Patent Application
20160109583
The present disclosure relates to a method of locating a machine, and more particularly to a system and a method of determining a location of a machine.
Machines, such as trucks, dozers, excavators, and drill machines, are operated to perform various operations at a worksite. Generally, a location of the machine at the worksite is determined using a positioning system. The positioning system includes a Global Positioning System (GPS)/Global Navigation Satellite System (GNSS), and Inertial Measurement Unit (IMU). The positioning system combines information from the GPS/GNSS and IMU to determine a position and an orientation of the machine at the worksite. The position and the orientation of the machine determined using the positioning system includes an error due to factors such as modes of information transfer and the like. Hence, the positioning system implements various mechanisms such as filters and controllers to mitigate the error in the determined location of the machine to detect an actual location of the machine.
U.S. Pat. No. 6,721,657, hereinafter referred to as the '657 patent, describes an inertial GPS navigation system. The inertial GPS navigation system includes a receiver. The receiver uses a single processor to control a GPS sub-system and an inertial (“INS”) sub-system and, through software integration, shares GPS and INS position and covariance information between the sub-systems. The receiver time tags the INS measurement data using a counter that is slaved to GPS time. The receiver further uses separate INS and GPS filters to produce GPS and INS position information that is synchronized in time. The GPS/INS receiver utilizes GPS position and associated covariance information in the updating of an INS Kalman filter. The Kalman filter provides updated system error information that is used in propagating inertial position, velocity and attitude. Whenever the receiver is stationary after initial movement, the INS sub-system performs “zero-velocity updates,” to more accurately compensate in the Kalman filter for component measurement biases and measurement noise. Further, if the receiver loses GPS satellite signals, the receiver utilizes the inertial position, velocity and covariance information provided by the Kalman filter in the GPS filters, to speed up GPS satellite signal re-acquisition and associated ambiguity resolution operations. However, the '657 patent does not disclose a method of determining the location of the machine based on error estimates associated with the signals received from the positioning system.
In one aspect of the present disclosure, a method of determining a location of a machine is provided. The method includes receiving signals from an Inertial Measurement Unit (IMU) at each of a plurality of unit time. The method also includes determining a location of the machine based on the signals received from the IMU. The method includes triggering a satellite positioning unit of the machine at a first unit time. The method further includes determining a location of the machine corresponding to the first unit time based on signals received from the satellite positioning unit at a second unit time. The method includes determining an error associated with the location of the machine, by a processing unit, based on the location determined by the satellite positioning unit and the location determined based on the signals received from the IMU at a unit time successive to the first unit time. The method also includes adding the error to the location of the machine determined based on the signals received from the IMU at a successive unit time to the second unit time.
Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
Wherever possible, corresponding or similar reference numbers will be used throughout the drawings to refer to the same or corresponding parts.
The machine 12 includes a frame 14 for supporting various components of the machine 12 including an operator cab 16, a cutting tool 18, and a ripping tool 20. The operator cab 16 may include multiple control levers and/or switches for controlling movement of the machine 12 and the ripping and cutting operations of the machine 12. The machine 12 also includes a pair of tracks 22 to engage with a work surface and to move the machine 12 along the work surface to perform the ripping and cutting operations. The tracks 22 may be supported on the frame 14 and may receive driving power from a power source, such as an engine (not shown), to move the machine 12 at the worksite 10. It may also be contemplated that the machine 12 may include a number of wheels to engage with the work surface. The power source may be disposed at any location on the machine 12 to supply power to various systems of the machine 12. Further, a hydraulic system of the machine 12 may be in fluid communication with the cutting and ripping tools 18, 20 for performing the cutting and ripping operations, respectively.
The positioning system 24 determines a location of the machine 12 at the worksite 10. Referring to
The positioning system 24 also includes a satellite positioning unit 28 disposed on the machine 12. The satellite positioning unit 28 generates signals indicative of the location of the machine 12 at the worksite 10. In one example, the satellite positioning unit 28 may determine and generate signals corresponding to the latitude and/or longitude of the machine 12 at the worksite 10. In the illustrated embodiment, the satellite positioning unit 28 includes a Global Positioning Satellite (GPS)/Global Positioning System (GPS)/Global Navigation Satellite System (GNSS) receiver. The satellite positioning unit 28 may be disposed on a top portion of the machine 12 to communicate with a number of satellites 29 and to receive signals indicative of the location of the machine 12 at the worksite 10. In one example, the satellite positioning unit 28 is disposed on top of the operator cab 16 to receive signals from the satellites 29 without interfering with any components present in a surrounding of the machine 12. In other embodiments, the satellite positioning unit 28 may be disposed at any location on the machine 12 to receive signals from the satellites 29 without any obstruction.
The positioning system 24 further includes a processing unit 30. The processing unit 30 is in communication with the satellite positioning unit 28 and the IMU 26, and receives signals therefrom. The processing unit 30 may embody an embedded control system.
Referring now to
The processing unit 30 (see
The Indirect Kalman Filter estimates error in the location, based on the signals 42 received from the IMU 26 and the satellite positioning unit 28. The Indirect Kalman Filter combines the signals 42 indicative of the location of the machine 12 from the IMU 26 at a successive unit time “t2” to the first unit time “T1” and the satellite positioning unit 28. The error estimated by the Indirect Kalman Filter is added to the location determined using the signals 42 received from the IMU 26 at a successive unit time to the second unit time “T2”. In one example, the error determined by the Indirect Kalman Filter is added to the location at a third unit time “T3”.
The positioning system 24 also includes an output device 32. The output device 32 may embody any visual output device or an audio output device known in the art. The output device 32 is communicably coupled to the processing unit 30. The output device 32 provides the location of the machine 12 at the worksite 10 as determined by the processing unit 30. The output device 32 may be present in the machine 12, at the worksite 10, or at a remote base station, as per requirements.
The present disclosure relates to the positioning system 24 and a method 44 of determining the location of the machine 12. The positioning system 24 implements the Indirect Kalman Filter, which determines the error in the location of the machine 12 based on the signals 42 received from the IMU 26 and the satellite positioning unit 28 at the second unit time “T2”. The error is applied to the location at a time “T3” subsequent to time “T2”. The method 44 of the present disclosure does not store any previous locations of the machine 12 for applying the correction, hence the usage of memory is less compared to other conventional methods known in the art.
At step 52, the location of the machine 12 is determined by the processing unit 30 corresponding to the first unit time “T1” based on the signals received from the satellite positioning unit 28 at the second unit time “T2”. At step 54, the error associated with the location of the machine 12 is determined by the processing unit 30. The error is determined based on the location determined by the satellite positioning unit 28 and the location determined based on the signals received from the IMU 26 at the unit time “t2” successive to the first unit time “T1”. At step 56, the error is added to the location of the machine 12 based on the signals received from the IMU 26 at the third unit time “T3” successive to the second unit time “T2”.
In an example, the processing unit 30 receives the signals 42 from the IMU 26 at each of the unit times “t0”, “t1”, and the location of the machine 12 is determined by the processing unit 30 based on the signals 42 received from the IMU 26. Also, the satellite positioning unit 28 is triggered based on the pulse received at the first unit time, “T1”. Further, the processing unit 30 also receives the signals 42 from the IMU 26 at each of the unit times “t2”, “t3”, “t4”, “t5”, and the location of the machine 12 is determined by the processing unit 30 based on the signals 42 received from the IMU 26. The location of the machine 12 is determined by the processing unit 30 corresponding to the first unit time “T1” based on the signals received from the satellite positioning unit 28 at the second unit time “T2”. The processing unit 30 receives signals 42 from the IMU 26 at the unit time “t6”, and the location of the machine 12 is determined by the processing unit 30 based on the signals 42 received from the IMU 26.
While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.
