Hydrostatic bulldozer walking control method and system, and hydrostatic bulldozer

Abstract

This invention relates to the field of engineering machinery control technology, specifically providing a method and system for controlling the travel of a hydrostatic bulldozer, and a hydrostatic bulldozer. The method includes: receiving user input through a display and control unit; setting and storing a corresponding maximum speed limit for each of multiple gears; determining the currently active gear from the multiple gears in response to a gear switching signal; acquiring a handle angle signal output by a travel handle, wherein the travel handle is a stepless speed control handle, and its handle angle has a continuous linear correspondence with the target vehicle speed; and linearly outputting a vehicle speed control command based on the handle angle signal, with the maximum speed limit corresponding to the currently active gear as the upper limit, so that the actual vehicle speed changes steplessly within the range from zero to the corresponding maximum speed limit. This invention achieves graded linear speed and smooth operation, ensures operational safety, and provides personalized adaptation and rapid response.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery control technology, specifically to a hydrostatic bulldozer travel control method and system, and a hydrostatic bulldozer. Background Technology

[0002] Hydrostatic bulldozers (also known as fully hydraulic bulldozers) use a hydrostatic transmission system to replace the traditional hydraulic mechanical transmission system, offering advantages such as ease of operation and high transmission efficiency. Currently, the travel control of hydrostatic bulldozers mainly employs the following two technical solutions.

[0003] The first solution is a stationary gear control scheme. This scheme divides the travel speed into multiple fixed gears, such as forward gear I, II, and III, each corresponding to a fixed travel speed value. The operator switches gears via a gear selector, and the vehicle travels at the fixed speed corresponding to that gear. Some schemes add a fine-tuning function to the fixed gears, allowing the operator to make small-range speed adjustments around the gear speed. This scheme has the following drawbacks: First, the speed jumps between gears are significant, and the sudden change in vehicle speed during gear shifts creates a jerky feeling, affecting driving comfort and operational accuracy; second, the gear speed values ​​are preset by the manufacturer and cannot be personalized according to the operator's skill level or specific working conditions, resulting in insufficient adaptability; third, the operator needs to frequently switch gears to adapt to different working speed requirements, making the operation cumbersome.

[0004] A purely stepless speed control scheme. This scheme eliminates fixed gears and directly controls the vehicle speed via a travel handle. The handle angle has a linear relationship with the vehicle speed, allowing the operator to continuously change the speed from zero to the maximum speed, achieving a smooth and continuous speed adjustment process. However, this scheme has the following drawbacks: First, it lacks tiered speed limit protection, making it easy for novice operators or those unfamiliar with road conditions to accidentally exceed the speed limit, posing a safety hazard. Second, it cannot set a speed limit based on different work scenarios or operator skill levels, resulting in insufficient personalized management capabilities. Third, it cannot effectively constrain the vehicle speed in specific working conditions where a maximum speed limit is required.

[0005] Therefore, there is an urgent need for a driving control scheme that can achieve graded speed limit management, support personalized speed parameter settings, and retain the smooth characteristics of stepless speed regulation. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a hydrostatic bulldozer travel control method and system, and a hydrostatic bulldozer. By redefining the gears as customizable speed upper limits and combining them with stepless speed regulation via a handle, it achieves graded linear speeds and smooth operation, ensuring operational safety, and providing personalized adaptation and rapid response.

[0007] In a first aspect, the technical solution of the present invention provides a hydrostatic bulldozer travel control method, comprising the following steps: The display and control unit receives user input and sets and stores the corresponding maximum speed limit for each of the multiple gears; for any two gears, the maximum speed limit of the higher gear is greater than the maximum speed limit of the lower gear. In response to a gear shift signal, the currently active gear is determined from multiple gears; The handle angle signal output by the walking handle is obtained. The walking handle is a stepless speed control handle, and its handle angle has a continuous linear correspondence with the target vehicle speed. The maximum speed limit corresponding to the currently activated gear is used as the upper limit. The speed control command is linearly output according to the handle angle signal, so that the actual speed changes steplessly within the range of zero to the corresponding maximum speed limit.

[0008] Secondly, the technical solution of the present invention provides a hydrostatic bulldozer travel control system, comprising: Display and control unit: used to receive user input, set and store the corresponding maximum speed limit for each of the multiple gears; Walking handle: This is a stepless speed control handle used to output an analog handle angle signal corresponding to the handle angle; Walking controller: Electrically connected to the display and control unit and the walking handle respectively, used to execute the above control methods.

[0009] Thirdly, the technical solution of the present invention provides a hydrostatic bulldozer equipped with the above-mentioned control system.

[0010] As can be seen from the above technical solution, this application has the following advantages: First, the gear function is redefined as the speed upper limit boundary. Each gear corresponds to a settable maximum speed limit. The driving handle achieves stepless speed adjustment throughout the range from zero to this limit, retaining the safety management function of graded speed limits (different gears correspond to different maximum speed limits) while achieving a smooth operating experience with stepless speed adjustment. That is, the handle angle and vehicle speed are continuously and linearly correlated, and the two are organically integrated and do not contradict each other. Second, multiple gears are set, each corresponding to a customizable maximum speed limit, realizing graded speed limit protection. Novice operators can select a lower gear to limit the maximum speed within a safe range. Even if the handle is accidentally pushed to the maximum angle, the vehicle will not exceed the speed limit. At the same time, the maximum speed limit of the higher gear must be greater than the maximum speed limit of the lower gear, logically eliminating the safety risks caused by gear confusion. Third, user input is received through the display and control unit, allowing operators or managers to independently set the maximum speed limit for each gear. The same bulldozer can flexibly adjust the speed limit of each gear according to different operating scenarios, operator skill levels, and safety requirements, greatly improving its versatility and adaptability. Fourth, stepless speed regulation is achieved within the full travel range of the lever, with the maximum speed limit of the gear as the upper limit. When slow fine-tuning is needed, the operator can push the lever slightly; when rapid acceleration is needed, the operator can quickly push the lever to a large angle. Compared with traditional chuck-type gear shifters, this solution ensures both smooth speed regulation and rapid response. Attached Figure Description

[0011] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of a hydrostatic bulldozer travel control system provided in an embodiment of the present invention.

[0013] Figure 2 This is a schematic flowchart of a hydrostatic bulldozer travel control method provided in an embodiment of the present invention.

[0014] Figure 3 This is a schematic diagram of the handle angle-vehicle speed curve.

[0015] Figure 4 This is a schematic diagram of the vehicle speed curve during gear shifting. Detailed Implementation

[0016] To make the purpose, features, and advantages of this application more apparent and understandable, specific embodiments and accompanying drawings will be used to clearly and completely describe the technical solution protected by this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0017] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this application and in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] The key terms used in this invention will be explained below.

[0019] Friction positioning handle: This refers to a handle that can be stably held at any angle position by relying on its internal friction structure during the forward and backward pushing process, and does not automatically return to the center after being released, thus achieving position holding.

[0020] Stepless speed regulation: The vehicle speed does not change abruptly according to fixed gears, but changes continuously and linearly with the angle of the handle, achieving smooth speed regulation from 0 to the set upper limit.

[0021] Speed ​​limiter: Divides driving speed into multiple speed levels, each level corresponding to a settable maximum speed, and the speed adjustment by the lever shall not exceed the limit.

[0022] Self-reset button: When pressed, it triggers a signal and automatically springs back to its original position after being released. It will not remain in the pressed state and is used for gear shifting.

[0023] Display and control interaction: Vehicle speed parameters can be viewed, set, and saved through the display screen and operation interface, and data communication can be carried out with the travel controller.

[0024] Vehicle speed range overlap constraint: The speed ranges of different gears can partially overlap, but the setting value of the higher gear must be greater than the setting value of the lower gear to ensure the safety of the gear logic.

[0025] Figure 1 A schematic diagram of a hydrostatic bulldozer travel control system provided in an embodiment of the present invention is shown below. Figure 1 As shown, the system includes a display and control unit, a walking handle, and a walking controller.

[0026] Display and control unit: used to receive user input, set and store the corresponding maximum speed limit for each of the multiple gears; Walking handle: This is a stepless speed control handle used to output an analog handle angle signal corresponding to the handle angle; Travel controller: Electrically connected to the display and control unit and the travel handle, used to execute the travel control method for the hydrostatic bulldozer. The specific steps of this method are detailed in subsequent embodiments and will not be repeated here.

[0027] The display and control unit is preferably an in-vehicle display screen, which communicates with the travel controller via a CAN communication port. The display and control unit provides a human-machine interface, receives user input, and sets and stores the corresponding maximum speed limit for each of the multiple gear positions. Users can independently set the required maximum speed limit for each gear position based on factors such as the work scenario and their operational proficiency. The display and control unit also sends the set parameters to the travel controller via the CAN bus and displays the current gear status, vehicle speed information, etc., in real time.

[0028] Specifically, the display and control unit provides settings corresponding to the number of gears, with each setting associated with an editable numerical input box. After the operator inputs the required maximum vehicle speed limit via the touchscreen or physical buttons, the display and control unit sends the set value to the travel controller via the CAN bus. The travel controller then stores the received set value in non-volatile memory.

[0029] To prevent gear shift logic errors, the travel controller has a built-in gear shift constraint module. When the operator sets a maximum speed limit for a certain gear, the travel controller executes the following constraint logic: (1) If the gear is set to the lowest gear, there is no lower limit constraint, and only the setting value is checked to see if it is within the allowable range; (2) If the gear is not the lowest gear, the maximum speed limit value stored in the previous lower gear is read and the current setting value is forced to be greater than the value set in that lower gear. (3) If the setting value input by the operator does not meet the above constraints, the travel controller refuses to save the setting value and issues a prompt message through the display and control unit, such as displaying the text prompt "the speed of the high gear must be greater than the speed of the low gear" or issuing a warning sound.

[0030] For example, if the maximum speed in gear 1 is already set to 5 km / h, when the operator sets the maximum speed in gear 2, the travel controller will only allow input values ​​greater than 5 km / h, such as 5.1 km / h, 6 km / h, 8 km / h, etc.; if the operator attempts to set gear 2 to 5 km / h or 4.5 km / h, the travel controller will refuse to save and issue a prompt.

[0031] It should be noted that this embodiment allows for partial or complete overlap of the speed ranges of different gears. The only mandatory constraint is that for any two gears, the maximum speed limit of the higher gear must be greater than the maximum speed limit of the lower gear. This constraint does not involve the lower limit of the gear speed range, nor does it prohibit overlap between gear intervals. For example, if the maximum speed limit for gear 1 is set to 6 km / h and the maximum speed limit for gear 2 is set to 8 km / h, then the constraint condition is met. In this case, the actual speed ranges of the two gears can be 0-6 km / h and 0-8 km / h respectively, overlapping within the 0-6 km / h range, but this does not affect the normal operation of the system.

[0032] The travel handle is a stepless speed-regulating handle. Preferably, it is a friction-positioning handle, a handle with a damping potentiometer, or a Hall-effect non-contact handle. The friction-positioning handle has an internal friction positioning mechanism that allows the handle to maintain its position at any angle after being pushed or pulled, relying on friction. The use of a stepless speed-regulating handle achieves truly stepless continuous speed regulation without any jerking or jumps, significantly improving the handling feel. An angle sensor, which can be a Hall sensor or a potentiometer-type sensor, is installed at the pivot of the travel handle to detect the handle's rotation angle and output an analog voltage signal linearly related to the handle angle. The output terminal of the travel handle is electrically connected to the analog input port of the travel controller, outputting the analog voltage signal to the travel controller.

[0033] In some optional implementations, a self-resetting button is provided on the travel handle, including an upshift button and a downshift button. The gear selection buttons are preferably integrated into the handle, allowing for a seamless user experience by pushing the handle, pressing the gear selection button, and viewing the display. Both buttons are self-resetting switches, normally in the off state, closing when pressed, and automatically returning to the off state when released. The upshift button is electrically connected to the travel controller via a first I / O port, and the downshift button is electrically connected to the travel controller via a second I / O port, used to input upshift and downshift switching signals to the travel controller, respectively.

[0034] In other alternative implementations, the gear shift signal can also be generated by a rotary switch, a toggle switch, or a virtual button. Specifically, a rotary switch generates a shift signal by rotating to the corresponding position for different gears; a toggle switch generates a shift signal by moving to the corresponding position for different gears; and a virtual button is an interactive interface element displayed on the touchscreen of the control unit, where the user generates a shift signal through touch operation.

[0035] In some optional implementations, the travel controller can employ a microprocessor such as a single-chip microcomputer, DSP, or ARM, integrating non-volatile memory, an analog-to-digital converter, an I / O interface module, and a CAN communication module. The travel controller is electrically connected to the display and control unit, the travel handle, and the gear shift signal generator, respectively, to execute the hydrostatic bulldozer travel control method. The gear shift signal generator refers to the aforementioned rotary switch, toggle switch, virtual button, self-reset button, or other devices that generate gear shift signals.

[0036] Figure 2 This is a flowchart illustrating a hydrostatic bulldozer travel control method according to an embodiment of the present invention. The method is based on the aforementioned hydrostatic bulldozer travel control system. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0037] like Figure 2 As shown, the method includes the following steps.

[0038] S1 receives user input through the display and control unit, sets and stores the corresponding maximum speed limit for each of the multiple gears; wherein, for any two gears, the maximum speed limit of the higher gear is greater than the maximum speed limit of the lower gear.

[0039] S1.1 Receives the maximum speed limit setting value input by the user for the target gear through the display and control unit.

[0040] The operator selects the target gear and inputs the desired maximum speed limit setting value through the gear and speed setting interface of the display and control unit. The display and control unit sends this setting value to the travel controller via the CAN bus, and the travel controller 4 receives and temporarily stores the setting value.

[0041] S1.2, Read the stored maximum speed limit of the adjacent gear that is one gear lower than the target gear.

[0042] The driving controller reads the stored maximum speed limit of the adjacent gear one gear lower than the target gear from its internal non-volatile memory based on the received target gear number. If the target gear is the lowest gear (e.g., gear 1), there is no adjacent lower gear, and the process jumps directly to step S1.4 to perform the storage.

[0043] S1.3, determine whether the set value is greater than the maximum speed limit of the adjacent gear.

[0044] The driving controller compares the user-input setting with the maximum speed limit of the adjacent lower gear, and determines whether the setting is greater than the limit of the adjacent lower gear.

[0045] S1.4 If so, store the set value as the maximum speed limit for the target gear in a non-volatile memory.

[0046] If the judgment result is yes, meaning the set value is greater than the limit of the adjacent lower gear, the travel controller writes the user-input set value as the maximum speed limit of the target gear into the non-volatile memory, overwriting the original stored value. After storage is complete, the travel controller returns a storage success confirmation message to the display and control unit, and the display and control unit displays a "Setting successful" prompt.

[0047] S1.5 If not, refuse to store the set value and issue a prompt message through the display and control unit.

[0048] If the judgment result is negative, meaning the set value is not greater than the adjacent lower gear limit, the travel controller refuses to perform the storage operation and maintains the original maximum speed limit of the target gear unchanged. Simultaneously, the travel controller sends a prompt command to the display unit via the CAN bus. The display unit displays a warning message based on this command, such as the text "High gear speed must be greater than low gear speed," and may also issue an audible warning to remind the operator to re-enter the value.

[0049] S2, in response to the gear shift signal, determines the currently active gear from multiple gears.

[0050] Taking the self-reset button as an example of a gear shifting signal generator, the self-reset button includes an upshift button and a downshift button, both of which are electrically connected to the I / O interface of the travel controller and input switch signals to the travel controller using level triggering or edge triggering.

[0051] In some optional implementations, the travel controller internally maintains a currently active gear register to store the currently used gear number. During system initialization, the travel controller defaults to the lowest gear or reads the gear status stored before the last shutdown.

[0052] S2.1, the on / off state of the upshift button is detected in real time through the first I / O port, and the on / off state of the downshift button is detected in real time through the second I / O port.

[0053] The walking controller connects to the upshift and downshift buttons via two independent I / O ports. Both buttons use a self-resetting switch structure, which is normally in the open state, and the I / O port is kept high level through a pull-up resistor; when a button is pressed, the switch closes, and the I / O port level is pulled low.

[0054] The walking controller scans the level status of the two I / O ports in real time at a preset sampling period. When it detects that the level of a port changes from high to low (falling edge), it determines that the corresponding button has been pressed; when it detects that the level returns from low to high (rising edge), it determines that the button has been released.

[0055] To avoid false triggering caused by mechanical vibration, the walking controller can have a built-in button debounce filtering module: after detecting a change in level, the port status is read again after a delay of 20ms-50ms. If the two read statuses are consistent, it is confirmed as a valid button trigger event.

[0056] S2.2 When a valid level change is detected at the first I / O port, it is determined to be an upshift operation, and the current active shift number is incremented by 1; when a valid level change is detected at the second I / O port, it is determined to be a downshift operation, and the current active shift number is decremented by 1.

[0057] If a valid trigger event is detected on the I / O port corresponding to the upshift button, it is determined to be an upshift operation, and the current active gear number is incremented by 1; if a valid trigger event is detected on the I / O port corresponding to the downshift button, it is determined to be a downshift operation, and the current active gear number is decremented by 1; if valid trigger events are detected on both I / O ports at the same time, it is determined to be an invalid operation, the trigger is ignored, and the current active gear remains unchanged.

[0058] S2.3 Perform boundary checks on the calculated gear number. If it exceeds the preset maximum number of gears, lock it as the maximum gear number. If it is lower than the minimum gear number, lock it as the minimum gear number.

[0059] After the gear number calculation in step S2.2, a boundary check is performed on the calculation result. If the gear number after the upshift calculation exceeds the maximum number of gears preset by the system, the travel controller will lock the currently active gear to the maximum gear number and will not continue to increase it; if the gear number after the downshift calculation is lower than the minimum gear number, the travel controller will lock the currently active gear to gear 1 and will not continue to decrease it; if the calculation result is within the valid gear range, the travel controller will update the currently active gear to the calculated gear number.

[0060] S2.4, determine the gear number after boundary check as the currently active gear.

[0061] The travel controller writes the updated currently active gear number into the currently active gear register and sends the gear status information to the display and control unit via the CAN bus. The display and control unit displays the current gear number in real time for operator confirmation. Simultaneously, based on the updated currently active gear number, the travel controller reads the maximum speed limit corresponding to that gear from the non-volatile memory.

[0062] It should be noted that during gear shifting, the travel controller only changes the currently active gear number and does not process the handle angle signal in any way. If the travel handle is a friction positioning handle, the physical position of the handle remains unchanged while the operator presses the button. Therefore, the handle angle signal maintains its original value, ensuring that the vehicle speed does not change abruptly during gear shifting.

[0063] S3, acquire the handle angle signal output by the walking handle, wherein the walking handle is a stepless speed control handle, and its handle angle has a continuous linear correspondence with the target vehicle speed.

[0064] The travel controller acquires the handle angle signal output by the travel handle. In this embodiment, the travel handle is a continuously variable speed handle, and its handle angle has a continuous linear relationship with the target vehicle speed.

[0065] Specifically, an angle sensor is installed at the pivot of the walking handle. This angle sensor can be a Hall effect angle sensor or a potentiometer-type angle sensor. When the operator pushes or pulls the handle, the angle sensor detects the rotation angle of the handle in real time and outputs an analog voltage signal that is linearly related to the handle angle. For example, the handle's center position (0°) corresponds to a 0V output voltage, the handle's maximum angle (e.g., 30°) corresponds to a 5V output voltage, and any intermediate angle corresponds to a linear intermediate value between 0V and 5V.

[0066] The walking controller acquires the voltage signal through the analog input port and performs analog-to-digital conversion at a preset sampling period to obtain a digital quantity corresponding to the handle angle. Since the handle angle and the voltage signal are linearly related, the walking controller can directly convert the acquired voltage value into a handle angle ratio value, which continuously varies between 0 (handle center position) and 1 (handle maximum angle).

[0067] Figure 3 This diagram illustrates the lever angle versus vehicle speed curve, a straight line passing through the origin, representing the continuous linear relationship between lever angle and vehicle speed. The travel controller multiplies the lever angle proportional value by the maximum speed limit of the current gear to obtain the current target speed. Therefore, a continuous linear relationship is established between lever angle and target speed: a larger lever angle results in a higher target speed, and a smaller lever angle results in a lower target speed. Operators can precisely and continuously adjust the vehicle speed by controlling the lever angle, improving the smoothness of operation.

[0068] S4 uses the maximum speed limit corresponding to the currently activated gear as the upper limit and linearly outputs speed control commands based on the handle angle signal, so that the actual speed changes steplessly within the range of zero to the corresponding maximum speed limit.

[0069] In this embodiment, the travel controller generates a target speed value through a linear mapping algorithm based on the maximum speed limit corresponding to the currently active gear and the handle angle signal output by the travel handle, thereby achieving smooth transition control during gear switching.

[0070] S4.1, acquire the analog voltage signal output from the walking handle, obtain the voltage value through analog-to-digital conversion, and then process it according to the formula. Calculate the handle angle ratio value ,in This is the currently collected voltage value. This is the voltage value when the handle is in the neutral position. This is the voltage value when the handle is at its maximum angle.

[0071] S4.2, Read the maximum speed limit corresponding to the currently activated gear. and according to the formula Calculate the target vehicle speed .

[0072] The driving controller is based on the maximum speed limit of the currently activated gear. and handle angle ratio Calculate the target vehicle speed value according to a linear proportional relationship. .

[0073] For example, if the current gear is 2, the maximum speed limit is... Handle angle ratio (That is, the target vehicle speed is achieved when the handle is pushed to half of its maximum angle). .

[0074] S4.3, determine whether a gear shift event has been detected and whether the event has been confirmed as valid; if not, directly set the vehicle speed target value. Output the vehicle speed control command; if so, proceed to the next step.

[0075] In some alternative implementations, the travel controller internally maintains a gear shift event flag, which is set when a valid gear shift signal is detected and cleared after the gear shift process is completed. The travel controller can determine whether it is currently in the gear shift process by reading the state of this flag.

[0076] If the travel controller does not detect a gear shift event, or if the detected event is not confirmed as valid after anti-shake processing, the gear shift event flag will be in a false state. In this case, the travel controller will not perform transition processing and will directly use the vehicle speed target value calculated in step S4.2. The speed control command is output to the actuator.

[0077] If the travel controller detects a gear shift event and the event is confirmed to be valid, the gear shift event flag is set to true. At this time, the travel controller does not immediately update the vehicle speed target value to the value corresponding to the new gear, but enters step S4.4 and subsequent steps to perform smooth speed transition processing to avoid sudden speed changes and eliminate the impact and jerking caused by sudden speed changes.

[0078] In some optional implementations, the travel controller includes a ramp function generator to control the rate of change of the target vehicle speed. When a gear shift occurs, the travel controller executes the transition logic steps S4.4 and S4.5.

[0079] It should be noted that the confirmation method for the gear shift event corresponds to the button signal processing logic in step S2, and will not be elaborated here.

[0080] Through this judgment step, the driving controller distinguishes between steady-state operation and gear shifting. In steady state, it directly outputs vehicle speed command to ensure response speed, and enters transition processing during gear shifting to ensure smoothness, thus balancing response speed and handling smoothness.

[0081] S4.4, Read the maximum speed limit corresponding to the new gear. According to the formula Calculate the transition target vehicle speed value.

[0082] Figure 4 This is a schematic diagram of the shift speed curve; the lever position remains unchanged during gear shifting. The travel controller adjusts the speed according to the maximum speed limit of the new gear. and the current handle angle ratio value (Because the friction positioning handle remains in a fixed position during button operation,) (The value remains unchanged), calculate the transition target vehicle speed value. .

[0083] S4.5, Judgment Target speed before gear shift The size relationship between them: (1) If Then it enters the gear shift acceleration transition state, according to the formula Increase the target vehicle speed value periodically; (2) If Then it enters a gear shift deceleration transition state, according to the formula. Decrease the target vehicle speed value periodically; (3) If If the current target speed remains unchanged, then there is no need to perform a gear shift transition. in, The preset slope ascent rate, The preset slope descent rate, This is the control cycle; this step is repeated in each control cycle until the target vehicle speed is reached. achieve The updated vehicle speed target value will be output as the vehicle speed control command.

[0084] Vehicle speed target value achieve Afterward, it exits the transition state and enters the steady-state output mode. It can be understood that the transition state refers to the period during which the travel controller, after detecting a gear shift event, is smoothly adjusting the target vehicle speed.

[0085] Slope Ascent Rate and slope descent rate The system can receive user input for setting and storage based on vehicle characteristics and operational requirements via the display and control unit. For example, and All speeds are preset to 1.0 km / h / s, meaning the vehicle speed changes by 1 km / h per second. Operators can also customize these speeds via the display and control unit.

[0086] For example, suppose the current state is: maximum speed 6 km / h in gear 1, lever angle ratio α = 0.5, and the current target speed is 3 km / h. If the operator switches to gear 2 (maximum speed 8 km / h), the new target speed is 8 × 0.5 = 4 km / h. The travel controller, at a ramp ascent rate of 1.0 km / h / s, gradually increases the target speed from 3 km / h to 4 km / h within 1 second, achieving the desired result. Figure 4 The smooth transition curve shown.

[0087] For downshifting, such as switching from 2nd gear (8km / h) to 1st gear (6km / h), the lever angle ratio α=0.5 remains unchanged, and the target speed gradually decreases from 4km / h to 3km / h, thus achieving a smooth transition.

[0088] After the travel controller completes the calculation of the target vehicle speed, it will... As a vehicle speed control command, it is sent to the hydraulic pump / motor controller via the CAN bus. The hydraulic pump / motor controller executes the existing speed closed-loop control, that is, based on the deviation between the target vehicle speed and the actual vehicle speed, it adjusts the displacement of the electric proportional pump through a PID algorithm to achieve vehicle speed control.

[0089] This invention provides a hydrostatic bulldozer equipped with the hydrostatic bulldozer travel control system provided in the above embodiments, which executes the hydrostatic bulldozer travel control method provided in the above embodiments.

[0090] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for controlling the travel of a hydrostatic bulldozer, characterized in that, Includes the following steps: The display and control unit receives user input and sets and stores the corresponding maximum speed limit for each of the multiple gears; for any two gears, the maximum speed limit of the higher gear is greater than the maximum speed limit of the lower gear. In response to a gear shift signal, the currently active gear is determined from multiple gears; The handle angle signal output by the walking handle is obtained. The walking handle is a stepless speed control handle, and its handle angle has a continuous linear correspondence with the target vehicle speed. The maximum speed limit corresponding to the currently activated gear is used as the upper limit. The speed control command is linearly output according to the handle angle signal, so that the actual speed changes steplessly within the range of zero to the corresponding maximum speed limit.

2. The hydrostatic bulldozer travel control method according to claim 1, characterized in that, The gear shift signal can be generated in at least one of the following ways: a rotary switch is triggered, a toggle switch is triggered, a virtual button is triggered, or a self-reset button is triggered.

3. The hydrostatic bulldozer travel control method according to claim 1, characterized in that, The walking handle is a friction positioning handle, a handle with a damping potentiometer, or a Hall effect non-contact handle. The friction positioning handle is configured to remain at that angle position by friction after being pushed or pulled to any angle.

4. The hydrostatic bulldozer travel control method according to claim 1, characterized in that, The display and control unit receives user input and sets and stores the corresponding maximum speed limit for each of the multiple gears. Specifically, this includes: The display and control unit receives the maximum speed limit setting value input by the user for the target gear. Read the stored maximum speed limit of the adjacent gear that is one gear lower than the target gear; Determine whether the set value is greater than the maximum speed limit of the adjacent gear; If so, the set value is stored in non-volatile memory as the maximum speed limit for the target gear. If not, refuse to store the set value and issue a prompt message through the display and control unit.

5. The hydrostatic bulldozer travel control method according to claim 2, characterized in that, The self-reset buttons include the upshift button and the downshift button.

6. The hydrostatic bulldozer travel control method according to claim 5, characterized in that, In response to a gear shift signal, the currently active gear is determined from multiple gears, specifically including: The on / off state of the upshift button is detected in real time through the first I / O port, and the on / off state of the downshift button is detected in real time through the second I / O port. When a valid level change is detected at the first I / O port, it is determined as an upshift operation, and the current active shift number is incremented by 1; when a valid level change is detected at the second I / O port, it is determined as a downshift operation, and the current active shift number is decremented by 1. Perform boundary checks on the calculated gear number. If it exceeds the preset maximum number of gears, lock it as the maximum gear number. If it is lower than the minimum gear number, lock it as the minimum gear number. The gear number after boundary check is determined as the currently active gear.

7. The hydrostatic bulldozer travel control method according to claim 1, characterized in that, The maximum speed limit corresponding to the currently activated gear is used as the upper limit. The vehicle speed control command is linearly output according to the handle angle signal, specifically including: The analog voltage signal output from the walking handle is collected, the voltage value is obtained through analog-to-digital conversion, and then processed according to the formula. Calculate the handle angle ratio value ,in This is the currently collected voltage value. This is the voltage value when the handle is in the neutral position. This is the voltage value when the handle is at its maximum angle. Read the maximum speed limit corresponding to the currently activated gear. and according to the formula Calculate the target vehicle speed ; Determine if a gear shift event has been detected and confirmed as valid; if not, directly set the vehicle speed target value. Output as a vehicle speed control command; if so, proceed to the next step. Read the maximum speed limit corresponding to the new gear. According to the formula Calculate the target speed value during the transition period; judge Target speed before gear shift The size relationship between them: 1) If Then it enters the gear shift acceleration transition state, according to the formula Increase the target vehicle speed value periodically; 2) If Then it enters a gear shift deceleration transition state, according to the formula. Decrease the target vehicle speed value periodically; 3) If If so, the current target speed will remain unchanged; in, The preset slope ascent rate, The preset slope descent rate, This is the control cycle; this step is repeated in each control cycle until the target vehicle speed is reached. achieve The updated vehicle speed target value will be output as the vehicle speed control command.

8. The hydrostatic bulldozer travel control method according to claim 7, characterized in that, Slope Ascent Rate and slope descent rate The display and control unit receives user input for setting and storage.

9. A hydrostatic bulldozer travel control system, characterized in that, include: Display and control unit: used to receive user input, set and store the corresponding maximum speed limit for each of the multiple gears; Walking handle: This is a stepless speed control handle used to output an analog handle angle signal corresponding to the handle angle; Walking controller: electrically connected to the display and control unit and the walking handle respectively, and used to execute the control method according to any one of claims 1 to 8.

10. A hydrostatic bulldozer, characterized in that, It is equipped with the control system as described in claim 9.

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