WO2008033083A2 - Système de commande - Google Patents

Système de commande Download PDF

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Publication number
WO2008033083A2
WO2008033083A2 PCT/SE2007/000807 SE2007000807W WO2008033083A2 WO 2008033083 A2 WO2008033083 A2 WO 2008033083A2 SE 2007000807 W SE2007000807 W SE 2007000807W WO 2008033083 A2 WO2008033083 A2 WO 2008033083A2
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WO
WIPO (PCT)
Prior art keywords
control unit
central control
measuring sensor
sensors
sensor system
Prior art date
Application number
PCT/SE2007/000807
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English (en)
Other versions
WO2008033083A3 (fr
WO2008033083A9 (fr
Inventor
Jan-Erik Strömberg
Original Assignee
Dst Control Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dst Control Ab filed Critical Dst Control Ab
Publication of WO2008033083A2 publication Critical patent/WO2008033083A2/fr
Publication of WO2008033083A3 publication Critical patent/WO2008033083A3/fr
Publication of WO2008033083A9 publication Critical patent/WO2008033083A9/fr

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00—Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot
    • G05D1/0055—Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot with safety arrangements
    • G05D1/0077—Control of position, course or altitude of land, water, air, or space vehicles, e.g. automatic pilot with safety arrangements using redundant signals or controls

Definitions

  • the present invention relates to a control system for unmanned vehicles, such as unmanned aerial vehicles, which system comprises a central control unit.
  • Unmanned aerial vehicles or UAV systems with the ability to fly without requiring continuous intervention by a human operator, have until now been intended exclusively for military markets. Recent years, however, have seen an increasing demand from a broader and more varying market, while simultaneously the military requirements have been raised. Concurrently with this development, the requirements for the reliability of the systems and their capacity to make independent decisions in critical situations to avoid damage to property and personal injury have increased dramatically. This means in particular that the requirements on the control systems have increased.
  • UAV systems and also of unmanned land and sea vehicles/craft are relatively small and light compared to manned vehicles. While the low weight and the small size are one of the many advantages of a UAV system compared to conventional manned vehicles, this also means that the lifting capacity and the available space are very limited. The limited space is particularly an issue in hovering UAV systems, that is rotor-equipped vehicles. This results in problems which are unique to UAV systems and which often make it impossible to apply to UAV systems the technology used to construct safe and reliable control systems for manned aerial vehicles.
  • US 2006/0058928A1 discloses a system and a method for controlling unmanned vehicles.
  • This document describes a control system of the vehicle, consisting of one central processor which is in electronic communication with a plurality of sensors distributed in the vehicle.
  • This system is, however, vulnerable in at least two ways: a failing communication channel between the processor and a sensor risks to negatively affect controllability, and the failure of the central control unit or an individual sensor negatively affects controllability.
  • EP0754991 discloses a control system for a manned vehicle, in which a central control unit is eliminated and in which the control function is completely distributed among a plurality of distributed intelligent control units, which are capable of communicating with each other by groups via an optical ring bus.
  • a control system for a manned vehicle in which a central control unit is eliminated and in which the control function is completely distributed among a plurality of distributed intelligent control units, which are capable of communicating with each other by groups via an optical ring bus.
  • Such a system is, however, unsuitable for use in an unmanned vehicle since the components included in the form of, among other things, intelligent control units and high performance optical communication paths with associated interfaces result in a complex, expensive and heavy solution.
  • an object of the present invention is to provide a control system, which is designed such that the above-mentioned problems are eliminated or considerably reduced.
  • a control system which is of the type defined in the preamble to claim 1 and characterised in that the central control unit comprises the components which are the most critical for the control of the vehicle, that the system further comprises a plurality of actuating means and/or sensors which are distributed externally of the central control unit, and that the distributed means and/or sensors communicate with each other and with the central control unit via at least one bidirectional ring bus, to which the means and/or the sensors are connected in series.
  • the ring bus is connected to the central control unit by at least two ports.
  • the solution with at least one bidirectional ring bus provides improved safety and reduced risk of, for example, a cable failure affecting the control of the vehicle.
  • the system is designed according to a distribution principle, that is a plurality of individual components communicating with each other via one or more digital buses, a high degree of flexibility is achieved as well as an even distribution of the mass over the extension of the vehicle.
  • a distribution principle that is a plurality of individual components communicating with each other via one or more digital buses
  • the present solution has the advantage that particularly critical sensors and calculation units can be doubled or multiplied.
  • the solution also offers the advantage that the distributed function units have a much simpler design and are considerably less demanding for the bus.
  • the distributed means and/or the sensors communicate with each other and with the central control unit via two mutually independent bidirectional ring buses, which are connected to the central control unit by four ports.
  • the bus is circular and not, for instance, star-shaped is an important aspect for many reasons as it contributes to a minimum increase in weight and volume, in spite of the double number of cables, and to a doubling of the number of signal paths.
  • the total cable length is much longer and there are either more connectors in the control unit or more external cross-connection units (that is increased complexity, weight and volume).
  • the ring-shaped buses permit the bus traffic to flow clockwise or anticlockwise or in both directions simultaneously depending on if there is a cable failure in the bus. This is also the case of the power supply which can be distributed by the same bus cabling.
  • the central control unit comprises at least one high performance attitude measuring sensor system and at least two low performance attitude measuring sensor systems.
  • At least one high performance attitude measuring sensor system is combined with two or more low performance sensor systems to maximise reliability.
  • the high performance system is, for example, based on fibre-optic technique (FOG) or on the principle of laser interference, so-called laser gyro.
  • FOG fibre-optic technique
  • laser gyro laser gyro
  • These sensors are expensive (or even very expensive) and have a volume which for physical reasons is not insignificant. Owing to this, only one such sensor system is included in the control system.
  • the low performance sensors are based on so-called microelectromechanical technique (MEMS) and have a small volume, low price and moderate performance. They can thus advantageously be duplicated at low cost.
  • MEMS microelectromechanical technique
  • the central control unit is designed such that the high performance attitude measuring sensor system is located in the centre of the central control unit and the at least two low performance attitude measuring sensor systems are located on opposite sides of the high performance attitude measuring sensor system.
  • the central control unit comprises at least one interface unit, which comprises at least one low performance sensor system and at least one position measuring sensor system and through which interface unit all power supply to all the distributed means and/or the sensors passes to allow measuring of the power consumption.
  • the interface unit is also capable of disconnecting the power supply to the functions of the system that are not safety-critical, such as a payload.
  • the central control unit comprises at least one high performance attitude measuring sensor system, at least two low performance attitude measuring sensor systems, at least two position measuring sensor systems, and at least two calculation units arranged to calculate the attitude and the position of the vehicle. These units function independently of each other, but are capable of communicating with each other via an internal bus.
  • the central control unit is composed of two essentially identical halves.
  • the two calculations units have access to data from all the available sensor units, which means that the evaluation of all sensor data can be carried out by both calculations units independently of each other. This is possible even if one of the calculation units fails, since the bus and the interface units are designed to function irrespective of the accessibility of the calculation units.
  • the principle is that one of the two calculation units acts as a master (primary unit) in the buses under normal circumstances. This master independently decides on the bus traffic.
  • the other calculation unit acts as a passive node monitoring all traffic, and has the capacity, on the one hand, to retrieve data from all the distributed sensor and, on the other hand, to determine if the other calculation unit has failed or if a cable failure has occurred. When such an event has been established, the passive calculation unit can decide to act as a master for the bus in question.
  • Fig. 1 is a block diagram illustrating the basic structure of the invention.
  • the Figure shows a control system according to the invention.
  • the control system comprises a central control unit 1.
  • the central control unit 1 comprises a high performance attitude measuring sensor system 5, which is located in the centre of the central control unit.
  • the high performance sensors 5 can, for example, be based on fibre-optic technique (FOG) or the principle of laser interference, so-called laser gyroscope, or a similar technique. These sensors are expensive and have a volume, which for physical reasons, is not insignificant.
  • FOG fibre-optic technique
  • laser gyroscope so-called laser gyroscope
  • the central control unit 1 further comprises two low performance attitude measuring sensor systems 7, which are located on opposite sides of the high performance sensor system 5.
  • the low performance sensors 7 can, for example, be based on so-called microelectromechanical technique (MEMS) or a similar technique, resulting in a small volume, low price and moderate performance.
  • MEMS microelectromechanical technique
  • a high performance sensor system 5 being heavier than a low performance sensor system 7 and by arranging the heavier high performance sensor system 5 in the centre of the central control unit 1 and the two lighter low performance sensor systems 7 on opposite sides of the high performance sensor system 5, an advantageous distribution of the weight is obtained in the vehicle.
  • the high performance system is also located as close as possible to the centre of mass of the vehicle, which contributes to improved measurement accuracy.
  • Attitude is meant the solid angles and the roll, pitch and azimuth angles of the vehicle.
  • the unit 1 also comprises two position measuring sensor systems 8, which are also located on opposite sides of the high performance sensor system 5.
  • position is meant the location of the vehicle in space as expressed, for example, in latitude, longitude and sea-level altitude.
  • Attitude and position control is meant control actions required to keep the vehicle straight and in correct position, that is the correct roll, pitch and azimuth angles and the right position in space, irrespective of outer “disturbances” in the form of wind, turbulence and thermals (or heavy sea, wind, irregularities in the ground, slipperiness and the like in the case of sea and land vehicles).
  • the position measuring sensor systems maximise the reliability of the control system and serve to measure the azimuth angle of the vehicle with great accuracy.
  • the azimuth angle is calculated by arranging at least two aerials 9 at a distance from each other, for example under the main rotor disc and at the rear end of the tail boom of a helicopter, and by using simple trigonometry. This results in high angle accuracy and significantly better tolerance to disturbances (in particular interfering magnetic fields) compared to conventional magnetic compasses thanks to the technical development of the sensors.
  • a low performance sensor system 7 and a position measuring sensor system 8 together form an interface unit 12.
  • the central control unit 1 also includes two calculation units 11 , each comprising a processor (CPU) 6. According to an embodiment of the invention, the calculation unit also comprises a short distance radio link 10.
  • the link 10 is not necessary for the function of the calculation unit, but it can increase safety during the actual flight as it can continuously transmit information to the "ground".
  • the two calculation units 11 are located on opposite sides of the high performance sensor system 5.
  • the most critical components of the control system according to the invention are the calculation units 11 and the sensors for measuring the roll, pitch and azimuth angles and the position and speed of the vehicle. To avoid the risk of operational disturbances caused by errors in cabling and connectors, etc, it is essential for these sensor elements 5, 7, 8 to be contained in the central control unit 1.
  • the central control unit 1 comprises the components which are the most critical for the control of the vehicle and thus has a high performance sensor system 5 which is centrally placed and two parts (halves) which contain the corresponding components.
  • the parts function independently of each other, but can also communicate with each other via a bus 13, preferably an internal high-speed bus.
  • both calculation units 11 have access to data from all available sensor systems 5, 7 and 8. Consequently, the evaluation of all sensor data can be performed by both calculation units 11 independently of each other and irrespective of whether one of the two units ceases to function. This is possible even if one of the calculation units fails since the bus 13 and the interface units 12 are designed to function independently of the accessibility of the calculation units 11.
  • control system also comprises a plurality of distributed actuating means 14-17 and sensors 18-22, which communicate with the central control unit 1 via two mutually independent circular buses 3 and 4.
  • the actuating means 14-17 communicate via an actuator bus 3 and the sensors via a sensor bus 4.
  • the means 14-17 are connected in series to the actuator bus 3.
  • the sensors 18-22 are connected in series to the sensor bus 4.
  • the actuator bus 3 is connected to the central control unit 1 by two ports 2.
  • the sensor bus 3 is connected to the central control unit 1 by two ports 2.
  • the buses 3 and 4 are ring buses, they have two ends each and are connected to the control unit 1 by two ports 2 located on opposite sides of the control unit 1.
  • the buses 3 and 4 are circular and not, for example, star- shaped is an important aspect as it contributes to a minimum increase in weight and volume, in spite of the double number of cables, and to a doubling of the number of signal paths.
  • the total cable length is much longer and there are either more connectors in the control unit or more external cross-connection units (that is increased complexity, weight and volume).
  • the ring-shaped buses 3 and 4 are bidirectional, which makes it possible for the bus traffic to flow in the clockwise or anticlockwise direction or in both directions simultaneously depending on if there is a cable failure in the bus. This is also the case of the power supply which is distributed by the same bus cabling. Owing to the ring shape, it is also possible to determine exactly and unambiguously where a particular cable failure has occurred. In corresponding manner, two independent paths are obtained for the power supply if it is distributed by the same bus cabling.
  • tail rotor actuator 14 main rotor actuator 15, engine control actuator 16 and engine control unit 17.
  • the actuator bus 3 is also bidirectional, which means that valuable status information can be retrieved from the actuators 14-17 and analysed by the calculation units. This is very important to allow early detection of errors about to occur in the actuators (for example increased temperature, increased power consumption/increased mechanical load, resulting setting angle, etc.).
  • fuselage monitoring sensor/vibration monitor 18 As examples of distributed sensors, mention can be made of: fuselage monitoring sensor/vibration monitor 18, landing sensor 19, magnetic compass sensor 20, air data sensor 21 and engine monitoring unit 22.
  • the position measuring sensor systems 8 are, for example, supplemented by the external distributed magnetic compass sensor 20, which is disposed as far away as possible from all interference sources (for example on the outer end of the tail boom of a helicopter). This sensor 20 intervenes if the position measuring sensor systems 8 fail completely or partially.
  • the sensor 20 can also be used to detect errors in the position measuring systems 8.
  • the principle of the central control unit 1 is that one of the two calculation units 11 acts as a master in the communication buses 3 and/or 4 under normal circumstances. This master independently decides on the bus traffic.
  • the other calculation unit 11 acts as a passive node monitoring all traffic, but it also has the capacity to retrieve data from all the distributed sensors 18-22 and the actuators 14-17 and to determine if the other calculation unit 11 is failing or if a cable failure has occurred. When such an event has been established, the passive calculation unit 11 can decide to act as a master for the bus 3 and/or 4 in question. By monitoring which nodes in the bus are responding, it is possible to exactly localise a cable failure or a similar reason for a signal disturbance. All power supply to all the distributed nodes passes through the interface units 12 to allow measurement of the power consumption. This is also an important aspect of early detection of errors which are about to occur.
  • control system further comprises an additional number of distributed units, namely power supply units 23, payloads 24 and ground communication units 25.
  • the interface units 12 are capable of detecting deviations in the power supply 23, which in turn allows a decision to be taken to quickly land the vehicle due to the risk of an approaching voltage failure. In this situation, the interface units 12 can also disconnect the power supply to the functions which are not safety-critical, such as a payload 24.
  • the ground communication units 25 are connected via the central control unit 1 to both calculation units 11 to ensure reliable ground communication even if one of the two radio links is failing.
  • Short distance radio links 10 according to some suitable standard (for example wireless LAN/WLAN, i.e. IEEE 802.11) are used to rationalise the communication with the central control unit 1 during development, testing and transmission of telemetric data. This is because disc space in the calculation units 11 and sensor data in real time are made available owing to the wide bandwidth offered by these radio links. The disc space in the calculation units 11 is also used to store data in a non-volatile manner to be able to later analyse the behaviour of the vehicle and to gather information about any possible problems occurring.
  • some suitable standard for example wireless LAN/WLAN, i.e. IEEE 802.11
  • the disc space in the calculation units 11 is also used to store data in a non-volatile manner to be able to later analyse the behaviour of the vehicle and to gather information about any possible problems occurring.
  • control system By a control system according to the invention, the inherent properties of small and medium size UAV systems are used, among other things, the fact that the vehicles are relatively small and that the cable paths are comparatively short (in relation to manned systems). Moreover, the technical development (for example miniaturisation, price reduction) of certain components is used so that the selected actions result in relatively small costs in terms of volume and price.
  • the limited lifting capacity and available volume make it necessary to carefully adjust the number of units included in a control system, among other things, because each individual node in the distributed system needs to be encapsulated and have reliable connectors, which in turn contributes to the weight and volume without having a useful function.
  • control system can be modified in a number of ways within the scope of the invention such as defined by the following claims.
  • Calculation unit (comprises at least one processor 6 and possibly a short distance radio link 10)
  • Interface unit (comprises a low performance sensor system 7 and a position measuring sensor system 8)

Abstract

L'invention concerne un système de commande pour véhicules inhabités, tels que des véhicules aériens inhabités, lequel système comprend une unité de commande centrale (1) qui comprend les composants qui sont les plus critiques pour la commande du véhicule. L'unité de commande centrale (1) comprend au moins un système de capteurs de mesure d'attitude de performance élevée (53), au moins deux systèmes de capteurs de mesure d'attitude de faible performance (7), au moins deux systèmes de capteur de mesure de position (8) et au moins deux unités de calcul (11) qui sont disposées pour calculer l'attitude et la position du véhicule. Les unités fonctionnent indépendamment les unes des autres, mais sont capables de communiquer les unes avec les autres par l'intermédiaire d'un bus interne (13). Le système comprend en outre une pluralité de moyens d'actionnement (14, 15, 16, 17) et/ou de capteurs (18, 19, 20, 21, 22) qui sont distribués de façon externe à l'unité de commande centrale (1). Les moyens distribués (14, 15, 16, 17) et/ou les capteurs (18, 19, 20, 21, 22) communiquent les uns avec les autres et avec l'unité de commande centrale (1) par l'intermédiaire d'au moins un bus annulaire bidirectionnel (3, 4), auquel les moyens et/ou les capteurs sont connectés en série, et lequel bus annulaire (3, 4) est connecté à l'unité de commande centrale (1) par au moins deux ports (2).
PCT/SE2007/000807 2006-09-14 2007-09-14 Système de commande WO2008033083A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0601903 2006-09-14
SE0601903-8 2006-09-14

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WO2008033083A2 true WO2008033083A2 (fr) 2008-03-20
WO2008033083A3 WO2008033083A3 (fr) 2008-05-02
WO2008033083A9 WO2008033083A9 (fr) 2008-06-12

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102880182A (zh) * 2012-09-12 2013-01-16 北京航空航天大学 一种存在网络随机延迟的微小型无人飞行器控制方法
CN103365295A (zh) * 2013-06-29 2013-10-23 天津大学 基于dsp的四旋翼无人飞行器自主悬停控制系统及方法
US10155584B2 (en) 2012-11-15 2018-12-18 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof

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US5493497A (en) * 1992-06-03 1996-02-20 The Boeing Company Multiaxis redundant fly-by-wire primary flight control system
US5796935A (en) * 1995-07-20 1998-08-18 Raytheon Company Voting node for a distributed control system
US5841537A (en) * 1997-08-11 1998-11-24 Rockwell International Synthesized attitude and heading inertial reference
US20030060944A1 (en) * 2001-09-27 2003-03-27 Carroll Ernest A. Cable connections between an unmanned aircraft and a detachable data handling module
US20030130791A1 (en) * 2002-01-04 2003-07-10 The Boeing Company Apparatus and method for navigation of an aircraft
US20030135327A1 (en) * 2002-01-11 2003-07-17 Seymour Levine Low cost inertial navigator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5493497A (en) * 1992-06-03 1996-02-20 The Boeing Company Multiaxis redundant fly-by-wire primary flight control system
US5796935A (en) * 1995-07-20 1998-08-18 Raytheon Company Voting node for a distributed control system
US5841537A (en) * 1997-08-11 1998-11-24 Rockwell International Synthesized attitude and heading inertial reference
US20030060944A1 (en) * 2001-09-27 2003-03-27 Carroll Ernest A. Cable connections between an unmanned aircraft and a detachable data handling module
US20030130791A1 (en) * 2002-01-04 2003-07-10 The Boeing Company Apparatus and method for navigation of an aircraft
US20030135327A1 (en) * 2002-01-11 2003-07-17 Seymour Levine Low cost inertial navigator

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102880182A (zh) * 2012-09-12 2013-01-16 北京航空航天大学 一种存在网络随机延迟的微小型无人飞行器控制方法
US10155584B2 (en) 2012-11-15 2018-12-18 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
US10189562B2 (en) 2012-11-15 2019-01-29 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
US10196137B2 (en) 2012-11-15 2019-02-05 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
US10272994B2 (en) 2012-11-15 2019-04-30 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
US10472056B2 (en) 2012-11-15 2019-11-12 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
US11338912B2 (en) 2012-11-15 2022-05-24 SZ DJI Technology Co., Ltd. Unmanned aerial vehicle and operations thereof
CN103365295A (zh) * 2013-06-29 2013-10-23 天津大学 基于dsp的四旋翼无人飞行器自主悬停控制系统及方法

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WO2008033083A9 (fr) 2008-06-12

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