Patent Application
20210303003
The present invention relates to methods and systems for providing navigation guidance to autonomous vehicles. In particular, the present invention is related, but not restricted, to light-based guidance of autonomous vehicles, light-based guidance of unmanned areal vehicles and optical guidance systems.
Conventional navigation and guidance of autonomous vehicles such as ground vehicles or unmanned aerial vehicles (UAVs) use satellite positioning systems like the global positioning system (GPS) in conjunction with on-board inertial measurement units (IMUs) to calculate the absolute position and orientation of unmanned vehicles on earth or the position and orientation of unmanned vehicles relative to objects, to other vehicles or to mobile and ground stations. This conjunction is very effective in cruising maneuvers in a three-dimensional environment where the unmanned vehicles are widely spaced and far from any obstacle. However, in the case of maneuvers involving close proximity between autonomous vehicles, proximity to other objects or in aircraft maneuvers such as approaching, take-off and landing, the accuracy of satellite positioning systems is not enough to provide effective, accurate and safe motion of UAVs.
In the case of satellite-based navigation systems (for example, U.S. Pat. No. 3,789,409A), there is a theoretical limit to the position accuracy (4 meters RMS lateral accuracy for GPS under direct line of sight), which in some cases is not enough to navigate safely an UAV towards a mobile, ground station or for entering a warehouse. Moreover, since satellite navigation systems are based on measuring the different time of arrival of the radio waves emitted from the satellites, the position accuracy decreases dramatically in the presence of obstacles that produce multi-path reflection of such radio waves, resulting in significant position and orientation errors that restricts navigation of the autonomous vehicle. This is very common in urban environments, such as cities, or near high rise buildings. Furthermore, satellite-based navigation becomes impossible in situations without direct line of sight towards GPS satellites, in planets without GPS satellite infrastructure or in GPS denied environments such as the interior of a warehouse, inside building, in tunnels or underwater.
An alternative approach for guiding vehicles in GPS denied environments is based on the use of IMUs (for example, see U.S. Pat. No. 6,697,736B2), which can measure 3-axis acceleration, 3-axis angular rate of rotation and 3-axis magnetic field orientation. However, they operate with a finite sampling rate, which produces linear accumulation of acceleration errors over time, resulting in a quadratic and cubic error in velocity and position, respectively. Additionally, they are very sensitive to electromagnetic and magnetic interference, producing significant errors when used near power-lines or near objects with magnets or ferromagnetic materials and require frequent adjustment using a satellite navigation system, which is not accessible in indoors environments.
In the case of aircraft guidance in take-off and landing maneuvers, instrument landing systems have been widely used in the last decade (for example, U.S. Pat. No. 3,115,634A). They are based on arrays of antennas that produce radio-frequency waves of certain frequency and phase, generating signals that can be interpreted by the on-aircraft receiver as a glide path, providing lateral positioning and approach angle to the pilot. However, these systems require a very bulky, expensive, and power consuming infrastructure, restricting their usage to airports and guidance of large aircrafts. Furthermore, the on-board receiver is heavy, bulky, and require relatively large antennas, restricting their integration in small UAVs.
Recently, optical markers such as QR codes have been proposed as part of UAVs landing systems (such as Us. Pat. US20160122038A1). However, their implementation require high resolution on-board cameras and complex images processing algorithms which operate with a high power consumption. Another disadvantage is that such visual markers cannot be seen in fog, heavy rain, low light conditions or at large distances due to the finite camera resolution. Additionally, they are not secure and cannot be cryptographically authenticated. A malicious individual can replicate an optical marker and land UAVs outside the originally intended destination.
Consequently, there is a need for a guidance system for ground, maritime or aerial autonomous vehicles that can enable precise maneuvers such as cruise, approach, takeoff and landing in GPS denied environments or in places with intermittent access to satellite-based navigation. Moreover, there is a need for a system that can guide simultaneously a large number of unmanned vehicles in close proximity one from another, in a precise and safe manner. Additionally, there is a need for a compact guidance system for autonomous vehicles that consumes low power and can be mounted in small autonomous vehicles such as UAVs.
The invention disclosed herein includes a system and a method for precision guidance of multiple autonomous vehicles in a safe and collision-free manner. The invention comprises a plurality of light sources emitting light signals with an angular dependent intensity profile, detecting the emitted light signals with an on-board light detector, processing the light signals and using the processed light signals to find the orientation of the autonomous vehicle relative to the light sources. In fact, in the case of UAVs, the emitted light signals can define light paths in space that serve as virtual runways or airways that can be followed precisely by the autonomous vehicles in maneuvers such as cruising, parking, approaching, takeoff and landing.
In contrast to the existing guidance methods described in the section “BACKGROUND”, the invention disclosed herein enables centimeter precise guidance of multiple autonomous vehicles in places with intermittent access or without access to satellite-based navigation, in the presence of rain or fog and in good or poor illumination conditions. Furthermore, the present invention has a low power consumption and utilizes a simple, inexpensive and compact light-emitting infrastructure. Additionally, the required on-board light detection and processing logic is compact and light weight, making it suitable for all kinds of autonomous vehicles. Moreover, the emitted light signals can transmit information, which enables cryptographic authentication of the ground stations and the autonomous vehicles, making this system secure against malicious attempts to take control over the autonomous vehicles. Precision guidance of autonomous vehicles such as UAVs enables new forms of transportation and delivery of goods, such as in-roof delivery and in-balcony delivery in a quick, efficient and safe manner.
Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified.
Embodiments of systems, devices and methods for light-based guidance of autonomous vehicles are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-know structures, materials or operations are not shown or describe in detail to avoid obscuring certain aspects.
The content of this disclosure may be applied to multiple fields, such as navigation, autonomous vehicles, aerial vehicles, marine navigation, aerospace navigation, spacecrafts docking, and satellites.
Reference throughout this specification to “one embodiment”, “an embodiment”, or “some embodiments” means that a particular feature, structure, or characteristic described may be included in at least one embodiment of the present invention, and each of these embodiments may be combined with other embodiments in accordance with the present disclosure. Thus, the appearances of the phrases “in one embodiment”, “in an embodiment”, or “in some embodiments” throughout this specification do not necessarily all refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. These embodiments and others will be described in more detail with references to
Throughout this specification, several terms of art are used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise. Also, like characters generally refer to like elements unless indicated otherwise.
Embodiments of this disclosure utilize light sources that emit light signals with an angular dependent intensity profile. An exemplary radiation pattern of a light source that emits light signals with an angular dependent intensity profile is illustrated in the polar plot shown in
In another embodiment, a ground station 104 with two pairs of light sources comprised by light sources 105, 106, 107 and 108 generate two planar regions 110 and 111 in space of equal light intensity. This is illustrated in
To determine the orientation and position of the autonomous vehicle with respect to the light sources and with respect to the straight path define by light sources, the light signals are detected with an on-board light detector and processed with an on-board processing logic. Each light signal is unique so that they can be distinguished. Moreover, using an a priori knowledge of the position of the light sources and the unique signal each one emits, the position and orientation of the autonomous vehicle with respect to the light sources can be known.
In some embodiments, the on board light detector has a lens to create an image of the light sources on the light detector.
In an exemplary embodiment, the light signals are any of the following: amplitude modulated sinusoidal carrier signals, CDMA codes, a data stream, an encrypted data stream, an amplitude modulated signal of any other periodic waveform or a spread spectrum signal.
In some embodiments, the light signals are detected via one or a combination of the following: demodulation, decryption, CDMA decoding, polarization multiplexing, wavelength division multiplexing.
In some exemplary embodiments, the orientation of the autonomous vehicles is determined by the on-board processing logic with an a-priori knowledge of the relative orientation between the light sources in the ground station and the unique light signal each light source emits. By comparing the relative strength between the detected signals, a control signal is generated to guide with precision the autonomous vehicles towards the ground station, for example.
The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
