Patent Application
20060161316
1. Field of Invention
Embodiments of the invention relate generally to controlling operation of model aircraft, and more specifically to methods and systems for controlling pitch and roll of model aircraft.
2. Discussion of Related Art
In model aircraft, it is desirable to include attitude control systems that monitor and control the attitude of the aircraft, including pitch and roll, to assist in autopilot operations or to prevent an operator from controlling the aircraft in a manner that may increase the likelihood of a crash. Inexperienced operators of remote controlled model or toy aircraft often need assistance in controlling operation of the aircraft, and attitude control systems can be used to help such operators become more proficient at flying the aircraft without worrying about multiple crashes, which can be frustrating and can damage the aircraft.
Infrared sensors have been used in attitude control systems of aircraft. Typically, one or more sensors are positioned on the aircraft to detect the horizon, and in particular a pair of oppositely facing sensors are typically used to detect one of pitch and roll. The attitude of the aircraft can be determined using output data from the sensors along with the principle that the sky is generally cooler than the surface of the earth. Changes in pitch or roll can be detected based on differences in the outputs of a pair of sensors. For example, U.S. Pat. No. 6,181,989, issued to Gwozdecki on Jan. 30, 2001, incorporated herein by reference, discloses aircraft having up to six infrared sensors to detect pitch, roll and whether the aircraft is in inverted flight. With each additional sensor that is added, the cost of the aircraft increases due to the cost of the sensor itself and the cost of associated control electronics that are used with the sensors. In model aircraft, and in particular in toy aircraft, these costs can become so high, so as to prevent designers from including an attitude control system in model aircraft.
Embodiments of the invention provide systems and methods for controlling model aircraft. One aspect of the invention is directed to a control system for a model aircraft having a longitudinal axis that extends from a rear of the aircraft to a front of the aircraft, the longitudinal axis being substantially parallel to a surface of the Earth when the aircraft is in level flight. The control system includes a sensor having a viewing axis in a first direction that is substantially normal to the longitudinal axis, a diverter constructed and arranged to divert the viewing axis of the optical sensor to provide an effective viewing axis in at least a second direction that is different from the first direction, and a controller coupled to the sensor to receive output data from the sensor and adapted to provide output signals to control attitude of the model aircraft based on the data.
In the control system, the diverter may be constructed and arranged to selectively provide an effective viewing axis in a third direction that is different from the first direction and different from the second direction, and the second direction may be along an axis normal to the viewing axis and the third direction may be along an axis normal to the viewing axis. The controller may be configured to determine roll attitude of the aircraft based on data from the sensor. The controller may be configured to determine pitch attitude based on data from the sensor. The diverter may be constructed and arranged to selectively provide an effective viewing axis in a fourth direction and a fifth direction, with the second direction being opposite the third direction and the fourth direction being opposite the fifth direction. The diverter may include a mirror that is rotatable to change direction of the effective viewing axis. The controller may be configured to provide output signals to control position of the mirror. The sensor may include an infrared sensor.
Another aspect of the invention is directed to a method of controlling a model aircraft. The method includes positioning a sensor on the aircraft such that a viewing axis of the sensor is in a first direction, diverting the viewing axis of the sensor to provide a first effective viewing axis in a second direction that is different from the first direction, diverting the viewing axis of the sensor to provide a second effective viewing axis in a third direction that is different from the first direction and the second direction, capturing data from the sensor, and controlling an attitude of the aircraft based on the data.
In the method of controlling a model aircraft, the second direction may be along an axis normal to the viewing axis and the third direction may be along an axis normal to the viewing axis. The method may further include determining roll attitude of the aircraft based on data from the sensor, and determining pitch attitude of the aircraft based on data from the sensor. The method may include diverting the viewing axis of the sensor to provide a third effective viewing axis in a fourth direction that is different from the first direction, diverting the viewing axis of the sensor to provide a fourth effective viewing axis in a fifth direction that is different from the first direction and the second direction, with the second direction being opposite the third direction and the fourth direction being opposite the fifth direction. The method may still further include controlling roll attitude and pitch attitude based on data from the sensor, and the sensor may include an infrared sensor.
Another aspect of the invention is directed to a method of controlling a model aircraft using an infrared sensor mounted to the aircraft and a controllable mirror positioned along a viewing axis of the infrared sensor to control an effective viewing axis of the infrared sensor. The method includes, with the controllable mirror in a first position, detecting infrared energy using the infrared sensor, moving the controllable mirror to a second position, with the controllable mirror at the second position, detecting infrared energy using the infrared sensor, and controlling attitude of the aircraft based at least in part on signals generated by the infrared sensor.
In the method of controlling an aircraft, at the first position, the effective viewing axis may be in a first direction normal to the viewing axis, and at the second position, the effective viewing axis may be in a second direction, opposite the first direction. The method may further include moving the controllable mirror to a third position, with the controllable mirror at the third position, detecting infrared energy using the infrared sensor, moving the controllable mirror to a fourth position, with the controllable mirror at the fourth position, detecting infrared energy using the infrared sensor, and controlling pitch and roll of the aircraft based at least in part on signals generated by the infrared sensor.
Yet another aspect of the invention is directed to a model aircraft. The model aircraft having a section having a longitudinal axis that extends from a rear of the aircraft to a front of the aircraft, the longitudinal axis being substantially parallel to a surface of the Earth when the aircraft is in level flight, and a control system. The control system includes an infrared sensor, mounted on the section and having a viewing axis in a first direction that is substantially normal to the longitudinal axis, a controllable mirror constructed and arranged to divert the viewing axis of the infrared sensor to selectively provide an effective viewing axis in at least a second direction that is different from the first direction and a third direction that is different from the first direction and different from the second direction, and a controller coupled to the infrared sensor to receive output data from the infrared sensor and adapted to provide output signals to control attitude of the model aircraft based on the data.
In the model aircraft, the controllable mirror may be constructed and arranged such that the second direction is opposite the first direction to allow the infrared sensor to obtain infrared images of two opposite horizons when the aircraft is in level flight, and the controller may be configured to determine at least one of pitch attitude and roll attitude of the aircraft. The control system may further include a mirror driver coupled to the controllable mirror to move the effective viewing axis between the first direction and the second direction, wherein the mirror driver is constructed and arranged to rotate the controllable mirror about an axis that is normal to the longitudinal axis. The mirror driver may be constructed and arranged to rotate the controllable mirror to each of four rotational positions separated by approximately ninety degrees. The controller may be configured to determine pitch and roll of the aircraft based on infrared data obtained for each of the four rotational positions of the controllable mirror. The controller may be operatively coupled to the mirror driver to control movement of the controllable mirror. The model aircraft may further include a receiver coupled to the controller to receive signals from an operator to control operation of the model aircraft.
The accompanying drawings, are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:
This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing”, “involving”, and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
At least one embodiment of the present invention provides an improved attitude control system for a model aircraft that can detect pitch and/or roll of an aircraft using only one infrared sensor. However, embodiments of the invention are not limited to control systems that utilize only one sensor and additional sensors may be added to provide additional detection and control capabilities.
In at least one embodiment described below, a remote controlled aircraft includes an improved attitude control system. Embodiments of the present invention may be used with various aircraft, motorized or non-motorized, including, but not limited to, gliders, hovercrafts, all types of airplanes, including flying wings, and helicopters. Further, embodiments of the invention may be used with remote controlled aircraft or with aircraft that are not remote controlled.
In one embodiment, the aircraft 100 is a remote controlled aircraft that is responsive to radio control signals received from a remote controller operated by a user on the ground. However, in other embodiments, the aircraft 100 may be controlled using an internal microcontroller, microprocessor or other control circuitry that controls flight of the aircraft in accordance with one or more programmed flight plans. In still another embodiment, the aircraft 100 may be controlled using an internal microcontroller, microprocessor or other control circuitry that controls attitude of the aircraft in flight.
A functional block diagram of a control system 120 for the aircraft 100 will now be described with reference to
The horizon sensing system 110 will now be described in greater detail with reference to
The thermal sensor 150 is positioned with respect to the mirror 152 such that the viewing axis of the thermal sensor is aligned with the axis of rotation and in the direction of the mirror. In one embodiment, the horizon sensing system is positioned at the intersection of the longitudinal axis and the transverse axis (see
With reference to
The mirror assembly 151 of one embodiment is shown in greater detail in
During flight of the aircraft 100, under the control of the controller 124, the thermal sensor can be configured to obtain thermal profiles in the front, back, left side and ride side of the aircraft. The controller is configured to compare thermal profiles of each side to determine roll attitude of the aircraft, and to compare thermal profiles from the front and back to determine pitch attitude of the aircraft. The controller uses attitude data along with control information from either the remote control device or stored instructions to control elevators, ailerons, rudders, other control surfaces, and/or one or more motors of the aircraft to provide desired flight patterns. In the embodiment described, both roll attitude and pitch attitude are determined using the sensor. In other embodiments only one of pitch and roll may be determined.
In embodiments described above, a thermal sensor is used to detect the horizon based on thermal differences between the earth and the sky. In other embodiments, other sensors, including optical sensors, could be used in place of the thermal sensor to detect the horizon.
Embodiments of the present invention described above provide several advantages, including the ability to detect both pitch and roll attitude using only one thermal sensor. Further, the use of a thermal sensor with a mirror or other deflector, allows the sensor to be mounted within the aircraft on a circuit board with other devices. The sensor may be mounted behind an IR transparent window to allow the sensor to be protected from the elements.
In embodiments of the invention described above, a thermal profile is detected at two positions (i.e., front and back) to determine pitch, and a thermal profile is detected at two positions (i.e., left and right) to determine roll. In other embodiments, changes in either roll or pitch are detected by viewing the same position at different times and detecting changes in the thermal profile indicating that the roll or pitch is changing.
In embodiments described above, the angle of a mirror or deflector arranged to change the effective viewing axis of the thermal sensor is 45 degrees. As will now be explained, in other embodiments, the mirror or other deflector may be placed at an angle other than 45 degrees, and used in a system to limit roll attitude or pitch attitude. In one such embodiment, as shown in
In embodiments described above, the horizon sensing system is located on a longitudinal axis on the top of the aircraft. In other embodiments, the sensing system may be placed closer to either the front or rear of the aircraft, placed nearer the left or right side of the aircraft or placed on similar locations on the bottom of the aircraft. In embodiments described above, a sensor is positioned to have a viewing axis normal to both a transverse axis and a longitudinal axis of an aircraft. In other embodiments, the sensor may be positioned such that its viewing axis is parallel to one of the longitudinal axis and the transverse axis, and a diverter may still be used to create an effective viewing axis that is different from the viewing axis.
In embodiments described above, a mirror or other diverter is rotated to different positions to take thermal measurements at different positions. In at least one embodiment, the mirror or diverter may be rotated continuously with the sensor configured to take readings at preset times and/or locations, using, for example, devices and/or circuits to detect and calculate the position of the mirror.
In embodiments of the invention described herein, the terms longitudinal axis and transverse axis are used to describe aircraft. Depending on the particular type of aircraft such as a helicopter, the longitudinal axis may be along a portion of the aircraft that is not greater in length than the portion coinciding with the transverse axis.
Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.
