BLADE TILT STEERING USING GLOBAL ANGLE

Abstract

A machine can include a frame, a blade coupled to the frame and configured to push a load, an inertial measurement unit (IMU) associated with the blade and configured to indicate a tilt of the blade relative to an absolute global frame of reference, and a controller configured to: receive steering commands; determine, based on the steering commands and the load, a desired blade tilt steering angle relative to the absolute global frame of reference; cause the blade to be tilted to the desired blade tilt steering angle; determine, based on information from the IMU, that an actual blade tilt angle is different from the desired blade tilt steering angle; cause, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, the blade to be tilted according to a corrected blade tilt angle, wherein, when the actual blade tilt angle is offset, in a first direction, from the desired blade tilt steering angle, the corrected blade tilt angle is to tilt the blade in a second direction, opposite the first direction, and wherein the corrected blade tilt angle causes the blade to be tilted, relative to the absolute global frame of reference, to match the desired blade tilt steering angle.

Description

TECHNICAL FIELD

The present disclosure generally relates to heavy machinery. More particularly, the present disclosure relates to a blade tilt steering system for the machinery.

BACKGROUND

Typical dozing machines comprise a tractor having a dozer blade carried at the front end thereof. In many instances, the tractor is a track-driven machine having a pair of mutually-spaced tracks that are driven to propel the machine. As such, ordinary steering of the machine is accomplished by varying the relative speed of the tracks. However, when pushing a load other steering techniques can be used.

For example, when pushing a load, blade tilt steering can be used. More particularly, steering can be accomplished by tilting the dozer blade about the longitudinal axis of the tractor to raise or lower one side of the blade during a push. The problem with blade tilt steering is that when the blade is tilted the side slope surface is affected. When driving over the surface the machine will roll causing the blade tip to dig in. The extra load on the blade tip can result in too much of a steering correction and a bad surface.

An example of blade tilt steering is described in U.S. Pat. No. 5,487,428, issued on Jan. 30, 1996, to Yamamoto et al.

SUMMARY

In an example, according to this disclosure, a machine can include a frame, a blade coupled to the frame and configured to push a load, an inertial measurement unit (IMU) associated with the blade and configured to indicate a tilt of the blade relative to an absolute global frame of reference, and a controller configured to: receive steering commands; determine, based on the steering commands and the load, a desired blade tilt steering angle relative to the absolute global frame of reference; cause the blade to be tilted to the desired blade tilt steering angle; determine, based on information from the IMU, that an actual blade tilt angle is different from the desired blade tilt steering angle; cause, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, the blade to be tilted according to a corrected blade tilt angle, wherein, when the actual blade tilt angle is offset, in a first direction, from the desired blade tilt steering angle, the corrected blade tilt angle is to tilt the blade in a second direction, opposite the first direction, and wherein the corrected blade tilt angle causes the blade to be tilted, relative to the absolute global frame of reference, to match the desired blade tilt steering angle.

In one example, a system to control a blade tilt on a machine can include an IMU on a blade, a controller to receive steering commands and deliver blade tilt steering commands and to receive information from the IMU regarding a tilt angle of the blade relative to an absolute global frame of reference, and wherein the controller is configured such that if the machine tilts one direction, the blade is tilted in an opposite direction so as to remain at a desired angle relative to the absolute global frame of reference.

In one example, a method for controlling a blade tilt of a machine can include receiving at a controller a steering command, tilting a blade in response to the steering command, wherein the tilting is done relative to a frame of the machine and relative to an absolute global frame of reference, receiving at the controller an IMU indication that the blade is tilted different than a desired tilt of the blade relative to the absolute global frame of reference, and further tilting the blade relative to the machine to compensate for any blade tilt error, such that the tilt of the blade is constant relative to the absolute global frame of reference regardless of the blade tilt relative to the frame.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 is side view depicting an example machine in accordance with this disclosure.

FIG. 2 is a front schematic view of the machine, in accordance with one example.

FIG. 3 is a front schematic view of the machine, in accordance with one example.

FIG. 4 is a front schematic view of the machine, in accordance with one example.

FIG. 5 shows a schematic of a control system, in accordance with one example.

FIG. 6 shows a blade tilt steering algorithm, in accordance with one example.

FIG. 7 shows a method for controlling a blade tilt of a machine, in accordance with one example.

DETAILED DESCRIPTION

FIG. 1 depicts an example machine 100 in accordance with this disclosure. In FIG. 1, machine 100 includes a frame 102, tracks 104, an implement comprising a blade 106, and a controller 120 implemented in one or more on-board electronic devices like, for example, an electronic control unit or ECU. Example machine 100 is a dozer configured for pushing a load 105 over a surface 101 using the blade 106.

The frame 102 is configured to support and/or mount one or more components of machine 100. For example, machine 100 can include an operator cabin 108 coupled to frame 102. The machine 100 can include, among other components, an engine and/or other drive system to propel the machine 100 over various terrain though a powertrain via the tracks 104. The engine can include various power generation platforms, including, for example, an internal combustion engine, whether gasoline or diesel.

The machine 100 includes the blade 106 coupled to the frame 102 through linkage assembly 110, which is configured to be actuated to articulate the blade 106 in various configurations, such as tilt, pitch, and yaw angles. The blade 106 may be configured to transfer the load 105 such as, soil or debris, from one location to another. Linkage assembly 110 can include one or more cylinders 114 configured to be actuated hydraulically, for example, to articulate the blade 106. For example, the linkage assembly 110 can be actuated by the cylinders 114 to raise and lower and/or rotate and/or tilt the blade 106 relative to the frame 102 of the machine 100.

Accordingly, the blade 106 can be hydraulically actuated to move vertically up or vertically down (which may also be referred to as blade lift, or raise and lower), roll left or roll right relative to the longitudinal axis of the machine 100 (which may be referred to as blade tilt, or tilt left and tilt right), and yaw left or yaw right (which may be referred to as blade angle, or angle left and angle right). Alternative embodiments can utilize a blade with fewer hydraulically controlled degrees of freedom, such as a 4-way blade that may not be angled or actuated in the direction of yaw.

As noted, the machine 100 also includes the operator cabin 108, which can be open or enclosed. The operator cabin 108 may include one or more control devices such as, a joystick 112, a steering wheel, pedals, levers, buttons, switches, among other examples. The control devices are configured to enable the operator to control the machine 100 and/or the blade 106. Operator cabin 108 may also include an operator interface such as, a display device, a sound source, a light source, or a combination thereof.

As discussed above, these dozing machines can have a feature that automatically steers the machine. To steer a machine under heavy load it is appropriate to use blade tilt steering. The problem with blade tilt steering is that when the blade is tilted the side slope surface can be changed. When driving over the surface the machine can roll causing the blade tip to dig in. Extra load on the blade tip, such as from digging in, can result in too much steering correction and a bad surface.

The present system provides one solution to this problem by controlling, when blade tilt steering, the tilt of the blade relative to a global angle. Controlling to a global angle allows the steering controller 120 to reject any role caused by deviations in the surface 101. By controlling to a global angle the controller 120 can prevent the blade tips from digging in when the machine 100 rolls, thus resulting in better steering commands and surface.

Accordingly the present system includes an IMU 130 (inertial measurement unit) on the blade 106 to measure a tilt of the blade 106 relative to an absolute global frame of reference. For example, the absolute frame of reference may be defined in the direction of gravity.

The controller 120 can be configured to receive or automatically configure steering commands and be configured to deliver blade tilt steering commands to control a tilt of the blade 106 in response to the steering commands and the load 105 in front of the machine 100 so that the blade 106 is tilted correctly to help steer the machine 100 in a desired direction.

The controller 120 further receives information from the IMU 130 and the controller 120 is configured to deliver blade tilt correction instructions based on the IMU information from the blade 106. The controller 120 is configured such that if the entire machine 100 tilts (including the blade 106), the blade 106 is then tilted in the opposite direction so as to remain at a constant angle relative to an absolute global frame of reference.

As noted, the controller 120 can be implemented in one or more on-board electronic devices like, for example, an electronic control unit or ECU. The controller 120 can encompass a separate or integrated PID controller which acts as a control loop mechanism employing feedback from the IMU 130 to continuously modulate the blade tilt angle.

In one example, the machine 100 can include a second IMU 132 on the frame 102. The second IMU 132 information can also be delivered to the controller 120 so the controller 120 can determine an absolute global tilt angle of the machine 100 and the frame 102. In an example, the controller 120 can compare the absolute tilt angle of the blade 106 to the absolute global tilt angle of the frame 102 such that if the machine 100 tilts one way the blade 106 is then tilted the other way so as to remain at a constant angle relative to the absolute global frame of reference.

FIGS. 2-4 show an example of the present system. FIG. 2 is a front schematic view of the machine 100 during use; FIG. 3 is a front schematic view of the machine 100; and FIG. 4 is a front schematic view of the machine 100, in accordance with one example. In FIGS. 2-4, the absolute global frame of reference is depicted as line 180, which depicts the absolute global frame of reference as defined by the direction of gravity.

In FIG. 2 the machine 100 is pushing the load 105 using the blade 106. If blade tilt steering is engaged, the blade 106 can be tilted relative to the machine to help steer, depending on the load 105. However, in FIG. 3, the machine 100 hits an obstruction or some change of ground slope, causing the entire machine 100, including the frame 102 and the blade 106, to tilt. Accordingly, referring to the above discussion, in FIG. 4, the controller 120, using information from one or more of the IMUs 130, 132 tilts the blade 106 back so as to be similarly angled as in FIG. 2, while the frame 102 is still at an angle due to running over the obstruction.

Accordingly, if the entire frame 102 angle changes, the controller 120 compensates by tilting the blade 106 correspondingly (e.g., by the same amount, such as the same absolute angle) in the opposite direction from the frame. For example, if the entire machine 100 tilts to the right, the blade 106 will automatically tilt to the left relative the frame 102 so that the blade 106 remains in the same relative position absolutely.

In various examples, the controller 120 receives the steering commands either automatically or manually and tilts the blade 106 to a desired blade tilt steering angle. If the desired blade tilt steering angle is different from the absolute global blade tilt angle received from the IMU 130 then the controller 120 adjusts the desired blade tilt steering angle to an adjusted second desired blade tilt steering angle to take account the machine as a whole tilting. In one example, the adjusted second blade tilt steering angle is relative to the absolute global frame of reference and not relative to the frame 102 of the machine 100. Thus, the blade 106 is tilted relative to the absolute global angle received from the IMU 130. Again, the global angle is the angle defined by an absolute frame of reference relative to gravity.

Thus, the controller 120 determines there is a blade tilt steering angle error if the blade 106 is not tilted correctly relative to an absolute global frame of reference (i.e. relative to gravity).

FIG. 5 shows a schematic of a control system to control a blade tilt on a machine during blade tilt steering, in accordance with one example.

The system generally includes the IMU 130 on the blade 106, the second IMU 132 on the frame 102, and the controller 120. Here the controller 120 receives steering instructions 140, which can be automatically generated by the controller 120 itself and/or from the operator, using the joystick 112, for example, and the controller delivers blade tilt steering commands. The controller 120 also receives information from the IMU 130 and the IMU 132 regarding a tilt angle of the blade 106 and the frame 102 relative to an absolute global frame of reference. The controller 120 is configured such that if the machine 100 tilts one direction, the controller 120 sends blade tilt adjustment instructions 150 to the blade 106 so that the blade 106 is tilted in the opposite direction so as to remain at a desired angle relative to the absolute global frame of reference.

Accordingly, if the frame angle changes, the controller 120 compensates by tilting the blade 106 correspondingly in the opposite direction. The controller 120 receives the steering commands and tilts the blade 106 to a desired blade tilt steering angle, and wherein if the desired blade tilt steering angle is different from the absolute global blade tilt angle received from the IMU then the controller 120 adjusts the desired blade tilt steering angle to an adjusted second desired blade tilt steering angle.

INDUSTRIAL APPLICABILITY

Example dozer machines in accordance with this disclosure can be used in a variety of industrial, construction, commercial or other applications. As noted above, these machines can have a feature that automatically steers the machine. To steer a machine under heavy load it is appropriate to use blade tilt steering. The present system allows for blade tilt adjustments to compensate when the machine drives over an obstruction or a different ground slope causing the machine to roll or tilt to one side.

FIG. 6 shows a blade tilt steering algorithm, in accordance with one example.

Here, the controller 120 receives a desired blade tilt steering command 160 and/or a manual tilt joystick command 162. The controller 120 also receives the global blade angle 164, for example from an IMU mounted on the blade. The controller can then calculate a desired blade angle 170 which is compared to the global blade angle. Any blade error can be fed to a PID controller 172 where the controller 120 then outputs an adjusted desired blade tilt command to the machine hydraulics. The algorithm then loops back to the beginning in a continual loop and continually fixes any blade tilt errors.

Accordingly, the controller 120 can be configured to: receive steering commands; determine, based on the steering commands and the load, a desired blade tilt steering angle relative to the absolute global frame of reference; cause the blade to be tilted to the desired blade tilt steering angle; determine, based on information from the IMU, that an actual blade tilt angle is different from the desired blade tilt steering angle; and cause, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, the blade to be tilted according to a corrected blade tilt angle. When the actual blade tilt angle is offset, in a first direction, from the desired blade tilt steering angle, the corrected blade tilt angle is to tilt the blade in a second direction, opposite the first direction, and wherein the corrected blade tilt angle causes the blade to be tilted, relative to the absolute global frame of reference, to match the desired blade tilt steering angle.

In some examples, the controller is further configured to detect, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, that the tilt of the blade is to be corrected. Moreover, the controller can be further configured to determine, based on a value of the difference between the actual blade tilt angle and the desired blade tilt steering angle, a value of the corrected blade tilt angle.

FIG. 7 shows a schematic view of a method (200) for controlling a blade tilt of a machine during blade tilt steering, in accordance with one example.

In this example, the method (200) can include receiving (210) at a controller a steering command, tilting (220) a blade in response to the steering command, wherein the tilting is done relative to a frame of the machine and to an absolute frame of reference, receiving (230) at the controller an IMU indication that the blade is tilted different than the desired tilt of the blade relative to the absolute frame of reference, and further tilting (240) the blade relative to the machine to compensate for any blade tilt error, such that the tilt of the blade is constant relative to the absolute frame of reference regardless of the blade tilt relative to the frame.

As discussed above, the controller receives the steering commands and tilts the blade to a desired blade tilt steering angle, and wherein if the desired blade tilt steering angle is different from the measured blade tilt angle relative to the absolute global frame of reference received from the IMU then the controller adjusts the desired blade tilt steering angle to an adjusted second desired blade tilt steering angle. The adjusted second blade tilt steering angle is relative to an absolute global frame of reference and not relative to the frame of the machine.

Again, there can be a second IMU on the frame, and wherein the second IMU information is delivered to the controller so the controller can determine an absolute global tilt angle of the machine, and wherein if the frame angle changes, the controller compensates by tilting the blade correspondingly in the opposite direction.

Overall, the present system provides an automatic blade tilt steering controlling system for a machine which can include calculating the desired blade tilt angle of blade by measuring the global blade angle (i.e., center of gravity angle of the blade) based on IMU information and then calculates the blade angle error (deviation). The system then communicates the blade angle error (deviation) to a PID controller which will generate a desired blade tilt command for controlling the blade to a global angle so that the blade tip does not dig into ground upon tilt steering.

Controlling to a global frame of reference angle allows the steering controller to reject any role caused by the surface. By controlling to a global angle the controller can prevent the blade tips from digging in when the machine rolls, thus resulting in better steering commands and surface.

In the past, the blade was typically tilted relative to the machine during blade tilt steering. However, if the machine rolls over an obstruction, such as rock, the whole machine tilts and allows the blade to be tilted. Accordingly, the present system puts an IMU on the blade and if machine as a whole moves the system moves the blade back so that the blade is still at the tilt desired relative to an absolute global frame of reference (gravity) and not the machine.

The above detailed description is intended to be illustrative, and not restrictive. The scope of the disclosure should, therefore, be determined with references to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A machine comprising:

a frame;

a blade coupled to the frame and configured to push a load;

an inertial measurement unit (IMU) associated with the blade and configured to indicate a tilt of the blade relative to an absolute global frame of reference; and

a controller configured to: receive steering commands; determine, based on the steering commands and the load, a desired blade tilt steering angle relative to the absolute global frame of reference; cause the blade to be tilted to the desired blade tilt steering angle; determine, based on information from the IMU, that an actual blade tilt angle is different from the desired blade tilt steering angle; cause, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, the blade to be tilted according to a corrected blade tilt angle, wherein, when the actual blade tilt angle is offset, in a first direction, from the desired blade tilt steering angle, the corrected blade tilt angle is to tilt the blade in a second direction, opposite the first direction, and wherein the corrected blade tilt angle causes the blade to be tilted, relative to the absolute global frame of reference, to match the desired blade tilt steering angle.

2. The machine of claim 1, wherein the IMU is a first IMU on the blade, and wherein the machine further comprises a second IMU on the frame.

3. The machine of claim 2, wherein the controller is further configured to determine an absolute global tilt angle of the frame based on information from the second IMU.

4. The machine of claim 3, wherein the controller is further configured to compensate for changes in the absolute global tilt angle of the frame by causing the blade to be tilted, by a corresponding amount, in a direction that is opposite an actual direction of the absolute global tilt angle of the frame.

5. The machine of claim 1, wherein the controller is further configured to detect, based on determining that the actual blade tilt angle is different from the desired blade tilt steering angle, that the tilt of the blade is to be corrected.

6. The machine of claim 5, wherein the controller is further configured to determine, based on a value of the difference between the actual blade tilt angle and the desired blade tilt steering angle, a value of the corrected blade tilt angle.

7. The machine of claim 1, wherein the machine is a dozer.

8. The machine of claim 1, wherein the machine includes a manual steering joystick, and wherein the controller is configured to receive the steering commands from the manual steering joystick.

9. The machine of claim 1, wherein the machine includes hydraulics to control the tilt of the blade.

10. The machine of claim 1, wherein, relative to the frame, the desired blade tilt steering angle and the actual blade tilt angle are equal.

11. A system to control a blade tilt on a machine, the system comprising:

an IMU on a blade; and

a controller to receive steering commands and deliver blade tilt steering commands and to receive information from the IMU regarding a tilt angle of the blade relative to an absolute global frame of reference;

wherein the controller is configured such that if the machine tilts one direction, the blade is tilted in an opposite direction so as to remain at a desired angle relative to the absolute global frame of reference.

12. The system of claim 11, wherein there is a second IMU on a frame of the machine.

13. The system of claim 12, wherein information from the second IMU is delivered to the controller so the controller can determine an absolute global tilt angle of the machine.

14. The system of claim 13, wherein if the machine angle changes, the controller compensates by tilting the blade correspondingly in the opposite direction.

15. The system of claim 11, wherein the controller receives the steering commands and tilts the blade to a desired blade tilt steering angle, and wherein if the desired blade tilt steering angle is different from the blade tilt angle relative to the absolute global frame of reference received from the IMU then the controller adjusts the desired blade tilt steering angle to an adjusted second desired blade tilt steering angle.

16. The system of claim 15, wherein the adjusted second blade tilt steering angle is relative to the absolute global frame of reference and not relative to a frame of the machine.

17. A method for controlling a blade tilt of a machine, the method comprising:

receiving at a controller a steering command;

tilting a blade in response to the steering command, wherein the tilting is done relative to a frame of the machine and relative to an absolute global frame of reference;

receiving at the controller an IMU indication that the blade is tilted different than a desired tilt of the blade relative to the absolute global frame of reference; and

further tilting the blade relative to the machine to compensate for any blade tilt error, such that the tilt of the blade is constant relative to the absolute global frame of reference regardless of the blade tilt relative to the frame.

18. The method of claim 17, wherein the controller receives the steering commands and tilts the blade to a desired blade tilt steering angle, and wherein if the desired blade tilt steering angle is different from the tilt angle received from the IMU then the controller adjusts the desired blade tilt steering angle to an adjusted second desired blade tilt steering angle.

19. The method of claim 18, wherein the adjusted second blade tilt steering angle is relative to the absolute global frame of reference and not relative to the frame of the machine.

20. The method of claim 17, wherein there is a second IMU on the frame, and wherein information from the second IMU is delivered to the controller so the controller can determine an absolute global tilt angle of the machine, and wherein if the frame angle changes, the controller compensates by tilting the blade correspondingly in an opposite direction.