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.

What is claimed is: 
     
         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.