Abstract:
A remotely-controlled unmanned mobile device (UMD) adapted to function as a robot scout to enter and reconnoiter the site of a disaster and to communicate to a rescue mission information regarding conditions prevailing at the site, making it possible for the mission to decide on rescue measures appropriate to these conditions. The UMD is operable in either of two modes. In its air-mobility mode the UMD is able to vertically take off and land, to fly to the site and then hover thereover. In its ground-mobility mode, the UMD can walk on legs over difficult terrain and through wrecked structures and ruins. The UMD is provided with condition-sensitive sensors for gathering data regarding conditions prevailing at the site, and position-sensitive sensors for avoiding obstacles in the path of the walking UMD, thereby assuring safe mobility. Other sensors govern geo-referenced navigation and flight control functions.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates generally to remotely-controlled unmanned mobile devices adapted to function as a robot scout to gather information regarding conditions prevailing at a disaster site and to communicate this information to a rescue mission.  
           [0003]    2. Status of Prior Art  
           [0004]    In disaster situations, the availability of timely and accurate information regarding conditions prevailing at the site of the disaster may be crucial to the success of a rescue mission. Typical, yet not exclusive, of such situations are an explosion at a chemical manufacturing facility, the leakage of hazardous materials at an urban site, a nuclear reactor accident or an earthquake as well as other serious ecological and natural catastrophes.  
           [0005]    Should a rescue mission seek to gain advance information regarding conditions prevailing in the region of a disaster so that the mission can decide on appropriate rescue procedures, in many cases this attempt may expose scouts assigned to this task to life-threatening risks. For example, if the disaster area is the site of a nuclear reactor accident in which released into the area are lethal radioactive particles, scouts would be ill advised to enter this area.  
           [0006]    The present invention resides in a remotely-controlled unmanned mobile device (UMD) functioning as a robot scout adapted to enter and reconnoiter a disaster site in behalf of a rescue mission to gather information in regard to conditions prevailing at the site and to communicate this information to the mission. The UMD is operable either in an air-mobility mode or in a ground-mobility mode, so that it is capable of fully exploring the site. While conditions prevailing at the site of a disaster may threaten the life of a living scout, they can do no injury to a robot scout.  
           [0007]    Because in its air-mobility mode the UMD operates in a manner similar to that of a vertical take-off and landing vehicle (VTOL), of prior art interest in this regard is the unmanned VTOL air vehicle described e.g. in U.S. Pat. No. 5,295,643 to Ebbert et al. This device is capable of vertical take-off and landing in confined areas. It is also capable of transition to horizontal high speed flight and is able to hover and loiter for a period of time. The vehicle includes coaxial forward and aft centerbodies, and a ducted rotor having a plurality of propellers. The ducted fan is aerodynamically efficient and is safe because of its unexposed rotor blades.  
           [0008]    And since a UMD in accordance with the invention when operating in a ground mobility mode can walk on the terrain of the disaster site, however difficult the terrain, of prior art interest is the multi-legged walking robot disclosed e.g. by Takeuchi in U.S. Pat. No. 5,842,533. This device is capable of walking on uneven ground while carrying a payload. This multi-legged walking robot provides some of the basic capabilities for the ground mobility portion of a dual-mode UMD device in accordance with the invention.  
           [0009]    In the six-legged walking robot described by Paynter in U.S. Pat. No. 5,040,626, each leg, composed of two links, has three controlled degrees-of-freedom of rotary motion. This device is also capable of walking on uneven ground and carrying a payload.  
           [0010]    Obstacle avoidance and indoor navigation capability is needed in order to execute the mission of a robot scout in a disturbed environment. A system for obstacle avoidance and path planning is disclosed by Takenaka in U.S. Pat. No. 5,502,638. A survey of sensors and techniques appropriate for indoor positioning is set forth in Borenstein, J., et. al., “Mobile Robot Positioning—Sensors and Techniques”, The Journal of Robotic Systems, Vol. 14, No. 4, 1997, pp. 231-249, and in Borenstein, J., et. Al., “Navigating Mobile Robots: Sensors and Techniques”, A. K. Peters Ltd., Wellesley, Mass., 1995.  
           [0011]    Of prior art background interest regarding ducted fan VTOL devices, walking robots, distributed decentralized command and control of multiple mobile devices, as well as a unit for command control of mobile devices are the following U.S. patents:  
           [0012]    U.S. Pat. No. 5,295,643 (1994)—ducted fan VTOL  
           [0013]    U.S. Pat. No. 5,842,533 (1998)—legged robot  
           [0014]    U.S. Pat. No. 5,040,626 (1991)—legged robot  
           [0015]    U.S. Pat. No. 5,502,638 (1996)—path planning and obstacle avoidance  
           [0016]    U.S. Pat. No. 5,340,056 (1994)—Active defense system—cooperative  
           [0017]    Operation of multiple UAVs (distributed-decentralized command and control of multiple unmanned devices).  
           [0018]    Also of prior art interest in regard to various features included in a UMD robot scout in accordance with the invention are the following publications:  
           [0019]    Chen, Chun-Hung et. al., “Motion Planning of Walking Robots in Environments with Uncertainty”, Journal of Robotic Systems, John Wiley &amp; Sons, Inc., Volume 16, No.10, 1999, pp. 527-545.  
           [0020]    Todd, D. J., “Walking Machines- An Introduction to Legged Robots”, Kogan Page Ltd., London U.K., 1985, pp. 63-168.  
           [0021]    Movarec, Hans P., “Robot Rover Visual Navigation”, UMI Research Press, Ann Arbor, Mich., 1981, pp. 49-147.  
           [0022]    Thorpe, Charles E., ed., “Vision and Navigation”, Kluwer Academic Publishers, Norwell Mass., 1990, pp.  
           [0023]    Robert, Luc, et. al., “Applications of Non-Metric Vision to Some Visually Guided Robotic Tasks”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 89-134.  
           [0024]    Weng, J. J., et. al.,“Visual Navigation Using Fast Content-Based Retrieval”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 178-217.  
           [0025]    Dean, Thomas, et. al., “Planning and Navigation in Stochastic Environments”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp., 251-274.  
           [0026]    Adams, Martin David, “Sensor Modeling, Design and Data Processing for Autonomous Navigation”, World Scientific Publishers, Singapore, 1999, pp. 153-208.  
           [0027]    Song, Shin-Min, et. al., “Machines That Walk”, The MIT Press, Cambridge, Mass., 1989, pp. 23-281.  
           [0028]    Fahlstrom, Paul G., et. al., “Introduction to UAV Systems”, UAV Systems Inc., Columbia, Md., 1993, pp. II 42-II 47.  
           [0029]    Kohlman, David L., “Introduction to V/STOL Airplanes”, Iowa State University Press, Ames, Iowa, 1981.  
           [0030]    Yavnai A., “Distributed Decentralized Architecture for Autonomous Cooperative Operation of Multiple Agent System”, in Proceedings of IEEE Symposium on Autonomous Underwater Vehicle Technology, Jul. 19-20, 1994, Cambridge, pp. 61-67.  
           [0031]    Arlowe, H. D., “Airborne Remote Operated Device”, Proceedings of the 15 th  Annual Technical Symposium of the Association of Unmanned Vehicle Systems, San-Diego, Calif., Jun. 6-8, 1988, pp. 1-13.  
           [0032]    Borenstein, J., et. al., “Mobile Robot Positioning—Sensors and Techniques”, The Journal of Robotic Systems, Vol. 14, No. 4, 1997, pp. 231-249.  
           [0033]    Borenstein, J., et. al., “Navigating Mobile Robots: Sensors and Techniques”, A.K. Peters Ltd., Wellesley, Mass., 1995.  
           [0034]    Even, S., “Graph Algorithms”, Computer Science Press, Maryland, USA, 1979.  
         SUMMARY OF THE INVENTION  
         [0035]    In view of the foregoing, the main object of this invention is to provide a remotely-controlled unmanned mobile device (UMD) adapted to function as a robot scout in behalf of a rescue mission to enter and reconnoiter the site of a disaster, to gather information regarding conditions prevailing at this site and to communicate this information to the mission which can then decide on rescue actions appropriate to the prevailing conditions. The UMD may be adapted to additional functions, all as required and appropriate.  
           [0036]    More particularly an object of this invention is to provide a dual mobility UMD which is operable either in an air mobility mode or in a ground mobility mode, making it possible for the robot scout to fully explore the disaster site.  
           [0037]    Among the significant advantages of a UMD robot scout according to the invention are the following:  
           [0038]    A. The UMD can fly from a nearby safe station to the disaster area and reconnoiter the area to gather information regarding the conditions which prevail in the area, which information is conveyed to rescue mission personnel who are exposed to no risk in gathering the information.  
           [0039]    B. When the UMD arrives at a disaster area, its on-board sensors then proceed to collect the information required by the rescue mission, which information is communicated to rescue mission personnel who are thereby advised of possible dangers they may encounter when entering the disaster area and can then take steps to avoid these dangers.  
           [0040]    C. In its ground mobility mode, the UMD can traverse difficult terrain and walk through wrecked structures and ruins in order to reconnoiter the entire site.  
           [0041]    D. When several UMD&#39;s are enlisted by a rescue mission to reconnoiter a disaster area, they can communicate with each other to coordinate their activity.  
           [0042]    E. The UMD is compact in form and light in weight, being composed mainly of miniature components.  
           [0043]    F. The UMD should preferably be equipped with payload, which can be activated whenever required.  
           [0044]    Briefly stated, these objects are accomplished in a remotely-controlled unmanned mobile device (UMD) adapted to function as a robot scout to enter and reconnoiter the site of a disaster and to communicate to a rescue mission information regarding conditions prevailing at the site, making it possible for the mission to decide on rescue measures appropriate to these conditions.  
           [0045]    The UMD is operable in either of two modes. In its air-mobility mode, the UMD is able to vertically take off and land, to fly to the site and then hover thereover. In its ground-mobility mode, the UMD can walk on its legs over difficult terrain and through wrecked structures and ruins. The UMD is provided with condition-sensing detectors for gathering data regarding conditions prevailing at the site, and position-sensing sensors for avoiding obstacles in the path of the walking UMD, thereby assuring safe mobility. Other sensors govern geo-referenced navigational and flight control functions. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS:  
       [0046]    For a better understanding of the invention as well as other objects and features thereof, reference is made to the annexed drawing wherein:  
         [0047]    FIGS.  1 ( a ) and  1 ( b ) are perspective views of an unmanned mobile vehicle in accordance with a preferred embodiment of the invention; FIG. 1( a ) showing the device when its legs are retracted, FIG. 1( b ) showing the same device with its legs extended;  
         [0048]    [0048]FIG. 2 is a perspective view of the unmanned mobile device in alternative mobility modes;  
         [0049]    FIGS.  3 ( a ) and  3 ( b ) are top and side views, respectively, of the unmanned mobile device in an all-terrain walking mode;  
         [0050]    [0050]FIG. 4 is a perspective view of the unmanned mobile device in a typical data gathering and situation-monitoring scenario in a disaster area;  
         [0051]    [0051]FIG. 5 is an overhead view of the display of the command and control portable unit;  
         [0052]    [0052]FIG. 6 is a functional diagram of the electronics unit architecture;  
         [0053]    [0053]FIG. 7 is a diagram of the main operational and mobility modes and the associated inter-mode transition logic; and  
         [0054]    FIGS.  8 ( a ) and  8 ( b ) are layouts of a building interior and its associated graph-based data structure representation. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0055]    Whilst for connivance of explanation, the description focuses mainly in UMD that is utilized by rescue forces in disaster areas, those versed in the art will readily appreciate that the UMD of the invention is by no means bound by this application. Accordingly, the UMD of the invention may be utilized by an operator or operators in any area of interest.  
         [0056]    The UND: A UMD in accordance with the invention is adapted to function as a robot scout to reconnoiter a disaster area. As shown in FIGS.  1 ( a ) and  1 ( b ) , the basic structure of UMD  10  is constituted by a toroidal duct  11  surrounding a rotor and propeller assembly  12  and a main center body  13 . Centerbody  13  is supported within duct  11  by structured elements such as an array of struts  14 . This basic structure creates a ducted aerodynamic fan blowing an air stream through the duct which acts to propel the UMD.  
         [0057]    The embodiment of the UMD illustrated herein is highly compact and light weight. Duct  11  has a diameter 0.4 meters. The gross take-off weight of the UMD is 2 kg (2000 grams). The primary structural material for the UMD is KELVAR which has a high strength-to-weight ratio. The invention can, of course, be embodied in other robot scout structures having different weights and dimensions.  
         [0058]    Centerbody  13  houses the main engine, the energy source and the electronics compartment containing a computer unit. In the present embodiment, the main rotor engine is an electrical brushless DC motor having 200 watts output power. The energy source is constituted by a bank of Lithium batteries. Structure elements  14  fix the centerbody  13  to the duct  11 .  
         [0059]    The air mobility capability of the UMD is based essentially on the concept of a ducted fan VTOL air vehicle as described in the Ebbert et. al. U.S. Pat. No. 5,295,643. A circular array of control vanes  15  mounted within toroidal duct  11  affords the aerodynamic means required to control the flight and attitude of the UMD.  
         [0060]    In operation, when the driven propellers in the ducted fan rotate to blow an air stream in the downward vertical direction, this provides the UMD with the necessary lift forces. To cause the UMD to descend vertically toward the ground, the rotor speed is reduced. The legs of the UMD are then outstretched to function as landing gear. Upon landing at a disaster site or elsewhere, the legs function to maintain the robot erect and as a walking mechanism.  
         [0061]    When the UMD is aloft, its flight direction is controlled by the four vanes  15  which intercept the air stream being blown out of the duct to produce a lateral force causing the UMD to fly in the North, South, East or West direction depending on the angular position of the four vanes in the circular array shown in FIG. 1( a ).  
         [0062]    To support the geo-navigation and flight control functions of the UMD, several sensors are required for this purpose. These include (see FIG. 6 which shows the units in the electronics compartment) the following:  
         [0063]    (a) Three piezoelectric gyros  62  (such as Piezo gyro model HXM1010, commercially available from HELI-MAX which weighs only 13 grams)  
         [0064]    (b) GPS receiver  63   
         [0065]    (c) 3D Magnetometer  64   
         [0066]    (d) Two piezoelectric tilt sensors  65 .  
         [0067]    Actuation means for flight control include rotor-control  76  and control vane servo actuators  77  for the four vanes. The required set of sensors  17  as shown in FIG. 1( a ) are assembled in a housing  16  mounted on the exterior of the toroidal duct.  
         [0068]    A communication unit  18  provided with an antenna  19  is mounted on the outer surface of the ducted fan  11 . Low weight components are preferred for implementing communication unit  18 . For example FM receiver model TETRA 301FM, commercially available from FMA Direct Inc., weighs only 14 grams and provides the onboard end of the uplink  68  (see FIG. 6). A video transmitter model TSG TX, commercially available from the Security Group which also weighs only 14 grams, provides the onboard end of the downlink  69 .  
         [0069]    Communication unit  18  establishes a two-way wireless data link between UMD  10  and remotely-located operating personnel. It also establishes a two-way wireless data link between UMD  10  and other UMDs in order to coordinate a mission assigned to a group of UMDs.  
         [0070]    Those versed in the art will readily appreciate that the invention is by no mean bound by the specific structure of the UMD in accordance with FIGS.  1 ( a ) and  1 ( b ), and by the same token it is not bound by the system architecture, described with reference to FIG. 6.  
         [0071]    Various approaches have heretofore been proposed to solve the problem of command and control of multiple unmanned mobile systems. In accordance with a preferred embodiment, a distributed-decentralized architecture is utilized, the details of which are disclosed in Yavnai A., “Distributed Decentralized Architecture for Autonomous Cooperative Operation of Multiple Agent System”, in Proceedings of IEEE Symposium on Autonomous Underwater Vehicle Technology, Jul. 19-20, 1994, Cambridge, pp. 61-67 and Guelman, M., and Yavnai, A., U.S. Pat. No. 5,340,056, 1994.  
         [0072]    The all-terrain ground mobility of the scouting device is achieved by using active multiple mechanical legs to support the UMD and cause it to walk on the terrain of the disaster site. FIG. 1( a ) illustrates a situation in which the legs are in a retracted state. FIG. 1( b ) illustrates a situation where the legs are in an extended outstretched position. In the present embodiment four legs are provided which are similar to those shown in FIG. 1 of U.S. Pat. No. 5,842,533 to Takeuchi. In the present embodiment, each leg has two links, namely, an upper link  21  and a lower link  20 . The kinematic arrangement of the leg&#39;s joints and links of the present invention is similar to that shown in FIG. 9 of the Paynter, U.S. Pat. No. 5,040,626. Upper link  21  is actuated by a double-actuator  22  mounted on the external surface of the duct  11 . An active joint  23  provides a relative one-degree-of-freedom controlled motion between upper link  21  and lower link  20 , each lower link  20  having a foot  24 . The legs also function as landing gear struts, preferably with energy absorbing capability. The legs are capable of compensating for ground irregularities, so that the main body of UMD  10  is kept in a level state.  
         [0073]    A payload housing  25  is mounted on top of centerbody  13  above the rotor assembly. Housing  25  has an optical window  26  to protect the internal electro-optical sensors and associated electronics. The main sensor housed in payload housing  25  is a video camera  70  such as a CCD video camera with resolution of 256×256 pixels, such as model SG-2000-CMOS, commercially available from The Security Group, (weighing  5  grams). A light emitting unit is aligned with the video camera  70  line-of-sight to facilitate camera operation under low light conditions. An infra-red uncooled camera  71  (see FIG. 6) is also included as an option. Payload housing  25  is capable of rotating 360 degrees around an axis which is aligned with the central axis of the centerbody  13  and with the axis of rotation of the rotor. This rotation is effected by a light weight DC servo motor  79 . A suitable motor for this purpose is DC servo model LS-3.0 commercially available from Wes-Technik, Germany (weight 3 grams).  
         [0074]    Whilst in the example above the payload includes housing  25  equipped with window  26  for accommodating video camera  70  and possibly also IR camera  71 , by another embodiment other payload equipment may be employed in addition or in lieu of the specified video camera and IR camera, depending upon the designated mission(s) of the UNM.  
         [0075]    Turning now to FIG. 2, UMD  10  is capable of operating in several alternative modes. In a standing mode  30 , UMD  10  is supported by the legs extended therefrom which support the weight of the UMD and also compensate for ground irregularities in order to maintain UMD&#39;s main body in a level state.  
         [0076]    In a hovering mode  31 , UMD  10  is capable of moving in one of three alternate directions: (1) vertical take-off  35 ; (2) vertical landing  34 ; and (3) hovering flight  36 . It is also capable of hovering above the same ground location in a keep-on-station mode. In cruise dash flying mode  32 , UMD  10  then flies in direction  37 . In a walking mode  33 , UMD  10  then walks on the ground or climbs stairs in the general direction  38 . In a ground mobility mode UMD  10  can creep or otherwise move along the ground using the legs as supporting mechanisms.  
         [0077]    FIGS.  3 ( a ) and  3 ( b ) show UMD  10  in an exemplary walking mode. FIG. 3( a ) being a top view and FIG. 3( b ) a side view. UMD  10  is shown moving on an uneven terrain  27  in the general direction  28 . In the present embodiment, UMD  10  has four legs, each leg being constituted by two interconnected links—the upper link  21  and the lower link  20 . The upper link  21  is actuated by a double-actuator  22  which is mounted on the external surface of the duct  11 . The double-actuator  22  provides two one-degrees-of-freedom controlled rotary motions around axes perpendicular to upper link  21 .  
         [0078]    In the present embodiment, each degree-of-freedom of the double-actuator  22  is provided by a light-weight (several grams) rotary DC servo brushless motor such as DC servo model LS-3.0, commercially available from Wes-Technik, Germany (weight 3 grams). An active joint  23  provides a relative one-degree-of-freedom controlled rotary motion between upper link  21  and lower link  20 . The one-degree-of-freedom motion of the active joint  23  of the present embodiment is also provided by a light weight (several grams) rotary DC servo brushless motor such as the above noted DC servo model LS-3.0.  
         [0079]    All three degrees-of-freedom of each leg are rotary, and each one thereof is provided by a one-degree-of-freedom rotary actuator. The kinematic arrangement of the leg&#39;s joints and links of the present invention is by one embodiment similar to that shown in FIG. 9 U.S. Pat. No. 5,040,626 to Paynter. The double-actuator  22  provides the two rotary motions around axes which are analogous to axis  1  and axis  2  in FIG. 9 of the Paynter patent. Actuator  23  provides the rotary motions around an axis which is analogous to axis  3  in the above-noted FIG. 9. The total number of active controlled degrees-of-freedom of the walking mechanism in the present embodiment is therefore twelve. Each lower link  20  has a foot  24 . The foot can be either fixed to the lower link  20 , or can be linked to the lower link  20  via a pivot or via a passive elastic energy absorbing element such as a spring, or a combination thereof. The legs also function as landing gear struts, preferably with energy absorbing capability. The legs are capable of compensating for ground irregularities to keep the main body level.  
         [0080]    Automatic control of legged locomotion is necessary in order to exploit the all-terrain mobility of the UMD. It is particularly required in a disrupted terrain or environment, such as when ruined buildings are encountered by the UMD. This capability raises relatively complex control problems. For example, in the present embodiment up to as many as twelve degrees-of-freedom must be controlled simultaneously. Thus, the control system is called upon to issue as many as twelve coordinated commands to the actuators, (e.g., to DC servo motors) simultaneously, in real time.  
         [0081]    Some of the principles of controlling the multi-legged walking mechanisms in the present embodiment are based on techniques described in the following publications: a) Todd, D. J., “Walking Machines—An Introduction to Legged Robots”, Kogan Page Ltd., London U.K., 1985, pp. 91-150; b) Song, Shin-Min, et. al., “Machines That Walk”, The MIT Press, Cambridge, Mass., 1989, pp. 23-164; c) Chen, Chun-Hung et. al., “Motion Planning of Walking Robots in Environments with Uncertainty”, Journal of Robotic Systems, John Wiley &amp; Sons, Inc., Volume 16, No. 10, pp. 527-545, 1999. The invention is, of course, not bound by these techniques.  
         [0082]    When UMD  10  is walking in general direction  28 , a plurality of sensors are activated in order to determine its geographical location; the geometrical features of the surrounding environment; its position relative to other objects; and any obstacles in its way. The plurality of sensors  17  which encompass a 360 degrees field of view satisfies these needs. Also supporting these needs are the electro-optical sensors housed in payload housing  25 , these being directed forward through optical window  26  which is capable of rotating 360 degrees around its main axis.  
         [0083]    Some of the sensing devices and techniques used in the present embodiment are disclosed in: a) Borenstein, J., et. al., “Mobile Robot Positioning—Sensors and Techniques”, The Journal of Robotic Systems, Vol. 14, No. 4, 1997, pp. 231-249; b) Borenstein, J., et. al., “Navigating Mobile Robots: Sensors and Techniques”, A. K. Peters Ltd., Wellesley, Mass., 1995; c) Adams, Martin David, “Sensor Modeling, Design and Data Processing for Autonomous Navigation”, World Scientific Publishers, Singapore, 1999, pp. 153-208. The invention is, of course, not bound by these techniques.  
         [0084]    It is known to use computer-controlled visual techniques for navigation and for obstacle detection and avoidance. Some of the visual devices and techniques for this purpose include the present embodiment, and are described in: a) Movarec, Hans P., “Robot Rover Visual Navigation”, UMI Research Press, Ann Arbor, Mich., 1981, pp. 49-147; b) Robert, Luc, et. al., “Applications of Non-Metric Vision to Some Visually Guided Robotic Tasks”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 89-134; c) Weng, J. J., et. al.,“Visual Navigation Using Fast Content-Based Retrieval”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 178-217; d) Dean, Thomas, et. al., “Planning and Navigation in Stochastic Environments”, in Aloimonos, Yiannis, ed., “Visual Navigation- From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp., 251-274. The invention is, of course, not bound by these techniques.  
         [0085]    Path planning techniques employed in the present embodiment are based, e.g. on techniques described in the following references: a) A system for obstacle avoidance and path planning disclosed in U.S. Pat. No. 5,502,638 to Takenaka b) “Motion Planning of Walking Robots in Environments with Uncertainty”, Chen et. al., Journal of Robotic Systems, John Wiley &amp; Sons, Inc., Volume  16 , No. 10, pp. 527-545, 1999.  
         [0086]    The problem of indoor navigation falls into two categories; namely navigating with an a-priori map or database; and navigating without this map or database. Where an a-priori map is available, the navigation function uses a-prior data about the building layout, by employing appropriate LFMs—local feature maps (see FIGS.  8 ( a ) and  8 ( b )). If an a-priori map is not available or if the object  54  to be visited has been damaged so that the a-priori map is no longer a true representation of the actual object, then a different navigation procedure is executed, the so-called “navigating in a maze”. A process called “map building” is then a part of the navigation process.  
         [0087]    In order to meet the requirements for a highly compact and light weight UMD, use is made in the present embodiment of miniature light weight sensors. For example, a CCD camera with a resolution of 256×256 pixles is only 5 grams in weight. (Model SG-2000-CMOS, commercially available from The Security Group) Also usable are acoustic sensors which weigh only 5 grams each, or infra-red LED-based range finders which weigh only 5 grams each. Scenario: Referring now to FIG. 4 illustrated therein is a typical, yet not exclusive, scenario of a UMD executing a data gathering and situation-monitoring mission within a disaster site.  
         [0088]    An operator  40  is put in charge of operating UMD  10  and of supervising its operation from a safe location, preferably in the vicinity of the disaster area. When arriving at the station from which to launch UMD  10  on its scouting mission and to thereafter manage its operation, operator  40  then has the following series of pre-mission activities to undertake: a) unpack UMD  10  from its protective packaging; b) place UMD  10  on an uncluttered surface for safe take-off and landing; c) press a key on the command and control portable unit keyboard in order to transmit an ON command (see OnCmd  99  in FIG. 7) so as to “Wake-Up” UMD  10  and change its state from System Non-Active state  89  to System Preparing state  90 . Upon entering the state of System Preparing  90 , a Built-In-Testing (“BIT”) is automatically initiated; d) using the command and control portable unit  41  to edit a mission; e) press a key on the command and control portable unit keyboard in order to download the mission plan file to UMD  10  via wireless data link  42 .  
         [0089]    When this pre-mission series of activities is completed, UMD  10  is now ready for its mission. It is important that the pre-mission procedure be accelerated to enable a fast reaction to a disaster situation. Thus, the mission edition activity, the most time consuming activity of all pre-mission activities, is designed to be as rapid and as simple as possible. The mission editing display is shown in FIG. 5.  
         [0090]    As previously mentioned, operator  40  uses a command and control portable unit  41  to edit a mission plan and to control operation of UMD  10  while on its mission. A wireless communication unit  49  is connected to the command and control portable unit  42 , thereby establishing a two-way data link with UMD  10  and with self-contained unattended sensor means  46 , if these are deployed by UMD  10 .  
         [0091]    After a mission plan is edited and generated, it is transmitted and downloaded to UMD  10  via wireless data link  42 . While in operation, operator  40  may transmit orders to UMD  10  and receive data from it via data link  42 .  
         [0092]    As shown in FIG. 4, UMD  10  is travelling along the planned path  43  in the general direction  44 . And in a manner appropriate to the situation, UMD  10  is moving in various alternate modes, as described in connection with FIG. 2. In the actual scenario illustrated in FIG. 4, UMD  10  is moving either outside or inside a burning building  45 . When UMD  10  is walking or otherwise moving within this building, it then navigates its way either with or without an a-priori map. Where an a-priori map is available and is applicable to the situation, the navigation function uses a-priori data about the building layout, by employing the appropriate LFMs—local feature maps (see FIGS.  8 ( a ) and  8 ( b )). When an a-priori map is not available or where the building  45  to be explored has been so damaged that an a-priori map is no longer applicable, a different navigation procedure is executed and a process called “map building” becomes a part of the navigation process.  
         [0093]    As may be appropriate to the circumstances, UMD  10  can land vertically, stand for a while on a supporting surface, take-off vertically, and then hover over the site. This sequence of movements can be repeated when necessary. When UMD  10  is gathering data and monitoring the situation, its sensors are then operative. The electro-optical sensor housed in payload housing  25  has a field-of-view  48  which is directed forward in the direction of movement or toward an area of interest. Other sensors which constitute payload whose activation depends on the specific situation may include a microphone  72 , a smoke detector  73  and a gas detector  74 . It may also be desirable to include a seismograph to sense earth tremors.  
         [0094]    UMD  10 , when landing vertically, can then deploy by using a device release actuator  80 , self-contained unattended sensor means  46  for further data gathering in the disaster area. Sensor means  46  which may be situated on various supporting surfaces such as on the ground transmits data it gathers to communication unit  49  attached to the command and control portable unit  41  via a wireless data link  47 .  
         [0095]    Shown in FIG. 5 is an overhead view of display  50  of the command and control portable unit  41  in accordance with one embodiment of the invention. Display  50  comprises a video display window  51 , as well as an alphanumeric display window  53 . When UMD  10  is on the disaster site, a scene  52  sensed by the electro-optical video sensor, (see video camera  70  in FIG. 6) and transmitted from UMD  10  via wireless RF data link  42  to the communication unit  49 , is displayed on video display window  51 . The largest area of the display is then used for the graphical symbolic representation of the main elements of the mission plan. By way of example, two objects  54  in the disaster site have to be monitored.  
         [0096]    Operator  40  edits a mission plan consists by this embodiment of the following elements: a) a mission starting and terminating location ST  55 ; b) a travelling route represented by an ordered series of way-points, WP  56 , connected by route segments  58 . In the example shown in FIG. 5, there are seven way-points WP  56  designated WP 1  to WP 7  by the order they are planned to travel. Each WP  56  represents a specific location; c) a series of ordered device deployment locations DD  57 . In FIG. 5, there are two DD  57  points, DD 1  and DD 2 ; d) a return segment  59  which connects the last way-point WP 7  to the terminal point  55 ; e) an indoor travelling segment inside an object to be monitored, this segment being between WP 5  and WP 6 .  
         [0097]    In a situation where local feature maps- LFMs, (see FIG. 8 b ), of the object  54  to be monitored, are available a-priori, these are linked to the mission plan and downloaded from the memory storage of the command and control portable unit  41  to UMD  10 , along with the mission plan. For such situations, the command and control portable unit  41  has a data base of the LFMs, (see FIGS.  8 ( a ) and  8 ( b )) of objects in the disaster area. This data base is downloaded and stored in the command and control portable unit  41  before going to the disaster area.  
         [0098]    As shown in FIG. 6, the functional architecture of the electronics unit is of the “Bus Network Topology” type. Computer unit  60  is connected to all of the associated elements via a local area network—LAN  61 . Computer unit  60  is provided with processing elements, memory elements, and I/O elements and whatever other elements are desirable to execute all of the required computations, such as: a) flight control; b) navigation; c) sensor data processing; d) multi-legged control; e) path planning and obstacle avoidance.  
         [0099]    In UMD  10 , a set of three piezoelectric gyros  62  are used to measure the angular rate about three perpendicular axes which together establish a right-handed orthonormal coordinate system. GPS receiver  63  provides location and velocity navigational information, while a magnetometer  64  provides directional data with respect to the geomagnetic field which is in turn related to the geographic coordinate system and thus provides approximated azimuth information. A set of piezoelectric tilt sensors  65  serve to determine the attitude of the UMD  10  with respect to the gravity vector.  
         [0100]    Also provided are infra-red (“IR”) light emitting diodes (“LED”)-based rangefinders  66  to effect short range distance measurements (effective up to about 10 meters) to surrounding objects. These measurements provide crucial data for positioning, navigating and obstacle avoidance when UMD  10  is moving in its ground mobility mode. In the present embodiment, each rangefinder  66  weighs only 5 grams. A plurality of acoustic rangefinders  67  are also used for measuring distance to the surrounding objects. The addition of acoustic rangefinders  67  affords more comprehensive coverage than when using only IR-LED rangefinders  66 .  
         [0101]    The two-way wireless data link of the robot scout is preferably a radio-frequency RF data link. It comprises a RF uplink  68  for communicating data to UMD  10 , and an RF downlink  69  for communicating data, including video data, from the UMD. A commercially-available receiver for this purpose may weigh as little as 12 grams for a range of over 2 kilometers. A commercially-available video transmitter may weigh as little as 14 grams for a range of over 4 kilometers, providing that a line-of-sight exists between the transmitter and receiver.  
         [0102]    A video camera  70 , preferably a CCD type, serves to provide: a) a close-up viewing of the disaster site which can be displayed to remote operator  40 ; b) a visual sensor for visual positioning, navigation and obstacle avoidance. Similar arrangements are described in: a) Movarec, Hans P., “Robot Rover Visual Navigation”, UMI Research Press, Ann Arbor, Mich., 1981, pp. 49-147; b) Robert, Luc, et. al., “Applications of Non-Metric Vision to Some Visually Guided Robotic Tasks”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 89-134; c) Weng, J. J., et. al.,“Visual Navigation Using Fast Content-Based Retrieval”, in Aloimonos, Yiannis, ed., “Visual Navigation- From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp. 178-217; d) Dean, Thomas, et. al., “Planning and Navigation in Stochastic Environments”, in Aloimonos, Yiannis, ed., “Visual Navigation—From Biological Systems to Unmanned Ground Vehicles”, Lawrence Erlbaum Associates Publishers, Mahwah, N.J., 1997, pp., 251-274. The invention is, of course, not bound by these arrangements.  
         [0103]    In practice, flood lights may be added to the UMD in order to provide acceptable light conditions for the camera, especially in indoor situations. An uncooled infra-red camera  71  may be used for poor light situations, as well as a hot spot detector.  
         [0104]    For situation monitoring missions, such as for finding missing people in ruined buildings use may be made of microphones  72 . Acoustic signals received by the microphones  72  are conveyed to operator  40  at the remote station via the RF downlink  69 . A smoke detector  73  provides means to detect sources of smoke and smoke-generating situations. A gas detector  74  serves to detect gas contamination, especially in areas of high and dangerous gas concentration.  
         [0105]    The legs of UMD  10  may be equipped with leg load sensors  75  for controlling the multi-legged walking. As an alternative, measuring the current at the leg servo motors may provide the necessary control information.  
         [0106]    A rotor control function  76  provides the command signals necessary to control rotor motion. A vane servo actuators function  77  provides the command signals to control vanes  15 . A leg servo actuators function  78  provides the command signals for the plurality of leg actuators. A sensor payload servo actuator  79  provides the command signals to control the payload servo. A device release actuator  80  is used to produce the command signal to the device release actuator when unattended sensor means  46  has to be deployed. Power supply  81  supplies all of the electrical power consumed by all onboard units. For this purpose use may be made of a bank of Lithium batteries.  
         [0107]    [0107]FIG. 7 is a diagram state graph notation of the main operational and mobility modes of UMD  10  and of the transitions between these modes, in accordance with one embodiment of the invention. A notation of state is assigned to each mobility mode, as well as to start and standing situations. The following states constitute, by this embodiment, the state graph: a) system non-active  89 ; b) system preparing  90 ; c) standing  91 ; d) VTOL—vertical take-off/landing  92 ; e) hovering  93 ; f) transitioning  94 ; g) dash flying  95 ; h) walking  96 . In FIG. 7, states  92  through  95  are air mobility states and State  96  is a ground mobility state.  
         [0108]    Prior to the mission, and after completing the mission, the power is preferably off, and UMD  10  is then in its system non-active state. Upon receiving an On command OnCmd  99  from operator  40  via the data link, the state of UMD  10  is transitioned to system preparing state  90 . On entering the system preparing state  90 , a Built-In-Testing (“BIT”) procedure is automatically initiated. If the BIT result is OK, and the mission plan has been downloaded correctly, the condition SystemReady  100  is logically TRUE, and the state of UMD  10  is transitioned to standing state  91 . But if the BIT procedure failed, BITFailed condition  112  is TRUE. Or in case operator  40  sends a mission abort command AbortCmd  112 , the state of UMD  10  is transitioned to system non-active state  89  and the UMD  10  power is off.  
         [0109]    Depending on the specific phase of the mission, when in standing state  91 , various UNM functions may be active, as required. For example, UMD  10  when in the standing state  91  may be in a waiting situation, in a data gathering situation, or in a sensor means  46  deploying situation, or in a combination of these situations. Upon receiving a TakeOffCmd  101 , UND  10  is transitioned from standing state  91  to VTOL state  92 , starting to take-off. If flying conditions do not exist, the UMD is either in a staying or standing state  91  or is transitioned to walking state  96 .  
         [0110]    While in VTOL state  92 , UNM  10  is transitioned to hovering state  93  when its altitude approach the desired hovering altitude, the condition HoveringAltitude  102  is then logically TRUE. UMD  10  keeps hovering until one of the two following conditions is met: a) conditions for dash flight exists, condition DashConditionsOK  103  is TRUE and UMD  10  is then transitioned to intermediate transition state  94 ; b) a landing command LandindCmd  107  was issued, either by remote operator  40 , or internally by its mission controller, and UMD  10  is transitioned to VTOL state  92 , starting to land. When the UMD  10  is touching down a supporting surface, condition TouchDown  108  is TRUE, and the UNM  10  is transitioned to standing state  91 .  
         [0111]    Upon transitioning from hovering state  93 , to transitioning state  94 , UNM  10  is then performing a transitioning maneuver, in which the condition TransToDashCompleted  104  is TRUE, and UNM  10  then enters the dash flying state  95 . As long as the conditions for flying in a dash flying mode exists, UNM  10  remains in this state. If these conditions cease to exist, condition DashConditionsOut  105  is TRUE, and UMD  10  is transitioned to the temporary transitioning state  94 . Upon completing the transitioning maneuver, condition TransToHoverCompleted  106  is TRUE, and UMD  10  is transitioned to hovering state  93 .  
         [0112]    The transition from an air mobility mode to a ground mobility mode and vice versa, is always carried out by first going to standing state  91 , and thereafter to the desired mobility mode, either ground or air.  
         [0113]    While in standing state  91 , upon receiving a WalkingCmd  109 , UMD  10  is transitioned to walking state  96 . The WalkingCmd  109  is issued either by remote operator  40 , or internally by the UMD mission controller. When in the walking state  96 , UND  10  is keep walking unless it comes to the desired destination, AtLocation condition  110  is TRUE or stop command StopCmd  110  is issued either by remote operator  40  or internally by the UMD mission controller. A situation which is typical for the internal issuance of a StopCmd  110  is when UMD  10  encounters a large obstacle while walking. When UMD  10  is in standing state  91 , an off command OffCmd  111  will transit the UMD  10  state from standing state  91  to system non-active state  89 , and UMD  10  power will shut-off. OffCmd  111  is issued either internally by the UMD  10  mission controller or by the remote operator  40 . Upon completing the mission, OffCmd  111  is usually issued internally.  
         [0114]    [0114]FIG. 8( a ) shows the layout of a building interior section, while FIG. 8( b ) is its associated graph-based data structure representation (according to one possible variant), termed Local Feature Map—LFM. By this example, FIG. 8( a ) is a layout of a building section consisting of: a) two corridors C 1 - 121  and C 2 - 122 ; b) a corner CR 12   120  which connects the two corridors; c) four rooms R 1   123 , R 2   124 , R 3   125 , and R 4   126  which are accessed from the corridors through openings; d) the following openings: O 1   127  between corridor C 1   121  and room R 1   123 ; O 2   128  between corridor C 1   121  and room R 2   124 ; O 31  and O 32  both between corridor C 2   122  and room R 3   125 ; O 4   131  between corridor C 2   122  and room R 4   126 .  
         [0115]    [0115]FIG. 8( b ) is an example of the associated Local Feature Map—LFM which is used in the present embodiment to represent the essential features of the building section layout. The data structure which is used to represent the LFM is a non-directional graph (See Even, S., “Graph Algorithms”, Computer Science Press, Maryland, USA,  1979 , for more details on non-directional graphs).  
         [0116]    Referring now to FIG. 8( b ), the root node of the graph is the comer CR 12   140 . It has two associated daughter nodes, corridor C 1  node  141  and corridor C 2  node  142 . The connecting arcs  147  and  148  symbolizes the connection between the comer CR 12  and its connected corridors C 1  and C 2 . Corridor C 1  node  141  has two associated daughter nodes namely, room R 1  node  143  and room R 2  node  144 . The connecting arcs  149  and  150  symbolize the associated openings O 1   149  and O 2   150  respectively. Similarly, corridor C 2  node  142  has two associated daughter nodes namely, room R 3  node  145  and room R 4  node  146 . The connecting arcs  151 ,  152  and  153  symbolizes the associated openings O 31   151  and O 32   152  and O 4   153 , respectively. Whenever the layout of the buildings to be monitored by the UMD  10  is known a-priori, the associated LFMs can be prepared in advance. It should be noted however, that although an LFM is possibly prepared a-priori, during a major disaster, such as an earthquake, so many changes may occur that the original LFM may no longer represent the actual layout.  
         [0117]    While there has been disclosed a preferred embodiment of a UMD functioning as a robot scout, it is to be understood that many changes may be made therein without departing from the scope of the following claims: