Optical sensing system and system for stabilizing machine-controllable vehicles

• US 20050165517A1
• Filed: 03/21/2005
• Published: 07/28/2005
• Est. Priority Date: 09/23/2002
• Status: Active Grant

• Current Assignee: Iron Bird LLC (Jeffrey M. Gross)
• Original Assignee: Stefan Reich
• Inventors: Reich, Stefan
• Granted Patent: US 7,400,950 B2
• Time in Patent Office: Days
• US Class Current: 701/11
• CPC Class Codes: A63H 27/04 Captive toy aircraft
• CPC Class Codes: A63H 27/12 Helicopters A63H27/04 takes precedence; Flying tops
• CPC Class Codes: A63H 30/04 using wireless transmission
• CPC Class Codes: G01P 3/36 Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: G01P 3/68 using optical means, i.e. using infrared, visible, or ultraviolet light G01P3/80 takes precedence ; by reflection of waves G01S17/58
• CPC Class Codes: G01P 3/806 in devices of the type to be classified in G01P3/68
• CPC Class Codes: G01S 11/12 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G05D 1/0858 specially adapted for vertical take-off of aircraft

Abstract

In order to measure the movement of a vehicle, especially an aircraft, an imaging optical system 2 which is to be positioned on the vehicle is used to detect an image of the environment 4, and an optoelectronic shift sensor 3 chip of the type comprising an inherent evaluation unit is used to measure any shift of the image from structures thereof. The shift sensor is equal or similar to the sensor used on an optical mouse. The sensor is positioned in such a way that infinite objects are focused. The measuring signal is evaluated to indicate movements and/or the position of the aircraft. The inventive system can also be used to measure distances e.g. in order to control the flight altitude. The invention further relates to methods for automatically controlling particularly a hovering flight by means of a control loop using optical flow measurement.

Claims

1. Optical sensing system for measuring the movement and/or the position of a vehicle which is machine-controllable or equipped with a drive mechanism, in at least one of its six spatial degrees of freedom, wherein the system comprises an optical imaging means provided on board with the vehicle and suitable for projecting an image section of a surrounding into an image plane;

an opto-electronical shift sensor of the type equipped with a plurality of photosensitive partial areas (pixels) and, arranged on a same common substrate, with a digital and clocked electronic evaluation circuit for detecting the shift of a pixel image and for outputting a measurement signal for the shift;

wherein the optical imaging means is adapted and arranged such that infinitely remote structures are projected onto the shift sensor.

2. System according to claim 1, wherein at least the chip of a sensor designated for optical mice, or a chip which is equal in structure to this, is used as shift sensor.

3. System according to claim 1, wherein the shift sensor is provided with an output for outputting measurement values of the shift in the form of incremental shift values or shift jumps.

4. System according to claim 1, wherein the shift sensor has less than 1500 pixels and wherein the read-out rate of the pixels and the evaluation rate are higher than 120 Hz.

5. System according to claim 1, further comprising an electronic device suitable adapted for obtaining in an electronic evaluation process at least one of the following measurement quantities from the output signals of at least one measurement coordinate given by the shift sensor:

degree of shift by summation of incremental shifts, velocity of the measured shift, rate of change of velocity, event of a measured movement.

6. System according to claim 5, wherein the further electronic device is suitably adapted for transforming the measurement signals output by the shift sensor into a measurement value for the velocity of the measured shift, in that said electronic device measures a frequency of the shift increments or shift jumps output by the shift sensor, taking into account the direction of the shift as leading sign.

7. System according to claim 1, wherein an electronic (control) device is provided for generating a control value out of an actual value derived from the measurement signal of the shift sensor, wherein the electronic (control) device is connected to actuating elements which control an airborne object for stabilizing the flight of the airborne object.

8. System according to claim 1, wherein the systems comprises at least one gyroscope and an electronic circuit adapted for compensation mixing of signals derived from the gyroscope and the shift sensor.

9. System according to claim 1, wherein the system is included in an airborne object, in particular a helicopter or another rotorcraft.

10. System according to claim 7, wherein the system further comprises a feedback loop which uses an opto-electronically generated measurement value output by the shift sensor, at least in part as an actual value, and generates a control value from the measurement value, wherein the control value is defined proportional and opposed to a velocity deviation, and controls at least a roll movement.

11. System according to claim 10, wherein a roll inclination angle is controlled by means of a feedback loop.

12. System according to claim 1, wherein at least two shift sensors are used, and are directed such that their main lines of sight resulting from the optical imaging are divergent by a predetermined angle, and in that the signals of the sensors are analysed in relation to each other.

13. System for controlling at least a roll attitude for stabilizing hovering flight of an airborne object, wherein an opto-electronical sensing means is provided for obtaining an optical flow measurement signal from a section of a ground image, the system comprising an electronic circuit adapted for generating from the optical flow signal of at least a lateral movement direction, at least in part, a control signal in the manner of a negative feedback loop, the generated control signal being adapted for driving an actuating element affecting roll movements of the airborne object.

14. System according to claim 13, wherein the optical line of sight of the imaging has an essential vertical component directed downwards, and wherein the control signal is defined as proportional and opposed to a velocity deviation in a manner of comparison of actual value and target value.

15. System according to claim 13, wherein the measurement signal is purged from effects resulting from rotational movements like rolling and/or pitching of the vehicle at least in part, by compensation mixing of a rotation signal signalling an angle or an angular velocity of a rotational measurand, with the measurement signal.

16. System according to claim 13, wherein a combination is obtained of a measurement signal from an optical flow sensor that is differentiated with regard to time in at least a part of it'"'"'s frequency range, and a rotation signal proportional to the angular velocity of the inclination that is integrated with regard to time in at least a part of it'"'"'s frequency range.

17. System according to claim 13, wherein the feedback loop combines the control of the inclination and the control of the horizontal movement by mixing and jointly controlling measurement quantities for inclination or inclination rate, and for horizontal movement and/or position.

18. System according to claim 13, wherein at least one gyroscope and an electronic circuit are provided which are adapted for compensation mixing of signals derived from the gyroscope and the shift sensor.

19. Method for measuring the movement and/or the position of a vehicle, which is machine-controllable or equipped with a drive mechanism, in at least one of its six spatial degrees of freedom, using optical sensor technology, characterized by the following steps:

an image section of the surroundings which can be viewed from the actual position is captured by means of an optical imaging means on board with the vehicle and projected onto the photosensitive area of an opto-electronical shift sensor comprising on a common substrate a plurality of photosensitive partial areas and a digital and clocked electronic evaluation circuit for detecting the shift of the image of projected structures and for outputting a measurement signal for the shift and positioned optically behind the optical imaging means at a place where the optical resolution of image structures at infinity is sufficient for the detection of shift;

measurement data of the photosensitive partial areas are supplied to the electronic evaluation circuit;

within the electronic evaluation circuit changes resulting from shifts of the structures are evaluated by continuous comparison with previous measurement data and a measurement signal for the shift is generated, which is output as an output signal and used as measure for at least one position and/or movement quantity of the vehicle.