A tractor pto control system and control method

Abstract

The present application relates to the technical field of PTO control system, more specifically, the present application relates to a tractor PTO control system and control method, the system includes PTO controller, three point suspension state acquisition unit, PTO state acquisition unit, engine and vehicle state acquisition unit and PTO execution unit.PTO controller in three point suspension descent stage, the suspension height sequence is corresponded with PTO load state sequence according to time, the load climbing section is extracted and the work window anchor record with window mark is generated;When the suspension is lifted out of the work height window, the work exit confirmation record is formed in combination with the reverse change of the load, and the window locking state is entered under the head lifting condition;When the suspension reenters the same work height window, the recovery test lower than the target PTO output is executed first, and whether the PTO output is recovered is determined according to the matching result of the test load response and the load climbing reference characteristic.

Description

Technical Field

[0001] This invention relates to the field of PTO control system technology, and more specifically, to a tractor PTO control system and control method. Background Technology

[0002] A tractor's PTO (Power Take-Off) is typically used to transfer power from the tractor's engine or transmission system to agricultural implements such as rotary tillers, straw return machines, mowers, ditchers, and fertilizer spreaders. These implements are usually used in conjunction with the tractor's three-point suspension during operation. The driver controls the implementation's height via the three-point suspension and controls the power input to the implement's working components via the PTO.

[0003] In actual field operations, when a tractor reaches the edge of a field, turns, avoids obstacles, or reverses, the driver typically raises the three-point suspension to move the implement away from the working position; upon re-entering the working row, the three-point suspension is lowered to resume operation. Under these conditions, the PTO output state is directly related to changes in the three-point suspension height and the implement load. If the PTO maintains a high output, it may cause the implement to continue rotating when not in operation; frequent complete disengagement and re-engagement of the PTO can easily increase PTO clutch slippage and transmission shock.

[0004] Existing tractor PTO (Prestress Tolerance) control mostly uses manual switching or sets PTO engagement and disengagement points based on the three-point suspension position. The PTO is disengaged when the three-point suspension is above a certain position and engaged when it is below. While this method achieves basic linkage between the PTO and suspension position, its control is usually based on a fixed height point or range, making it difficult to reflect the actual operating conditions under different implements, working depths, and terrain conditions. Especially during the process of the implement descending into the soil or contacting the work object, reaching a certain three-point suspension height does not necessarily mean the implement has entered a stable operating state. Instead, whether the implement has truly entered an operating state often requires judgment based on changes in PTO load, engine load, or PTO output shaft speed. If only suspension height is used as the basis for PTO recovery, problems such as premature PTO recovery before the implement has stably contacted the work object, or significant impact on PTO recovery when the load on the implement suddenly increases, can easily occur.

[0005] Therefore, we propose a tractor PTO control system and control method to solve the above problems. Summary of the Invention

[0006] In order to overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a tractor PTO control system and control method to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a tractor PTO control system, including a PTO controller, and a three-point suspension state acquisition unit, a PTO state acquisition unit, an engine and vehicle state acquisition unit, and a PTO execution unit connected to the PTO controller: the three-point suspension state acquisition unit outputs the suspension height and suspension lifting status of the three-point suspension to the PTO controller; the PTO state acquisition unit outputs the PTO output shaft speed and PTO load status to the PTO controller; the engine and vehicle state acquisition unit outputs the engine status and vehicle operating status to the PTO controller; the PTO controller is configured to: during the three-point suspension descent phase, correlate the suspension height sequence with the PTO load status sequence according to time, extract the load climbing segment where the PTO load transitions from a non-operating load state to an operating load state, and generate an operating window anchoring record, the operating window anchoring record including a window identifier, an operating height window, and a load climbing reference feature; when the PTO is running and the three-point suspension is lifted out of the operating height window, based on the suspension height separation state and the reverse change of the PTO load relative to the load climbing reference feature, A work exit confirmation record is generated. When a work exit confirmation record is generated and the vehicle's operating status meets the conditions for ground lifting, a PTO hold authorization record with a window identifier is generated. The work window anchoring record is set to a window locked state, and the generation of new work window anchoring records is suspended while the window is locked. While the window is locked, the PTO execution unit is controlled to perform a short-term PTO hold, and PTO recovery is restricted to be performed only based on a PTO hold authorization record with the same window identifier. When the PTO hold authorization record is valid and the three-point suspension re-descends into the work height window corresponding to the window identifier, a recovery trial authorization record is generated, and the PTO execution unit is controlled to perform a PTO recovery trial below the target PTO output based on the recovery trial authorization record. The trial load response during the PTO recovery trial is collected. When the trial load response matches the load climb reference characteristics, a PTO recovery access record is generated, and the PTO output is recovered based on the PTO recovery access record. When the trial load response does not match the load climb reference characteristics, a recovery prohibition record is generated, and the short-term PTO hold is maintained or the PTO hold authorization record is revoked.

[0008] In a preferred embodiment, the load climb reference features include at least two of the following: load climb start height, load climb end height, load climb direction, and load climb amplitude.

[0009] In a preferred embodiment, the PTO load state is the PTO output torque, or a load substitution amount formed by at least one of the engine load rate change, the PTO output shaft speed change, and the PTO clutch pressure change.

[0010] In a preferred embodiment, after the PTO controller lifts the three-point suspension and leaves the working height window, if the PTO load state changes from the working load state to the non-working load state, and this change corresponds in time to the process of the suspension height leaving the working height window, then a work exit confirmation record is generated.

[0011] In a preferred embodiment, the vehicle operating state includes vehicle speed state, steering state, and reverse gear state; the ground lifting conditions include the vehicle being in a low speed state, the steering state meeting the ground lifting conditions, and the reverse gear state not being detected.

[0012] In a preferred embodiment, PTO short-term holding includes PTO deceleration holding or PTO low torque holding; the PTO holding authorization record includes a window identifier, holding start time, and holding time limit; within the holding time limit, if the three-point suspension does not re-enter the working height window corresponding to the window identifier, or if reverse gear is detected, the PTO controller cancels the PTO holding authorization record and controls the PTO to perform disengagement or braking.

[0013] In a preferred embodiment, the test load response includes at least two of the following: the test load rising direction, the test load rising magnitude, and the test response duration.

[0014] In a preferred embodiment, when generating a PTO recovery access record, the PTO controller also determines the suspension descent speed and engine speed status. When the suspension descent speed is lower than the descent impact threshold, the engine speed is within the PTO recovery allowable range, and the trial load response matches the load climb reference characteristics, a PTO recovery access record is generated. The PTO execution unit restores the PTO output according to the PTO recovery access record, following the sequence of PTO clutch pre-engagement, low torque engagement, and target speed recovery. During the recovery process, if the PTO load recovery characteristics no longer match the load climb reference characteristics, or the engine speed drop exceeds the speed reduction threshold, the PTO controller cancels the PTO recovery access record.

[0015] In a preferred embodiment, after generating a recovery prohibition record, if the test load response mismatch continues until the PTO hold authorization record expires, the PTO controller cancels the PTO hold authorization record, unlocks the window, and controls the PTO execution unit to perform PTO separation or braking.

[0016] In a preferred embodiment, a tractor PTO control method, applied to the aforementioned tractor PTO control system, includes: acquiring the suspension height and suspension lifting state of the three-point suspension, and acquiring the PTO output shaft speed, PTO load state, engine state, and vehicle operating state; during the three-point suspension descent phase, corresponding the suspension height sequence with the PTO load state sequence by time, extracting the load climb segment where the PTO load transitions from a non-operating load state to an operating load state, and generating an operating window anchoring record, the operating window anchoring record including a window identifier, an operating height window, and a load climb reference feature; when the PTO is running and the three-point suspension lifts out of the operating height window, based on the suspension height departure state and the reverse change of the PTO load relative to the load climb reference feature, forming an operation exit. Confirmation record; when a work exit confirmation record is generated and the vehicle's operating status meets the conditions for ground lifting, a PTO hold authorization record with a window identifier is generated, and the work window anchoring record is set to a window locked state; in the window locked state, a short-term PTO hold is performed, and PTO recovery is restricted to be performed only based on the PTO hold authorization record with the same window identifier; when the three-point suspension re-descends and enters the work height window corresponding to the window identifier, a PTO recovery probe is performed, and the probe load response during the PTO recovery probe is collected; when the probe load response matches the load climb reference characteristics, a PTO recovery access record is generated, and PTO output is restored based on the PTO recovery access record; when the probe load response does not match the load climb reference characteristics, no PTO recovery access record is generated.

[0017] The technical effects and advantages of this invention are as follows: 1. In the three-point suspension descent phase, this invention correlates the suspension height sequence with the PTO load state sequence by time, extracts the load climbing segment where the PTO load transitions from a non-operational load state to an operational load state, and thus forms an operational window anchoring record with a window identifier. This operational height window is not simply determined by a fixed suspension height point, but corresponds to the actual process of the machine entering the operational load, which can reduce the problem of mismatch between fixed height thresholds for different machines and different operating depths.

[0018] 2. When the three-point suspension lift is removed from the working height window, this invention does not solely rely on changes in suspension height as the basis for PTO shutdown. Instead, it combines the reverse change in the PTO load relative to the load climbing reference characteristic to form a work exit confirmation record. This allows for the distinction between a true removal from the working state and short-term suspension fluctuations, reducing false PTO separation caused by ground undulations, machine vibrations, or minor suspension changes.

[0019] 3. In the case of field hoisting operations, this invention generates a PTO hold authorization record carrying a window identifier and sets the work window anchoring record to a window locked state. In the window locked state, the system suspends the generation of new work window anchoring records and restricts PTO recovery to be performed only based on PTO hold authorization records carrying the same window identifier. This avoids the regeneration of work windows due to height and load fluctuations during short-term field hoisting, ensuring that PTO hold and recovery both point to the same work state.

[0020] 4. In the case of the present invention performing short-term PTO holding in the window locked state, so that in the scenario of turning at the ground and continuing to work after a short lift, the PTO does not need to be completely disengaged and then re-engaged every time. This can reduce the slippage and impact caused by frequent engagement and disengagement of the PTO clutch, while retaining the protection path of disengaging or braking the PTO in non-grounding state, reverse gear state, or holding failure state. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the tractor PTO control system in this invention; Figure 2 This is a schematic diagram illustrating the generation of job window anchoring records in this invention; Figure 3 This is a schematic diagram of the load ramping reference features in this invention; Figure 4 This is a schematic diagram illustrating the PTO load state source in this invention; Figure 5 This is a schematic diagram illustrating the formation of the job exit confirmation record in this invention; Figure 6 This is a schematic diagram illustrating the determination of the conditions for improving the field elevation in this invention; Figure 7 This is a schematic diagram illustrating the PTO's maintenance of authorization records and its short-term retention in this invention; Figure 8 This is a schematic diagram illustrating the PTO's retention of authorization revocation in this invention; Figure 9 This is a schematic diagram of the PTO recovery trial authorization and trial load response acquisition in this invention; Figure 10 This is a schematic diagram illustrating the generation of trial load response matching and PTO recovery access records in this invention; Figure 11 This is a schematic diagram of the phased recovery of PTO and the cancellation during recovery in this invention; Figure 12 This is a schematic diagram of the tractor PTO control method in this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Reference Figure 1 A tractor PTO control system includes a PTO controller, and a three-point suspension status acquisition unit, a PTO status acquisition unit, an engine and vehicle status acquisition unit, and a PTO execution unit connected to the PTO controller.

[0024] The PTO controller, as the core of this system, can be implemented using an independent control area within the tractor's overall controller or a separately configured PTO control unit. The PTO controller connects to the three-point suspension status acquisition unit, the PTO status acquisition unit, and the engine and vehicle status acquisition unit via the vehicle communication bus, analog input interface, pulse input interface, or digital input interface. The PTO controller connects to the PTO execution unit via a solenoid valve drive interface, a proportional valve drive interface, a relay output interface, or a bus control interface. The interface type is not limited, as long as it allows the status data from each acquisition unit to enter the PTO controller and enables the PTO controller's control commands to act on the PTO execution unit.

[0025] The PTO controller does not receive a single height signal or a single PTO switch signal in isolation. Instead, it records the three-point suspension status and PTO status in association, based on the same sampling period or the same time marker. Each set of association records includes at least the sampling time, suspension height, suspension lifting / lowering status, PTO output shaft speed, and PTO load status. This association record serves as the foundational data for subsequent determination of load ramp-up phases, work window anchoring records, and recovery trial judgments.

[0026] The three-point suspension status acquisition unit outputs the suspension height and suspension lifting status of the three-point suspension to the PTO controller. Specifically, the three-point suspension status acquisition unit may include position detection devices installed at the lifting arm, pull rod, lifting shaft, or lifting cylinder. The position detection devices output signals corresponding to the three-point suspension positions, and the PTO controller receives these signals and converts them into suspension height. The suspension height can be the lifting arm angle, lifting cylinder stroke, pull rod angle, or a relative height value calculated from the above parameters.

[0027] The suspension lifting / lowering state is determined by the PTO controller based on continuous changes in suspension height. Specifically, during continuous sampling, if the suspension height continuously changes along the lifting direction, it is marked as a lifting state; if the suspension height continuously changes along the lowering direction, it is marked as a lowering state; if the suspension height remains constant within a set allowable fluctuation range, it is marked as a holding state. To avoid misjudgments caused by ground vibration or minor fluctuations in the hydraulic system, the PTO controller can introduce a minimum change amount and a minimum duration when determining the lifting / lowering state. That is, only when the height change exceeds the allowable fluctuation range and continues for a set time is the corresponding lifting or lowering state confirmed.

[0028] The suspension height and suspension lifting status output by the three-point suspension status acquisition unit are written into the suspension status sequence by the PTO controller. The suspension status sequence is arranged in chronological order and is time-correlated with the PTO load status sequence in subsequent control processes.

[0029] When the driver lowers the three-point suspension from the ground-lift position to the working position, the three-point suspension status acquisition unit continuously outputs the suspension height. After recognizing the descent, the PTO controller begins saving the suspension height sequence and waits for the PTO status acquisition unit to provide the PTO load status for the same time period. If the subsequent PTO load status continuously transitions from a lower load status to a working load status, the PTO controller uses the suspension height range corresponding to that load change as a candidate range for generating the work window anchoring record.

[0030] The PTO status acquisition unit outputs the PTO output shaft speed and PTO load status to the PTO controller. Specifically, the PTO status acquisition unit may include a PTO output shaft speed detection device and a PTO load detection device. The PTO output shaft speed detection device can be a speed sensor, encoder, magnetoelectric sensor, or Hall sensor, and its installation position can be located on the PTO output shaft, PTO drive shaft, or a transmission component that rotates synchronously with the PTO output shaft. After receiving the PTO output shaft speed signal, the PTO controller forms a PTO speed sequence, which is used to determine whether the PTO is in an operating state, a short-term holding state, a recovery trial state, or a formal recovery state.

[0031] The load status of the PTO can be directly characterized by the PTO output torque or by the load substitution amount. While the PTO is operating and the three-point suspension is raised, the PTO status acquisition unit continues to output the PTO load status. If the three-point suspension height deviates from the previously established working height window, and the PTO load status changes in the opposite direction relative to the load climb reference characteristic (i.e., from a working load status to a non-working load status), the PTO controller generates a work exit confirmation record accordingly.

[0032] Therefore, it is evident that the three-point suspension status acquisition unit and the PTO status acquisition unit in this embodiment do not simply provide display data, but rather together constitute the data foundation for PTO linkage control. The three-point suspension status acquisition unit provides the timing basis for changes in the work position, while the PTO status acquisition unit provides the status basis for load entry, exit, and recovery attempts. Only after the PTO controller correlates the two in time can it generate subsequent work window anchoring records, window lock status, recovery attempt authorization records, and recovery access records.

[0033] The three-point suspension status acquisition unit can also receive the position of the suspension control handle, the control signal of the lifting solenoid valve, or the pressure signal of the lifting cylinder to assist in confirming the suspension lifting status. When the suspension height signal fluctuates briefly but the control handle or hydraulic actuation signal does not change accordingly, the PTO controller can maintain the original suspension status marker to avoid the anchoring record of the work window being falsely triggered due to local vibration. 13 When the PTO load status is abnormally missing, the PTO controller can use load substitution quantities to make a degradation judgment. The degradation judgment is only used to maintain the basic logic of job exit confirmation or recovery attempt; if the key load substitution quantities are all unavailable, the PTO controller will not generate a new job window anchoring record, nor will it generate a PTO recovery access record, and can control the PTO to remain in a short-term hold, disengage, or brake state.

[0034] Reference Figure 4 The PTO load condition is the PTO output torque, or the load substitution formed by at least one of the engine load rate change, PTO output shaft speed change, and PTO clutch pressure change.

[0035] The PTO controller preferentially uses the PTO output torque as the PTO load state. The PTO output torque is obtained by a torque sensor located on the PTO output shaft, PTO drive shaft, or a synchronously driven component of the PTO output shaft, and is written into the PTO load state sequence at each sampling time. If the tractor does not have a direct torque sensor, the PTO controller uses a load substitute to characterize the PTO load state. The load substitute can be derived from one or more of the following: engine load rate change, PTO output shaft speed change, and PTO clutch pressure change.

[0036] The engine load rate change is provided by the engine control unit or engine and vehicle status acquisition unit, reflecting the change in engine load after the implement enters the work area; the PTO output shaft speed change is provided by the PTO status acquisition unit, reflecting the speed response of the PTO output terminal when the load increases; the PTO clutch pressure change is provided by the PTO actuator or corresponding pressure detection device, reflecting the pressure response during PTO power transmission. These signals do not need to be precisely equivalent to the PTO output torque individually, but should be able to characterize the trend of PTO load changing from a non-operating load state to an operating load state.

[0037] When multiple load substitutions are used, the PTO controller first writes each load substitution into the same load state record at the sampling time, and then determines whether each load substitution points to the same load change direction. If the engine load rate increases, the PTO output shaft speed changes in accordance with the load increase, or the PTO clutch pressure change meets the characteristics of increased power transmission load, then the sampling interval is marked as an effective load change interval. If there is a significant conflict between the load substitutions, the PTO controller will not use this interval as a valid source of the load ramp-up segment to avoid the erroneous generation of the working height window due to a single signal anomaly. When the PTO load state is formed by load substitutions, the PTO controller does not require the engine load rate change, PTO output shaft speed change, and PTO clutch pressure change to be converted into the same physical quantity. Instead, it converts each substitution into a load direction marker, a load amplitude marker, and a validity marker, respectively. When the engine load rate continuously increases during the three-point suspension descent, it is recorded as the direction of load increase; when the PTO output shaft speed decreases or fluctuates in the same or similar PTO output control state, corresponding to the load increase, it is recorded as the direction of load increase; when the PTO clutch pressure changes during power transmission, corresponding to the load load, it is recorded as the direction of load increase. If at least one alternative quantity forms an effective load direction marker, and there are no other alternative quantities with obvious opposite markers, then this sampling interval can be used as the effective load change interval; if multiple alternative quantities contradict each other, the PTO controller will not use this sampling interval to generate the load ramp-up segment or PTO recovery access record.

[0038] The engine and vehicle status acquisition unit outputs engine status and vehicle operating status to the PTO controller. Engine status includes at least engine speed and engine load rate, and may also include throttle opening, engine operating status, or engine deceleration status if necessary. Vehicle operating status includes at least vehicle speed, steering status, and reverse gear status. In this embodiment, the engine status and vehicle operating status do not independently determine the working height window, but rather, together with the three-point suspension status and PTO load status, constitute the associated inputs of the PTO controller. Specifically, engine load rate can serve as one alternative source of PTO load status; vehicle speed, steering status, and reverse gear status are primarily used for subsequent determination of ground lifting conditions, PTO authorization maintenance, and restoration of prohibition.

[0039] Reference Figure 2 After receiving the suspension height and suspension lifting status from the three-point suspension status acquisition unit, the PTO controller assembles them into a suspension height sequence in chronological order. Each suspension height data point carries a sampling time or a corresponding sequence number. Similarly, the PTO load status output from the PTO status acquisition unit is also assembled into a PTO load status sequence in chronological order. If the sampling periods for suspension height and PTO load status differ, the PTO controller establishes a correspondence using sampling points at the same sampling time, adjacent sampling times, or time differences not exceeding the allowable range, ensuring that each change in suspension height corresponds to a change in PTO load within the same time period.

[0040] During the three-point suspension descent phase, the PTO controller begins extracting the load climb segment. The descent phase is determined by the suspension lifting status; the PTO controller only initiates load climb segment extraction when the suspension height continuously changes along the descent direction and exceeds the allowable fluctuation range. If the suspension height only fluctuates briefly, or the descent duration does not reach the valid descent confirmation time, the PTO controller does not generate a load climb segment.

[0041] The load ramp-up phase is determined by the PTO load transitioning from a non-operating load state to an operating load state. The non-operating load state refers to the lightly loaded, unloaded, or low-load state when the implement has not yet stably contacted the work object; the operating load state refers to the state where the PTO load reaches and remains within the required operating load range after the implement enters the work object. During the suspension descent phase, the PTO controller continuously reads the PTO load state sequence, first identifying the sampling point where the load begins to rise significantly, and then identifying the sampling point where the load enters a relatively stable operating state. The corresponding load change range between these two points constitutes the load ramp-up phase.

[0042] When determining the load ramp-up phase, the PTO controller checks at least three constraints. First, the load change direction should be from low load to high load; second, this load change should occur during the three-point suspension descent, not during suspension holding or lifting; third, the load change should continue for a preset confirmation time, or maintain the same trend in consecutive sampling points. These constraints prevent the load ramp-up phase from being incorrectly extracted due to ground bumps, momentary sensor fluctuations, or short-term engine disturbances.

[0043] After the load climb segment is determined, the PTO controller reads the suspension height corresponding to the start and end times of the load climb segment and generates a working height window based on this suspension height range. Specifically, the PTO controller uses the higher of the two suspension heights as the upper boundary of the working height window and the lower of the two suspension heights as the lower boundary. When considering suspension sensor errors, hydraulic hysteresis, or machine attitude fluctuations, height margins can be set outside the upper and lower boundaries respectively. Whether the three-point suspension enters the working height window depends on whether the current suspension height falls within the range defined by the aforementioned upper and lower boundaries and height margins. When subsequently determining whether the three-point suspension has re-entered the same working height window, the PTO controller not only compares whether the suspension height falls within that range, but also verifies whether the window identifier in the current working window anchoring record is consistent with the window identifier in the PTO maintenance authorization record. Only when both conditions are met is the three-point suspension considered to have re-entered the working height window corresponding to the window identifier. This working height window represents the suspension height range corresponding to when the equipment enters the working state from a non-working state. Unlike fixed height points, this working height window is derived from the time correspondence between suspension height and PTO load changes during this operation, reflecting the actual operation entry process under the current equipment, current working depth, and current site conditions.

[0044] Simultaneously, the PTO controller generates a job window anchoring record. This record includes a window identifier, a job height window, and a load climb reference feature. The window identifier distinguishes different job window generation processes and can use an incrementing number, a timestamp number, or a number formed by both the machine type and the generation time. The job height window is used to subsequently determine whether the three-point suspension has left the current job state and whether it has re-entered the same job state. The load climb reference feature is used for subsequent job exit confirmation, resumption probe, and resumption access determination.

[0045] The specific components and recording method of the load climb reference feature are described below: After the work window anchoring record is generated, the PTO controller saves the record as the currently valid work window. Subsequently, when the three-point suspension is raised and leaves the work height window, the PTO controller can call the load climb reference feature in the record to determine whether the PTO load has changed in the opposite direction to the work exit; when the three-point suspension descends again into the same work height window, the PTO controller can call the window identifier and load climb reference feature in the record to determine whether to allow the generation of a recovery trial authorization record and whether to grant permission for formal recovery.

[0046] The operating height window is not directly determined by the driver's preset height point, nor is it calculated solely by the suspension height. Instead, it is formed by the correspondence between the suspension height sequence and the PTO load state sequence during the descent phase.

[0047] When different machines or different operating conditions require setting judgment parameters such as load range, duration, and allowable fluctuation range, the above parameters can be obtained through whole machine calibration.

[0048] Reference Figure 3 The load ramp reference features include at least two of the following: load ramp start height, load ramp end height, load ramp direction, and load ramp amplitude.

[0049] The PTO controller has already established a load climbing section during the three-point suspension descent phase. This load climbing section has corresponding start and end sampling points. The PTO controller reads the suspension height corresponding to the start sampling point as the load climbing start height; it reads the suspension height corresponding to the end sampling point as the load climbing end height. The load climbing start height represents the suspension height when the agricultural implement transitions from a non-operating load state to an operating load state, and the load climbing end height represents the suspension height when the PTO load enters a relatively stable operating state.

[0050] The load ramp-up direction is used to characterize the direction of change of the PTO load within the load ramp-up segment. In this embodiment, the load ramp-up direction is the change from a non-operating load state to an operating load state. This feature does not require a formula; the PTO controller only needs to confirm that the PTO load state shows a continuous change from low load to high load in continuous sampling points, and that this change occurs during the three-point suspension descent process, to record it as the load ramp-up direction.

[0051] The load ramp-up magnitude is used to characterize the degree of change in the PTO load state within the load ramp-up segment. If the PTO load state is represented by the PTO output torque, the load ramp-up magnitude is the increase in output torque at the end of the load ramp-up segment relative to the initial output torque. If the PTO load state is represented by load substitution, the load ramp-up magnitude is the degree of load change reflected by the change in engine load rate, the change in PTO output shaft speed, or the change in PTO clutch pressure within the load ramp-up segment. This magnitude is used for subsequent comparison with the load reversal at lift exit and the test load response during recovery testing.

[0052] When generating the job window anchoring record, the PTO controller saves at least two of the aforementioned load climb reference characteristics. In the main implementation path, the PTO controller saves the load climb start height, load climb end height, load climb direction, and load climb amplitude. This saving method ensures that the job window anchoring record includes not only a height range but also the load change basis at the time that height range was formed. Subsequent three-point suspension lifting, ground hold, and recovery probes all reference the same job window anchoring record, avoiding the use of independent judgment references in each control stage.

[0053] Reference Figure 5 When the PTO is running and the three-point suspension lift is out of the working height window, the PTO controller generates a work exit confirmation record based on the suspension height disengagement state and the reverse change of the PTO load relative to the load climb reference characteristics.

[0054] When the PTO load state is determined by multiple load substitution parameters, the PTO controller can employ consistency judgment. Specifically, at least one of the engine load rate change, PTO output shaft speed change, and PTO clutch pressure change should exhibit a load reduction trend consistent with job exit. If multiple substitution parameters are available simultaneously, the one that continuously reflects load changes is prioritized. If multiple substitution parameters contradict each other, for example, if the suspension height has fallen out of the working height window but the engine load rate continues to rise, the PTO controller will not generate a job exit confirmation record and may extend the confirmation time or wait for subsequent sampling results.

[0055] Based on the aforementioned anchoring record generated in the work window, this paper further addresses the issue of premature triggering of PTO control actions after three-point suspension lifting. In the existing fixed height point control method, PTO may be triggered to stop or hold as long as the three-point suspension height exceeds a certain position. However, this height change may be due to ground undulations, short-term suspension fluctuations, or adjustments in implement posture, and does not necessarily indicate that the agricultural machinery has actually been removed from the working load.

[0056] After the three-point suspension lift leaves the working height window, if the PTO load status changes from the working load status to the non-working load status, and this change corresponds in time to the process of the suspension height leaving the working height window, then a work exit confirmation record is generated.

[0057] The PTO controller first determines whether the PTO is in operation. The PTO's operating status can be determined by the PTO output shaft speed reaching the operating condition, the PTO actuator being engaged or holding output, or the PTO target output being valid. If the PTO is not in operation, the PTO controller does not generate a work exit confirmation record to avoid misidentifying suspension lifting in a stopped state as work exit. Specifically, after detecting that the three-point suspension is in a raised state, the PTO controller continuously reads the suspension height and compares the current suspension height with the work height window in the work window anchoring record. When the suspension height moves from inside the work height window to outside the work height window, and this state continues for a preset confirmation time, or multiple consecutive sampling points are outside the work height window, the PTO controller confirms that the suspension height disengagement state is established. If the suspension height only fluctuates briefly near the boundary of the work height window, a suspension height disengagement state is not formed.

[0058] After the suspension height disengagement state is established, the PTO controller reads the PTO load state within the same time period. The PTO load state can be the PTO output torque, or a load substitution quantity formed by at least one of the following: engine load rate change, PTO output shaft speed change, and PTO clutch pressure change. The PTO controller does not use the instantaneous drop of a single sampling point as the basis for work exit, but rather determines whether the PTO load state changes from the working load state to the non-working load state, and whether this change corresponds in time to the process of the suspension height disengaging from the working height window.

[0059] Temporal correspondence refers to the fact that the start time, duration, or confirmation time of the PTO load change from a working load state to a non-working load state falls within the same control judgment window as the process of the suspension height leaving the working height window. In practice, the PTO controller uses the moment the suspension height begins to leave the working height window as a reference and reads the PTO load state in adjacent sampling intervals before and after it. If, within these adjacent sampling intervals, the PTO load exhibits a trend opposite to the load climb-up reference characteristic and continuously meets the exit confirmation condition, then the two are considered to correspond temporally. Temporal correspondence is determined through the control judgment window. Specifically, the PTO controller uses the sampling time when the suspension height begins to leave the working height window as the reference time and reads the PTO load state in adjacent control cycles before and after this reference time. The length of the control judgment window is jointly determined by the three-point suspension height sampling period, the PTO load state sampling period, the signal transmission delay, and the overall machine control cycle, and can be obtained through overall machine calibration. When the start time, duration, or confirmation time of the PTO load change from a working load state to a non-working load state falls within this control judgment window, and the direction, magnitude, and duration of the load change meet the exit confirmation conditions, the PTO controller confirms that the load change corresponds in time to the suspension height disengagement process. If the PTO load change occurs outside this control judgment window, it will not be used as the basis for this operation exit confirmation record.

[0060] The exit confirmation conditions include at least the following: the load change direction is opposite to the load climb direction; the duration of the load change meets the confirmation requirements; and the load change amplitude reaches a level sufficient to characterize the detachment of the implement from the work object. If the PTO output torque is used as the PTO load state, the PTO controller determines whether the PTO output torque changes from the working torque range to the low torque range; if the load substitution amount is used, it determines whether the corresponding substitution amount shows a load decreasing trend. This process ensures that work exit is no longer determined solely by the suspension height, but is jointly defined by the suspension disengagement process and the PTO load exit process.

[0061] When the suspension height detachment state is established, and the PTO load state changes from a working load state to a non-working load state, corresponding in time to this detachment process, the PTO controller generates a job exit confirmation record. The job exit confirmation record includes at least a window identifier, suspension detachment time, suspension detachment height, PTO load detachment state, and exit confirmation time. The window identifier comes from the aforementioned job window anchoring record and indicates the specific working height window corresponding to this job exit confirmation record. When subsequently generating a PTO hold authorization record, the PTO controller calls this window identifier, ensuring that ground hold and subsequent recovery are both constrained within the same job window.

[0062] If the three-point suspension has moved out of the working height window, but the PTO load status has not changed from a working load state to a non-working load state, the PTO controller will not generate a work exit confirmation record. At this time, the PTO controller can continue to monitor subsequent sampling data; if simultaneously there are abnormal increases in PTO load, abnormal fluctuations in PTO output shaft speed, or reverse gear status, the PTO will be disengaged or braked according to subsequent protection logic. This procedure is used to prevent the implement from accidentally entering a short-term holding process while still under load.

[0063] When a work exit confirmation record is generated and the vehicle's operating status meets the conditions for ground lifting, a PTO hold authorization record with a window identifier is generated, the work window anchoring record is set to a window locked state, and the generation of new work window anchoring records is paused while the window is locked.

[0064] After the work exit confirmation record is generated, the PTO controller further reads the vehicle's operating status. The vehicle's operating status includes at least vehicle speed, steering status, and reverse gear status. When the end-of-way lifting conditions are met, the PTO controller identifies the current lifting process as an end-of-way lifting process. End-of-way lifting conditions include the vehicle being at low speed, the steering status meeting the end-of-way turning conditions, and no reverse gear detected. Low speed indicates the vehicle is in a turn or short-distance adjustment situation; steering status indicates the vehicle is performing a turn; and no reverse gear detected excludes situations involving reversing to avoid obstacles or reversing operations.

[0065] Once the job exit confirmation record has been generated and the site lifting conditions are met, the PTO controller generates a PTO hold authorization record. This PTO hold authorization record carries the window identifier from the aforementioned job exit confirmation record and includes the hold start time and hold duration.

[0066] PTO hold authorization is not a regular PTO hold command, but a restricted authorization generated based on a confirmed job exit status and end-of-work lifting conditions. The purpose of this authorization is to allow the PTO to remain in a deceleration hold or low torque hold state when the vehicle may re-enter the same work line after a short end-of-work lift, preventing immediate and complete PTO disengagement with each end-of-work lift. If a job exit confirmation record is not generated, or if the vehicle's operating status does not meet the end-of-work lifting conditions, the PTO controller will not generate a PTO hold authorization record, but will instead enter a PTO disengagement, braking, or other protective control path.

[0067] While generating the PTO hold authorization record, the PTO controller sets the corresponding job window anchoring record to a window locked state. The window locked state indicates that the job height window serves as the only valid recovery reference during the current short-term hold period. While in the window locked state, the PTO controller retains the window identifier, job height window, and load climb reference characteristics in the job window anchoring record, and restricts subsequent PTO recovery to the job height window corresponding to that window identifier.

[0068] While the window is locked, the PTO controller suspends the generation of new job window anchoring records. Specifically, even if new height changes or short-term load fluctuations occur during lifting, turning, or short-term descent while the three points are suspended at the ground, the PTO controller will not treat these changes as sources of new load climb segments and will not regenerate a new job height window. Only after PTO recovery is complete, the PTO hold authorization record is revoked, or PTO separation is complete, will the PTO controller unlock the window and allow subsequent job processes to regenerate job window anchoring records.

[0069] This pause mechanism addresses the issue in the background technology where height and load fluctuations during short-term field lifting can cause control baseline drift. If a new work window is regenerated during field holding, subsequent PTO recovery may no longer correspond to the original work state, leading to cross-window recovery or erroneous recovery. This implementation maintains the same window identifier by locking the window, ensuring that field holding, recovery probe, and recovery access all reference the same work window anchor record, thus guaranteeing the consistency of the control chain.

[0070] When the tractor reaches the end of the field, the driver raises the three-point suspension. The PTO controller detects that the suspension height has deviated from the working height window and simultaneously determines that the PTO load has changed from a working load state to a non-working load state, generating a work exit confirmation record. Subsequently, if the vehicle is turning at low speed and not reversing, the PTO controller generates a PTO hold authorization record carrying the same window identifier and sets the corresponding working window anchoring record to a window locked state. Afterward, the PTO execution unit can perform PTO deceleration hold or low torque hold; if the three-point suspension re-enters the working height window corresponding to the window identifier within the hold time limit, the system then enters the subsequent recovery trial process.

[0071] If the vehicle's operating status does not meet the conditions for short-term lifting, such as when reverse gear is detected, the PTO controller will not generate a PTO hold authorization record. In this case, even if a job exit confirmation record has been generated, it will not enter short-term lifting mode; instead, it will control the PTO to disengage or brake. This logic is used to avoid maintaining PTO output in reversing or non-short-term lifting conditions, ensuring that the PTO hold authorization is only used for job scenarios corresponding to short-term lifting.

[0072] The job exit confirmation record, PTO hold authorization record, and window lock status form a continuous control chain. The job exit confirmation record addresses the question of "whether the job load has been truly exited"; the PTO hold authorization record addresses the question of "whether short-term hold at the field edge is allowed"; and the window lock status addresses the question of "whether the same job window should still be used as the recovery baseline in the future".

[0073] Low-speed conditions, turning conditions, and holding time can be determined through machine calibration. For different implements or different operating scenarios, the holding time can be set to a time range that matches the average duration of the turning point.

[0074] Reference Figure 6 Based on the existing operation exit confirmation record and PTO hold authorization record, further restrictions are placed on the field lifting operation. The purpose is to distinguish between short-term field lifting and other operation conditions such as reversing, transportation, and stopping lifting, to avoid the system maintaining PTO output solely due to three-point suspension lifting, and to avoid frequent complete disconnection of PTO during short-term field lifting.

[0075] Vehicle operating status includes vehicle speed, steering status, and reverse gear status; the conditions for lifting off the ground include the vehicle being at low speed, the steering status meeting the conditions for lifting off the ground, and no reverse gear being detected.

[0076] The engine and vehicle status acquisition unit outputs the vehicle operating status to the PTO controller. Vehicle speed status can be provided by a vehicle speed sensor, transmission output shaft speed signal, wheel speed signal, or the vehicle controller; steering status can be provided by a steering angle sensor, steering control signal, or vehicle steering status indicator; reverse gear status can be provided by a gear position detection unit, transmission controller, or reverse gear switch signal. After receiving the above vehicle operating status, the PTO controller does not directly use any single signal as the basis for determining the head-up position, but uses it in conjunction with the already formed work exit confirmation record. The target PTO output refers to the PTO output state used by the tractor to drive the implements in the current operating mode. It can be characterized by the target PTO output shaft speed, target transmitted torque, or target control pressure of the PTO actuator. The target PTO output can originate from the PTO speed gear set by the driver, implement operating mode parameters, or the overall machine control strategy.

[0077] PTO recovery testing is a limited output process that results in a PTO output lower than the target PTO output. Specifically, when the target PTO output is characterized by the PTO output shaft speed, the PTO output shaft speed during the recovery testing phase is lower than the target PTO output shaft speed; when the target PTO output is characterized by transmitted torque or control pressure, the transmitted torque or control pressure during the recovery testing phase is lower than the target value during the formal recovery phase. The recovery testing output should be higher than the lowest output in the fully disconnected state or short-term hold state in order to generate a identifiable test load response, but must not reach the target PTO output. The PTO controller uses the test start time in the recovery testing authorization record as the starting point of the effective test interval and collects the test load response within the effective test interval.

[0078] The PTO controller first confirms that a work exit confirmation record has been generated. This means the three-point suspension has been raised out of the working height window, and the PTO load status has changed from a working load state to a non-working load state. Only under these conditions will the PTO controller proceed to determine if the vehicle's operating status meets the conditions for a head start. If a work exit confirmation record has not been generated, even if the vehicle is at low speed or turning, the PTO controller will not generate a PTO hold authorization record corresponding to the head start.

[0079] The low-speed state is used to characterize situations where the tractor is turning, making a U-turn, or making a short-distance adjustment at the edge of the field. In practice, the PTO controller compares the vehicle's current speed with a preset low-speed threshold. If the vehicle speed is not higher than this threshold, and this state continues for a set confirmation time, the vehicle is confirmed to be in a low-speed state. The low-speed threshold can be calibrated based on the tractor model, the type of implement, and the usual field operation habits. If the vehicle speed is significantly higher than this threshold, the PTO controller will not recognize the current lifting process as a short-term lift at the edge of the field, to avoid accidental triggering of the PTO short-term hold during transport or travel.

[0080] The steering state meeting the ground turn condition means that the vehicle's steering state reaches a level that can characterize a ground turn. In practice, the PTO controller reads the steering angle or steering status indicator; when the steering angle exceeds the ground turn threshold, or the steering status indicator shows that the vehicle is in a continuous steering process, and this state coincides with the holding time after a three-point suspension lift, the steering state is confirmed to meet the ground turn condition. If the vehicle is not turning and it is only a suspension lift during straight-line driving, the PTO controller does not treat this lift process as a ground turn.

[0081] The absence of a reverse gear is an exclusion condition in the handover lifting process. The PTO controller reads the reverse gear status while simultaneously determining the low-speed and steering states; if a reverse gear is detected, a PTO hold authorization record for the handover lift is not generated. This process excludes situations involving reversing to avoid obstacles, reversing to adjust, or reversing operations, preventing short-term PTO hold during reversing. If a reverse gear is detected after a PTO hold authorization record has already been generated, the PTO controller cancels the record according to subsequent cancellation logic and controls the PTO to either disengage or brake.

[0082] When the lifting conditions at the site are met, the PTO controller confirms that the current lifting process is a short-term lifting at the site. At this time, the PTO hold authorization record already carries a window identifier consistent with the work window anchoring record, and the PTO controller uses this window identifier as an index for subsequent PTO short-term hold and recovery restrictions. If the lifting conditions at the site are not met, the PTO controller does not enter the short-term hold path at the site, but instead controls PTO disengagement or braking based on the PTO operating status, load status, and vehicle status.

[0083] Perform a short PTO hold while the window is locked, and restrict PTO recovery to be performed only based on PTO hold authorization records that carry the same window identifier.

[0084] "Restricting PTO recovery to be based solely on PTO hold authorization records carrying the same window identifier" means that before entering the subsequent recovery process, the PTO controller first checks whether the window identifier in the PTO hold authorization record is consistent with the window identifier in the current job window anchoring record. Only if they are consistent, the PTO hold authorization record is still valid, and the three-point suspension re-enters the job height window corresponding to that window identifier, will the PTO controller allow the generation of a recovery probe authorization record. If the window identifiers are inconsistent, the PTO hold authorization record has expired, or the height range entered by the three-point suspension does not belong to the job height window corresponding to that window identifier, the PTO controller will not allow PTO output recovery.

[0085] The aforementioned window identification verification process provides a prerequisite constraint for subsequent recovery attempts. In other words, the PTO controller will not resume PTO simply because the three-point suspension has descended to a certain height, but will require that the descent action return to the same previously locked working height window, and that there is a valid PTO maintenance authorization record.

[0086] Low-speed conditions, end-of-field turning conditions, and holding time can be determined through machine calibration. For different implements or operating scenarios, the holding time can be set to a range that matches the average duration of end-of-field turning. For PTO-driven implements with high inertia, such as rotary tillers and straw return machines, the holding time can be set to cover the typical end-of-field turning time; for implements unsuitable for maintaining rotation, the holding time can be shortened, or low-torque holding can be used directly after the PTO holding authorization record is established.

[0087] Reference Figure 7 After the work exit confirmation record has been generated, the vehicle's operating status meets the conditions for end-of-field lifting, and the window is locked, the issue of whether the PTO (Power Take-Off) should immediately and completely disengage during short-term end-of-field lifting is further addressed. For agricultural implements driven by the PTO, such as rotary tillers and straw return machines, end-of-field lifting is usually short-lived, after which the three-point suspension will descend again and continue working. If the PTO is immediately and completely disengaged each time it is lifted and then re-engaged during descent, it is easy to cause frequent PTO clutch operation; if the original working output is maintained without restriction, the agricultural implement may maintain a high power output at non-working heights. Therefore, this embodiment sets a short-term PTO hold and limits its effective scope with a PTO hold authorization record.

[0088] PTO short-term hold includes PTO deceleration hold or PTO low torque hold. When determining the conditions for a lift at the end of a road, if key input signals regarding vehicle speed, steering, or reverse gear status are unavailable, or if there is a significant conflict between vehicle operating states, the PTO controller will not generate a PTO hold authorization record. In this case, the PTO controller can maintain a short-term observation state, or control the PTO to disengage or brake based on the PTO operating state and the three-point suspension status. This process is used to avoid misjudging transport lifts, reversing to avoid obstacles, or stop lifts as short-term lifts at the end of a road when the vehicle operating state cannot be reliably confirmed.

[0089] When the PTO controller is in the window locked state, it reads the PTO hold authorization record. After confirming the record's validity, it outputs a short-term hold control command to the PTO execution unit. Upon receiving this command, the PTO execution unit neither maintains the original target PTO output nor immediately performs a complete disengagement. Instead, it enters a restricted output state. This restricted output state is the short-term PTO hold, which covers the waiting time after a turn or short lift and preserves control continuity for subsequent recovery attempts within the same window.

[0090] When using PTO speed reduction and holding, the PTO controller uses the current operating PTO output speed as a reference to reduce the PTO output shaft speed to the holding speed range. The holding speed range is lower than the target PTO output speed but higher than the completely stopped state. The PTO controller can adjust the PTO clutch control pressure, proportional valve opening, or the target speed command from the PTO actuator to bring the PTO output shaft into this holding speed range. The PTO status acquisition unit continuously acquires the PTO output shaft speed and feeds it back to the PTO controller; if the actual speed is lower than the lower limit of the holding speed or higher than the upper limit of the holding speed, the PTO controller corrects the actuator's output command to maintain the PTO within the short-term holding range.

[0091] When using PTO low torque hold, the PTO controller does not primarily control the holding speed. Instead, it limits the torque transmitted by the PTO clutch or restricts the output capability of the PTO actuator, keeping the PTO transmission path in a low torque engagement state. In this state, the PTO system maintains recoverable power transmission conditions but does not output the full load required for operation. The PTO load status can be directly fed back from the PTO output torque, or it can be fed back from load substitution quantities formed by changes in engine load rate, changes in PTO output shaft speed, or changes in PTO clutch pressure. If the load abnormally increases during low torque hold, the PTO controller does not continue to maintain the holding state but instead enters the hold authorization revocation or PTO disengagement path.

[0092] Both PTO (Pulse-To-Operate) deceleration hold and PTO low torque hold are short-term, limited PTO states, and neither should be interpreted as a formal PTO recovery. Formal recovery still requires the three-point suspension to re-enter the same working height window corresponding to the same window identifier, and is executed after reviewing the recovery trial authorization record and trial load response. Through this limitation, short-term PTO hold only addresses the transition control issue during short-term lifting at the field head, preventing it from replacing subsequent recovery access judgments.

[0093] PTO maintains authorization records including window identifier, maintain start time, and maintain duration.

[0094] In this embodiment, the PTO hold authorization record is generated by the PTO controller after the operation exit confirmation record is formed and the vehicle's operating status meets the ground lifting conditions. This record is not a simple hold command, but rather an access credential for short-term PTO hold. When the PTO controller generates this record, it writes the window identifier from the current operation window anchoring record into the PTO hold authorization record, thus binding the hold action to the aforementioned operation height window. When the three-point suspension subsequently lowers again, the PTO controller checks whether it has returned to the same operation height window using this window identifier; if the window identifiers are inconsistent, it does not enter the recovery probe stage, nor is it allowed to enter the formal recovery stage.

[0095] The hold start time is the moment when the PTO hold authorization record is generated and the short-term PTO hold begins. The PTO controller uses this moment as the starting point for hold timing to determine whether the short-term hold is still within the allowed period. The hold start time can be represented by the PTO controller's internal clock, the vehicle controller's timestamp, or the control cycle number, as long as it can be used to calculate the hold duration.

[0096] The hold time limit is the validity period of the PTO hold authorization record. This time limit is used to define the maximum duration of short-term PTO hold, preventing the PTO from remaining in a hold state after the three-point suspension has not lowered for an extended period, the vehicle has left the turning position, or the driver has changed their operating intentions. In each control cycle, the PTO controller compares the interval between the current time and the hold start time; if the interval does not exceed the hold time limit, and there is no reverse gear, abnormal load, or abnormal PTO output, the PTO hold authorization record remains valid; if the hold time limit is exceeded, the PTO controller cancels the record and controls the PTO to perform disengagement or braking.

[0097] If, within the holding time limit, a reverse gear state, an abnormal increase in PTO load, uncontrolled PTO output shaft speed, or the three-point suspension fails to re-enter the same working height window as expected, the PTO controller will not continue to rely on the PTO holding authorization record to perform holding control. For reverse gear state or the expiration of the holding time limit, the PTO controller will revoke the PTO holding authorization record and control the PTO to disengage or brake; for abnormal load or speed, the PTO controller can directly revoke the PTO holding authorization record and prohibit the generation of a recovery trial authorization record. This backoff mechanism ensures that short-term PTO holding only exists during controlled ground lifting.

[0098] The window identifier, hold start time, and hold duration collectively define the object, start point, and validity period of a short-term PTO hold. The window identifier addresses which job window the hold action corresponds to; the hold start time addresses when the hold time begins to be calculated; and the hold duration addresses when the hold state must end. These three elements work together to ensure that a short-term PTO hold does not operate independently of the job window anchor record, nor is it maintained indefinitely after the field hoisting is completed.

[0099] Short-term PTO holding differs from both immediate disconnection in existing fixed-height control and unconditional maintenance of PTO output. Its technical basis lies in the continuous constraints of job exit confirmation records, PTO holding authorization records, and window lock states. This implementation path supports the beneficial effects of reducing frequent complete PTO disengagement during short-term hoisting at the field head, reducing slippage and impact caused by repeated engagement, and avoiding maintaining the original job output at non-operational heights.

[0100] The speed range, low torque holding limit, and holding time can be determined through machine calibration. Calibration can be performed by considering the implement type, PTO rated speed, implement inertia, and average turning time at the end of the road.

[0101] Reference Figure 8 If, within the holding time limit, the three-point suspension does not re-enter the working height window corresponding to the window indicator, or if reverse gear is detected, the PTO controller cancels the PTO holding authorization record and controls the PTO execution unit to perform PTO disengagement or braking.

[0102] After the PTO hold authorization record is generated, the PTO controller uses the hold start time in the record as the timing start point, and reads the current time, three-point suspension height, and reverse gear status in each control cycle. The hold time limit is the maximum allowed duration for short-term PTO hold, and its value can be determined through machine calibration and adapted to the normal duration of tractor head turns. Within the hold time limit, the PTO controller continuously determines whether the three-point suspension has re-entered the working height window defined by the same window identifier.

[0103] "The working height window corresponding to the window identifier" refers to the working height window saved in the aforementioned working window anchoring record, and the window identifier in this working window anchoring record is consistent with the window identifier carried in the PTO maintenance authorization record. When the PTO controller determines whether the three-point suspension has re-entered the same working height window, it not only compares whether the current suspension height falls within the working height window, but also verifies whether the window identifier is consistent with the window identifier in the PTO maintenance authorization record. If the suspension height enters another height range, or if the currently existing working window identifier is inconsistent with the PTO maintenance authorization record, then the three-point suspension is not considered to have re-entered the same working height window.

[0104] If the three-point suspension fails to re-enter the working height window corresponding to the same window identifier within the holding time limit, it indicates that the conditions for continued operation after the short-term lifting at the ground have not been formed. At this point, continuing to maintain the PTO short-term hold no longer has a basis for window recovery. The PTO controller cancels the PTO hold authorization record and outputs a PTO disengagement command or a PTO braking command to the PTO execution unit. PTO disengagement can be achieved by releasing the PTO clutch; PTO braking can be achieved through the PTO brake or the braking actuator corresponding to the PTO output shaft. The specific choice between disengagement and braking can be determined by the PTO output shaft speed, the machine's inertia, and the overall machine calibration strategy.

[0105] If reverse gear is detected within the holding time limit, the PTO controller will not wait for the three-point suspension to re-enter the working height window, but will instead cancel the PTO hold authorization record. Reverse gear indicates that the vehicle's operating intention has changed from continuing forward operation after a short turn at the head of the field. Maintaining PTO output for a short time might put the implement in an unsuitable power state during reversing or obstacle avoidance. Therefore, reverse gear is used as an immediate condition for canceling the hold authorization. After canceling the PTO hold authorization record, the PTO controller removes the authorization for short-term PTO hold from that record and controls the PTO to disengage or brake.

[0106] After a PTO hold authorization record is revoked, the PTO controller does not generate a recovery attempt authorization record, nor does it allow entry into a PTO recovery attempt. Correspondingly, the window lock state can be released after PTO disengagement or braking is completed, or released in a subsequent control cycle according to the overall machine control flow. This fallback path is used to prevent PTO from continuing to wait for recovery when the hold time expires, reverse gear is engaged, or the window recovery conditions are not met, thus addressing the issue of the lack of a clear exit boundary for the PTO hold state in the background art.

[0107] Reference Figure 9 When the PTO authorization record remains valid and the three-point suspension re-descends into the operation height window corresponding to the window identifier, a recovery trial authorization record is generated, and a PTO recovery trial lower than the target PTO output is executed based on the recovery trial authorization record.

[0108] The PTO controller generates a recovery attempt authorization record only when three conditions are met simultaneously: First, the PTO hold authorization record is still within its hold period and has not been revoked; second, the three-point suspension is in the re-lowering process, and the current suspension height enters the working height window corresponding to the window identifier in the PTO hold authorization record; third, no reverse gear, PTO actuator malfunction, or abnormal PTO output shaft speed is detected. These conditions confirm that the recovery attempt occurs within the same working window after a short lift at the same workhead, and not in a new working window, reverse condition, or abnormal state.

[0109] The recovery attempt authorization record is generated by the PTO controller and includes at least a window identifier, attempt start time, attempt output limit, and attempt validity status. The window identifier is used to continue binding the aforementioned job window anchoring record; the attempt start time is used to limit the acquisition range of the attempt load response; the attempt output limit is used to constrain the PTO recovery attempt from reaching the target PTO output; and the attempt validity status indicates whether the current recovery attempt can still be used to form a PTO recovery admission record.

[0110] Based on the recovery test authorization record, the PTO controller outputs a recovery test control command to the PTO execution unit. The PTO recovery test is a restricted output process below the target PTO output. If the target PTO output is a target speed, the recovery test output is below that target speed; if the target PTO output is characterized by clutch transmission torque or control pressure, the torque or pressure during the recovery test phase is below the target value for the formal recovery phase. The purpose of this test process is not to directly enter the working output, but to observe the load response when the machine re-contacts the work object under restricted output.

[0111] During the PTO recovery trial, the PTO controller maintains a locked window, does not generate new job window anchoring records, and does not allow skipping the trial to directly restore the target PTO output. If, during the trial, the three-point suspension again disengages from the job height window, reverse gear is engaged, the PTO output shaft speed is abnormal, or the PTO load abnormally increases, the PTO controller revokes the recovery trial authorization record and processes the case according to the path of authorization revocation or PTO disengagement. This constraint makes the recovery trial a controlled verification step before formal recovery, rather than a normal soft engagement process.

[0112] The test load response is collected during the PTO recovery test. After the tractor completes a turn at the end of the field, the driver lowers the three-point suspension. The PTO controller confirms that the PTO hold authorization record is still valid and, after verifying that the current suspension height enters the working height window corresponding to the same window identifier, generates a recovery test authorization record. Subsequently, the PTO execution unit executes a recovery test at a level lower than the target PTO output. The PTO status acquisition unit collects the PTO load status during the test, and the PTO controller forms a test load response record. This record serves as the basis for subsequent PTO recovery access or recovery prohibition decisions.

[0113] The PTO (Power Toll Collection) short-term holding has clearly defined cancellation conditions, while the recovery attempt has clearly defined entry conditions and output limitations. If the three-point suspension fails to return to the same working height window within the holding time limit, reverse gear is engaged, or the preconditions for the recovery attempt are not met, the PTO will not continue waiting for recovery; only when it descends again under the same window identifier constraint and enters the corresponding working height window will it enter a restricted recovery attempt. This process supports the beneficial effects of avoiding cross-window recovery, reducing false recovery caused by fixed-height recovery, and reducing the impact on the PTO output when directly recovering the target.

[0114] The hold time limit, test output limit, and test effective range can be determined through whole-machine calibration. For PTO driven machines with large inertia, the test output limit can be set to a range below the target output that can produce a recognizable load response; for machines with small load changes, the test effective range can be extended to obtain a stable test load response.

[0115] Based on the already generated recovery trial authorization record and executed PTO recovery trial, further limit the content of the trial load response collection and its usage. After the three-point suspension re-descends into the working height window, the PTO target output should not be restored simply because the height condition is met. Instead, it should be confirmed that the machine exhibits a load response consistent with the previous working state under the restricted PTO output before deciding whether to allow formal recovery.

[0116] The test load response includes at least two of the following: test load increase direction, test load increase magnitude, and test response duration. During the PTO recovery test, the PTO controller uses the test start time in the recovery test authorization record as the data acquisition starting point and reads the PTO load status output by the PTO status acquisition unit. The PTO load status can be the PTO output torque or a load substitution quantity formed by at least one of the following: engine load rate change, PTO output shaft speed change, and PTO clutch pressure change. The PTO controller writes continuous load data after the test start time into the test load response record.

[0117] The test load upward direction is used to characterize whether the PTO load changes from a non-operating load state to an operating load state after the PTO recovery test begins. The PTO controller compares the load state at the start of the test with the subsequent load state within the effective test range; if the load change trend shows a change from low load to high load, and this change corresponds to the time period after the three-point suspension re-enters the operating height window, then the test load upward direction is recorded as valid. If the load does not rise, falls in the opposite direction, or fluctuates irregularly, then the test load upward direction is not valid.

[0118] The test load increase magnitude is used to characterize the extent of PTO load increase during the recovery test. If PTO output torque is used, the PTO controller records the change between the output torque at the start of the test and the higher output torque reached within the effective test range; if load substitution is used, it records the load change reflected in the engine load rate change, PTO output shaft speed change, or PTO clutch pressure change within the effective test range. This increase magnitude is not required to be exactly equal to the previous load ramp-up magnitude, but should fall within the allowable range that matches the aforementioned load ramp-up baseline characteristics.

[0119] The test response time characterizes the time elapsed from the start of the PTO (Plan-to-Operate) recovery test to the test load response reaching a verifiable state. The PTO controller records the time interval from the start of the test load, the time it takes to reach the set verifiable state, or the time it enters a stable change state, starting from the test initiation time. This time interval is used to determine whether the load build-up speed after the implement re-enters the work area matches the previous load ramp-up process. A response that is too fast and accompanied by a sudden increase in load may indicate a large impact upon entering the soil; a response that is too slow or shows no significant load change may indicate that the implement has not yet stabilized in the working state.

[0120] The PTO controller uses at least the direction and magnitude of the test load increase to form the test load response. For agricultural implements with a slow load build-up process or large inertia, the test response duration is further used as a judgment criterion. All of the above are derived from continuous sampling data during the recovery test, rather than from a single instantaneous sampling point. Through this processing, the test load response can reflect the process of the implement being reloaded within the same operating height window, providing a basis for subsequent access restoration judgments.

[0121] Reference Figure 10 When the test load response matches the load ramp-up baseline characteristics, a PTO recovery admission record is generated, and the PTO output is restored based on the PTO recovery admission record. After generating the test load response record, the PTO controller calls the load ramp-up baseline characteristics in the job window anchoring record. The load ramp-up baseline characteristics include at least two of the following: load ramp-up start height, load ramp-up end height, load ramp-up direction, and load ramp-up amplitude. The PTO controller first confirms that the window identifier corresponding to the current recovery test is consistent with the window identifier in the job window anchoring record; if the window identifiers are inconsistent, no matching judgment is performed, and no PTO recovery admission record is generated.

[0122] Provided the window identifiers are consistent, the PTO controller compares the trial load response with the load ramp-up baseline characteristics. The matching determination includes at least the following: the direction of the trial load increase should be consistent with the direction of the load ramp-up; the magnitude of the trial load increase should be within a range sufficient to characterize the machine re-entering the operating load; and the trial response duration should be within the allowable response time range. If the trial load response as defined in the claims includes only two of these two elements, the PTO controller completes the matching determination based on those two elements.

[0123] The PTO controller first determines whether the test load changes from low to high load; if the direction is inconsistent, the match fails. If the direction is consistent, it then determines whether the increase in test load reaches the allowable range corresponding to the load ramp-up; if the increase is insufficient or exceeds the allowable range, the match fails. For cases using test response time, the PTO controller also determines whether the load setup time is within a preset allowable range; if the response is too slow or too fast and accompanied by abnormal fluctuations, the match fails. Only when all the above conditions are met is the test load response considered to match the load ramp-up baseline characteristics.

[0124] When a match is found, the PTO controller generates a PTO recovery admission record. The PTO recovery admission record includes at least a window identifier, recovery admission time, trial match result, and recovery execution status. The window identifier is used to continue binding the same job window; the recovery admission time is used to determine the start time of formal recovery control; the trial match result indicates that the recovery admission originates from a restricted recovery trial, rather than a simple height judgment; and the recovery execution status allows the PTO execution unit to perform subsequent recovery actions.

[0125] When the test load response does not match the load ramp-up baseline characteristics, a recovery prohibition record is generated, and the PTO short-term hold or PTO hold authorization record is maintained or revoked. If the test load rise direction is inconsistent with the load ramp-up direction, the test load rise amplitude is insufficient to characterize the work load establishment, the test load rise amplitude increases abnormally, or the test response duration does not exceed the allowable range, the PTO controller determines that the test load response does not match the load ramp-up baseline characteristics. When the match is not established, the PTO controller does not generate a PTO recovery access record, nor does it allow the PTO execution unit to enter the target PTO output recovery.

[0126] The restoration prohibition record is generated by the PTO controller and includes at least the window identifier, the time of prohibition generation, the reason for the mismatch, and the subsequent processing status. The reason for the mismatch may include inconsistent load direction, insufficient load amplitude, abnormal load amplitude, abnormal response time, or inconsistent window identifier. The subsequent processing status instructs the PTO controller to either continue maintaining the PTO short-term hold or revoke the PTO hold authorization record.

[0127] If the hold time has not expired, no reverse gear is detected, and the PTO output status is not abnormal, the PTO controller can maintain the PTO hold for a short period and wait for the three-point suspension status or PTO load status to meet the recovery trial conditions again in a subsequent control cycle. In this case, the recovery prohibition record only prevents the current recovery trial from entering formal recovery; it does not automatically unlock the window. This procedure is applicable when the machine has just resumed descent but the load has not yet stabilized.

[0128] If the PTO hold authorization record is generated close to or exceeds the hold time limit, or if conditions such as reverse gear, abnormally high PTO load, or abnormal fluctuations in PTO output shaft speed occur simultaneously, the PTO controller will revoke the PTO hold authorization record. After revocation, the PTO execution unit will no longer perform short-term PTO hold, and the PTO controller will control PTO disengagement or braking. This process avoids repeatedly attempting to restore PTO output when the test load response already shows a mismatch.

[0129] After the tractor completes the turn at the end of the field, the three-point suspension lowers back into the same working height window. The PTO controller generates a recovery test authorization record and executes a restricted recovery test. If the PTO load is established according to the direction, amplitude, and response time corresponding to the previous load climb reference characteristics during the test, a PTO recovery access record is generated and the PTO output is restored. If the test load response does not match the previous reference, a recovery prohibition record is generated. When the hold authorization is still valid and there are no abnormalities such as reverse gear, the PTO is maintained for a short time. When the hold authorization fails or an abnormal state occurs, the PTO hold authorization record is revoked and the PTO is disengaged or braked.

[0130] Formal PTO recovery is restricted to after "same window identifier, restricted recovery probe, and load response matching" are all met. This logic provides specific technical support for the beneficial effects of "formal PTO recovery having a pre-verification process" and "reducing the impact caused by directly recovering PTO when the equipment is not yet stably in the ground or the load is abnormal." At the same time, the recovery prohibition record provides an explicit output for matching failure, preventing the system from repeatedly entering the target PTO output recovery when the recovery conditions are not met.

[0131] The permissible range of the test load increase, the permissible interval of the test response time, and the judgment threshold for abnormal load surges can be determined through whole-machine calibration. Calibration can be combined with the implement type, PTO target speed, operating depth, and ground resistance. If the application documents require further proof of the effect of restored access control, it is recommended to supplement the embodiments with comparative test data, such as the number of engine speed drops, PTO clutch slippage time, PTO recovery impact peak, or number of times restoration prohibition triggers under fixed-height direct recovery and test-matched recovery in this embodiment.

[0132] After the test load response has been established, the conditions for generating the PTO recovery access record are further defined. Even if the test load response matches the load climb reference characteristics, if the three-point suspension descends too quickly, or the engine speed is not suitable for receiving the PTO recovery, directly entering the target PTO output may still result in ground impact, engine speed drop, or PTO clutch slippage. Therefore, before generating the PTO recovery access record, the PTO controller also introduces the suspension descent speed and engine speed status as common access conditions.

[0133] When generating the PTO (Plan-to-Operate) recovery access record, the PTO controller also determines the suspension descent speed and engine speed. The suspension descent speed is determined by the suspension height sequence provided by the three-point suspension status acquisition unit. The PTO controller reads the suspension height within the current control cycle and retrieves the suspension height from the previous sampling time or several adjacent sampling times to determine the degree of descent change of the three-point suspension within a unit of time. This degree of descent change is used as the suspension descent speed to characterize how quickly the agricultural machinery descends when it re-enters the working height window. If there are short-term fluctuations in the suspension height signal, the PTO controller can use the changing trend of multiple consecutive sampling points to confirm the descent speed, avoiding using a single abnormal point as the basis for recovery access.

[0134] Engine speed status is provided by the engine and vehicle status acquisition unit. The PTO controller reads the current engine speed and determines whether it is within the PTO recovery allowable range. The PTO recovery allowable range is the engine speed range that supports the PTO from recovery probe to formal recovery; this range can be determined through overall machine calibration. When the engine speed is too low, PTO recovery can easily cause engine speed drop; when the engine speed is too high, PTO clutch engagement and PTO output recovery may produce a large shock. Therefore, engine speed status is a necessary judgment condition before recovery access.

[0135] When the suspension descent speed is below the descent impact threshold, the engine speed is within the PTO recovery allowable range, and the test load response matches the load climb baseline characteristics, a PTO recovery access record is generated.

[0136] The descent impact threshold limits the maximum permissible descent speed when the three-point suspension re-enters the working height window. The PTO controller compares the current suspension descent speed with the descent impact threshold; when the descent speed is below this threshold, it indicates that the implement's entry into the working height window is relatively smooth, and the recovery access judgment can continue. If the suspension descent speed reaches or exceeds the descent impact threshold, even if the trial load response shows a trend matching the load climb baseline characteristics, the PTO controller does not generate a PTO recovery access record, but instead maintains PTO for a short period or enters recovery prohibition processing. This constraint is used to prevent the implement from directly restoring the PTO target output when it falls rapidly.

[0137] Engine speed within the PTO recovery allowable range means that the engine speed is neither lower than the lower recovery limit nor higher than the upper recovery limit, and there is no significant speed drop within the judgment period. The PTO controller continues to read the engine speed after testing the load response matching; if the engine speed is within the recovery allowable range, it indicates that the engine has the operating conditions to accept the formal PTO recovery. If the engine speed is lower than the lower recovery limit, higher than the upper recovery limit, or if an abnormal speed drop has occurred during the testing period, the PTO controller will not generate a PTO recovery access record.

[0138] The matching result between the test load response and the load climb reference characteristics is still based on the work window anchoring record corresponding to the same window identifier mentioned above. The PTO controller first confirms that the recovery test authorization record, PTO hold authorization record, and work window anchoring record carry the same window identifier, and then determines whether the selected items in the test load rise direction, test load rise magnitude, and test response duration match the load climb reference characteristics. If the window identifiers are inconsistent, or the test load response does not match, the formal recovery path after the suspension descent speed and engine speed are jointly approved will not be entered.

[0139] The generation of a PTO recovery access record requires the simultaneous fulfillment of three conditions: First, the three-point suspension has re-descended into the working height window corresponding to the window identifier, and the suspension descent speed is below the descent impact threshold; second, the engine speed is within the PTO recovery allowable range; and third, the trial load response matches the load climb reference characteristics. If any of the above conditions are not met, the PTO controller will not generate a PTO recovery access record. This process ensures that formal PTO recovery no longer relies solely on the suspension height returning to a certain position, nor solely on a single judgment of the load response, but simultaneously considers the implement descent process, engine load status, and the load matching results within the same window.

[0140] The PTO recovery access record is generated by the PTO controller and includes at least the window identifier, recovery access time, suspension descent speed judgment result, engine speed judgment result, and trial load response matching result. The window identifier is used to ensure that the recovery action is consistent with the aforementioned operation window anchoring record; the recovery access time is used to determine the control point at which the PTO execution unit begins formal recovery; the suspension descent speed judgment result and engine speed judgment result are used to indicate that the recovery access is not simply triggered by height and load response; the trial load response matching result is used to indicate that this recovery has been verified through limited trial.

[0141] After generating a PTO recovery access record, the PTO controller sends the record to the PTO execution unit as a prerequisite control for formally restoring the PTO output. The PTO execution unit only restores the PTO output in the order of pre-engagement, low-torque engagement, and target speed recovery after receiving a valid PTO recovery access record. If no PTO recovery access record is generated, the PTO execution unit maintains a short PTO hold, performs PTO disengagement, or enters a recovery prohibition path, without directly restoring the target PTO output.

[0142] The suspension descent speed is used to limit the mechanical impact when the implement re-enters the soil; the engine speed status is used to limit the power supply conditions during PTO recovery; and the trial load response matching is used to confirm that the implement has returned to the load establishment process within the same operating window. These three factors work together to ensure that the PTO recovery access record has a clear data source and trigger boundaries, supporting the beneficial effect of reducing the impact caused by directly resuming PTO when the implement is not yet stably in the soil or when the load is abnormal.

[0143] The descent impact threshold and the permissible PTO recovery range can be obtained through whole-machine calibration. Calibration can be performed by combining the three-point suspension hydraulic descent speed, implement weight, PTO target speed, and engine rated operating range. If further evidence is needed to demonstrate the effectiveness of "reducing recovery impact" or "reducing engine speed drop" in the embodiments, it is recommended to supplement with comparative test data, such as the engine minimum speed drop under fixed-height direct recovery and the minimum speed drop under the access recovery of this embodiment, PTO clutch slippage time, PTO recovery impact peak value, or number of recovery prohibition triggers.

[0144] Reference Figure 11 Based on the PTO recovery access record already generated, the recovery sequence of PTO output and the termination conditions during the recovery process are further restricted. Even if the access conditions such as the same window identifier, recovery trial matching, suspension descent speed, and engine speed status are met, the PTO output should not jump directly to the target output state. Instead, a controllable, phased recovery process should be implemented to gradually bring the PTO clutch, PTO output shaft, and implement load into the working state. During the recovery process, if the load recovery state deviates from the aforementioned load climb reference characteristics, or if the engine speed drops too much, the current recovery access should be cancelled to avoid further increasing transmission shock.

[0145] The PTO actuator restores the PTO output according to the PTO recovery access record, following the sequence of PTO clutch pre-engagement, low torque engagement, and target speed recovery.

[0146] After receiving a valid PTO recovery access record, the PTO execution unit enters the formal recovery process.

[0147] During the PTO clutch pre-engagement phase, the PTO controller outputs a pre-engagement control command to the PTO execution unit, causing the PTO clutch to transition from a disengaged or briefly held state to a pre-engaged state. The focus of control in this phase is to eliminate free travel and engagement gaps in the PTO transmission path, placing the PTO clutch in a ready-to-transmit power state, but without immediately outputting the target operating torque. During this phase, the PTO controller reads the PTO output shaft speed, PTO clutch pressure, and engine speed. Only after confirming that the PTO clutch pressure build-up process is normal, that there are no abnormal sudden increases in PTO output shaft speed, and that there are no abnormal drops in engine speed, is the controller allowed to proceed to the next phase.

[0148] During the low-torque engagement phase, the PTO controller gradually increases the transmission capacity of the PTO clutch by controlling the PTO actuator, allowing the PTO output to transition from a limited output after recovery testing to a low-torque output state capable of handling the working load. The output during this phase is still lower than the target PTO output and is not considered the final working output. The PTO controller continuously acquires the PTO load status during this phase and observes whether the PTO load recovery characteristics remain consistent with the load ramp-up reference characteristics. If the load recovery process shows a smooth transition from low load to working load without any abnormal surges, reverse changes, or prolonged periods of unresponsiveness, then the process is allowed to proceed to the target speed recovery phase.

[0149] During the target speed recovery phase, the PTO controller controls the PTO actuator to gradually restore the PTO output shaft speed to the target PTO output speed. This phase can be achieved by adjusting the PTO clutch pressure, proportional valve opening, or the PTO target speed command. During the recovery process, the PTO controller continues to read the PTO output shaft speed and PTO load status, using the window identifier in the PTO recovery access record as a constraint to confirm that the current recovery still corresponds to the same work window anchor record. If the PTO output shaft speed reaches the target PTO output speed, and the PTO load status enters a stable range corresponding to the work load, then the PTO recovery is complete.

[0150] The three stages described above are subject to sequential constraints. The PTO actuator must not directly enter low-torque engagement without completing the pre-engagement of the PTO clutch, nor may it directly enter target speed recovery if the load condition does not meet the recovery requirements during the low-torque engagement stage. Through this sequential control, the formal PTO recovery is linked to the aforementioned recovery probe, giving the recovery action a continuous control chain from probe, entry to formal output, rather than simply restoring the target PTO output based on suspension height.

[0151] During the recovery process, if the PTO load recovery characteristics no longer match the load ramp-up baseline characteristics, or if the engine speed drop exceeds the speed drop threshold, the PTO controller will cancel the PTO recovery access record.

[0152] The PTO load recovery characteristics are collected by the PTO controller during the formal recovery process. The data source is consistent with the aforementioned PTO load state, and can be either the PTO output torque or a load substitution quantity formed by at least one of the following: engine load rate change, PTO output shaft speed change, and PTO clutch pressure change. The PTO controller continuously records the PTO load change direction, load change amplitude, and load establishment time at each stage of PTO clutch pre-engagement, low torque engagement, and target speed recovery, and uses these as the PTO load recovery characteristics during the recovery process.

[0153] The matching of PTO load recovery characteristics and load ramp-up baseline characteristics is still based on the work window anchoring record. If the load ramp-up baseline characteristics show that the load gradually increased from a non-operational load state to an operational load state when the previous operation state was entered, then the load recovery characteristics in this recovery process should also show a load building process in the same direction. If, during the recovery process, the load decreases instead of increasing, the load suddenly increases beyond the allowable range, the load cannot be built up for a long time, or the load fluctuations are significantly inconsistent with the aforementioned load ramp-up baseline characteristics, the PTO controller determines that the PTO load recovery characteristics no longer match.

[0154] The engine speed drop is determined by the engine speed provided by the engine and vehicle status acquisition unit. The PTO controller uses the engine speed at the time of formal recovery or the engine speed at the time of recovery access as a reference, continuously reading the engine speed changes during the recovery process. When the engine speed drop exceeds the speed reduction threshold, it indicates that the engine is insufficient to handle the current PTO recovery load, and continued recovery may lead to a significant engine speed drop or increased PTO transmission shock. At this point, even if the PTO load recovery characteristics are not yet completely abnormal, the PTO controller will cancel the PTO recovery access record.

[0155] The speed drop threshold can be determined through whole-machine calibration, and its value should be determined in conjunction with the engine's rated operating range, PTO target speed, implement inertia, and operating load characteristics. When judging the engine speed drop, the PTO controller does not rely solely on a single instantaneous sampling point; if the engine speed fluctuates only momentarily due to sensor disturbances, the speed drop status can be confirmed through continuous sampling points. If continuous sampling shows that the speed drop exceeds the speed drop threshold, or if the speed drop continues for a set confirmation time, the PTO recovery access record is revoked.

[0156] After the PTO recovery access record is revoked, the PTO controller stops the current formal recovery process and outputs the revoked control command to the PTO execution unit. Specific processing may include reducing PTO output, reverting to PTO short-term hold, controlling PTO disengagement, or controlling PTO braking. If the PTO hold authorization record is still valid and there is no reverse gear or the hold time has expired, the PTO controller can revert to PTO short-term hold and wait for subsequent recovery conditions; if the PTO hold authorization record has expired, or if a risky state such as engine speed drop or abnormal load increase has occurred during the recovery process, the controller will control PTO disengagement or braking.

[0157] After the PTO controller generates the PTO recovery access record, the PTO execution unit first performs PTO clutch pre-engagement, putting the PTO transmission path into a ready state for power transmission; then, it performs low-torque engagement, observing whether the PTO load is established according to the aforementioned load ramp-up reference characteristics; finally, it enters the target speed recovery phase, restoring the PTO output to the target operating state. Throughout the recovery process, the PTO controller continuously compares the PTO load recovery characteristics with the load ramp-up reference characteristics and monitors the engine speed drop. Once the load recovery state deviates from the reference, or the engine speed drop exceeds the speed reduction threshold, the PTO recovery access record is revoked, and the PTO execution unit stops continuing the recovery.

[0158] The PTO recovery access record serves not only as the trigger condition for recovery initiation but also as a continuous constraint during the recovery process. PTO output recovery is divided into three stages: pre-engagement, low-torque engagement, and target speed recovery, with load matching and engine speed drop reversal paths preserved at each stage. This technical arrangement supports the beneficial effects of reducing the impact of direct recovery of the target PTO output, reducing PTO clutch slippage, and avoiding significant engine speed drops.

[0159] The allowable deviation ranges for PTO clutch pre-engagement time, low-torque engagement duration, target speed recovery slope, speed drop threshold, and load recovery characteristics can all be determined through whole-machine calibration. For PTO-driven machines with large inertia, the target speed recovery slope can be set more gradually; for machines with faster load build-up, the low-torque engagement duration can be shortened.

[0160] Based on the already generated recovery prohibition record, the exit path after recovery failure is further restricted. When the PTO recovery attempt fails to prove that the equipment has returned to the same operating state as the previous operation window, the system cannot continue to maintain the PTO short-term hold indefinitely, nor can it repeatedly attempt to restore the target PTO output. Therefore, with the valid state of the recovery prohibition record and the PTO hold authorization record as constraints, the short-term hold control chain ends when the mismatch continues until the hold authorization expires.

[0161] After generating the recovery prohibition record, if the trial load response mismatch continues until the PTO hold authorization record expires, the PTO hold authorization record is revoked, the window is unlocked, and the PTO is controlled to perform detach.

[0162] The fields for restoring prohibited records can reuse the aforementioned record content; this stage mainly calls its window identifier, mismatch reason and prohibited status to determine whether to end the current window locking process.

[0163] After the resumption of the prohibited record generation, the PTO controller does not allow the PTO execution unit to enter the target PTO output recovery. At this time, the system is still in a window-locked state, and the PTO hold authorization record may not have expired. In subsequent control cycles, the PTO controller continues to read the validity status of the PTO hold authorization record, the three-point suspension height, the PTO load status, the reverse gear status, and the hold time information to determine whether the trial load response mismatch continues.

[0164] The persistent test load response mismatch state refers to the PTO controller failing to obtain a valid test load response matching the load ramp-up baseline characteristics within the control period after the self-recovery prohibition record is generated and the PTO maintains the authorization record. Specifically, the PTO controller uses the load ramp-up baseline characteristics corresponding to the same window identifier as a benchmark to check whether subsequently acquired PTO load states still fail to meet the selected conditions for the test load increase direction, test load increase magnitude, and test response duration. If no matching result is subsequently formed, the recovery prohibition state remains in effect; if a matching result is re-formed before the authorization expires, the aforementioned recovery admission logic can be followed instead of executing the reversal path in this section.

[0165] The PTO hold authorization record may expire due to the expiration of the hold time limit, the appearance of reverse gear, failure to meet the same work height window again, or abnormal short-term hold status of PTO. In the main implementation path, the PTO controller calculates the remaining authorization time based on the hold start time and hold time limit in the PTO hold authorization record. If the current time has exceeded the hold time limit and the mismatch between the trial load response and the current time limit has not been resolved, the PTO hold authorization record is considered invalid. If reverse gear is detected before the hold time limit expires, the record expires prematurely, and the PTO controller no longer waits for subsequent trial load responses.

[0166] When a PTO hold authorization record expires, the PTO controller revokes it. The revocation process includes invalidating the record's validity status and ceasing its use as the basis for authorizing PTO short-term hold and PTO recovery probes. After revocation, the PTO controller will no longer allow the generation of new recovery probe authorization records based on that window identifier, nor will it allow entry into the PTO recovery admission process based on that PTO hold authorization record.

[0167] After the PTO hold authorization record is revoked, the PTO controller releases the window lock. Once the window lock is released, the original work window anchoring record is no longer used as the recovery benchmark after this short-term hold at the field edge, and the system exits the "same window hold – same window recovery probe" control chain. If the tractor subsequently re-enters the work process, the PTO controller needs to re-form a new work window anchoring record based on the suspension height sequence and PTO load state sequence during the new three-point suspension descent phase, and cannot continue to use the expired window identifier.

[0168] Simultaneously, the PTO controller controls the PTO to disengage. Specifically, the PTO controller outputs a PTO disengagement command to the PTO execution unit, causing the PTO clutch to disengage from its engaged or held state and cutting off the PTO power transmission. If the PTO output shaft still has a high speed, the PTO controller can combine the PTO braking logic after disengagement to reduce the PTO output shaft to an allowable state; however, in the main implementation path of this section, PTO disengagement is the basic processing result after restoring the prohibition to continue until the holding authorization fails.

[0169] After the tractor completes the turn at the end of the field, the three-point suspension lowers back into the same working height window. The PTO controller generates a recovery attempt authorization record and executes the recovery attempt. If the test load response does not match the load climb reference characteristics, the PTO controller generates a recovery prohibition record and prohibits the recovery of the current target PTO output. If the mismatch is not resolved within the validity period of the PTO hold authorization record, and the hold time expires or a reverse gear state occurs, the PTO controller cancels the PTO hold authorization record, unlocks the window, and controls the PTO to perform disengagement. This process ensures that a short-term hold at the end of the field has a clear endpoint, avoiding continuous hold or repeated recovery when the recovery conditions are not met.

[0170] The recovery prohibition record is not simply a fault marker, but rather a basis for control routing after recovery failure; the failure of the PTO hold authorization record serves as a boundary condition for ending the current window lock control. Only when the probe load response mismatch persists to this boundary condition will the system revoke the hold authorization and release the window lock.

[0171] Reference Figure 12 The holding time limit, the observation period after the restriction is lifted, and the allowable output shaft speed after PTO separation can be determined through whole-machine calibration. For PTO-driven implements with large inertia, a longer output shaft deceleration observation time can be set after PTO separation; for operation scenarios with short turning times at the ground, the holding time limit can be shortened accordingly.

[0172] In conclusion, the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A tractor PTO control system, comprising a PTO controller, and a three-point suspension status acquisition unit, a PTO status acquisition unit, an engine and vehicle status acquisition unit, and a PTO execution unit connected to the PTO controller, characterized in that: The three-point suspension status acquisition unit outputs the suspension height and suspension lifting status of the three-point suspension to the PTO controller; The PTO status acquisition unit outputs the PTO output shaft speed and PTO load status to the PTO controller. The engine and vehicle status acquisition unit outputs the engine status and vehicle operating status to the PTO controller; The PTO controller is configured as follows: During the three-point suspension descent phase, the suspension height sequence is correlated with the PTO load state sequence by time. The load climbing segment where the PTO load changes from non-operational load state to operational load state is extracted, and an operation window anchoring record is generated. The operation window anchoring record includes window identifier, operation height window, and load climbing reference features. When the PTO is running and the three-point suspension lift is out of the working height window, an operation exit confirmation record is generated based on the suspension height separation status and the reverse change of the PTO load relative to the load climbing reference characteristics. When a work exit confirmation record is generated and the vehicle's operating status meets the conditions for ground lifting, a PTO hold authorization record with a window identifier is generated, the work window anchoring record is set to the window locked state, and the generation of new work window anchoring records is paused in the window locked state. When the window is locked, the control PTO execution unit performs short-term PTO holding and restricts PTO recovery to be performed only based on the PTO holding authorization record carrying the same window identifier; When the PTO authorization record remains valid and the three-point suspension re-descends into the operation height window corresponding to the window identifier, a recovery trial authorization record is generated, and the PTO execution unit is controlled to perform a PTO recovery trial that is lower than the target PTO output based on the recovery trial authorization record; Collect the test load response during the PTO recovery test. When the test load response matches the load ramp-up baseline characteristics, generate a PTO recovery admission record and restore the PTO output based on the PTO recovery admission record. When the test load response does not match the load ramp-up baseline characteristics, generate a recovery prohibition record and maintain the PTO hold for a short time or revoke the PTO hold authorization record.

2. The tractor PTO control system according to claim 1, characterized in that: The load ramp reference features include at least two of the following: load ramp start height, load ramp end height, load ramp direction, and load ramp amplitude.

3. A tractor PTO control system according to claim 1, characterized in that: The PTO load condition is the PTO output torque, or the load substitution formed by at least one of the engine load rate change, PTO output shaft speed change, and PTO clutch pressure change.

4. A tractor PTO control system according to claim 1, characterized in that: After the PTO controller lifts the three-point suspension and leaves the working height window, if the PTO load state changes from the working load state to the non-working load state, and this change corresponds in time to the process of the suspension height leaving the working height window, then a work exit confirmation record is generated.

5. A tractor PTO control system according to claim 1, characterized in that: Vehicle operating status includes vehicle speed, steering status, and reverse gear status; the conditions for lifting off the ground include the vehicle being at low speed, the steering status meeting the conditions for lifting off the ground, and no reverse gear being detected.

6. A tractor PTO control system according to claim 1, characterized in that: PTO short-term hold includes PTO deceleration hold or PTO low torque hold; PTO hold authorization record includes window identifier, hold start time and hold duration; If the three-point suspension fails to re-enter the working height window corresponding to the window indicator within the holding time limit, or if reverse gear is detected, the PTO controller will cancel the PTO holding authorization record and control the PTO execution unit to perform PTO disengagement or braking.

7. A tractor PTO control system according to claim 1, characterized in that: The test load response includes at least two of the following: the direction of the test load increase, the magnitude of the test load increase, and the test response duration.

8. A tractor PTO control system according to claim 1, characterized in that: When generating the PTO recovery access record, the PTO controller also determines the suspension descent speed and engine speed status. When the suspension descent speed is lower than the descent impact threshold, the engine speed is within the PTO recovery allowable range, and the test load response matches the load climb reference characteristics, the PTO recovery access record is generated. The PTO actuator restores the PTO output according to the PTO recovery access record, following the sequence of PTO clutch pre-engagement, low torque engagement, and target speed recovery. During the recovery process, if the PTO load recovery characteristics no longer match the load ramp-up baseline characteristics, or if the engine speed drop exceeds the speed drop threshold, the PTO controller will cancel the PTO recovery access record.

9. A tractor PTO control system according to claim 1, characterized in that: After generating a recovery prohibition record, if the test load response mismatch continues until the PTO hold authorization record expires, the PTO hold authorization record will be revoked, the window lock will be released, and the PTO will be controlled to perform detach.

10. A tractor PTO control method, applied to the tractor PTO control system according to any one of claims 1 to 9, characterized in that, include: The system acquires the suspension height and suspension lifting status of the three-point suspension, as well as the PTO output shaft speed, PTO load status, engine status, and vehicle operating status. During the three-point suspension descent phase, the suspension height sequence is correlated with the PTO load state sequence by time. The load climbing segment where the PTO load changes from non-operational load state to operational load state is extracted, and an operation window anchoring record is generated. The operation window anchoring record includes window identifier, operation height window, and load climbing reference features. When the PTO is running and the three-point suspension lift is out of the working height window, an operation exit confirmation record is generated based on the suspension height separation status and the reverse change of the PTO load relative to the load climbing reference characteristics. When a work exit confirmation record is generated and the vehicle's operating status meets the conditions for ground lifting, a PTO hold authorization record with a window identifier is generated, and the work window anchoring record is set to the window locked state. Perform a short PTO hold while the window is locked, and restrict PTO recovery to be performed only based on PTO hold authorization records that carry the same window identifier; When the three-point suspension re-descends and enters the working height window corresponding to the window indicator, a PTO recovery probe is performed, and the probe load response during the PTO recovery probe is collected. When the test load response matches the load ramp-up baseline characteristics, a PTO recovery admission record is generated, and the PTO output is restored based on the PTO recovery admission record; when the test load response does not match the load ramp-up baseline characteristics, no PTO recovery admission record is generated.

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