Abstract:
A vertical gyroscope is adapted for use as a pointing device for controlling the position of a cursor on the display of a computer. A motor at the core of the gyroscope is suspended by two pairs of orthogonal gimbals from a hand-held controller device and nominally oriented with its spin axis vertical by a pendulous device. Electro-optical shaft angle encoders sense the orientation of a hand-held controller device as it is manipulated by a user and the resulting electrical output is converted into a format usable by a computer to control the movement of a cursor on the screen of the computer display. For additional ease of use, the bottom of the controller is rounded so that the controller can be pointing while sitting on a surface. A third input is provided by providing a horizontal gyroscope within the pointing device. The third rotational signal can be used to either rotate a displayed object or to display or simulate a third dimension.

Description:
This is a continuation of application Ser. No. 08/406,727, filed on Mar. 20, 1995, now abandoned, which is a continuation of Ser. No. 08/000,651, filed on Jan. 5, 1993, now U.S. Pat. No. 5,440,326, which is a continuation of Ser. No. 07/497,127, filed on Mar. 21, 1990, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field 
     The present invention relates to the field of hand-held computer controllers. More specifically, the present invention relates to a hand-held gyroscopic pointer adapted for use as a cursor-control device for a computer. 
     2. Art Background 
     A. Computer controllers: 
     Historically, computer instructions have taken the form of commands entered as words on a keyboard. More recently, pointing devices and icon-based interface techniques have been developed which permit a computer user to select tasks and to enter commands by moving a cursor on a computer display screen in response to movement of a pointing device. Pointing devices used for this task have included joysticks, trackballs and mouse controllers. One early use of a mouse as a pointing device for an icon-based computer interlace was at Xerox PARC. More recently, the mouse has become well known as a computer input device with its use on the Apple Macintosh line of computers and on the workstation computers distributed by Sun Microsystem. 
     However, a mouse, requires a relatively large and flat 2-dimensional surface on which to move. Typically, this surface must be unobstructed and dedicated to mouse movement and measure over 9″×9″ . As  as a result. Other controllers, such as the trackball and joystick, are often used when flat surfaces are unavailable. as in the case of portable computers. However, trackballs and joysticks are constrained to use on a surface for practical applications. 
     Further, trackballs, joysticks, keys and mice are not mobile in free space nor do they provide three-dimensional output. One controller which is mobil  mobile in space is taught by Ronald E. Milner in this U.S. Pat. No. 4,862,152. “Sonic Positioning Device,” issued Jan. 25, 1990. This device senses the position of a controller device in three dimensions by sensing the position of an ultrasonic transmitter relative to an array of receivers. However this device is not a true pointing device as it senses position rather than a vector from the device. Since the controller must be repositioned in space, rather than simply reoriented, relatively large hand movements are required to define cursor movements. Another controller mobil  mobile in free space, the Mattel Power Glove video game controller, incorporates two ultrasonic transmitters in a single controller and thus can determine a position as web as  and define a “pointing” vector through the two transmitters. However, both of these ultrasonic controllers are based on ranging techniques and thus have range and resolution limitations. Specifically, both must be used in conjunction with an array of receivers to determine the exact position of the controllers. This results in reduced accuracy as the controller is moved to a position more distant from the receivers. Further, these controllers are only use able  usable in an active volume of space defined by those receivers. Further still, both are limited to use in relatively noise-free environments. 
     B. Gyroscopes: 
     Attitude indicators in aircraft, known as artificial horizons, use two-degree-of-freedom gyroscopes for inertia space reference and the measurement of pitch and roll relative to the gravitational vector. The gravity vector is approximated by a pendulous device (suspended weight) which indicates the apparent vertical, that is, the combined effect of gravity and acceleration. Such a device, as described in Gyroscopic Theory Design, and Instrumentation, 1980, Wrigley, Hollister and Denhard, The M.I.T. Press, Cambridge, Mass., does not correctly indicate the true direction of gravity at any instant because of vehicle accelerations. However, the average direction of the apparent vertical over a period of several minutes approximates the direction of gravity well enough to provide an attitude reference. Gyroscopes thus provide a known technique for measuring roll and pitch relative to a gravity vector. However, gyroscopes are typically heavy and expensive and have not been successfully adapted to practical use as a handheld pointing devices for cursor control in computers. 
     Accordingly, it is desirable to provide a hand-held computer control device which has a long range and high resolution. Further, the controller should not be constrained to use on a flat surface or within a confined space. Further, it is desirable to have a controller which responds to a vector defined by the controller, i.e. responds to “pointing” of the controller, as opposed to merely detecting the position of the controller. It is desirable to have a controller which is self-contained and not subject to interference form  from outside sources of noise or subject to reduced accuracy as it is moved distant from an array of receivers. 
     Further, it is desirable to provide a controller that produces three-dimensional output. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a hand-held gyroscope adapted for use as a cursor control device for a computer. A motor at the core of the gyroscope is suspended by two pairs of orthogonal gimbals from a hand-held controller device which provide two-degrees-of-freedom for the gyroscope. The spin axis of the motor is norminally oriented vertically by a pendulous device. Electro-optical shaft angle encoders sense the rotation of a hand held controller device about the gyroscope as it is manipulated by a user and the resulting electrical output is converted into a format usable by a computer to control the x-y movement of a cursor on a two dimensional display screen of a computer display. The controller thus responds to angular movements of a user&#39;s hand, which permits relatively large and accurate movements of a cursor to be accurately defined without requiring correspondingly large and tiring hand movements. Further, the controller is self-contained and is thus not subject to sources of outside noise or constrained to use within any active volume. For additional ease of use, the bottom of the controller is rounded so that the controller can be reoriented or “pointed” while sitting on a surface 
     The resulting controller device is thus responsive to a vector 
     defined by the controller, i.e. the “pointing” of the controller, as opposed to merely detecting its position, and can be used either in free space or while sitting on a surface. Unlike a classical pointing device such as a stick or a flashlight, it does not require both position and vector information to “point” to another fixed position. Rather, the vector information (i.e. “pitch” and “roll”) is transformed directly into the “x” and “y” coordinates of a cursor position on a computer display. Further, by including a second gyroscope in the controller with the spin axis of the second gyroscope orthogonal to the first, “yaw” information, i.e. the angle of rotation of the controller about the spin axis of the first gyroscope, can be measured. This angle is transformed directly into the “z” information, and used to control rotation of objects or to otherwise alter the computer display, such as by making an object appear closer or further away, in response to “z” axis information. This controller is highly accurate as the result of using electro-optic shaft angle encoders, and not limited to use on a flat surface or an active volume. It allows the input of three dimensional input, in the form of “pitch,” “roll,” and “yaw” angles, which are transformed into “x,” “y,” and“z” coordinates for input to a computer for the control of the cursor location and screen display. Further, since it is self contained, it is not subject to ambient noise, such as is the case with ultrasonic controllers. 
     These and other advantages and features of the invention will become readily apparent to those skilled in the art after reading the following detailed description of the invention and studying the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 1A  are an expanded perspective view of one embodiment of the preferred invention. 
         FIG. 2  is an expanded perspective view of inner gimbal  115  and bearing  122 . 
         FIG. 3  is an illustration of the optical pattern on inner module  110 , the optical pattern on gimbal frame  135 , and the elements of shaft angle encoder sensing optics  165 . 
         FIG. 4  is an illustration of a quad photodiode. 
         FIG. 5  is an illustration of the preferred embodiment of a gyroscopic pointing device  500  coupled to a computer and computer display  505 . 
         FIG. 6  is a top view of an alternative embodiment of the present invention. 
         FIG. 7  is a top perspective view of the embodiment of FIG.  6 . 
         FIG. 8  is a perspective illustrator of a directional gyroscope used to provide three-dimensional output in the embodiment of FIGS.  6  and  7 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  is an expanded perspective view of one embodiment of the present invention. A brushless D.C. motor  105  at the core of the gyroscope spins continuously, providing the angular momentum that stabilizes the inner part of the gyroscope. Brushless D.C. Motors  105  is a motor such as used in miniature cooling fans distributed by U.S. TOYO Fan Corporation. Brushless D.C. Motors  105  is illustrated in the vertical cross section A—A of  FIG. 1 , and is firmly mounted to inner module  110  with motor shaft  108  aligned orthogonally with respect to the axis of rotation of inner module  110  about inner gimbals  115  and  120 . Inner module  110  consists of injection molded plastic and two conductive inner gimbals gimbal  115  and gimbal  120 . Inner gimbals  115  and  120  are located on and aligned with the axis of rotation of inner module  110 . Further, inner gimbals  115  and  120  are electrically coupled to motor  105 . The center of mass of inner module  110 , which includes motor  105 , is slightly displaced along the axis of rotation of motor shaft  108  below the axis of rotation of inner module  110 . This results in a pendulous affect which causes motor shaft  108  to generally align with the gravity vector. 
     Inner gimbals  115  and  120  mechanically support inner module  110  and also provide an electrical path for the transmission of power from the gimbals to motor  105  without restricting the travel of inner module  110 . Two bearings support the inner gimbals relative to gimbal frame  135 . Specifically, bearing  122  is mounted within bearing alignment hole  125  of gimbal frame  135  and supports inner gimbal  115 . Similarly, bearing  124  is mounted within bearing alignment hole  130  of gimbal frame  135  and supports inner gimbal  120 . Gimbal frame  135  includes two conductive outer gimbals  140  and  145 . Two bearings support the outer gimbals relative to shock frame  160 . Specifically, bearing  146  is mounted within bearing alignment hole  150  of shock frame  160  and supports outer gimbal  140 . Similarly, bearing  147  is mounted within bearing alignment hole  155  of shock frame  160  and supports outer gimbal  145 . Outer gimbal  140  is electrically coupled to inner gimbal  115 . Similarly, outer gimbal  145  is electrically coupled to inner gimbal  120 . This completes the electrical path from the non-rotating shock frame  160  to motor  105  within inner module  110 . 
     Shock frame  160  is mounted with shock absorbing rubber to outer housing  175 , which consists of two halves. This shock mounting prevents damage to the bearings or optical sensors in the event that the gyroscope is dropped, and permits the inner assemblies to be constructed with finer tolerances than would be possible without the shock mounting. Shaft angle encoder sensing optics  165 , discussed in more detail below, are mounted on shock frame  160 . 
     Outer housing  175  is opaque so as to prevent outside light from interfering with the optical sensing system and is adapted for hand holding as described more fully below with reference to  FIGS. 5 and 6 . 
     Cabling  180  transmits power from an interlace  interface box  185  to outer housing  175  and returns data signals from shaft angle encoder sensing optics  165 . In the preferred embodiment interface box  185  translates signals from the optical sensing system  165  into serial data for an RS-232 port. Wall adapter  190  provides D.C. power for motor  105  and shalt  shaft angle encoder sensing optics  165 . 
     The construction details of the inner and outer gimbals is  are shown in further detail in FIG.  2 .  FIG. 2  is an expanded perspective view of inner gimbal  115  and bearing  122 . Inner gimbal  115  includes a circular plug  205  which fits within the inner race of bearing  122 . A conductive pin  210 , having a diameter smaller than that of plug  205 , is mounted concentrically with plug  205  and electrically coupled to motor  205 . Pin  210  is preferably made of a low-friction conductive material such as carbon-teflon and designed to protrude from the inner race of bearing  122 . The diameter of pin  210  is smaller than the diameter of the inner race so as not to contact the inner race and to minimize the friction of the rotating contact. A stainless steel spring  215  is mounted to gimbal frame  135  and aligned with and in electrical contact with protruding surface  220  of pin  210 . 
     Spring  215  is electrically coupled to a D.C. power source through outer gimbal  140 . Spring  215  presses against pin  210  providing a low friction electrical connection between gimbal frame  135  and inner module  110 . Inner gimbal  120  and outer gimbals  140  and  145  are constructed in an identical manner. 
     Inner module  110  has a hemispherical outer surface with an optical pattern which interacts with shaft angle encoder sensing optics  165  to sense the rotation of inner module  110  around the axis of rotation through gimbals  115  and  120 . This optical pattern is illustrated in FIG.  3 . The optical pattern on inner module  110  is constructed by first painting the hemispherical surface with a highly reflective aluminum flaked paint and then machining grooves of 0.015 inch depth and width along “lines of longitude” from gimbal  115  towards gimbal  120  along the surface. The grooves are machined to within 30 degrees of each inner gimbal and are 0.015 inches apart at 30 degrees from each gimbal. The pattern causes the spacing between the groove centerlines to widen to approximately 0.04 inches at the middle (“equator”) of inner module  110 . Inner module  110  is molded from a non-reflective black plastic. Thus the grooved portions of inner module  110 . where the reflective paint has been machined off, are non-reflective. This provides a precise optical pattern on inner module  110  having a relatively high contrast ratio. 
     AndA second optical pattern is machined into gimbal frame  135  along a cylindrical section  170  of gimbal frame  135 . This pattern interacts with shaltshaft angle encoder sensing optics  165  for sensing rotation of gimbal frame  135  around its axis of rotation through gimbals  140  and  145 . This cylindrical section is geometrically centered about the axis of rotation of gimbal frame  135 , which passes through gimbals  140  and  145 . As with the optical pattern on the inner module  110 , the optical pattern on gimbal frame  135  is constructed by applying reflective paint to cylindrical section  170  and then machining grooves of 0.015 inch depth and width on the surface of the cylinder. 
     These grooves are machined along lines parallel to the axis of rotation of gimbal frame  135  and evenly spaced so that the light and dark strips are of equal width. Cylindrical section  170  is displaced slightly from the center of gimbal frame  135  so as not lo interfere with the interaction of shaft angle encoder sensing optics  165  and the optical pattern on inner module  110 . Specifically, the closest edge of cylindrical section  170  is spaced approximately 0.15 inches away from the “equator” of frame  170  passing through inner gimbals  115  and  120 . 
     Shaft angle encoder sensing optics  165  interact with the optical pattern on inner module  110  so as to determine the rotation of the inner module  110  about its axis of rotation. More specifically, shaft angle encoder sensing optic  165  include sources for illuminating the patterns, lenses for focusing images of the patterns, and photodetectors for detect a  detecting dark or light areas. Referring to  FIG. 3 , a first LED  305  is mounted to shock frame  160  at an angle of 30 degrees from vertical in a plane parallel to the axis through gimbals  140  and  145  so as to floodlight an area  310  of the optical pattern on inner module  110 . This area is centered on the “equator” of frame  135  so as to provide maximum range of detectable movement in both directions. Lens  315  and mirror  320  focus and reflect the image of the illuminated optical pattern onto quad photodiode  325 . Lens  315  is an injection molded lens of approximately ⅛ inch in diameter having a focal length of approximately 0.2 inches. 
     Quad photodiode  325  comprises four photodiodes,  402 ,  404 ,  406  and  408 , located in a row as illustrated in FIG.  4 . The sides of quad photodiode  325  are aligned with the edges of the projected image of the optical pattern on inner module  110 . One period of the projected image of the optical pattern on inner module  110  (one light and one dark bar) nominally covers the quad photodiode  325 , which comprise four photodiodes centered 0.02 inches apart. Photodiodes  402  and  406  are counted  coupled to comparator  420    410 . Photodiodes  404  and  408  are coupled to comparator  410    420 . The output V 1  of comparator  410  is thus in phase quadrature with the output V 2  of comparator  420 . These outputs are then detected by conventional means to determine the rotation of the inner module. An example of phase quadrature resolution is provided in U.S. Pat. No. 4,346,989 titled Surveying Instrument, issued to Alfred F. Gori  Gort and Charles E. Moore Aug. 31, 1982 and assigned to the Hewlett-Packard Company. A prototype of this embodiment of the present invention results in a resolution of approximately 100 counts per inch. 
     Shaft angle encoder sensing optics  165  also interacts with the optical pattern on gimbal frame  160  so as to determine the rotation of gimbal frame  135  about its axis of rotation. More specfically, a second sensing system, similar to the one described but oriented 90 degrees with respect to the first, is positioned on frame  160  so as to interact with the optical pattern on frame  135  and to detect rotation of frame  135  about its axis of rotation. Referring again to  FIG. 3 , a second LED  330  is mounted to shock frame  160  at an angle of 30 degrees from vertical in a plane parallel to the axis through gimbals  115  and  120  in alignment with cylindrical section  170  so as to floodlight an area  335  of the optical pattern on cylindrical section  170 . Lens  340  and mirror  320  focus and reflect the image of the illuminated optical pattern onto quad photodiode  345 . Lens  340  is an injection molded lens of approximately ⅛ inch in diameter having a focal length of approximately 0.2 inches. 
     Quad photodiode  345  comprises four photodiodes located in a row and is identical in construction to quad photodiode  325  illustrated in FIG.  4 . The sides of quad photodiode  345  are aligned with the edges of the projected image of the optical pattern on gimbal frame  135 .  FIG. 5  is an illustration of the preferred embodiment of a gyroscopic pointing device  500  coupled to a computer  502  and computer display  505 . Computer  502  is adapted so that changing the pitch of controller  500  relative to the gravity vector charges  changes the vertical position of cursor  510  on computer display  505 . That is, rotating the controller forward (“pitch”) causes the cursor to drop on a vertical computer screen, rotating it back causes the cursor to drop on a vertical computer screen,rotating it back causes the cursor to rise, as if the controller was pointing at the cursor. Similarly, rotating the controller from side to side (“roll”) changes the horizontal position of cursor  510  on computer display  505 . That is, rotating the controller left causes the cursor to move left on a vertical computer screen, rotating it right causes the cursor to move to the right, again, as it  if the controller was pointing at the cursor. Controller  500  further includes a thumb operated push button  520  and has a rounded hemispherically shaped bottom portion  525  adapted for smoothly rocking on a flat surface when the pitch and roll of controller  500  is varied while resting on a flat surface. This can be a two position switch, where initial pressure on the switch activates the controller and causes the cursor to move in response to the controller, and a second position of the switch results in a “pick” or “select” signal being transmitted to the computer. 
       FIG. 6  is a top view of an alternative embodiment of the present invention.  FIG. 7  is a top perspective view of the same embodiment. Specifically,  FIGS. 6 and 7  illustrate a controller shaped so as to be hand held in a manner such that the palm will be facing down while controller  610  is resting on a flat surface. The under side of controller  610  is rounded to facilitate changes of its orientation with respect to vertical. A palm button  620  is actuated when the controller is grasped, thus permitting the controller to be deactivated, moved or reoriented, then reactivated. A pick button  630  is located for selective activation by a users lingersuser&#39;s fingers in a manner similar to the use of a pick button on a mouse controller. 
     The embodiment of  FIGS. 6 and 7  includes a first gyroscope as discussed with regards to  FIGS. 1-4  for the measurement of pitch and roll. Further, it includes a second gyroscope, as illustrated in  FIG. 8 , for measurement of yaw about the vertical axis. Specifically, a rotating gyroscopic element  810  is mounted in a two-degree-of freedom gimbal system with its spin axis  820  in a horizontal direction. In the preferred embodiment a mass gives the gyroscope a pendulosity at right angles to spin axis  820 . More specifically, gyroscope  810  is mounted to inner frame  815 . Inner frame  815  is mounted to gimbal frame  825  by inner gimbals  845 . Gimbal frame  825  is mounted to an outer housing  860  by gimbal  850 . A shaft angle encoder  870  is coupled to detect the rotation of gimbal frame  825  relative to outer housing  860 . Oscillations are damped out by applying an antipendulous torque caused by liquid flow of a viscous fluid through a constriction in a tube, as in damper  840 . Computer  502  is further adapted to convert the angle measured by shaft angle encoder  870 . This conversion could be to rotation of the cursor or a cursor-selected object or for providing a “z” input for a three dimensional display or a two-dimensional display simulating a three dimensional view. 
     While the invention has been particularly taught and described with reference to the preferred embodiment, those versed in the art rill  will appreciate that minor modifications in form and detail may be made without departing from the spirit and scope of the invention. For instance, although the illustrated embodiment teaches one system of shaft angle encoders, many alternative systems could be used for detecting the orientation of the gyroscopic controller. Further, while the preferred embodiment leaches  teaches a vertically oriented gyroscope and detection of two angles from vertical such as in an artificial horizon instrument. Other gyroscopic orientations, such as those used for directional gyroscopes, could be substituted. Further, while the present invention teaches the detection of two angles from a vertically oriented gyroscope and one angle from a horizontally oriented gyroscope, two angles could be detected from the horizontal gyroscope, and one from the vertical gyroscope. Further, many techniques equivalent techniques  to the pendulous technique are known for orienting gyroscopes. Accordingly, all such modifications are embodied within the scope of this patent as  and properly come within our  my contribution to the art and  as are particularly pointed out by the following claims.