JP2020164160A - Automatic travel farm field work vehicle - Google Patents

Abstract

To provide an automatic travel work vehicle capable of automatically steering-traveling with high accuracy even in work travel along a set target travel passage.SOLUTION: An automatic travel field work vehicle comprises: a positional deviation arithmetic operation part for arithmetically operating positional deviation d being positional dislocation in a lateral direction of one's own vehicle to a target travel passage; an azimuth deviation arithmetic operation part for arithmetically operating an azimuth deviation θ between the target travel passage and itself; a first control arithmetic operation part for outputting a first steering value by using the positional deviation d and target positional deviation as an input parameter; a second control arithmetic operation part for outputting a second steering value by using the azimuth deviation θ, the target azimuth deviation, and the positional deviation d as the input parameter; a target steering arithmetic operation part for outputting a target steering value for traveling along the target travel passage on the basis of a first steering value and a second steering value; and a steering driving control part for outputting a steering driving signal by using the target steering value as input.SELECTED DRAWING: Figure 1

Description

The present invention relates to an automatic traveling field work vehicle that automatically steers and travels along a set target traveling route.

As a work vehicle having an automatic steering function that is automatically steered along a set target traveling path, Patent Document 1 describes a teaching path generated by a teaching path generating means based on position information measured by a GPS device. A rice transplanter that generates a target route parallel to the target route and autonomously travels on the target route is disclosed. In this rice transplanter, the actual traveling route during automatic traveling is measured by the GPS unit, the amount of deviation between the target route and the actual traveling target route is calculated, and is compared with a preset threshold value. At that time, the angle formed by the target path direction and the traveling direction is used as the deviation amount, and if the deviation amount exceeds the threshold value, the deviation direction with respect to the reference line is detected and determined, and the deviation is left. If there is a deviation, the steering device is corrected to the right according to the amount of deviation, and if there is a deviation to the right, the steering device is corrected to the left according to the amount of deviation. However, in a work vehicle that adopts the principle of automatic driving, only the angle formed by the target route direction and the traveling direction is used for steering control as a traveling deviation, so that the target route and the vehicle body are close to each other. If only the amount of deviation is large, or if the amount of deviation is small but the target route and the vehicle body are far apart, proper driving becomes difficult.

In the vehicle-based travel control technology disclosed in Patent Document 2, for a target travel path (target track) in which various curvatures are mixed, the amount of lateral deviation from the target travel path, the amount of azimuth deviation, and the target travel The curvature of the path is measured, and the steering angle corresponding to the two deviation amounts and the curvature is calculated and output. Specifically, a reference point is provided so that the vehicle position is in the normal direction of the target travel path, and the coordinate system is relative to the coordinate system based on the reference point from the absolute coordinate system of the vehicle position. In addition to converting to, the relative lateral deviation and azimuth deviation from the target travel path are calculated, and the feedback operation amount according to the deviation amount and the feed forward according to the curvature and lateral deviation amount of the target trajectory are calculated by proportional control. The steering angle is determined by the amount of operation. However, although it may be effective for automobiles traveling on paved roads, the traveling speed of rice transplanters, tractors, combines, agricultural work machines such as lawnmowers, and civil engineering work machines such as dozers is high. Since the speed is low, it takes more time to eliminate the travel deviation than a vehicle traveling at high speed at the same steering angle. Furthermore, the position may be instantly deviated from the target position due to slipping or riding on a mass of soil. Therefore, the travel control technology disclosed in Patent Document 2 cannot be directly applied to the automatic steering travel of the work vehicle.

Japanese Unexamined Patent Publication No. 2008-131880 Japanese Unexamined Patent Publication No. 2002-215239

In view of the above circumstances, an object of the present invention is to provide an automatic traveling field work vehicle capable of automatically steering and traveling with high accuracy even during work traveling along a set target traveling route. ..

The automatic traveling field work vehicle according to the present invention, which automatically steers along a target traveling route set in the field, has an own vehicle position calculation unit that calculates the own vehicle position and a own vehicle orientation that calculates the own vehicle driving direction. The calculation unit, the position deviation calculation unit that calculates the position deviation that is the lateral displacement of the own vehicle with respect to the target travel route, and the azimuth deviation between the azimuth line of the target travel route and the travel direction are calculated. The azimuth deviation calculation unit, the first control calculation unit that outputs the first steering value with the position deviation and the target position deviation as input parameters, and the azimuth deviation, the target azimuth deviation, and the position deviation as input parameters. 2 A second control calculation unit that outputs a steering value, and a target steering calculation unit that outputs a target steering value for traveling along the target traveling path based on the first steering value and the second steering value. It includes a steering drive control unit that outputs a steering drive signal with the target steering value as an input, and a steering drive unit that steers the steering wheels based on the steering drive signal.

According to this configuration, the target steering value for traveling along the target travel route is output from the position deviation with respect to the target travel route and the azimuth deviation with respect to the target travel route. However, instead of simply obtaining the first steering value calculated for eliminating the deviation from the position deviation with respect to the target traveling path and the second steering value calculated for eliminating the deviation and the azimuth deviation with respect to the target traveling path. When determining the second steering value, the position deviation with respect to the target travel path is also taken into consideration. For example, when the position deviation is large, if the orientation deviation is ignored to some extent and the target steering value that emphasizes the elimination of the position deviation is output, the vehicle body slips or the soil mass rides on the vehicle, resulting in a large position deviation (position deviation). ) Occurs, the position deviation can be quickly eliminated. This is an advantage for work vehicles such as rice transplanters, combines, tractors, lawnmowers, etc., where it is necessary to avoid large deviations from the straight target driving path at the expense of simply traveling straight. There is.
In the present application, assuming that the target traveling path is linear, the position deviation is the length of the perpendicular line drawn from the vehicle body to the target traveling path, and the azimuth deviation is the angle formed by the traveling direction line of the vehicle body and the target traveling path. It is defined as a value that can be represented.

In the case of a control system that outputs a target steering value for appropriately eliminating deviations when traveling at low speed or medium speed, if the steering angle is the same, the higher the vehicle speed, the greater the change in the position and orientation of the vehicle body over a certain period of time. Become. As a result, there is a problem that the vehicle body tends to meander when traveling at high speed. In order to solve this problem, in one of the preferred embodiments of the present invention, a vehicle speed calculation unit for calculating the vehicle speed is provided, and the target steering calculation unit is set to the first steering value and the second steering value. Based on this, when the target steering value is output, an adjustment coefficient that shows a decreasing tendency as the vehicle speed increases is used, and when the vehicle speed is large, the target steering value is reduced. Specifically, an adjustment function for deriving an adjustment coefficient (for example, a value greater than 0 and less than or equal to 1) is introduced using the vehicle speed as a variable, and at that time, this adjustment function tends to decrease as the vehicle speed increases. It shall be. That is, when the vehicle speed is s and the adjustment function is K, the adjustment coefficient k is obtained by K (k), and K is a function that decreases monotonically or gradually decreases. The adjustment factor k is used in multiplication. As a result, when the vehicle speed becomes high, the target steering value is reduced, so that appropriate deviation elimination is realized from low speed running to high speed running, and automatic steering running is stable.

As another measure for the problem that the steering angle for eliminating the deviation has a greater influence on the vehicle body as the vehicle speed becomes higher, in one of the preferred embodiments according to the present invention, the target steering calculation unit is the target. It has an upper limit limiter function for the steering value, and the upper limit limit value is set according to the vehicle speed. It is preferable that this upper limit value can be changed depending on the work type. As a result, appropriate deviation elimination is realized from low-speed running to high-speed running, and automatic steering running is stabilized.

As described above, one of the features of the present invention is that when the position deviation is large, the target steering value with an emphasis on eliminating the position deviation is output by ignoring the azimuth deviation to some extent. At that time, it is more likely that automatic steering running more suitable for the work can be obtained by changing the degree of ignoring the azimuth deviation depending on the soil condition and the work type on which the work is carried out. Therefore, in one of the preferred embodiments of the present invention, the degree of weight reduction using the weighting coefficient of the azimuth deviation depending on the magnitude of the position deviation in the second control calculation unit can be changed. It is configured as follows.

In order to simplify the target steering calculation unit that outputs the target steering value for traveling along the target traveling path based on the first steering value and the second steering value, in one of the preferred embodiments of the present invention. The target steering calculation unit is configured to add and calculate the first steering value and the second steering value to output the target steering value. As a result, while controlling the traveling direction of the vehicle body to match the line parallel to the target traveling route, the vehicle body is gradually brought closer to the target traveling route, thereby performing a straight line particularly required for field work. Work running along the target running route of the shape is properly performed.
The automatic traveling field work vehicle according to the present invention is an automatic traveling field work vehicle that automatically steers and travels along a target traveling route set in the field, and has an own vehicle position calculation unit for calculating the own vehicle position and the own vehicle. The vehicle orientation calculation unit that calculates the travel direction, the position deviation calculation unit that calculates the position deviation that is the lateral displacement of the vehicle with respect to the target travel route, the azimuth line of the target travel route, and the travel orientation. An orientation deviation calculation unit that calculates an orientation deviation between the two, a target steering calculation unit that outputs a target steering value for traveling along the target travel path based on the position deviation and the target position deviation, and the above-mentioned Based on the steering drive control unit and the steering drive signal that outputs the front stage output value based on the target steering value and the actual steering angle and outputs the steering drive signal based on the previous stage output value and the actual steering speed. It is equipped with a steering drive unit that steers the steering wheels.
Further, the steering drive control unit may output the previous stage output value by PI control or PID control.
Further, the steering drive control unit may output the steering drive signal by PI control or PID control.

It is a schematic diagram explaining the basic principle of automatic steering running control. It is a side view of the tractor which is one of the embodiments of the automatic traveling field work vehicle by this invention. It is a functional block diagram which shows the control system mounted on a tractor. It is a control diagram which shows the automatic steering control system. It is a control diagram which shows another automatic steering control system. It is a control diagram which shows another automatic steering control system.

Before explaining a specific embodiment of the automatic traveling field work vehicle according to the present invention, the basic principle of the automatic steering traveling control according to the present invention will be described with reference to FIG. Here, as an automatic traveling field work vehicle (hereinafter, simply abbreviated as a work vehicle), an agricultural work machine such as a rice transplanter, a tractor, or a combine that repeats a linear traveling work in a field while making a U-turn is assumed. This work vehicle is configured to automatically steer along a preset target travel path. In order to perform automatic steering, it is necessary to know the current position of the work vehicle (hereinafter referred to as the own vehicle position) and the current traveling direction (hereinafter referred to as the own vehicle direction). Therefore, this work vehicle is equipped with satellite navigation equipment using satellites called GPS (Global Positioning System) or GNSS (Global Navigation Satellite System) and inertial navigation equipment using accelerometers and gyros. As shown in FIG. 1, here, the vehicle position is indicated by the positioning value (latitude, longitude) of the center of the work vehicle, and the vehicle orientation is the traveling direction calculated from the change in the vehicle position per unit time. Indicated by.

As shown in FIG. 1, the distance between the straight line drawn parallel to the target traveling path (azimuth line) from the center of the work vehicle and the target traveling path: d is treated as a position deviation, and the vehicle body passes through the center of the vehicle body. The angle formed by the front-back direction line (traveling direction) and the target traveling path: θ is treated as the bearing deviation. The target vehicle position in the automatic steering travel control is a point on the target travel route, and the target vehicle orientation is the orientation of the target travel route. Therefore, the position deviation from the vehicle position with respect to the target travel path is d, and the azimuth deviation between the azimuth line and the travel direction of the target travel path is θ.

The first steering value for eliminating the deviation is calculated based on the position deviation. PID control calculation can be preferably adopted for this calculation. The second steering value for eliminating the deviation is calculated based on the azimuth deviation, and the position deviation is also taken into consideration at that time. When the position deviation is large, the second steering value for eliminating the deviation based on the azimuth deviation is reduced. Specifically, a weighting function for deriving a weighting coefficient using the position deviation as a variable is introduced, and at that time, the weighting function tends to decrease as the position deviation increases. That is, if the position deviation is d and the weighting function is G, the weighting coefficient w is obtained by G (d), and G is a function that decreases monotonically or decreases stepwise. w is usually greater than 0 and less than or equal to 1. The weighting factor w is used in multiplication. As a result, the second steering value for eliminating the deviation is output based on the position deviation and the azimuth deviation on the condition that the weight of the azimuth deviation is reduced when the position deviation is large. The final target steering value for traveling along the target traveling path is output based on the first steering value and the second steering value thus obtained. For example, with respect to the value obtained by the function F (θ) that derives the second steering value based on the azimuth deviation, the weighting coefficient w (0 <w <1) that becomes smaller as the position deviation increases is derived. A function W (d) is created, and the second steering value is obtained by W (d) × F (θ). That is, when the position deviation is large, the weight of the azimuth deviation is reduced, and then the second steering value for eliminating the deviation is output based on the position deviation and the azimuth deviation. It is also preferable that the PID control calculation is adopted when deriving the second steering value based on the azimuth deviation.

By inputting the first steering value and the second steering value obtained in this way, the target steering value for the work vehicle to travel along the target traveling path is obtained and output. Most simply, the target steering value can be obtained by an addition operation considering the signs of the first steering value and the second steering value. Further, a steering control system is provided that receives the target steering value as an input and outputs a steering drive signal to the steering drive unit that drives the steering angle of the steering wheel (including the crawler) of the work vehicle. The steering drive unit can consist of an electric motor, hydraulic equipment, or both. The steering control system is preferably constructed by the PI feedback control method, but other control methods may be used. Here, the steering speed and the steering angle are adopted as feedback.

Although it is shown by a dotted line in FIG. 1, it is also preferable to consider the traveling speed of the work vehicle, that is, the vehicle speed when obtaining the target steering value from the first steering value and the second steering value. That is, in the case of the same steering angle, the faster the vehicle speed, the larger the amount of change in the posture of the vehicle body per hour. If the amount of posture change per hour becomes too large, the inconvenience of ruining the field occurs. Therefore, the target steering value calculated from the first steering value and the second steering value is preferably weakened as the vehicle speed increases. For example, the calculated target steering value may be used as it is during low-speed driving, and the target steering value may be reduced at a predetermined reduction rate during high-speed driving of a predetermined value or higher.

Next, one specific embodiment of the automatic traveling field work vehicle of the present invention will be described. In this embodiment, the work vehicle is a tractor equipped with a work device for performing agricultural work such as tilling work on a field bounded by ridges. In this tractor, a control portion 30 is formed in a central portion of a vehicle body 3 supported by front wheels 2a and rear wheels 2b. The rear part of the vehicle body 3 is equipped with a ground work device 5 via a hydraulic elevating mechanism 4. The front wheel 2a functions as a steering wheel, and the traveling direction of the tractor is changed by changing the steering angle thereof. The steering angle of the front wheels 2a is changed by the operation of the steering mechanism 6. The steering mechanism 6 is provided with a steering drive unit 60 for automatic steering. The electric motor constituting the steering drive unit 60 is controlled by a steering drive signal from the electronic control unit 7, which will be described later. The steering angle of the front wheels 2a can also be adjusted by operating the steering wheel as in the conventional manner, and the steering wheel is arranged on the steering wheel 30 of the tractor together with various operating levers and a seat on which the driver sits on the steering wheel 30. .. The control unit 30 is also provided with a positioning unit 8 for measuring the position of the own aircraft required for automatic steering steering. The positioning unit 8 includes a satellite navigation module configured as a GNSS module and an inertial navigation module configured as a gyro module incorporating a gyro acceleration sensor and a magnetic orientation sensor. The satellite navigation module includes a satellite antenna for receiving GPS signals and GNSS signals, but it is omitted in FIG.

FIG. 3 shows a control system equipped on this work vehicle. This control system uses the basic principle of automatic steering control described with reference to FIG. The control system shown in FIG. 3 includes an electronic control unit 7, a positioning unit 8, a switch sensor group 9, and a steering drive unit 60.

The positioning unit 8 includes a satellite navigation module 81 that detects directions such as latitude and longitude using GNSS, and its configuration is similar to that of a positioning unit used in a car navigation system or the like. The positioning unit 8 includes an inertial navigation module 82 having a gyro acceleration sensor or the like in order to detect the momentary movement (direction vector or the like) or direction of the work vehicle and to complement the satellite navigation module 81. It is equipped. The steering drive unit 60 adjusts the steering angle of the front wheels 2a, which are steering wheels, based on the steering drive signal output from the electronic control unit 7. The switch / sensor group 9 is a general term for switches and sensors that detect the running state and setting status of the work vehicle, and the detection signals from these are input to the electronic control unit 7 and used as input parameters for various controls. Will be done. The switch sensor group 9 also includes a sensor that outputs a detection signal for calculating the vehicle speed and a sensor that outputs a detection signal for calculating the driving state (for example, operating speed and steering angle) of the steering drive unit 60. include.

The electronic control unit 7 includes a reference route acquisition unit 71, a reference route setting unit 72, a vehicle position calculation unit 731, a vehicle orientation calculation unit 732, a position deviation calculation unit 741, and an orientation as functional units particularly related to the present invention. The deviation calculation unit 742, the first control calculation unit 751, the second control calculation unit 752, the target steering calculation unit 76, the vehicle speed calculation unit 78, and the steering drive control unit 79 are included.

The reference route acquisition unit 71 includes field information such as map position of the field to be worked on and position data of ridges defining the boundary line of the field, and device setting data (for example, work width) related to the field work to be performed. ) And other work information, the target travel route for automatic steering work travel is acquired. Regarding the acquisition of the target travel route, it is possible to adopt downloading from a management server in a remote location, reading from the target travel route owned by the work vehicle itself for each field and each work, and the like. It may be calculated and calculated each time by an algorithm for calculating a target travel route. In addition, the target travel route may be calculated through teaching travel. When the target travel route is determined, the reference route setting unit 72 incorporates the target travel route into the work travel map and internally processes it so that it can be used as a control target for automatic steering travel.

The own vehicle position calculation unit 731 calculates the own vehicle position on the work travel map based on the positioning data sent from the positioning unit 8. The own vehicle orientation calculation unit 732 calculates the traveling orientation of the own vehicle on the work travel map based on the positioning data sent from the positioning unit 8. The position deviation calculation unit 741 calculates the position deviation (indicated by the symbol d in FIG. 1) from the position of the own vehicle with respect to the target traveling route. The azimuth deviation calculation unit 742 calculates the azimuth deviation (indicated by the symbol θ in FIG. 1) between the azimuth line of the target travel path and the travel azimuth.

The first control calculation unit 751 outputs the first steering value for eliminating the deviation based on the position deviation. When the position deviation is large, the second control calculation unit 752 reduces the weight of the azimuth deviation by using the weighting coefficient as described above, and then sets the second steering value for eliminating the deviation based on the position deviation and the azimuth deviation. Output. The second control calculation unit 752 outputs a provisional second steering value for eliminating the deviation based on the azimuth deviation, reduces the provisional second steering value as the position deviation increases, and outputs it as a formal second steering value. It may be configured to do so. The degree of reduction of the azimuth deviation, which depends on the magnitude of the position deviation, can be adjusted through the input device.

The target steering calculation unit 76 outputs a target steering value for the work vehicle to travel along the target traveling path based on the first steering value and the second steering value. In the simplest form, the result of addition of the first steering value and the second steering value is the target steering value. The target steering value output from the target steering calculation unit 76 is used in the steering drive control unit 79 as an input parameter in the control calculation for outputting the steering drive signal for driving the steering drive unit 60.

In this embodiment, the target steering calculation unit 76 considers the vehicle speed of the work vehicle obtained from the vehicle speed calculation unit 78 when calculating the target steering value, and when the vehicle speed is high, the first steering value and the second steering value It also has a function to reduce the target steering value that is calculated and output based on the steering value. Further, the target steering calculation unit 76 incorporates a steering upper limit setting unit 760, and the steering upper limit setting unit 760 is a target obtained by using the first steering value, the second steering value, and the vehicle speed. It has a function of clamping the upper limit with respect to the steering value, that is, an upper limit limiter function. It is preferable that this upper limit value also fluctuates depending on the vehicle speed. That is, by setting the maximum target steering value to be output to decrease as the vehicle speed increases, the steering stability during high-speed driving is improved.

A more specific control mechanism of the electronic control unit 7 configured as described above will be described with reference to the control diagram shown in FIG. The first control calculation unit 751 uses PI control to calculate and output a first steering value for reducing the position deviation: d by using the target position deviation: Δd and the position deviation: d as input parameters. PID control may be used instead of PI control. The second control calculation unit 752 uses PI control to calculate and output a provisional second steering value for reducing the azimuth deviation: θ by using the target azimuth deviation: Δθ and the azimuth deviation: θ as input parameters. Here, too, PID control may be used instead of PI control. However, when the position deviation is large, the second control calculation unit 752 reduces the provisional second steering value obtained based on the azimuth deviation proportionally or non-linearly according to the amount of the position deviation. , Output as the second steering value. The target steering calculation unit 76 controls and outputs the sum of the first steering value output from the first control calculation unit 751 and the second steering value output from the second control calculation unit 752 as the target steering value.

The steering drive control unit 79 is configured as a feedback type steering control module. For the input target steering value, the steering angle command value: Sθ * obtained by the comparison calculation with the actual steering angle: Sθ is input, and the previous stage output value is obtained using PI control. This previous stage output value is calculated by comparison with the actual steering speed: Sw, and the steering drive signal is output using the PI control with the calculation result as an input. The steering drive signal drives the motor constituting the steering drive unit 60 via the driver to steer the front wheels 2a. The PI control in the steering drive control unit 79 may be replaced with the PID control.

FIG. 5 shows a modified example of the control diagram of the electronic control unit 7 shown in FIG. The control diagram of FIG. 5 is different from that of FIG. 4 in that the target steering calculation unit 76 is provided with a function of reducing the target steering value that is finally output according to the vehicle speed. That is, in this modification, the added value of the first steering value output from the first control calculation unit 751 and the second steering value output from the second control calculation unit 752 is further increased as the vehicle speed increases. The calculation function to reduce is added.

FIG. 6 shows a modified example of the control diagram of the electronic control unit 7 shown in FIG. The control diagram of FIG. 6 is different from that of FIG. 5 in that the target steering calculation unit 76 is provided with a function of upper limit clamping the target steering value finally output. That is, in this modification, the maximum target steering value output by the threshold value that changes according to the vehicle speed is suppressed before the obtained target steering value is output. It is set so that the higher the vehicle speed, the smaller the output maximum target steering value.

[Another Embodiment]
(1) In the above-described embodiment, the steering drive control unit 79 is configured as a steering control module in which the actual steering angle and steering speed are used as feedback amounts. However, the present invention does not limit the control configuration of the steering drive control unit 79, and other known control configurations can also be adopted.
(2) In the above-described embodiment, the target traveling route is regarded as a straight line, but the present invention can be applied even if the target traveling route is a curved line.
(3) In the above-described embodiment, the positioning unit 8 is composed of the satellite navigation module 81 and the inertial navigation module 82, but it is also possible to configure the positioning unit 8 only with the satellite navigation module 81.

The present invention is applicable not only to agricultural work vehicles but also to work vehicles equipped with various work devices and capable of automatically steering and traveling.

2a: Front wheels 2b: Rear wheels 3: Vehicle body 6: Steering mechanism 7: Electronic control unit 8: Positioning unit 9: Sensor group 30: Control unit 60: Steering drive unit 71: Reference route acquisition unit 72: Reference route setting unit 76: Target steering calculation unit 78: Vehicle speed calculation unit 79: Steering drive control unit 81: Satellite navigation module 82: Inertial navigation module 731: Own vehicle position calculation unit 732: Own vehicle orientation calculation unit 741: Position deviation calculation unit 742: Direction Deviation calculation unit 751: 1st control calculation unit 752: 2nd control calculation unit 760: Steering upper limit setting unit

Claims (3)

It is an automatic traveling field work vehicle that automatically steers along a target traveling route set in the field.
The own vehicle position calculation unit that calculates the own vehicle position and
The own vehicle orientation calculation unit that calculates the driving orientation of the own vehicle,
A position deviation calculation unit that calculates a position deviation that is a lateral displacement of the own vehicle with respect to the target travel path, and a position deviation calculation unit.
An azimuth deviation calculation unit that calculates an azimuth deviation between the azimuth line of the target travel path and the travel azimuth,
A target steering calculation unit that outputs a target steering value for traveling along the target traveling path based on the position deviation and the target position deviation.
The steering drive control unit and the steering drive signal that output the front stage output value based on the target steering value and the actual steering angle and output the steering drive signal based on the front stage output value and the actual steering speed. An automatic traveling field work vehicle equipped with a steering drive unit that steers the steering wheels based on the steering wheel. The automatic traveling field work vehicle according to claim 1, wherein the steering drive control unit outputs the previous stage output value by PI control or PID control. The automatic traveling field work vehicle according to claim 1 or 2, wherein the steering drive control unit outputs the steering drive signal by PI control or PID control.

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