Abstract:
A teleconferencing robot for enabling a remote conferee to project a sense of presence into a group meeting. The teleconferencing robot includes: a base; a video monitor movably mounted to the base for receiving and displaying an image of the remote conferee; an attention getting device for getting the attention of conferees in the group meeting; a control device mounted on the base for moving the video monitor and actuating the attention getting device in response to an input control signal derived from a remote signal generated by the remote conferee and sending an outgoing data signal to the remote conferee providing feedback to the remote conferee from the robot; and the video monitor and attention getting device move in response to the input control signal to enable the remote conferee to project a sense of presence into the group meeting, and to confirm the movement by the outgoing data signal.

Description:
RELATED APPLICATION  
       [0001]     This is a continuation of U.S. application Ser. No. 09/423,414 entitled “Teleconferencing Robot with Swiveling Video Monitor”, which is a 371 of PCT/CA98/00463 and claims the benefit of U.S. provisional application Ser. No. 60/045,793 filed May 7, 1997. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to an apparatus for enabling a remote conferee to project his or her presence into a group meeting environment using a combination of videoconferencing /teleconferencing technology and robotics technology. Combining videoconferencing/teleconferencing elements with robotics elements helps create a sense that the remote conferee has a physical presence in the room which allows for more direct personal interaction in group meeting environments and social situations.  
       BACKGROUND OF THE INVENTION  
       [0003]     Videoconferencing/teleconferencing is an effective form of communication which allows distant conferees the ability to see and hear each other over long distances. Unfortunately this technology is not being utilized as effectively as it could be due to the inherent nature of how people view television. When people view television they tend to sit passively and absorb information. This passive viewing behaviour is counter-productive when people utilize videoconferencing/teleconferencing where direct two-way non-passive interaction is required. Currently available videoconferencing/teleconferencing systems suffer from this drawback.  
         [0004]     In conventional teleconferencing systems, it often appears as if the remote conferee is avoiding the viewer&#39;s eyes since the video camera capturing the image of the remote conferee is typically positioned above, below, or to one side of the video monitor which the remote conferee is viewing. There are proposals intended to enable a remote conferee to facilitate direct eye contact with the local conferees as described, for example, in U.S. Pat. No. 4,928,301, issued May 22, 1990; U.S. Pat. No. 5,117,285, issued May 26, 1992; U.S. Pat. No. 5,359,362, issued Oct. 25, 1994; and U.S. Pat. No. 5,400,069, issued Mar. 21, 1995. These proposals are intended to make the remote conferee appear as if he or she is gazing directly into the eyes of the viewer. This apparent direct eye contact can further add to the sense of personal contact and reinforce the remote conferee&#39;s sense of presence in the group meeting space. Many of these proposals are complex and to the applicant&#39;s knowledge they have not enjoyed significant success in the marketplace. Additionally the remote conferee&#39;s image, and the video camera which provide an image to the remote conferee are both essentially stationary, limiting the effective field of view for the remote conferee and his or her sense of participation in a conference.  
       SUMMARY OF THE INVENTION  
       [0005]     To transform the television into a more dynamic interactive device a substantially life-sized image of a remote conferee&#39;s face is displayed on a television or video monitor and the television or video monitor is controlled to swivel left or right to create the impression that the remote conferee is turning his or her head to look at a person speaking. The swiveling video monitor may also be lifted up or lowered down to an appropriate height by a vertical lifting and lowering mechanism to mimic a standing or sitting position or achieve some height in between. The swiveling video monitor and the vertical lifting and lowering mechanism can further be coupled to a mobile ground unit to allow the remote conferee to move around the room in which the group meeting is taking place. The video monitor together with the vertical lifting and lowering mechanism may also mimic a bowing motion to be used as a form of greeting when appropriate. An attention-getting mechanism may also be incorporated so that the remote conferee may politely interrupt a conversation. For example, a mechanical representation of a raised and waving hand may be used for such a purpose. These physical movements shatter the mental construct that people have for what television is and allows them to think of television in a new way: the television is no longer simply a passive object but rather assumes a robotic presence, in essence becoming a part of what may be called a teleconferencing robot.  
         [0006]     As already stated, preferably, the image of the remote conferee&#39;s face on the video monitor is substantially life-size. This gives people interacting with the teleconferencing robot a frame of reference that is based on conventional human dynamics (i.e. the size of the head) as opposed to a conventional teleconference where the head could appear either very small or large. The remote conferee can remotely control the teleconferencing robot to look left or right. Optionally, a sound location system built into the teleconferencing robot can be used to determine where the speaking person is positioned relative to the teleconferencing robot, and can be used to generate a control signal to automatically swivel the video monitor head left or right so that the remote conferee appears to be turning to look at the person speaking. This allows the remote conferee to concentrate on the social interaction, rather than on controlling the movement of the teleconferencing robot.  
         [0007]     In accordance with the present invention, there is provided a teleconferencing robot, for enabling a remote conferee to project a sense of presence into a group meeting, the teleconferencing robot comprising: a base: a video monitor movably mounted to the base for receiving and displaying an image of the remote conferee: a video camera movably mounted on the base: control means mounted on the base for moving the video monitor and video camera in response to an input control signal: and wherein said video monitor and video camera move in response to said input control signal to enable a remote conferee to project a sense of presence into the group meeting.  
         [0008]     In a further aspect of the present invention, there is provided a teleconferencing robot, for enabling a remote conferee to project a sense of presence into a group meeting, the teleconferencing robot comprising: a base; a video monitor movably mounted to the base for receiving and displaying an image of the remote conferee; attention getting means for getting the attention of conferees in the group meeting; control means mounted on the base for moving the video monitor and the attention getting means in response to an input control signal derived from a remote signal generated by the remote conferee and sending an outgoing data signal to the remote conferee providing feedback to the remote conferee from the teleconferencing robot; and wherein said video monitor and attention getting means move in response to said input control signal to enable the remote conferee to project a sense of presence into the group meeting, the remote conferee can confirm the movement by said outgoing data signal.  
         [0009]     In accordance with another aspect, the present invention provides a teleconferencing robot in combination with a remote teleconferencing unit which comprises a second microphone and a second video camera for obtaining an audio signal and an image from the remote conferee for transmission to the video monitor of the teleconferencing robot, and a second video monitor and a second speaker for providing an image and an audio signal received from the teleconferencing robot, wherein the video monitor of the teleconferencing robot is provided with a speaker for outputting an audio signal received from the microphone of the remote teleconferencing unit; and wherein the input control signal is provided by the remote teleconferencing unit. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, which show a preferred embodiment of the present invention and in which:  
         [0011]      FIG. 1  is a perspective view of the teleconferencing robot on a rolling stand;  
         [0012]      FIGS. 2   a - c  are perspective views of the teleconferencing robot&#39;s swiveling feature in operation;  
         [0013]      FIG. 3  is a side view of the teleconferencing robot with a cut-out view of the swivel base;  
         [0014]      FIGS. 4   a - 4   c  are perspective views of the teleconferencing robot in various desk storage arrangements;  
         [0015]      FIG. 5  is a simplified side cross-sectional view or the teleconferencing robot with vertical lifting and lowering mechanism and remote-controllable mobile ground unit;  
         [0016]      FIGS. 6   a - 6   c  are perspective views of the teleconferencing robot and mobile ground unit of  FIG. 5  in operation;  
         [0017]      FIGS. 7   a - 7   c  are perspective views of the vertical lifting and lowering mechanism of  FIG. 5  in operation;  
         [0018]      FIG. 8   a - 8   d  are perspective views of the attention-getting mechanism in operation;  
         [0019]      FIG. 9  is a schematic block diagram showing the link between the remote teleconferencing unit at the remote conferee&#39;s site and the teleconferencing robot at the local group meeting site;  
         [0020]      FIG. 10  is a schematic block diagram of the remote teleconferencing unit at the remote conferee&#39;s site;  
         [0021]      FIG. 11  is a schematic block diagram of the teleconferencing robot at the local group meeting site;  
         [0022]      FIG. 11   a  is a perspective view of one embodiment of a position sensor shown in  FIG. 11 ;  
         [0023]      FIG. 11   b  is a side view of another embodiment of a position sensor shown in  FIG. 11 ;  
         [0024]      FIG. 12  is a schematic block diagram of the vertical lifting and lowering mechanism;  
         [0025]      FIG. 13  is a schematic block diagram of the mobile ground unit; and  
         [0026]      FIGS. 14   a - 14   c  are perspective views of an alternative design of the teleconferencing robot. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0027]     The preferred embodiment of the invention will now be described with reference to the figures.  
         [0028]      FIG. 1  shows a perspective view of a teleconferencing robot  100  placed on a rolling stand  10 . The teleconferencing robot  100  has a swivel base  20  having a lower stage  22  secured to the stand and rotating upper stage  24  rotatable about a vertical axis with respect to lower stage  22 . The rotating upper stage  24  has a defined forward direction. In the preferred embodiment of the invention, the top-front portion of rotating upper stage  24  is rounded and forwardly sloped to prevent loose items from being placed there. A video monitor  40  is placed on or fastened to the top-rear portion of the rotating upper stage  24 . A supporting arm  12  extends from the lower stage  22  and supports a platform  16  positioned just above the video monitor  40 . The platform  16  supports a speaker location system  60 . One such system is commercially available from PictureTel Corporation of Andover, Mass., USA. The speaker location system includes a video camera  50  with a pan/tilt video camera base  52 .  
         [0029]     Microphones  62   a,    62   b  and  62   c  pick up the sound coming from the person speaking and generate an appropriate control signal to control the pan/tilt video camera base  32  and the zoom on the video camera  50  so that the video camera  50  is directed at the person speaking. These functions are described in greater detail below with reference to  FIGS. 9-11 .  
         [0030]     Now referring to  FIGS. 2   a - 2   c,  the swiveling feature of the teleconferencing robot  100  is shown in a series of three perspective views. In the first view,  FIG. 2   a,  the teleconferencing robot  100  is shown in a default starting position with video monitor  40 , video camera  50  and microphones  62   a,    62   b  and  62   c  substantially directed in the same forward direction as that defined by the forward direction of rotating upper stage  24  of swivel base  50 . In  FIG. 2   b,  in response to a control signal, the rotating upper stage  24  of the swivel base  20 , the video monitor  40  and the video camera  50  have turned partially towards the viewer/speaker (viewer/speaker not shown but assumed to be in the same viewing position for all of  FIGS. 2   a - 2   c ). This function will be explained later in greater detail with reference to  FIGS. 9-13 . In  FIG. 2   c,  the rotating upper stage  24 , video monitor  40 , and video camera  50  have turned fully towards the viewer/speaker. During this turning operation, the rotating upper stage  24 , video monitor  40 , and video camera  50  are substantially synchronized to each other. The rolling stand  10 , the supporting arm  12  the lower stage  12  of the swivel base  20 , platform  16  and microphones  62   a,    62   b  and  62   c  remain fixed in position during the swiveling operation illustrated in  FIGS. 2   a - 2   c.    
         [0031]      FIG. 3  shows a side view of the teleconferencing robot  100  with a simplified cut-out view of swivel base  20 . The rotating upper stage  24  and lower stage  22  are connected by a swiveling mechanism  25 . Alternative coupling arrangements between the rotating upper stage  24  and lower stage  22  are possible. However, regardless or the coupling arrangement, a swivel point  21  is formed. The rotating upper stage  24  rotates about a vertical axis passing through the swivel point  21 . The rotating upper stage  24  is engaged to a rotating upper stage drive unit  30 , such as a servo-motor, which can swivel the rotating upper stage  24  about the vertical axis passing through the swivel point  21 . A micro-controller  28  controls the rotating upper stage drive unit  30 . A detailed description of this function is provided later with reference to  FIGS. 9-11 .  
         [0032]     Still referring to  FIG. 3 , the screen of video monitor  40  is placed at or near the vertical axis passing through the swivel point  21  so that the screen of video monitor  40  may be viewed from a wider angle. If the screen of video monitor  40  is positioned too far forward, then the viewing angle will be significantly reduced for those conferees who are sitting to either side and close to the video monitor  40 . In the present invention, the placement of the screen of video monitor  40  is such that two straight lines lying in a horizontal plane and crossing at the vertical axis passing through the swivel point  21 , and touching the left and right edges of the screen of video monitor  40 , respectively, form an angle of 160° to 200°.  
         [0033]      FIGS. 4   a - 4   c  show some desk storage arrangements for the teleconferencing robot  100  with a desk shown at  170 .  FIG. 4   a  shows one possible storage arrangement for the teleconferencing robot  100  where the teleconferencing robot is positioned under the desk  170 . The desk is then provided with a removable panel to enable the robot  100  to be raised, in a manner described below, to a position flush with the top of the desk  170 .  FIG. 4   b  shows the teleconferencing robot  100  mounted in an operating position, on the desktop.  FIG. 4   c  shows an alternative storage arrangement where the supporting arm  12  supports a removable desktop panel  18 . A vertical lifting and lowering mechanism  70  raises the teleconferencing robot  100  raises into an operating position level with the desktop, and simultaneously displaces the panel  18  vertically upwards.  
         [0034]      FIG. 5  shows a simplified side cross-sectional view of a further embodiment of the teleconferencing robot  100  provided with the vertical lifting and lowering mechanism  70  and a mobile ground unit  80 . The vertical lifting and lowering mechanism  70  comprises piston assemblies  71   a,    71   b  and  71   c  which may be extended and retracted in concert to raise and lower the teleconferencing robot  100 . The piston assemblies  71   a,    71   c  are parallel and spaced apart, so that the three piston assemblies provide three point support. Piston assembly drive units  74   a,    74   b  and  74   c  are operationally engaged to piston assemblies  71   a,    71   b  and  71   c,  respectively. Vertical lifting and lowering control unit  73  controls the piston drive units  74   a,    74   b  and  74   c.  The piston assemblies  71   a,    71   b  and  71   c  are protected and hidden by a flexible accordion sleeve  72 . A more detailed description of the operation of the vertical lifting and lowering mechanism is provided later, with particular reference to  FIG. 12 .  
         [0035]     Still referring to  FIG. 5 , the mobile ground unit  80  houses a power source  87 , drive motors  81   a  and  81   b  engaged to drive wheels  82  and  83 , respectively, and a mobile ground unit control  88  to control the direction and speed of drive motors  81   a  and  81   b.  The mobile ground unit  80  is remotely controllable by using a remote control unit  89 . Typically, instructions transmitted by a radio signal from the remote control unit  89  are received by an antenna  86  and relayed down to the mobile ground control unit  88 . However, many other communication means are possible. A more detailed description of the operation of the mobile ground unit  80  is provided later with particular reference to  FIG. 13 .  
         [0036]      FIGS. 6   a - 6   c  show the teleconferencing robot  100  and mobile ground unit  80  in operation.  FIG. 6   a  shows the teleconferencing robot  100  and the mobile ground unit  80  in a default starting position, with rotating upper stage  24 , lower stage  22 , video monitor  40  and dynamic speaker locating system  60  all oriented in a defined forward direction. The forward path of mobile ground unit  80  (i.e. the direction of travel if both drive wheels  82  and  83  are engaged in the same direction at the same speed) is also oriented in the same defined forward direction.  FIG. 6   b  shows the teleconferencing robot with the rotating upper stage  24  video monitor  40  and video camera  50  all rotated to face the viewer. When the remote conferee wishes to approach the viewer, in order to maintain eye contact, the mobile ground unit  80  turns toward the viewer while the rotating upper stage  24 , video monitor  40  and video camera  50  simultaneously turn in the opposite direction at the same rate of rotation, i.e. so as to appear to remain stationary. The resulting position is shown in  FIG. 6C . Consequently, the remote conferee can maintain “eye contact” with the viewer when turning the mobile ground unit  80  to approach the viewer. The details of this operation will be further described below with reference to  FIGS. 9-13 .  
         [0037]     Next, referring to  FIGS. 7   a - 7   c,  the vertical lifting and lowering mechanism  70  is shown in operation.  FIG. 7   a  shows the vertical lifting and lowering mechanism  70  fully retracted.  FIG. 7   b  shows the vertical lifting and lowering mechanism  70  in a partially raised position.  FIG. 7   c  shows the vertical lifting and lowering mechanism  70  in a fully extended position. The height of the teleconferencing robot  100  when the vertical lifting and lowering mechanism  70  is fully extended represents approximately the height of a standing person. The vertical lifting and lowering mechanism  70  is adjustable to any height between the fully extended and fully retracted positions, shown in  FIG. 7   c  and  FIG. 7   a  respectively, so that an appropriate height can be established for a given situation. For example, when the teleconferencing robot  100  is positioned next to a conference table, the height might be appropriately adjusted to represent a sitting position. If the remote conferee or local conferee is a tall person, the vertical lifting and lowering mechanism  70  may be extended to reflect the remote conferee&#39;s height. Optionally, the remote conferee may want to match the height of the person to whom the remote conferee is speaking.  
         [0038]     Now, referring to  FIGS. 8   a - 8   d,  the operation of the attention-getting mechanism  90  is shown.  FIG. 8   a  shows a representation of a hand and arm  90  in a standby position, laying against the side of video monitor  40 .  FIG. 8   b  shows the movement of the hand and arm  90  by rotation outwardly from the shoulder coupling point  91  so that it is then at an angle from the side of video monitor  40 .  FIG. 8   c  shows a further action of hand and arm  90  where it is rotated through a 90° angle about an axis along the arm thereof such that the hand appears to be in a “palm-open” position in relation to the viewer.  FIG. 8   d  shows the representation of a hand and arm  90  in the palm-open position being rotated alternately outwardly and inwardly to mimic a waving motion. Such a motion may be easily achieved, for example, by using motors and mechanisms similar to that used for automobile windshield wipers.  
         [0039]      FIG. 9  is a simplified block diagram showing the interconnection between the remote teleconferencing unit  120 , located at the remote conferee&#39;s site, and the teleconferencing robot  100 , located at the local group meeting site. Audio/video/data communications controllers  128  and  129  receive and transmit a plurality of audio-, video- and data-signals between the remote teleconferencing unit  120  and the teleconferencing robot  100  via a transmission system  130 , which can be any suitable transmission system, including known telephone lines, wireless transmission, etc. The plurality of signals shown in  FIG. 9  are explained in greater detail below. The teleconferencing robot  100  includes the micro-controller  28  which controls the attention getting mechanism  90  as well as various other teleconferencing robot components represented by block  99 . The micro-controller  28  also controls the vertical lifting and lowering mechanism  70  and mobile ground unit  80  when provided, both of these units being optional.  
         [0040]     Now referring to  FIG. 10 , the schematic layout of remote teleconferencing unit  120  is shown. Remote teleconferencing unit  120  (“RTU  120 ”) includes a microphone  121  to pick up the voice of the remote conferee and send a RTU outgoing audio signal (“RTUOAS”) to audio/video/data communications controller  128  (“AVDCC  128 ”). The AVDCC  128  controls the transmission and reception of all of the various RTU signals to and from an equivalent communications controller, AVDCC  129  (shown in  FIG. 9 ), located at the local group meeting site.  
         [0041]     RTU  120  further includes a video camera  122  to capture an image of the remote conferee. The video camera  122  sends an RTU outgoing video signal (“RTUOVS”) to AVDCC  128 . Amplified speaker  123  receives an RTU incoming audio signal (“RTUIAS”) from AVDCC  128 . The RTUIAS originates from the teleconferencing robot  100  (shown in  FIG. 9 ) and typically consists of the voices of the local conferees at the group meeting site.  
         [0042]     RTU  120  further includes a teleconferencing robot remote control system  119  which remotely controls the operation of the teleconferencing robot  100  of  FIG. 9 . The teleconferencing robot remote control system  119  comprises a video monitor  124 , an operations panel  125 , a graphics overlay unit  126  and a main control unit  127 . The remote conferee controls the teleconferencing robot  100  of  FIG. 9  by means of input at the operations panel  125 . Operations panel  125  may be a keyboard, joystick, mouse or any other input device or a combination thereof. The main control unit  127  receives the input from operations panel  127  and sends out an RTU outgoing data signal (“RTUODS”) to AVDCC  128  and eventually to micro-controller  28  of  FIG. 9 .  
         [0043]     The RTUODS contains instructions and control signals to control the various functions of the teleconferencing robot  100  of  FIG. 9 . The main control unit  127  also provides feedback to the remote conferee by means of graphics overlay unit  126  which may display various characters, symbols and icons on video monitor  124 . An RTU incoming video signal (“RTUIVS”) originating from the teleconferencing robot  100  of  FIG. 9  is received by the graphics overlay unit  126  and is passed through to video monitor  124 , either with or without any characters, symbols and icons superimposed on the video image created by the RTUIVS on video monitor  124 .  
         [0044]     The main control unit  127  further receives an RTU incoming data signal (“RTUIDS”) which contains at least one of a plurality of feedback signals from the teleconferencing robot  100 , the vertical lifting and lowering mechanism  70  (“VLLFS”) and the mobile ground unit  80  (“MOUFS”), all shown in  FIG. 9 . Some of the feedback contained in the RTUIDS may be represented graphically to the remote conferee via the graphics overlay unit  126  and video monitor  124 . For example, a graphic may show the current rotational position of the rotating upper stage  24  of  FIGS. 2   a - 2   c  so that the remote conferee is aware of any limitations of turning further left or further right.  
         [0045]     Now referring to  FIG. 11 , the teleconferencing robot components  99  of  FIG. 9  are shown in greater schematic detail. The micro-controller  28  controls the operation of various components based on control instructions received from the main control unit  127  shown in  FIG. 9 . These control instructions contained in the RTUODS are transmitted by the AVDCC  128  through the transmission system  130  and to the AVDCC  129 , all shown on  FIG. 9 . The AVDCC  129  of  FIG. 9  transmits the same control instructions to the micro-controller  28  as the teleconferencing robot incoming data signal (“TRIDS”) as shown in  FIG. 11 . The micro-controller  28  also provides feedback to the main control unit  127  of  FIG. 10  by means of the teleconferencing robot outgoing data signal (“TRODS”) which is transmitted to the AVDCC  129  of  FIG. 10 .  
         [0046]     The micro-controller  28  activates the attention-getting mechanism  90  upon receiving an instruction from the remote conferee via the operations panel  125  shown in  FIG. 10 . Activation causes the attention-getting mechanism to rotate the representation of the hand and arm outwards, twist the hand 90° into a “palm-open” position, then start a waving motion back and forth, as illustrated in  FIGS. 8   a - 8   d,  above. The required motion may be obtained quite easily, for example, by using mechanisms and motors similar to that used for automobile windshield wipers.  
         [0047]     The swivelling feature of the teleconferencing robot  100 , as illustrated in  FIGS. 2   a - 2   c,  can be either automatic or manually controlled by the remote conferee. A switch unit  63  receives a speaker location control signal (“SLCS”) to control the zoom function of the video camera  50  and control the pan/tilt video camera base  52 . The switch unit  63  also receives a teleconferencing robot control signal (“TRCS”) from the micro-controller  28 . The remote conferee can cause the switch unit  63  to switch between automatic mode, where the SLCS is used, and manual mode, where the remote conferee provides the pan, tilt and zoom signals.  
         [0048]     In automatic mode, the speaker location control unit  61  receives input signals from a microphone array  62  comprising three microphones  62   a,    62   b  and  62   c,  as shown in  FIG. 1 . Using the signals from the microphone array  62 , the speaker location control unit  61  determines from which direction the sound is coming from. The speaker location control unit  61  then produces the SLCS to control the zoom function of video camera  50  and control the pan/tilt video camera base  52 .  
         [0049]     For manual mode, the remote conferee first sends a switch signal to switch unit  63  to enter the manual mode. Then the remote conferee provides pan, tilt and zoom control signals via the operations panel  125 , shown in  FIG. 10 . The remote conferee can switch back to automatic mode by sending another switch signal to switch unit  63 .  
         [0050]     In either automatic or manual mode, the switch unit  63  sends on a pan/tilt/zoom control signal (“PTZCS”) to the camera pan/tilt/zoom control unit  64 . The camera pan/tilt/zoom control unit  64  controls pan drive unit  53 , tilt drive unit  54  and zoom drive unit  55  to drive the pan/tilt video camera base  52  and the zoom on video camera  50 . The camera pan/tilt/zoom control unit  64  also provides a teleconferencing robot feedback signal  1  (“TRFS 1 ”) to the micro-controller  28  to communicate to the main control unit  127  of  FIG. 10  the camera pan/tilt/zoom control information.  
         [0051]     The pan control signal (“PCS”) from the camera pan/tilt/zoom control unit  64  to the pan drive unit  53  is split and is also provided as an input to switch unit  57 . An optional position sensor  56  is positioned to read the position and rotation of the pan base of pan/tilt video camera base  52 . The position sensor  56  provides a position sensor feedback signal (“PSFS”) which is compatible with the PCS signal and which provides essentially the same pan position and rotation information. The position sensor  56  may be any number of devices which senses the panning movement of the pan/tilt video camera base  52 . Two such devices are shown in  FIGS. 11   a  and  11   b,  operationally coupled to the pan/tilt video camera bases  52   a  and  52   b,  respectively.  
         [0052]      FIG. 11   a  shows a perspective view of one embodiment of a position sensor  56   a  with a shaft head  150  mechanically engaged to the pan/tilt video camera base  52   a  by a wire  151  set at an appropriate tension to cause the shaft head  150  to rotate as the pan/tilt video camera base  52   a  pans left and right. A base  152  of the position sensor  56   a  generates a signal corresponding to the rotation of the shaft head  150  and the signal is transmitted via a communication link  153  to the switch unit  57  of  FIG. 10 .  
         [0053]      FIG. 11   b  shows a side view of another embodiment of a position sensor  56   b  with a shaft head  160  frictionally engaged to a spherical, dome shaped top of a pan/tilt video camera base  52   b.  The rotation of the pan/tilt video camera base  52   b  causes the shaft head  160  to rotate. A base  162  of the position sensor  56   b  generates a signal corresponding to the rotation of the shaft head  160  and the signal is transmitted via a communication link  163  to switch unit  57  of  FIG. 11 .  
         [0054]     In addition to the above two mechanisms, numerous other, mechanical and non-mechanical means of sensing the rotation of the pan/tilt video camera base  52  are available.  
         [0055]     The switch unit  57  can be manually set to pass on either the PCS signal or the PSFS signal from the optical position sensor  56 . The switch unit  57  passes on the selected signal as a rotating upper stage control signal (“RUSCS”) to the rotating upper stage drive unit  23 . The rotating upper stage drive unit receives the RUSCS and drives the rotating upper stage  24  left or right. Since the RUSCS is either the PCS or the PSFS, both of which provide information on the video camera  50  pan position, the rotating upper stage  24  is essentially driven to the same pan position as the video camera  50 . The rotating upper stage drive unit  23  provides a teleconferencing robot feedback signal  2  (“TRFS 2 ”) to the micro-controller  28  so that the remote conferee is aware of the position of the rotating upper stage  24 .  
         [0056]     Still referring to  FIG. 11 , the video monitor  40  displays a substantially life-sized image of the remote conferee&#39;s face on the screen. This image is received as the teleconferencing robot incoming video signal (“TRIVS”) from the AVDCC  129 , shown in  FIG. 9 . The TRIVS corresponds to the RTUOVS shown in  FIG. 10 . Video monitor  40  is placed on or fastened to the rotating upper stage  24 , as shown in  FIG. 1 . Thus, the video monitor  40  is rotating with the rotating upper stage  24  and is essentially synchronized to the pan position and rotation of the video camera  50 .  
         [0057]     The video camera  50  provides and image of the local conferee, typically the local conferee that is speaking, and sends a teleconferencing robot outgoing video signal (“TROVS”) to the AVDCC  129  of  FIG. 9 . The TROVS corresponds to the RTUIVS of  FIG. 10 .  
         [0058]     Microphone  42  picks up the sound from the local conferees and sends a teleconferencing robot outgoing audio signal (“TROAS”) to the AVDCC  129 . Optionally, if the automatic speaker location system is being used, the sound picked up by the microphone array  62  may be supplied as the TROAS (this optional configuration is not shown in  FIG. 11 ). The TROAS corresponds to the RTUIAS of  FIG. 10 .  
         [0059]     The amplified speaker  26  receives a teleconferencing robot incoming video signal (“TRIAS”) from the AVDCC  129 , shown in  FIG. 9 . The TRIAS corresponds to the RTUOAS of  FIG. 10  and provides the local conferees with sound from the remote conferee.  
         [0060]     Now referring to  FIG. 12 , a schematic of the vertical lifting and lowering mechanism  70  (“VLLM  70 ”) is shown. The VLLM  70  comprises piston assemblies  71   a,    71   b  and  71   c  which are positioned in an arrangement as shown in  FIG. 5 . Piston assembly drive units  74   a,    74   b  and  74   c  drive the piston assemblies  71   a,    71   b  and  71   c  respectively. The piston assembly drive units  74   a,    74   b  and  74   c  are controlled by the vertical lifting and lowering control unit  73  (“VLLCU  73 ”). The VLLCU  73  receives a vertical lifting and lowering control signal (“VLLCS”) from the micro-controller  28  of  FIG. 9 . The VLLCU  73  also provides a vertical lifting and lowering feedback signal (“VLLFS”) to the micro-controller  28  of  FIG. 9  so that the remote conferee receives feedback as to the state of the VLLM  70 .  
         [0061]     In order to raise the teleconferencing unit  100 , as illustrated in  FIGS. 7   a - 7   c,  the piston assemblies  71   a,    71   b  and  71   c  are extended in concert at the same rate, starting from a fully retracted position as shown in  FIG. 7   a.  In  FIG. 7   c,  the piston assembles  71   a,    71   b  and  71   c  (hidden inside the flexible accordion sleeve  72 ) are fully extended. To lower the teleconferencing unit  100 , the piston assemblies  71   a,    71   b  and  71   c  are retracted at the same rate. By controlling the amount of extension of piston assemblies  71   a,    71   b  and  71   c,  the teleconferencing robot  100  can be set at a height anywhere between a fully retracted and fully extended position.  
         [0062]     Referring back to  FIG. 5 , in order to mimic bowing, the center piston assembly  71   b  can be extended less than the outer piston assembles  71   a  and  71   c.  This will cause the teleconferencing robot  100  to tilt forward and assume a bowing position. Extension of the center piston assembly  71   c  back to the same extension of the outer piston assemblies  71   a  and  71   c  will cause the teleconferencing robot to return to an up-right position.  
         [0063]     Now referring to  FIG. 13 , a schematic diagram of the mobile ground unit  80  (“MGU  80 ”) is shown. A power source  87  provides power to MGU control  88  and the wheel drive motors  81   a  and  81   b.  The MGU control  88  receives an MGU control signal (“MGUCS”) from the micro-controller  28 , as shown in  FIG. 9 . The MGU control  88  provides a MGU feedback signal (“MGUFS”) back to the micro-controller  28  to provide feedback about the MGU to the remote conferee.  
         [0064]     The MGUCS contains control information to operate the rotation speed and direction of rotation of the drive wheels  82  and  83 . In order to move forward, the left wheel drive motor  81   a  and the right wheel drive motor  81   b  turn the drive wheels  82  and  83  in a forward direction at the same rate. Reversing the direction causes the MGU  80  to move backwards, but this will typically not be used since the remote conferee requires visual feedback from the video camera  50 , as shown in  FIGS. 6   a - 6   c,  in order to operate the MGU  80 .  
         [0065]     To turn right, the right wheel drive motor  81   b  will hold the right drive wheel  83  stationary while the left wheel drive motor  81   a  drives the left drive wheel in a forward direction. To make a wider right turn, in known manner, the right wheel drive motor  81   b  can drive the right drive wheel  83  at a slower rate than the left wheel drive motor  81   a  is driving the left drive wheel  82 . To turn right while staying in position, the right wheel drive motor  81   b  can drive the right drive wheel  83  in a reverse direction at the same rate as the left wheel drive motor  81   a  drives the left drive wheel  82  in a forward direction. Left turns can be made in an analogous fashion with the wheels and directions reversed.  
         [0066]     In order to perform the manoeuvre shown in  FIGS. 6   a - 6   c,  the teleconferencing robot  100  is operated as described above so that the video monitor  40  is directed towards the viewer. To turn the MGU  80  towards the viewer, in preparation for moving towards the viewer, the MGU  80  is operated to turn left while staving in position. In order to achieve this, referring back to  FIG. 11 , the rotating upper stage drive unit  23  provides a feedback signal, TRFS 2 , to the micro-controller  28 . Using the TRFS 2 , the micro-controller  28  then calculates the amount of rotation required by the MGU  80  to rotate into position. The micro-controller  28  then sends appropriate control signals TRCS and MGUCS (shown in  FIG. 9 ) so that the MGU  80  is rotating in position towards the viewer and the rotating upper stage  24  and the video camera  50  are rotating at the same rate of rotation but in the opposite direction.  
         [0067]     It will be appreciated that, while the preferred embodiment of the invention has been described, there are numerous variations possible within the scope of the present invention. For example, rather than having a swivel base, a ceiling mounted swivel mechanism may be used to support a hanging video monitor. In such a case, the video camera and speaker location unit may be fastened to a platform hanging beneath the video monitor. Furthermore, a vertical lifting and lowering mechanism may be mounted from the ceiling to raise and lower a video monitor from the ceiling. In addition, many different designs and configurations possible. For example, in  FIGS. 14   a - 14   c,  the rotating upper stage  24  and lower stage  22  of  FIG. 1  are replaced by rotating upper stage  24   a  and lower stage  22   a.