# US 2018/0321386 A1 · Light detection and ranging (lidar) ice detection system

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- Number: US 2018/0321386 A1
- Document ID: US20180321386A1
- Status: Published application
- Kind: A1
- Application number: 15/669,166
- Filed: 2017-08-04
- Published: 2018-11-08
- Earliest claimed: 2017-05-04
- Assignees: The Boeing Company
- Applicants: The Boeing Company
- Inventors: Cris K. Bosetti; John J. Biel-Goebel; Michael C. Cates; W. Brendan Blanton; Bernard P. Paul, JR.; Ken L. Bernier
- Web page: https://patentgrep.com/patent/US20180321386A1

## CPC

- G01S 17/95: for meteorological use
- B64D 15/20: Means for detecting icing or initiating de-icing
- G01S 7/4802: {using analysis of echo signal for target characterisation; Target signature; Target cross-section}
- G01S 7/4808: {Evaluating distance, position or velocity data}
- G01S 7/499: using polarisation effects
- G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46)
- G01S 17/87: Combinations of systems using electromagnetic waves other than radio waves
- G01S 17/88: Lidar systems specially adapted for specific applications
- G01S 17/89: for mapping or imaging
- G08B 19/02: Alarm responsive to formation or anticipated formation of ice
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- G08B: SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS

## Abstract

A Light Detecting and Ranging (LIDAR) based system detecting and quantifying ice accretions and shedding on an aircraft. This system can be used to detect ice, operate ice protection systems, and satisfy aircraft icing certification requirements. This system can also be used to determine the shape, thickness, type, and location of the ice accretions.

## Claims

### Claim 1

A detector, comprising:
one or more Light Detection and Ranging (LIDAR) devices on an aircraft, each of the LIDAR devices including a transmitter and a receiver, wherein:
each of the transmitters repetitively scan an aerodynamic surface on the aircraft using laser pulses, forming scattered laser pulses scattered from the aerodynamic surface,
each of the receivers receive the scattered laser pulses and output data comprising timing of the scattered laser pulses received in the receiver, and
temporal changes in coordinates of the aerodynamic surface, indicating a presence or absence of ice on the aerodynamic surface, are calculated from the output data.

### Claim 2 (depends on 1)

The detector of claim 1, wherein:
the aerodynamic surface is the surface of a wing, the empennage, or rotor on the aircraft,
the LIDAR devices are coupled to a computer,
the computer calculates temporal changes in a thickness of the wing, the empennage, or the rotor from the temporal changes in the coordinates, and
the computer uses the temporal changes in the thickness to determine accumulation of the ice or shedding of the ice.

### Claim 3 (depends on 1)

The detector of claim 1, wherein:
the transmitters scan the aerodynamic surface of a wing in one or more line patterns across cross sections of the wing; and
the computer uses one or more scanning speeds of the scan to measure distances between the cross sections.

### Claim 4 (depends on 1)

The detector of claim 1, comprising two of the LIDAR devices, wherein:
one of the LIDAR devices is positioned to scan the aerodynamic surface comprising an upper surface of the wing and output the data used to determine the coordinates of the upper surface, and
another of the LIDAR devices is positioned to scan to the aerodynamic surface comprising a lower surface of the wing and output the data used to determine coordinates of the lower surface.

### Claim 5 (depends on 1)

The detector of claim 1, wherein:
the LIDAR devices comprise a first LIDAR device, a second LIDAR device, a third LIDAR device, and a fourth LIDAR device,
the first LIDAR device scans the aerodynamic surface comprising an upper surface of the wing, wherein the timing outputted from the first LIDAR device is used to determine the coordinates of the upper surface in a first direction;
the second LIDAR device scans the upper surface of the wing, wherein the timing outputted from the second LIDAR device is used to determine the coordinates of the upper surface in a second direction;
the third LIDAR device scans the aerodynamic surface comprising a lower surface of the wing, wherein the timing outputted from the third LIDAR device is used to determine the coordinates of the lower surface in the first direction; and
the fourth LIDAR device scans the lower surface of the wing, wherein the timing outputted from the fourth LIDAR device is used to determine the coordinates of the lower surface in the second direction.

### Claim 6 (depends on 1)

The detector of claim 1, wherein the LIDAR devices are housed in a wing fairing on the aircraft.

### Claim 7 (depends on 1)

The detectors of claim 1, further comprising a computer coupled to the LIDAR devices, wherein:
the data comprises a data set outputted for each of the plurality of scans representing the coordinates at different times, and
for each of the data sets, the computer:
extracts a shape of the aerodynamic surface from the data set using a shape model;
determines one or more deformations in the shape due to flexing of the aerodynamic surface due to weight of the wing and/or pressure of airflow over the wing;
transforms the data set into common coordinates in a common reference frame using a transformation function, wherein:
the common reference frame comprises the aerodynamic surface without the deformations, and
the transformation function transforms the aerodynamic surface having the deformations into the aerodynamic surface without the deformations;
temporal changes in the common coordinates in the common reference frame are used to detect the presence of the absence or the ice.

### Claim 8 (depends on 7)

The detector of claim 7, wherein the computer filters the data to remove data corresponding to obscurants.

### Claim 9 (depends on 1)

The detector of claim 1, wherein the receiver further comprises a spectrum analyzer and/or polarization detector outputting information on an optical property of the laser pulses associated with a presence or absence of the ice.

### Claim 10 (depends on 9)

The detector of claim 9, wherein the optical property is at least one property selected from polarization, intensity, chirp, frequency, and absorption of the laser pulses.

### Claim 11 (depends on 1)

The detector of claim 1, wherein the LIDAR devices detect shedding of the ice from the aerodynamic surface.

### Claim 12 (depends on 1)

The detector of claim 1 coupled to avionics, wherein:
the avionics reverts stall warning tables to normal, allowing the aircraft to fly under non-icing conditions after the detector alerts the ice has been shed from the aerodynamic surface.

### Claim 13

A method for detecting accumulation or shedding of ice from aerodynamic surfaces on an aircraft, comprising:
providing one or more Light Detection and Ranging (LIDAR) devices on an aircraft, each of the LIDAR devices including a transmitter and a receiver;
repetitively scanning one or more aerodynamic surfaces on the aircraft using laser pulses transmitted from one or more of the transmitters, forming scattered laser pulses scattered from the aerodynamic surface,
receiving the scattered laser pulses in one or more of the receivers;
outputting data from the receivers comprising timing of the scattered laser pulses received in the receivers, and
calculating, from the data, temporal changes in coordinates of the aerodynamic surface that indicate accumulation of ice on the aerodynamic surfaces and/or shedding of the ice from the aerodynamic surfaces.

### Claim 14 (depends on 13)

The method of claim 13, wherein the aerodynamic surfaces include a surface of a wing, the empennage, or rotor on the aircraft, the method further comprising:
calculating temporal changes in a thickness of the wing, the empennage, or the rotor from the temporal changes in the coordinates; and
using the temporal changes in the thickness to determine the accumulation or the shedding of the ice.

### Claim 15 (depends on 13)

The method of claim 13, further comprising:
scanning the aerodynamic surfaces of a wing in one or more line patterns across cross sections of the wing and using one or more scanning speeds; and
using the one or more scanning speeds to measure distances between the cross sections.

### Claim 16 (depends on 13)

The method of claim 13, wherein the LIDAR devices include a first LIDAR device and a second LIDAR device, the method further comprising:
positioning the first LIDAR device transmitting the laser pulses to the aerodynamic surface comprising an upper surface of the wing, wherein the timing outputted from the first LIDAR device is used to determine the coordinates of the upper surface; and
positioning the second LIDAR device transmitting the laser pulses to the aerodynamic surface comprising a lower surface of the wing, wherein the timing outputted from the second LIDAR device is used to determine the coordinates of the lower surface.

### Claim 17 (depends on 13)

The method of claim 13, wherein the LIDAR devices comprise a first LIDAR device, a second LIDAR device, a third LIDAR device, and a fourth LIDAR device, the method further comprising:
positioning the first LIDAR device transmitting the laser pulses to the aerodynamic surface comprising an upper surface of the wing, wherein the timing outputted from the first LIDAR device is used to determine the coordinates of the upper surface in a first direction;
positioning the second LIDAR device transmitting the laser pulses to the upper surface of the wing, wherein the timing outputted from the second LIDAR device is used to determine the coordinates of the upper surface in a second direction;
positioning the third LIDAR device transmitting the laser pulses to the aerodynamic surface comprising a lower surface of the wing, wherein the timing outputted from the third LIDAR device is used to determine the coordinates of the lower surface in the first direction; and
positioning the fourth LIDAR device transmitting the laser pulses to the lower surface of the wing, wherein the timing outputted from the fourth LIDAR device is used to determine the coordinates of the lower surface in the second direction.

### Claim 18 (depends on 13)

The method of claim 13, further comprising:
receiving the data comprising a data set outputted for each of the plurality of scans and representing the coordinates of one of the aerodynamic surfaces at different times,
for each of the data sets:
extracting a shape of the aerodynamic surface from the data set using a shape model;
determining one or more deformations in the shape due to flexing of the aerodynamic surface;
transforming the data set into coordinates in a common reference frame using a transformation function, wherein:
the common reference frame comprises the aerodynamic surface without the deformations, and
the transformation function transforms the aerodynamic surface having the deformations into the aerodynamic surface without the deformations;
detecting the accumulation or the shedding of ice on the aerodynamic surface using temporal changes in the coordinates in the common reference frame.

### Claim 19 (depends on 13)

The method of claim 13, wherein the data further comprises information on an optical property of the laser pulses, the method further comprising using the optical property to detect the accumulation or the shedding of the ice.

### Claim 20 (depends on 13)

The method of claim 13, further comprising alerting avionics when the detector indicates ice has been shed from the aerodynamic surfaces so that the avionics reverts stall warning tables to normal and allows the aircraft to fly under non-icing conditions.