within a predetermined time period after the first operating condition; and in response to the occurrence of the first operating condition and the occurrence of the third operating condition within the predetermined time period after the first operating condition, limits the calculated load to the maximum load for which the industrial vehicle is designed to move.

[0027] Another aspect of the present invention relates to calculating the load according to the following formula:

[0028]

[0029] T C It's a torque command, T IT This refers to the inertial torque. The gearbox ratio is the predetermined gearbox ratio for the industrial vehicle; the gearbox efficiency is the predetermined gearbox efficiency for the industrial vehicle; the driven wheel radius is the radius of the traction wheel; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, expressed as a percentage; VA g It is the acceleration of the industrial vehicle, expressed in g; Individual load value = TVM – (unloaded weight of the industrial vehicle).

[0030] Another aspect of the invention relates to the conversion of torque applied to the traction wheel into an equivalent force F. A The calculated load is then determined using the following formula:

[0031]

[0032] Where F A This is the equivalent value; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, as a percentage; VA g It is the acceleration of an industrial vehicle in g; Individual load value = TVM – (unloaded weight of the industrial vehicle). Attached Figure Description

[0033] Figure 1A This is a perspective view of a material handling vehicle according to one aspect of the present invention.

[0034] Figure 1B and 1C This is a view of another material handling vehicle according to one aspect of the present invention.

[0035] Figure 2A It shows the use of in Figure 1A-1CThe vehicle control module (VCM) of a vehicle provides the computing environment for control logic.

[0036] Figure 2B Selected features of a vehicle and an exemplary vehicle control module (VCM) according to the principles of the present invention are illustrated schematically.

[0037] Figure 3A and 3B It is a graph showing the relationship between vehicle load, maximum travel speed and surface slope according to the principles of the present invention.

[0038] Figure 4 It is a graph showing the relationship between vehicle speed, travel distance, and acceleration according to the principles of the present invention.

[0039] Figure 5 and Figure 6 This is a flowchart of an exemplary process for calculating or estimating the load on a moving vehicle without directly measuring or sensing the value, according to the principles of the present invention. Detailed Implementation

[0040] In the following detailed description of preferred embodiments, reference is made to the accompanying drawings, which form a part of the description, and specific preferred embodiments in which the invention can be practiced are shown in the drawings by way of illustration rather than limitation. It should be understood that other embodiments may be utilized and changes may be made without departing from the spirit and scope of the invention.

[0041] Now for reference Figure 1A The image shows a material handling vehicle 10 (hereinafter referred to as "vehicle"), which is a forklift.

[0042] Vehicle 10 includes a main body or power unit 12, which includes a frame 14 defining the main structural components of vehicle 10 and housing a battery 15. Vehicle 10 also includes: a pair of fork-side support wheels 16 connected to first and second cantilever beams 18; driven and steering wheels 20 (also referred to herein as “traction wheels”) mounted near a first corner at the rear 12A of power unit 12; and casters (not shown) mounted to a second corner at the rear 12A of power unit 12. The wheels 16, 20 allow vehicle 10 to move on a floor surface.

[0043] The operator's compartment 22, located within the power unit 12, accommodates the operator of the vehicle 10. A steering knob 24 is located within the operator's compartment 22 for controlling the steering of the vehicle 10. The speed and direction of movement (forward or backward) of the vehicle 10 are controlled by the operator via a multi-function control handle 26 located near the operator's seat 28. This control handle 26 can control one or more other vehicle functions, as will be understood by those skilled in the art. The vehicle 10 also includes an overhead guard 30, which comprises a vertical support structure 32 fixed to the vehicle frame 14.

[0044] The load-carrying assembly 40 of vehicle 10 typically includes a mast assembly 42 and a carriage assembly 44, the carriage assembly being movable vertically along the mast assembly 42. The mast assembly 42 is located between cantilever beams 18 and includes a fixed mast member 46 fixed to a frame 14 and nested first and second movable mast members 48, 50. It should be noted that the mast assembly 42 may include... Figure 1A The two components shown (i.e., the first and second movable mast components 48, 50) have more or fewer movable mast components. The carriage assembly 44 includes a conventional structure comprising an extension assembly 52, a fork carriage 54, and a fork structure including a pair of forks 56A, 56B. The movable assembly 47, as defined herein, includes lower and upper movable mast components 48, 50 and the carriage assembly 44. The mast assembly 42 may be constructed as a monolithic mast as described in U.S. Patent No. 8,714,311 to Steven C. Billger et al., which was granted on May 6, 2014, and assigned to the applicant, Crown Equipment Corporation, the entire disclosure of which is hereby incorporated herein by reference.

[0045] Provided through examples Figure 1A Vehicle 10, and many different types of material handling vehicles are conceivable within the scope of this invention. For example, Figure 1B and 1C A towing industrial vehicle or material handling vehicle 10' is shown. Similar to... Figure 1A The vehicle 10, towing tractor 10', includes a main body or power unit 12', which includes a frame defining the main structural components of the vehicle 10' and housing a battery 15'. Traction and steering or driven and steering wheels (not shown) located at corner portions of the power unit 12' drive and steer the towing tractor 10'. An operator controls the speed, direction of movement (forward or backward), and steering of the vehicle 10' via a multi-function control handle 100. As will be understood by those skilled in the art, the control handle 100 can control one or more other vehicle functions.

[0046] like Figure 1C As shown, the towing tractor 10' can be used to tow multiple trailers 102, each trailer having a corresponding linkage 104 for coupling to the vehicle 10' or another trailer 102. As explained in more detail below, when the vehicle 10' begins to move forward from a stationary state, the linkage or coupling 104 may have a certain degree of slack, such that all trailers do not initially move forward together until the slack of all linkages or couplings 104 is overcome.

[0047] Although the invention has been described herein with reference to the material handling vehicles 10 and 10' shown, it will be apparent to those skilled in the art that the invention can be used with a variety of other types of material handling vehicles.

[0048] Figure 2A A block diagram-level view of a computing environment for providing control logic and software applications in a vehicle control module (VCM) 200, according to one or more embodiments shown and described herein, is illustrated. The vehicle control module 200 and its interface with various operator control and other functional systems of the vehicle 10 may be similar to the control structures disclosed in U.S. Patent Publications 2010 / 0228428, 2014 / 0188324, and 2017 / 0043787, the entire contents of which are incorporated herein by reference. The VCM is one of many cooperating modules that, in addition to a traction control module (TCM) or a steering control module (SCM), may also cooperatively control the operation of the vehicle 10 or 10'. Each cooperating module may include one or more corresponding processors, memory storing executable program code, and other circuitry configured to perform their respective functions and communicate with each other, as described in detail below. The TCM may also be referred to herein as a "traction controller," and the SCM may also be referred to herein as a "steering controller."

[0049] In the illustrated embodiment, VCM 200 includes one or more processors or microcontrollers 216, input / output hardware 218, network interface hardware 220, data storage unit 222, and memory unit 202. Each of the data storage unit 222 and memory unit 202 can be configured as volatile and / or non-volatile memory, and therefore may include random access memory (including SRAM, DRAM, and / or other types of RAM), flash memory, secure digital storage (SD) memory, registers, optical disc (CD), digital versatile optical disc (DVD), and / or other types of non-transitory computer-readable media. Any stored information intended to be available after vehicle 10, 10' is stopped and restarted can advantageously be stored in non-volatile memory. Furthermore, according to a particular embodiment, the aforementioned non-transitory computer-readable media may reside within and / or outside the VCM 200.

[0050] Additionally, memory unit 202 may store software or applications that can be executed (i.e., using executable code) by one or more processors or microcontrollers 216. Therefore, memory unit 202 may store operating application or logic 204, traction application or logic 208, steering application or logic 206, lifting application or logic 210, and accessory application or logic 212. Operating logic 204 may include an operating system and other software, such as diagnostic-related applications for managing components of VCM 200. Traction application or logic 208 may be configured with one or more algorithms and parameters for optimized traction control of vehicles 10, 10'. Steering application or logic 206 may be configured with one or more algorithms and parameters for optimized steering control of vehicles 10 or 10'. Lifting application or logic 210 may include one or more algorithms and parameters for optimized lifting control of vehicles 10, 10', which serves as the main load-carrying component system for raising and lowering the movable component 47 of vehicle 10. Additionally, the accessory application or logic 212 may include one or more algorithms and parameters for providing control over accessories to vehicles 10, 10', such as auxiliary load handling assembly systems that perform additional tasks, such as tilting and lateral movement of carriage assembly 44. Local communication interface 214 is also included. Figure 2A It can also be implemented as a bus or other communication interface to facilitate communication between components of the VCM 200.

[0051] One or more processors or microcontrollers 216 may include any processing unit that can be used to receive and execute instructions, such as program code from data storage unit 222 and / or memory unit 202. The processor or microcontroller 216 may include any kind of device that receives input data, processes that data according to computer instructions, and generates output data. Such a processor may be a microcontroller, handheld device, laptop or notebook computer, desktop computer, microcomputer, digital signal processor (DSP), mainframe, server, mobile phone, personal digital assistant, other programmable computer device, or any combination thereof. Such a processor may also be implemented using a programmable logic device such as a field-programmable gate array (FPGA), or alternatively, implemented as an application-specific integrated circuit (ASIC) or similar device. The term "processor" is also intended to cover combinations of two or more of the above-described devices, such as two or more microcontrollers.

[0052] Input / output hardware 218 may include and / or be configured to interface with a monitor, positioning system, keyboard, touchscreen, mouse, printer, image capture device, microphone, speaker, gyroscope, compass, and / or other devices for receiving, transmitting, and / or presenting data. Network interface hardware 220 may include and / or be configured to communicate with any wired or wireless network hardware, including antennas, modems, LAN ports, Wi-Fi cards, WiMax cards, mobile communication hardware, and / or other hardware for communicating with other networks and / or devices. This connection facilitates communication between VCM 200 and other computing devices, including other components coupled to a CAN bus or similar network on vehicle 10 or 10'.

[0053] It should be understood that Figure 2A The components shown are merely exemplary and are not intended to limit the scope of this disclosure. Although Figure 2A The components shown are depicted residing within the VCM 200, but this is merely an example. In some embodiments, one or more components may reside outside the VCM 200. It should also be understood that, although Figure 2A VCM 200 is shown as a single device; however, this is merely an example. In some embodiments, the traction application 208, steering application 206, lifting application 210, and / or accessory application 212 may reside on different devices. Furthermore, while VCM 200 is shown as having the traction application 208, steering application 206, lifting application 210, and accessory application 212 as separate logical components, this is also an example. In some embodiments, a single composite software application may enable VCM 200 to provide the described functionality.

[0054] It should also be understood that the VCM 200 can communicate with various sensors and other control circuits of the vehicle 10 to coordinate various conditions of manual and automatic operation of the vehicle 10.

[0055] Figure 2B The schematic illustration shows the selectable features of vehicle 10 or 10' and an exemplary vehicle control module 200, which helps to describe vehicle control operations utilizing traction and steering applications. From Figure 2B The relative to is omitted in the middle. Figure 1A and Figure 2A Other features of the vehicle 10 or 10' and VCM 200 described herein are omitted to avoid obscuring exemplary aspects of the vehicle operation controls described herein.

[0056] refer to Figure 2BThe VCM 200 includes a processor 216, shown as including a steering application 206, a traction application 208, and other applications (not shown) to be executed by the processor 216. In other example embodiments, the VCM 200 may include more than one microcontroller, such as a master microcontroller and slave microcontrollers.

[0057] exist Figure 2B In the middle, forming including Figure 1A The steering control input sensor 276, which is part of the steering mechanism of the steering knob 24 of the vehicle 10 shown, provides the vehicle control module (VCM) 200 with a sensor output signal value (e.g., analog voltage) that defines one or more steering command signals 278. Figure 1B and 1C The operator control handle 100 of vehicle 10' can be similarly configured. Steering control input sensor 276 can also be part of another steering device, including a steering wheel, steering rudder, or similar steering element. Steering command signal 278 can be adjusted or otherwise regulated and can be provided, for example, to an input pin of processor 216 within VCM 200. This signal can be further regulated and provided as an input value to steering application 206 executed by processor 216. For example, the voltage of steering command signal 278, or the rate of change of this voltage, can vary based on the position and rate of change of position of steering control input sensor 276 associated with the steering device (i.e., rudder knob 24 in the illustrated embodiment). Based on the input signal received by steering application 206 corresponding to steering command signal 278, steering application 206 determines a setpoint for control attributes related to the vehicle's steering wheels 20. For example, the voltage value can be used with a lookup table to associate the voltage value with a specific wheel angle value of the steering setpoint, or the rate of change of voltage can be multiplied by a predetermined scaling factor to convert the rate of change into a setpoint that changes the steering motor angular velocity. Therefore, the control attribute can be, for example, the steering wheel angle or the angular velocity of the steering motor 274, and thus, the setpoint value can be the steering wheel angle θ1 or the steering motor angular velocity ω1. The steering setpoint ω1 or θ1 can be provided to the steering control module (SCM) 272. The SCM 272 uses the setpoint ω1 or θ1 to control the steering motor 274, which positions the steering wheel 20 to the desired position indicated by the operator's manipulation of the steering control input sensor 276. The SCM 272 can also provide feedback values ​​θ2 or ω2 of the control attributes related to the steering wheel. Specifically, the feedback value is either the measured or actual steering wheel angle θ2 of the steering wheel 20, or the measured or actual angular velocity ω2 of the steering motor 274. The SCM 272 can, for example, provide the feedback value θ2 or ω2 to the steering application 206.

[0058] Steering application 206 additionally generates a target steering angle θ for traction application 208. T The target steering angle can be calculated as discussed in U.S. Patent Publication No. 2017 / 0043787, which is previously incorporated herein by reference. The target steering angle θ is received from the steering application 206 at the traction application 208. T As a limiting constraint, this limiting constraint is converted by the traction application 208 into a traction control speed limit via a predetermined desired speed-wheel-angle relationship, and is used to determine the desired traction speed setting ω4 and traction torque setpoint τ1. The traction wheel speed or traction motor speed can be considered as a control attribute related to the traction wheel or driven wheel 20 of the vehicle 10, and the desired traction speed setting ω4 for the traction motor 264 or traction wheel 20 and the traction torque setpoint τ1 for the traction motor can be considered as the corresponding setpoints for this control attribute related to the traction wheel.

[0059] A traction torque setpoint τ1 can be provided to a traction control module (TCM) 258. The TCM 258 uses the traction torque setpoint τ1 to control the operation of the traction motor 264. The TCM 258 monitors the traction motor 264 and provides a traction feedback speed ω3 to the traction application 208 and the steering application 206. The traction feedback speed ω3 can be the angular velocity / rate of the traction motor 264 or the driven wheel 20, as discussed further below. In some embodiments, it may be beneficial to convert the traction speed or speed feedback ω3 into the actual linear velocity of the vehicle 10 via the traction application 208. If, for example, the speed feedback ω3 is the angular velocity of the traction motor 264, the traction application 208 can scale this value to the actual linear velocity v3 of the vehicle 10 based on a) the gear ratio between the traction motor 264 and the driven wheel 20 and b) the circumference of the driven wheel 20. Alternatively, if the speed feedback ω3 is the angular velocity of the driven wheel 20, the traction application 208 can scale this value to the actual linear velocity v3 of the vehicle 10 based on the circumference of the driven wheel 20. Assuming the driven wheel does not slip, the linear velocity of the vehicle is equal to the linear velocity of the driven wheel 20.

[0060] The traction setpoint τ1 is determined by the traction application 208 based on the traction speed command signal 260 received from the traction speed control input sensor 262 controlled by the operator, such as the multifunction control handle 26 of the vehicle 10, and the target steering angle θ output from the steering application 206. T The traction setpoint τ1 is output as a torque value from the traction application 208 to the TCM 258, which results in the corresponding speed of the traction motor 264 under the control of the TCM 258.

[0061] It is also advantageous to be able to control the vehicle speed based on the trailer load or forklift load to ensure safe braking. Specifically, embodiments of the invention relate to determining or estimating the vehicle load without any means of directly measuring the vehicle load. In some cases, an unloaded vehicle 10 or 10' may weigh about 1,000 kg, but can tow a load of up to 5,000 kg.

[0062] Figure 3A The top of the chart has a vertical axis 308, which represents the maximum speed of vehicle 10 or 10' based on the braking capacity of vehicle 10 or 10'. The horizontal axis 306 represents the drag force, which may depend on the gradient of the vehicle's travel and the weight of the vehicle's current load. Figure 3A The lower part of the chart has a horizontal axis 302 and a vertical axis 304. The horizontal axis represents the load moved by vehicle 10 or 10', and the vertical axis represents the gradient of the vehicle's travel (in...). Figure 3A In this context, any percentage greater than 0% is a downhill slope.

[0063] For unloaded vehicles traveling on a level floor, the maximum permissible speed is 12.5 km / h (kph). However, on a downhill slope of 5%, the maximum permissible speed for the same vehicle is 9.2 kph. Figure 3B Is with Figure 3A A similar chart, but with emphasis, states that the maximum permissible speed is 7.5 kph on a level floor if the vehicle is moving a load of 5 metric tons or 5,000 kilograms, and 2.0 kph on any downhill slope of 3% or more.

[0064] Those skilled in the art will recognize that for a towing tractor 10' or forklift 10, the force to accelerate the vehicle can be provided by the output torque of an electric motor or an internal combustion engine. By way of example only and not intended to limit the scope of the invention, the following description describes the use of a three-phase induction motor, the traction motor 264 in the illustrated embodiment, and the processor 216 in the illustrated embodiment to control the traction speed of vehicle 10 or 10'. Theoretically, if the output torque of such a motor can be known with high fidelity at any time, the equivalent force can be determined by converting the rotational torque into an equivalent linear force using the gearbox ratio (as used herein, "gearbox ratio" refers to the ratio of the driven wheel RPM to the electric motor shaft RPM) and the diameter of the driven wheel 20. The equivalent force (Newtons) applied to vehicle 10 or 10' will be the motor torque (Nm) multiplied by the gearbox ratio and the gearbox efficiency (as used herein, "gearbox efficiency" refers to torque loss or power loss expressed as a percentage of the motor torque), divided by the radius (meters) of the driven wheel or traction wheel 20. The processor 216 can use the change in rotation or angular velocity (rpm) of the traction motor 264 to calculate the vehicle's acceleration (m / s²), which is received from the traction control module 258, divided by 60 seconds / minute, divided by the gearbox ratio, multiplied by the circumference of the driven wheel or traction wheel 20 (m), and divided by the sampling rate (seconds) of the angular velocity provided by the traction control module 258.

[0065] However, other significant forces act on the vehicle during acceleration of vehicle 10 or 10', which can also be considered when converting motor torque into equivalent force. A certain amount of torque is required to accelerate the rotating components of vehicle 10 or 10' (e.g., motor rotor, gears, and driven wheel 20). Rolling resistance and road surface slope or inclination also play a positive or negative role depending on whether vehicle 10 or 10' is accelerating uphill or downhill. Therefore, the total force required to move the load on the vehicle can be calculated using Equation 1, as follows:

[0066] Total force required = (force to accelerate the total vehicle and load mass) + (force for climbing / going downhill) + (force to accelerate the inertia of rotating parts) + (force to overcome rolling resistance)

[0067] As described above, assuming no tire slippage, vehicle acceleration can be calculated by converting the rotational acceleration of the traction motor into linear acceleration. Alternatively, an accelerometer can be present on vehicle 10 or 10' and directly sense the vehicle's acceleration. Uphill / downhill gradients can be determined using the same onboard accelerometer or a combination of accelerometer and gyroscope. The torque required to accelerate the inertia of the vehicle's rotating components (e.g., motor rotor, gears, and driven wheels 20) can be calculated by determining the moment of inertia (i.e., rotational inertia) of the aforementioned rotating components and multiplying it by the angular acceleration of the traction motor 264. As is known to those skilled in the art, this "rotational inertia" value can be a pre-calculated constant, varying for different vehicles and readily calculable. Rolling friction or rolling resistance is a function of many varying vehicle and environmental factors, such as vehicle and load weight, tire material, temperature, and floor conditions. A constant rolling resistance value is estimated as a percentage, such as 1.5%. Therefore, rolling resistance can be determined by multiplying a constant rolling resistance value (e.g., 0.15) by the weight of the vehicle combined with any load. Once the vehicle is in motion, the rolling friction or rolling resistance becomes relatively constant.

[0068] Under steady-state driving conditions on a horizontal surface (i.e., without vehicle acceleration), rolling resistance is likely to be the maximum resistance on vehicle 10 or 10', but under high acceleration, rolling resistance may become minimal. Therefore, as described below, according to the principles of the invention, calculations regarding vehicle load can be performed when the vehicle is under high acceleration to give greater importance to the component of (force of total vehicle and load mass accelerating) in Equation 1 above.

[0069] Initial acceleration includes the slack or looseness of the linkages or couplings 104 of one or more trailers 102 connected to and pulled by vehicles 10, 10'. As the slack is absorbed in each coupling, a sudden acceleration or pull may occur due to the additional load borne by vehicles 10, 10', caused by… Figure 4 The acceleration spikes shown in the exemplary data indicate how vehicle speed, acceleration, and distance can change over time as vehicle 10 or 10' accelerates from a stationary state. Therefore, it may be beneficial to delay load calculations until all couplings are fully engaged.

[0070] Figure 5 and Figure 6 This is a flowchart illustrating an exemplary process for calculating or estimating the load on a moving vehicle without directly measuring or sensing that value, according to the principles of the present invention. For example, Figure 5 and Figure 6The process can be implemented using executable code executed by the VCM200 described previously. Various operating conditions of vehicle 10 or 10' can be sensed using appropriate sensors located on components of vehicle 10 or 10'. These sensed values ​​can be used directly by the process or used to derive other values ​​that the process can use.

[0071] Typically, and as described more fully below, the process calculates individual values ​​(referred to herein as “individual load values”) for estimating the load currently moving by the vehicle under certain vehicle operating conditions. After calculating a minimum number or a predetermined maximum number of individual load values, the average of these individual load values ​​is taken as the load estimate of the valid set (referred to herein as “set load value”). Several sets of set load values ​​are calculated, and the running average of these set load values ​​is maintained. The VCM 200 takes the running average as the load currently moving by vehicle 10 or 10' (referred to herein as “output load value” or “LoadOut”). The VCM 200 can then use this output load value as the load currently moving by the vehicle when determining the maximum permissible speed of vehicle 10 or 10'.

[0072] As mentioned above, Figure 5 and Figure 6 An exemplary process for calculating or estimating the load moved by an industrial vehicle is shown. For an industrial vehicle with a movable load support platform (e.g., the fork carriage 54 of vehicle 10), Figure 5 and Figure 6 The exemplary process shown assumes that the forks of the industrial vehicle do not move. When executing... Figure 5 and Figure 6 At any step, if the industrial vehicle detects that the fork is being raised or lowered, the control returns to step 502 and limits the calculated load of the industrial vehicle to the maximum load that the industrial vehicle is designed to move, such as 5000 kg.

[0073] First, in step 502, several values ​​used in subsequent steps of the process are initialized. These values ​​include: a "count" value, representing the number of individual load values ​​calculated in the current set; a "sum" value, representing the running sum of individual load values ​​calculated in the current set; a "LDCount" value, representing the number of set load values ​​calculated; a "LDSum" value, representing the running sum of the calculated set load values; a "valid" value, indicating whether a valid set of individual load values ​​has been collected; and a "dist" value, representing the distance traveled by the vehicle. Each of these values ​​is initially set to "0". Another value initialized in step 502 is the "LoadOut" value, representing the output load value, which the process treats as the current load on which the vehicle is moving. This value is initially set to the maximum load the vehicle is designed to move, for example, 5000 kg.

[0074] In step 502, the process also begins calculating the value of "dist" after initialization. In the following discussion, the exemplary sampling rate is considered to be 0.01 seconds, which can be represented as "dt". Those skilled in the art will readily recognize that larger or smaller sampling rates can be used without departing from the scope of the invention. The distance value "dist" can be calculated according to the following formula:

[0075] Formula 2: dist(n) = dist(n-1) + (vehicle linear velocity xdt)

[0076] Where "dist(n)" is the current distance value being calculated, "dist(n-1)" is the previously calculated distance value, and "vehicle linear velocity" can be determined based on the feedback value ω3 discussed earlier. As described above, TCM 258 monitors traction motor 264 and provides traction feedback velocity ω3 to traction application 208 and steering application 206. In some embodiments, it may be beneficial to convert the traction velocity or velocity feedback ω3 into the actual linear velocity of vehicle 10 via traction application 208. If, for example, the velocity feedback ω3 is the angular velocity of traction motor 264, then traction application 208 can scale this value to the actual linear velocity of vehicle 10 based on a) the gear ratio between traction motor 264 and driven wheel 20 and b) the circumference of driven wheel 20. Alternatively, if the velocity feedback ω3 is the angular velocity of driven wheel 20, then traction application 208 can scale this value to the actual linear velocity of vehicle 10 based on the circumference of driven wheel 20. Assuming the driven wheel does not slip, the linear velocity of the vehicle is equal to the linear velocity of driven wheel 20.

[0077] In step 504, it is determined whether the distance traveled by the vehicle is greater than a predetermined distance (also referred to herein as the "predetermined distance" (e.g., 1.0 meter)) and whether the vehicle's acceleration is greater than a predetermined acceleration (also referred to herein as the "first predetermined value" (e.g., 0.2 m / s²)). 2 The process continues. A predetermined distance is selected such that all slack in the linkages or couplings 104 of one or more trailers 102 connected to vehicles 10, 10' should be absorbed. A predetermined acceleration is selected as a value sufficiently large to represent a relatively "large" acceleration. If the distance traveled by the vehicle is not greater than the predetermined distance (e.g., 1.0 meter) and / or the acceleration of the vehicle is not greater than the predetermined acceleration (e.g., 0.2 m / s²), the process will continue. 2 If the condition in step 504 is not met, the process returns to step 502, and the loop is repeated by executing step 504 again. Once both conditions in step 504 are met, the process proceeds to step 506, where individual load values ​​are collected or calculated. For each collected individual load value, the "count" and "sum" are incremented by calculating or collecting the current individual load value. Next, in step 508, the process checks whether the number of individual load values ​​already calculated for the current set (equal to the "count" value as described above) is equal to the minimum count or a predetermined maximum count or value. The value of the "count" can be compared with the predetermined maximum count (also referred to herein as the "predetermined number") (e.g., "100"). The "predetermined count" can be any value other than 100, but is preferably greater than 1. More preferably, the predetermined maximum count does not exceed, for example, 200 at a sampling rate of 0.01 seconds, more preferably not more than 150 at a sampling rate of 0.01 seconds, and even more preferably not more than 100 at a sampling rate of 0.01 seconds. It is also preferable to select a predetermined maximum count number and sampling rate such that the count reaches the predetermined maximum count number within 2 seconds, preferably within 1.5 seconds, and most preferably within 1 second from the time of the first count increment. This is because when the vehicle is under high acceleration, using Formula 1 above to calculate a more accurate "individual load value" makes the component of Formula 1 (force of total vehicle and load mass) more significant. Therefore, it is preferable to select a predetermined count number such that when the "count" value reaches the predetermined maximum count number, the vehicle is most likely still accelerating and has not yet reached a steady-state driving state. Once the predetermined number of individual load values ​​have been collected, i.e., the count equals the predetermined number, the "valid" value can be set to "1" or "true", etc.

[0078] If the test in step 508 fails, control proceeds to step 516 to determine whether the vehicle is currently accelerating, i.e., whether the vehicle's acceleration is greater than a predetermined acceleration (e.g., 0.2 m / s²). 2If not, then in step 518 determine whether the value of "valid" is "0" or "1" (or "false" or "true", etc.). First pass Figure 5 In this part of the process, the value of "valid" will be "0", so the process returns to step 502. This path indicates an operational condition where the vehicle begins to accelerate but does not continue for a sufficient period of time to collect the minimum or predetermined maximum number of individual load values ​​for the first set. The phrase "first pass" means that the process has not even successfully reached step 510 once since it was last initialized in step 502.

[0079] However, if the value of "valid" in step 518 is "1", the process proceeds to step 514, and then to... Figure 6 Step 602. This path represents an operational state in which one or more set load values ​​can be pre-calculated before a minimum or predetermined maximum number of individual load values ​​can be collected, but the vehicle stops accelerating during the current set.

[0080] If it is determined in step 516 that the vehicle is still accelerating, the process loops back to steps 506 to 508 to collect another individual load sample, i.e., to calculate another individual load value. As described above, in the first pass Figure 5 During the process, once the minimum or predetermined maximum number of individual load values ​​or samples have been collected, the value of "Valid" can be changed to "1" instead of "0," and the average of the individual load values ​​can be calculated from "Count" and "Sum" to calculate the current set load value, i.e., Current set load value = Sum divided by Count. The process continues to step 510, where the "LDCount" value is incremented, and the "LDSum" value is incremented by the just-calculated current set load value. The running average "LoadOut" value can also be updated based on the new values ​​of "LDCount" and "LDSum," i.e., LoadOut = LDSum divided by LDCount.

[0081] In step 512, the vehicle (e.g., VCM 200) determines whether the vehicle has stopped moving and stopped accelerating. For example, the process may determine whether the vehicle's speed is less than a second predetermined value (e.g., 0.02 m / s) and the vehicle is not currently accelerating, i.e., its acceleration is less than a first predetermined value (0.2 m / s). 2 Those skilled in the art will recognize that other predetermined values ​​can be substituted, and it will also be recognized that functionally equivalently, determining in step 512 that the speed is above a predetermined threshold and the vehicle is currently accelerating, leads to the conclusion that the opposite vehicle condition has been detected (e.g., the vehicle is neither stopped nor accelerating). If both conditions in step 512 are met, the process proceeds to step 514, and then to... Figure 6Step 602. In step 512, if the process determines that the vehicle's speed is not less than a second predetermined value (e.g., 0.02 m / s) and / or determines that the vehicle is currently still accelerating, i.e., its acceleration is greater than or equal to a first predetermined value (0.2 m / s). 2 If the vehicle speed and acceleration are detected to have stopped moving, i.e., both conditions in step 512 have been met, then the process continues to the next step 514. Therefore, the current aggregate load value is calculated relatively quickly during the initial vehicle acceleration, and then the individual load value is calculated only after both conditions in step 512 are met, and as will be discussed in more detail below, the vehicle has traveled a distance at least greater than a predetermined distance (e.g., 1.0 meter), and the vehicle has accelerated to a value greater than a first predetermined value (e.g., 0.2 m / s). 2 The value of ).

[0082] In step 602, the value “dist” is initialized to “0” again. In step 604, the process determines whether the speed of vehicles 10 and 10' remains less than a second predetermined value (e.g., 0.02 m / s). If vehicles 10 and 10' remain stationary, i.e., their speed is less than the second predetermined value for a predetermined time period (e.g., 5 seconds), the process returns to... Figure 5 In step 502, all previously estimated load calculations for the vehicle's movement are discarded, and the process restarts with all values ​​reinitialized. This path is represented by steps 604 and 606, where step 604 determines whether the vehicle speed remains approximately equal to "0" (e.g., below a predetermined value such as a second predetermined value), and step 606 determines that the vehicle stopping condition has lasted for at least a predetermined time period (e.g., 5 seconds). Therefore, in step 608, the process returns to step 502. If, in step 606, the process determines that the vehicle stopping state has lasted for less than the predetermined time period, the process returns to step 604.

[0083] If the process determines in step 604 that the speed of vehicles 10, 10' is equal to or greater than a second predetermined value, the process proceeds to step 610. This occurs when a vehicle only decelerates or stops for a short period of time less than a predetermined time interval, but subsequently increases its speed to above the second predetermined value. Step 610 determines that the vehicle acceleration is greater than approximately zero (e.g., greater than a predetermined value such as a first predetermined value), and then waits in step 612 until the vehicle has traveled at least a minimum distance (e.g., 1.0 meter). Under these conditions, the "sum" and "count" values ​​are set to "0," which effectively discards individual load values ​​that are part of the current set load value and returns the process to the previous step by proceeding to step 616 to begin a new set. Figure 5 Step 506.

[0084] exist Figure 5 and Figure 6 At any point during the process, a value “LoadOut” is available for use by other processes (e.g., traction application 208) to control the vehicle’s maximum permissible traction speed based on the load the vehicle is currently moving under. This prevents the vehicle from exceeding speeds that would prevent it from braking within preset guidelines or requirements. VCM 200 can store a lookup table in its storage unit 202 that provides the maximum truck speed to traction application 208 based on the input of “LoadOut” and a slope angle or percentage and sign, where a positive sign indicates an uphill slope in the direction of movement, and a negative sign indicates a downhill slope in the direction of movement.

[0085] As mentioned above, in Figure 5 In step 506, the individual load value is calculated. A possible method according to the principles of the present invention is described below.

[0086] As described above, the vehicle's current linear velocity v3 or VSM (m / s) can be sensed or calculated by the VCM using the angular velocity ω3 of the traction motor 264. This value can be used to help detect when the vehicle speed is essentially zero, and can also be used to derive the vehicle's linear acceleration VA. M (m / s 2 As mentioned above, the linear acceleration of the vehicle can also be derived using the angular velocity of the traction motor 264. In addition to deriving the vehicle acceleration from the VSM sample using the VCM 200 or using the angular velocity of the traction motor 264 to measure / calculate the vehicle acceleration, it is also possible to measure the vehicle acceleration directly using a separate accelerometer.

[0087] Within the TCM 258 or traction motor 264, sensors can be present to monitor the speed of various components. For example, the rotational speed MS of the electric motor shaft can be measured using a properly positioned sensor. M (RPM). The motor speed can be converted by the processor 216 in the VCM 200 into a value representing the motor speed, expressed in rad / s, MS, according to the following formula. R (rads / s):

[0088] MS R (rads / s)=MS M x(2πrads / revolution)x(1 minute / 60 seconds).

[0089] The processor 216 in the VCM 200 can sample MS at a preset sampling rate (e.g., dt = 0.01s). R The current value allows the calculation of the two most recent MS values ​​according to the following formula. R The change in electric motor speed ΔMS between sampled values R (rads / s):

[0090] ΔMS R (rads / s)=MS R [n]-MS R [n-1]

[0091] And calculate the angular acceleration of the motor shaft of the traction motor 264 during the sampling period according to the following formula:

[0092] MA (rads / s) 2 ): = ΔMS R / dt.

[0093] As mentioned above, there exists a predetermined constant value for the moment of inertia RI (kg m). 2 For example, 0.0153 kg m 2 It is the moment of inertia of rotating components (such as motor rotors, gears, and driven wheels 20) in the vehicle's powertrain. Therefore, the inertial torque T can be calculated using the following formula. IT (Nm), which is the inertial torque required to accelerate RI:

[0094] T IT (N m) = MA x RI.

[0095] VCM 200 calculates the torque command T equal to the traction torque setpoint τ1. C The torque command T C It is provided to TCM258 to control the operation of traction motor 264 and is intended to represent the total torque currently provided by the shaft of the traction motor. However, due to the existence of inertial torque T IT The existence of this means that the inertial torque T is subtracted from the torque command Tc. IT To calculate the effective torque T provided to the drivetrain by the traction motor 264 E As shown below:

[0096] T E =T C -T IT .

[0097] The electric traction motor 264 can be mechanically connected to the driven wheel 20 via one or more gears and one or more shafts. Therefore, the torque applied to the driven wheel 20 is based on T. E However, it also depends on the gearbox ratio and gearbox efficiency of the gears between the electric traction motor 264 and the driven wheel 20. A constant exemplary gearbox ratio could be 15.6, and a constant exemplary gearbox efficiency could be 0.95. Therefore, the torque T applied to the driven wheel 20 can be calculated or determined according to the following formula. T (Nm):

[0098] T T (Nm)=T E x(gearbox transmission ratio) x(gearbox efficiency).

[0099] Assuming the driven wheel shaft passes through the center of the driven wheel or traction wheel 20, then it is related to the torque T. T The associated torque arm will be the radius of the driven or traction wheel 20. Therefore, the equivalent torque T can be calculated. T The forces acting on vehicles 10 and 10'; in this case, the equivalent linear force can be calculated according to the following formula:

[0100] F A (N)=T T / (Driven wheel radius, in meters).

[0101] As mentioned above, vehicle acceleration is also affected by rolling resistance and the slope of the surface the vehicle travels on. The rolling resistance value R% (unitless / 100) is considered a predetermined constant, but may vary for different vehicles and different surfaces. The slope G% (unitless / 100) has a positive or negative sign and can be detected by the vehicle's sensors (e.g., accelerometers and / or gyroscopes).

[0102] If the surface slope is uphill in the direction of travel of vehicle 10, 10', then the sign of G% is positive. If the surface slope is downhill in the direction of travel of vehicle 10, 10', then the sign of G% is negative.

[0103] Therefore, equivalent F A It can be divided into three components to complete three different tasks:

[0104] F A =(F T : Force that accelerates the total vehicle mass (TVM) +

[0105] F G Force for climbing / going downhill +

[0106] F R (Force to overcome rolling resistance)

[0107] in:

[0108] TVM (kg) is the combined mass of load, any trailer, and vehicle.

[0109] F T (N) = (TVM x VA) M ),

[0110] F G (N) = (TVM x G% x 9.8m / s) 2),and

[0111] F R (N) = (TVM x R% x 9.8m / s) 2 ),

[0112] Formula 4 is derived:

[0113] F A =(TVM x VA) M )+(TVM x G% x 9.8m / s 2 )+(TVM x R% x 9.8

[0114] m / s 2 ).

[0115] Formula 4 can be processed by dividing both sides by 9.8 m / s. 2 Let's calculate TVM (kg):

[0116]

[0117] Where VA g (Unitless) is the vehicle acceleration expressed in g, equal to VA. M / (9.8m / s 2 ).

[0118] Therefore, the load moved by the vehicle is determined according to the following formula: Figure 5 and Figure 6 In step 506, the load is calculated as an individual load value (which can be the weight of the trailer plus the weight of the goods on or in the trailer, or an estimate of the weight of the load (goods) on the forks):

[0119] Load (kg) = TVM – (Unloaded vehicle weight, kg)

[0120] The unloaded vehicle weight is the known unloaded weight of the vehicle.

[0121] In the exemplary process described above for estimating the load on the moving vehicles 10, 10', the torque applied to the driven wheel 20 is converted into an equivalent linear force applied to the floor by the wheel 20. This conversion is not required, and as described in detail below, each individual load value can be calculated based on the torque value. As mentioned above, the torque command T... C This results in the effective torque T applied to the electric motor shaft. E and the inertial torque T applied to overcome the rotational inertia RI IT This makes T C =T E +T IT The formula for effective torque can be rearranged as follows:

[0122] T E =T C -T IT

[0123] As described above, the torque applied to the driven wheel 20 is based on T E However, it also depends on the gearbox ratio and gearbox efficiency of the gears between the electric traction motor 264 and the driven wheel 20. A constant exemplary gearbox ratio could be 15.6, and a constant exemplary gearbox efficiency could be 0.95. Therefore, the torque T applied to the driven wheel 20 can be calculated according to the following formula. T (Nm):

[0124] T T =T E x(gearbox ratio) x(gearbox efficiency)

[0125] Where T T It is the torque applied to the driven wheel 20.

[0126] Using the two formulas above, T can be calculated according to the following formula. T :

[0127] T T =(T C -T IT x (gearbox transmission ratio) x (gearbox efficiency).

[0128] Assuming the driven wheel shaft passes through the center of the driven wheel, then it is related to the torque T. T The associated torque arm will be the radius of the driven wheel. As described above, the equivalent torque T can be determined. T The force F acting on the vehicle A The formula for the equivalent linear force is:

[0129] F A =T T / (Driven wheel radius, in meters).

[0130] Combining the two formulas above, the force F can be... A The formula can be rewritten as:

[0131]

[0132] As mentioned above, vehicle acceleration is also affected by rolling resistance and the slope of the surface the vehicle travels on. The rolling resistance value R% (unitless / 100) is considered a predetermined constant, but it may vary for different vehicles and different surfaces. Therefore, the equivalent force F... A It can be divided into three components to complete three different tasks:

[0133] F A =(F T : Force that accelerates the total vehicle mass (TVM) +

[0134] F G Force for climbing / going downhill +

[0135] F R (Force to overcome rolling resistance)

[0136] in:

[0137] TVM (kg) is the combined mass of load, any trailer, and vehicle.

[0138] F T (N) = (TVM x VA) M ),

[0139] F G (N) = (TVM x G% x 9.8m / s) 2 ),and

[0140] F R (N) = (TVM x R% x 9.8m / s) 2 ).

[0141] Therefore, it is the same as formula 4 above:

[0142] F A =(TVM x VA) M )+(TVM x G% x 9.8m / s 2 )+(TVM x R% x 9.8

[0143] m / s 2 ).

[0144] The elements in the formula above are rearranged to provide:

[0145]

[0146] As in the previous exemplary embodiment, dividing both the numerator and denominator on the right by 9.8 yields:

[0147]

[0148] Where VA g (Unitless) is the vehicle acceleration expressed in g, equal to VA. M / (9.8m / s 2 ).

[0149] The above equivalent F A Substituting the formula into the above equation, TVM can be calculated using the following formula:

[0150]

[0151] Therefore, the load moved by the vehicle is determined according to the following formula. Figure 5 and Figure 6 In step 506, the load is calculated as an individual load value (which can be the weight of the trailer plus the weight of the goods on or in the trailer, or an estimate of the weight of the load (goods) on the forks):

[0152] Load (kg) = TVM – (Unloaded vehicle weight, kg)

[0153] The weight of the unloaded vehicle is a known value of the vehicle.

[0154] The system and processor implementation method for controlling the maximum vehicle speed of an industrial vehicle have been described above, comprising: determining a torque applied to the traction wheel of the industrial vehicle; determining the acceleration of the industrial vehicle when the torque is applied to the traction wheel; calculating a load moving by the industrial vehicle based at least in part on the acceleration and torque; and controlling the maximum speed of the industrial vehicle based on the calculated load moving by the industrial vehicle. In some cases, the torque can be converted into an equivalent value, wherein the calculated load value is calculated at least in part based on the equivalent value.

[0155] As an example, the load could be one or more trailers towed by an industrial vehicle, whether empty or not. As another example, the industrial vehicle could have a forklift assembly or some other type of lifting platform to carry the load.

[0156] When an industrial vehicle is started for the first time, there may be a period of time before operating conditions allow for the calculation of the load to be moved. As a result, in the system and method described above, the initial value for the calculated load can be set to the maximum load that the industrial vehicle is designed to move.

[0157] like Figure 4 As shown, the acceleration of an industrial vehicle starting from a stationary state fluctuates significantly in the first few seconds after travel begins. Therefore, it may be beneficial to wait until the industrial vehicle has traveled a minimum predetermined distance before calculating the load moved by the vehicle. Accordingly, the aforementioned system and method may include: determining whether the industrial vehicle has traveled more than a predetermined distance when it begins to travel after a previous stop, wherein the calculation of the load moved by the industrial vehicle is delayed until it is determined that the industrial vehicle has traveled more than the predetermined distance.

[0158] However, in Formula 1, the term representing the force that accelerates the entire vehicle and its load mass is larger when the industrial vehicle is at maximum acceleration, while it is smaller when the industrial vehicle approaches its steady-state speed. Furthermore, before estimating the load value, the exemplary process described above uses the maximum load that vehicles 10 and 10' are designed to move as the estimated or calculated load. As mentioned above, a maximum speed limit for vehicles 10 and 10' can be imposed based on this calculated load. Therefore, it is advantageous to use the above process to calculate an initial load value, which corresponds to the maximum speed limit that vehicles 10 and 10' are designed to move, before vehicles 10 and 10' can reach a speed equal to the maximum speed limit. For example, if the initially calculated load is less than the maximum load that vehicles 10 and 10' are designed to move, and the maximum speed limit of the initially calculated load (hereinafter referred to as the first maximum speed limit) is greater than the maximum speed limit for a load equal to the maximum load that vehicles 10 and 10' are designed to move (hereinafter referred to as the second maximum speed limit), then by calculating the initially calculated load before the vehicle reaches a speed equal to the second maximum speed limit, the situation where the vehicle decelerates to the second maximum speed limit and then is allowed to increase its speed to the first maximum speed limit is avoided.

[0159] For industrial vehicles, their ability to successfully brake within predetermined criteria is affected by the weight of the industrial vehicle, the load it moves, the gradient angle, and the speed of the industrial vehicle. Therefore, the aforementioned system and method may include: determining a maximum speed limit using, for example, a lookup table or formula, based on a calculated load or a calculated load and gradient moved by the industrial vehicle; and limiting the maximum speed of the industrial vehicle based on the determined maximum speed limit. For example, VCM 200 may store, in its storage unit 202, information including, for example... Figure 3A A lookup table is used to determine the maximum truck speed based on the input of "LoadOut" and the slope angle or percentage and sign, and this maximum truck speed is provided to the traction application 208, where a positive sign indicates that the slope is uphill in the direction of movement, and a negative sign indicates that the slope is downhill in the direction of movement. In the embodiment shown, for all positive uphill slopes, the slope % is considered equal to 0% in Figure 3. For all downhill slopes, the slope % is used... Figure 3A The corresponding slope percentage is provided in the table. However, it is conceivable that a separate lookup table or formula could be provided for positive upslopes.

[0160] Other forces also affect the acceleration capability of industrial vehicles. One example of such a force is rolling resistance. Furthermore, the force generated by the gradient of the vehicle's path is another example of this force. Therefore, the aforementioned system and method may include: a) determining the rolling resistance of the industrial vehicle when moving a load, wherein the load moved by the industrial vehicle is calculated based at least in part on the rolling resistance; and / or b) determining the gradient of the path traveled by the industrial vehicle when moving a load, wherein the load moved by the industrial vehicle is calculated based at least in part on the gradient.

[0161] Instead of calculating a single estimate for the load moving by industrial vehicles, multiple individual load values ​​can be calculated and then averaged together as a way to improve the accuracy of the calculated load. Therefore, a set of individual load values ​​can exist such that their average is considered the set load value. Furthermore, before being considered a valid set, the set can be limited to include at least a minimum number or a predetermined maximum number of individual load values. Therefore, the above system and method can include: calculating a set comprising a predetermined number of individual load values ​​of the load moving by industrial vehicles; and averaging said predetermined number of individual load values ​​to determine the corresponding set load value.

[0162] In addition to having a predetermined set of individual load values, the collection of individual load values ​​can be limited to certain operating conditions of the industrial vehicle. As an example, as previously mentioned, load calculation can be delayed until the industrial vehicle has traveled at least a certain minimum distance. Another constraint might be that the load is calculated only if the industrial vehicle's acceleration exceeds a first predetermined value. Therefore, the above-described system and method can include: in response to the industrial vehicle accelerating above the first predetermined value and traveling at least a predetermined distance, calculating a predetermined set of individual load values ​​including the load moved by the industrial vehicle; and averaging the predetermined set of individual values ​​to determine a corresponding set load value for that set.

[0163] The estimate of the calculated load can be further refined by averaging the load values ​​from several sets. Therefore, the system and method described above may include: collecting multiple sets of individual load values ​​of loads moved by vehicles; and averaging the corresponding values ​​from the multiple sets to determine the calculated load.

[0164] Because raising and lowering the lifting mechanism (e.g., fork) of an industrial vehicle may indicate a change in the moving load, the load calculation as described above can be stopped when movement of the lifting mechanism is detected. Furthermore, there can be a period of time before the load calculation can be restarted in the above manner; therefore, when movement of the lifting mechanism is detected, the calculated load value can be set equal to the maximum load that the industrial vehicle is designed to move. Therefore, the above system and method may include determining when to raise or lower the lifting mechanism of the industrial vehicle, wherein when the lifting mechanism is raised or lowered, the calculation of the load moved by the industrial vehicle based on acceleration and torque is not performed. Furthermore, the above system and method may include: in response to determining that the lifting mechanism of the industrial vehicle is raised or lowered, limiting the calculated load to the maximum load that the industrial vehicle is designed to move.

[0165] The control inputs of an operator of an industrial vehicle may not always be smooth and precise. Therefore, even if the operator's intention is to continue accelerating, the industrial vehicle may experience brief periods of acceleration, deceleration, or even complete stoppage. In other cases, the operator's intention may be to stop the vehicle, which allows for changes in the moving load. Therefore, when calculating the load moved by the vehicle, it may be useful to determine which operating conditions correspond to brief decelerations and which correspond to a complete stop.

[0166] Thus, the above system and method may include collecting a set of individual load values, then detecting the occurrence of a first operating condition, and then detecting the occurrence of a subsequent second operating condition. The first operating condition includes: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value. The subsequent second operating condition includes, within a predetermined time period following the first operating condition, the industrial vehicle a) again begins to accelerate to exceed the first predetermined value, and b) has traveled a predetermined distance. These operating conditions may correspond to industrial vehicles that only briefly decelerate. Therefore, in response to the occurrence of the first and second operating conditions, the above system and method may include: collecting another set of individual load values ​​of the load moved by the industrial vehicle; averaging the corresponding values ​​from the plurality of sets to calculate a calculated load.

[0167] Furthermore, the aforementioned system and method may include collecting a set of individual load values, then detecting the occurrence of a first operating condition, and then detecting the occurrence of a subsequent third operating condition. The first operating condition includes: a) the acceleration of the industrial vehicle is less than a first predetermined value, and b) the speed of the industrial vehicle is less than a second predetermined value. The subsequent third operating condition includes the industrial vehicle's speed not reaching or exceeding the second predetermined value within a predetermined time period following the first operating condition. These operating conditions may correspond to an industrial vehicle that has already stopped. Therefore, in response to the occurrence of the first and third operating conditions, the aforementioned system and method may include limiting the calculated load to the maximum load for which the industrial vehicle is designed to move.

[0168] The systems and methods described above may include specific methods for calculating or estimating each individual load value discussed above. Specifically, the individual load values ​​of loads moved by industrial vehicles are calculated according to one of at least two different formulas:

[0169]

[0170] or

[0171]

[0172] Where F A It is the equivalent value of the torque applied to the traction wheel 20; T C It is a torque command; T IT It is the inertial torque; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, as a percentage; VA g It is the acceleration of an industrial vehicle in g; Individual load value = TVM – (unloaded weight of the industrial vehicle).

[0173] Although specific embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications falling within the scope of the invention be covered in the appended claims.

Claims

1. A method for controlling the maximum vehicle speed of an industrial vehicle, comprising: The processor of the industrial vehicle determines the torque applied to the traction wheels of the industrial vehicle; The industrial vehicle's acceleration when torque is applied to the traction wheel is determined by the industrial vehicle's processor; The load moved by the industrial vehicle is calculated by the vehicle's processor, based at least in part on acceleration and torque applied to the traction wheel, wherein the calculated load includes: In response to the industrial vehicle accelerating to exceed a first predetermined value, a set of at least a minimum number of individual load values ​​including the load moved by the industrial vehicle is calculated; The minimum number of individual load values ​​are averaged to determine the corresponding set load value for the set; The processor of the industrial vehicle collects multiple sets of load values ​​of the load moving by the industrial vehicle, and calculates each subsequent set of load values ​​after detecting that the acceleration of the industrial vehicle is less than a first predetermined value and subsequently accelerates to exceed the first predetermined value; and The corresponding values ​​of the multiple set load values ​​are averaged to determine the calculated load; and The processor of the industrial vehicle controls the maximum speed of the industrial vehicle based on the calculated load caused by the movement of the industrial vehicle.

2. The method of claim 1, wherein the load comprises one or more trailers towed by an industrial vehicle.

3. The method according to claim 1, further comprising: The processor of the industrial vehicle converts the torque applied to the traction wheel into an equivalent value; and The load moved by the industrial vehicle is calculated based at least in part on the equivalent value.

4. The method according to claim 1, comprising: The processor determines the maximum speed of the industrial vehicle based on the calculated load and the gradient of the path the industrial vehicle travels.

5. The method according to claim 1, comprising: The rolling resistance of the industrial vehicle is determined by the vehicle's processor when moving loads. and The load moved by the industrial vehicle is calculated based at least in part on the rolling resistance.

6. The method according to claim 1, comprising: The gradient of the path traveled by the industrial vehicle is determined by the processor of the industrial vehicle when moving the load. and The load moved by the industrial vehicle is calculated based at least in part on the slope.

7. The method of claim 1, wherein the load value of each individual load moved by the industrial vehicle is calculated according to the following formula: in F A is the equivalent force value, equivalent to the torque applied to the traction wheel; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, expressed as a percentage. VA g is the acceleration of the industrial vehicle expressed in g; and Individual load value = TVM – unloaded weight of industrial vehicle.

8. The method of claim 1, wherein the load value of each individual load moved by the industrial vehicle is calculated according to the following formula: in T C is a torque command, T IT It is inertial torque; The gearbox transmission ratio is the predetermined gearbox transmission ratio for industrial vehicles; Gearbox efficiency is the predetermined gearbox efficiency for industrial vehicles; The radius of the driven wheel is the radius of the traction wheel; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, expressed as a percentage. VA g The acceleration of an industrial vehicle is expressed in terms of g; and Individual load value = TVM – unloaded weight of industrial vehicle.

9. The method of claim 1, wherein the industrial vehicle includes a fork assembly.

10. The method of claim 1, further comprising: The processor of the industrial vehicle limits the initial value of the calculated load to the maximum load that the industrial vehicle is designed to move.

11. The method of claim 1, further comprising: The processor in the industrial vehicle determines when the lifting mechanism of the industrial vehicle should raise or lower. When the lifting mechanism raises or lowers, the load moved by the industrial vehicle based on acceleration and torque is not calculated.

12. The method of claim 1, wherein calculating a set of at least a minimum number of individual load values ​​comprising the load moved by the industrial vehicle comprises: In response to the industrial vehicle accelerating to a value exceeding the first predetermined value and traveling at least a predetermined distance, a set of individual load values ​​including a predetermined number of loads moved by the industrial vehicle is calculated. and The predetermined number of individual load values ​​are averaged to determine the corresponding set load value for the set.

13. The method of claim 1, further comprising: The processor of the industrial vehicle determines whether the industrial vehicle has traveled more than a predetermined distance when it resumes driving after a previous stop, in order to allow the absorption of slack in the trailer linkage. and The delay calculation is performed on the load moved by the industrial vehicle until it is determined that the industrial vehicle has traveled more than a predetermined distance.

14. A system for controlling the maximum vehicle speed of an industrial vehicle, comprising: Storage device that stores executable instructions; as well as The processor, which communicates with the storage device, executes executable instructions as follows: Determine the torque applied to the traction wheels of the industrial vehicle; Determine the acceleration of the industrial vehicle when torque is applied to the traction wheel; The load on the moving industrial vehicle is calculated at least in part based on acceleration and torque applied to the traction wheel, wherein the calculated load includes: In response to the industrial vehicle accelerating to exceed a first predetermined value, a set of individual values ​​including at least a minimum number of loads moved by the industrial vehicle is calculated; The minimum number of individual values ​​are averaged to determine the corresponding value for the set; Collect multiple sets of individual values ​​of the load moved by the industrial vehicle, and calculate each subsequent individual value after detecting that the acceleration of the industrial vehicle is less than a first predetermined value and subsequently accelerates to exceed the first predetermined value; and The corresponding values ​​from the plurality of sets are averaged to determine the calculated load; and The maximum speed of the industrial vehicle is controlled based on the calculated load from the movement of the industrial vehicle.

15. The system of claim 14, wherein the load comprises one or more trailers towed by an industrial vehicle.

16. The system of claim 14, wherein the processor, when executing executable instructions: The torque applied to the traction wheel is converted into an equivalent force; and The load moved by the industrial vehicle is calculated based at least in part on the equivalent value.

17. The system of claim 14, wherein the processor, when executing executable instructions: The maximum speed of the industrial vehicle is determined based on the calculated load and the gradient of the path along which the industrial vehicle travels.

18. The system of claim 14, wherein the processor, when executing executable instructions: Determine the rolling resistance of industrial vehicles under moving loads; and The load moved by the industrial vehicle is calculated based at least in part on the rolling resistance.

19. The system of claim 14, wherein the processor, when executing executable instructions: Determine the gradient of the path traveled by the industrial vehicle while moving the load; and The load moved by the industrial vehicle is calculated based at least in part on the slope.

20. The system of claim 14, wherein the industrial vehicle includes a fork assembly.

21. The system of claim 14, wherein the processor, when executing executable instructions: The initial value of the calculated load is limited to the maximum load that the industrial vehicle is designed to move.

22. The system of claim 14, wherein the processor, when executing executable instructions: Determine when the lifting mechanism of an industrial vehicle should be raised or lowered. When the lifting mechanism raises or lowers, the load moved by the industrial vehicle based on acceleration and torque is not calculated.

23. The system of claim 14, wherein the processor, when executing executable instructions: In response to the industrial vehicle accelerating to a value exceeding the first predetermined value and traveling at least a predetermined distance, a set of at least a minimum number of individual values ​​comprising the load moved by the industrial vehicle is calculated by calculating a set of individual values ​​comprising a predetermined number of individual values ​​comprising the load moved by the industrial vehicle; and The predetermined number of individual values ​​are averaged to determine the corresponding values ​​for the set.

24. The system of claim 23, wherein the processor limits a predetermined number of individual values ​​of the load to equal or less than 200 when executing executable instructions.

25. The system of claim 23, wherein the processor, when executing executable instructions, limits a predetermined number and sampling rate of individual values ​​of the load such that the count of individual values ​​of the load reaches the predetermined number within 2 seconds from the first increment of the count.

26. The system of claim 14, wherein the load value of each individual load moved by the industrial vehicle is calculated according to the following formula: in F A It is the equivalent linear force value, which is equivalent to the torque applied to the traction wheel; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, expressed as a percentage. VA g The acceleration of an industrial vehicle is expressed in terms of g; and Individual load value = TVM – unloaded weight of industrial vehicle.

27. The system of claim 14, wherein the load value of each individual load moved by the industrial vehicle is calculated according to the following formula: in: T C It is a torque command; T IT It is inertial torque; The gearbox transmission ratio is the predetermined gearbox transmission ratio for industrial vehicles; Gearbox efficiency is the predetermined gearbox efficiency for industrial vehicles; The radius of the driven wheel is the radius of the traction wheel; R% is the rolling resistance value; G% is the current slope of the surface on which the industrial vehicle travels, expressed as a percentage. VA g The acceleration of an industrial vehicle is expressed in terms of g; and Individual load value = TVM – unloaded weight of industrial vehicle.

28. The system of claim 14, wherein the processor, when executing executable instructions: Determine whether the industrial vehicle has traveled more than a predetermined distance after a previous stop to allow for the absorption of slack in the trailer linkage; and The delay calculation is performed on the load moved by the industrial vehicle until it is determined that the industrial vehicle has traveled more than a predetermined distance.

29. A method for controlling the maximum vehicle speed of an industrial vehicle, comprising: The processor of the industrial vehicle determines the torque applied to the traction wheels of the industrial vehicle; The industrial vehicle's acceleration when torque is applied to the traction wheel is determined by the industrial vehicle's processor; The load moved by the industrial vehicle is calculated by the vehicle's processor, based at least in part on acceleration and torque applied to the traction wheel; as well as The industrial vehicle's processor controls the maximum speed of the industrial vehicle based on the load calculated from the vehicle's movement. The computational load includes: In response to the industrial vehicle accelerating to a level exceeding a first predetermined value and traveling at least a predetermined distance, a set of individual load values, including a predetermined number of loads moved by the industrial vehicle, is calculated. and The predetermined number of individual load values ​​are averaged to determine the corresponding set load value for the set; Further individual load values ​​are calculated only if at least one of the following vehicle conditions is met: a) The acceleration of the industrial vehicle is less than a first predetermined value, and b) The speed of the industrial vehicle is less than the second predetermined value.

30. The method of claim 29, wherein further individual load values ​​are calculated only after at least two of the vehicle conditions are met.

31. A method for controlling the maximum vehicle speed of an industrial vehicle, comprising: The processor of the industrial vehicle determines the torque applied to the traction wheels of the industrial vehicle; The industrial vehicle's acceleration when torque is applied to the traction wheel is determined by the industrial vehicle's processor; The load moved by the industrial vehicle is calculated by the vehicle's processor, based at least in part on acceleration and torque applied to the traction wheel; as well as The industrial vehicle's processor controls the maximum speed of the industrial vehicle based on the load calculated from the vehicle's movement. The computational load includes: In response to the industrial vehicle accelerating to a level exceeding a first predetermined value and traveling at least a predetermined distance, a set of individual load values, including a predetermined number of loads moved by the industrial vehicle, is calculated; and The predetermined number of individual load values ​​are averaged to determine the corresponding set load value for that set. The processor of the industrial vehicle detects a first operating condition, which includes: a) The acceleration of the industrial vehicle is less than a first predetermined value, and b) The speed of the industrial vehicle is less than the second predetermined value; Following the first operating condition, the processor of the industrial vehicle determines the second operating condition, which includes a predetermined time period following the first operating condition: a) Begin accelerating again to exceed the first predetermined value, and b) The predetermined distance has been traveled; In response to the occurrence of a first operating condition and the occurrence of a second operating condition within a predetermined time period following the first operating condition, the processor of the industrial vehicle collects another set of load values ​​of the load moved by the industrial vehicle; and The corresponding values ​​of multiple set load values ​​are averaged to calculate the calculated load.

32. A system for controlling the maximum vehicle speed of an industrial vehicle, comprising: Storage device that stores executable instructions; as well as The processor, which communicates with the storage device, executes executable instructions as follows: Determine the torque applied to the traction wheels of the industrial vehicle; Determine the acceleration of the industrial vehicle when torque is applied to the traction wheel; The load on the movement of industrial vehicles is calculated at least in part based on acceleration and the torque applied to the traction wheels; and The maximum speed of industrial vehicles is controlled based on the calculated load from their movement. When the processor executes executable instructions to calculate the load: In response to an industrial vehicle accelerating to a value exceeding a first predetermined value and traveling at least a predetermined distance, a set of individual values ​​including a predetermined number of loads moved by the industrial vehicle is calculated. and The predetermined number of individual values ​​are averaged to determine the corresponding set load value for the set. Detecting a first operating condition, the first operating condition includes: a) The acceleration of the industrial vehicle is less than a first predetermined value, and b) The speed of the industrial vehicle is less than the second predetermined value; Following the first operating condition, a second operating condition is determined, which includes the industrial vehicle operating within a predetermined time period following the first operating condition: a) Begin accelerating again to exceed the first predetermined value, and b) The predetermined distance has been traveled; In response to the occurrence of a first operating condition and the occurrence of a second operating condition within a predetermined time period following the first operating condition, another set of load values ​​of the load moved by the industrial vehicle is collected; and The corresponding values ​​of multiple set load values ​​are averaged to calculate the calculated load.

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