Abstract:
An impact emulator that provides impact effects to a player of a video game system is provided. The video game system has a magnetic field generator that is able to produce magnetic field to generate a force on a magnet on a remote controller. The amount of magnetic field to be produced is depending on the relative movement of the remote controller and a target element.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a video game system. In particular, to an impact emulator that produces impact reaction force to a video game player. 
       BACKGROUND OF THE INVENTION 
       [0002]    An electronic video game is usually played by a user who interacts with a video game system through a user interface. Typically, the user reacts when there are visual activities displayed on an electronic video device such as a television screen. The “brain” of a video game system, also known as a platform, can be a personal computers or a video game console. The user interface, also known as a game controller, is typically a joystick used to give inputs to video games. The user interface can be different from platform to platform. For example, the number of buttons on a dedicated joystick may range from one to more than ten. 
         [0003]    Beyond the common element of visual feedback, video games have utilized other means to provide interaction and information to the player. For example, sound effect is produced when there is a collision between a baseball bat and a baseball. On the other hand, when a reaction force is required to provide physical impact effect to a user when playing on a video game, for example, when a tennis ball is strike by a tennis racquet, a vibration on the game controller or handler is produced to emulate the impact reaction force. 
         [0004]    Wii, designed by Nintendo, revolutionized video game&#39;s user interface. The key to Nintendo Wii&#39;s interface lies inside a controller. Instead of using a joystick to control the game, the primary control is the controller itself. The controller contains solid-state accelerometers and gyroscopes that allow the controller to sense motions of the controller. A player holds the remote controller that maps a user&#39;s movement (the controller&#39;s movement actually) to joystick buttons. The video game system reflects the movement of the user by showing that on a display. The video game system also makes a reaction based on the algorithm stored in the system and shows that on the display accordingly. 
         [0005]    When there is a collision between objects such as a baseball bat and a baseball, Wii makes impact effects by producing a “pop” sound and a vibration on the remote controller. However, the impact effects of Wii are not genuine since the “feel” of vibration is not comparable to the “feel” when one is using a real bat to hit a baseball because it does not reflect some important parameters, such as a reaction force applied on the hitter with a specific direction and strength. In addition, the user is expecting a feedback force when the ball is hit. If there is no such feedback force, the user may overuse his or her arm and that may cause injury to the user. 
         [0006]    Using haptic peripherals to produce a reaction force such as that in video game arcade is not applicable to Wii since the remote controller is a free body and there is no physical contact between the remote controller and a solid reference such as the wall or the ground. Therefore, the arcade-type impact reaction force can not be provided on Wii. 
       SUMMARY OF THE INVENTION 
       [0007]    It is an object of the present invention to provide an impact emulator that provides impact effects, especially to produce a reaction force to the player when the player moves a remote controller to make a hit on an object that displayed on a video display. It is another object of the present invention to provide a method that provides impact effects, especially to produce a feedback force to the player when the player moves a remote controller to make a hit on an object that displayed on a video display. 
         [0008]    According to a first aspect of the present invention there is provided a video game system comprising a magnetic field generator, wherein the magnetic field generator dynamically produces magnetic field to generate a force on a permanent magnet on a remote controller, wherein the amount of magnetic field is produced according to the relative movement of the remote controller. 
         [0009]    According to a second aspect of the present invention there is provided a video game system comprising a magnetic field generator, wherein the magnetic field generator produces a steady magnetic field to generate a force on an electromagnet attached to a remote controller, wherein the magnitude of the electromagnet is produced according to the relative movement of the remote controller. 
         [0010]    According to a third aspect of the present invention there is provided a method for a video game system for generating an emulated force to a player, comprising the step of producing a magnetic field to generate a force on a permanent magnet on a remote controller, wherein the amount of magnetic field is produced according to the relative movement of the remote controller. 
         [0011]    According to a fourth aspect of the present invention there is provided a method for a video game system for generating an emulated force to a player, comprising the step of producing a steady magnetic field to generate a force on an electromagnet attached to a remote controller, wherein the magnitude of the electromagnet is produced according to the relative movement of the remote controller. 
         [0012]    In order to facilitate an understanding of the invention, the preferred embodiments of the invention are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described or to use in connection with the apparatus illustrated herein. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  shows a top view of major components in one embodiment of the present invention. 
           [0014]      FIG. 2  shows a front view of major components in the embodiment of  FIG. 1 . 
           [0015]      FIG. 3  shows a magnetic field distribution of  FIG. 1  when impulse currents are applied. 
           [0016]      FIG. 4  shows a magnetic field distribution of  FIG. 2  when impulse currents are applied. 
           [0017]      FIG. 5  shows an enlarged perspective view of one embodiment of a remote controller in  FIGS. 1-4 . 
           [0018]      FIG. 6  shows a top view of major components and magnetic field distribution in a second embodiment of the present invention. 
           [0019]      FIG. 7  shows a front view of major components and magnetic field distribution in the embodiment of  FIG. 6 . 
           [0020]      FIG. 8  shows an enlarged perspective view of one embodiment of a remote controller in  FIGS. 6 and 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 1  shows a top view of major components of one exemplary video game system  10  of the present invention.  FIG. 2  shows a front view of major components in the embodiment of  FIG. 1 . Referring to  FIGS. 1 and 2 , the video game system  10  has a console  20 , a remote controller  30 , a sensor bar  40 , a video display  50 , a plurality of electrical wires  60 ,  70 , and a current generator  80 . 
         [0022]    The console  20  has a built-in microprocessor to execute software programs. The software program can be stored in a disk and can be read by the microprocessor of the console  20 . The console  20  is electronically coupled to the sensor bar  40 . The sensor bar  40  contains a plurality of LEDs. The console  20  is also electronically coupled to the video display  50 . When there is a movement in the remote controller  30 , the video game system  10  detects and reflects the movement by showing movements of two objects on the video display  50 . One object represents the player who moves the controller  30  while the other object represents an opponent who can be another player of the video game system, sometimes also called the computer. The video game system  10  also makes a reaction on the opponent object based on the algorithm stored in the console  20  or just to reflect the reaction from another player and shows that on the display  50  accordingly. 
         [0023]    The remote controller  30  is the primary controller for the console  20 . The remote controller  30  has built-in accelerometers and gyroscopes. When the remote controller  30  is moving relatively to the LEDs within the sensor bar  40 , the infra-red detection is able to sense its position in 3D space on the remote controller  30 . This enables users to control the game by moving physically as well as pressing buttons. As shown in  FIG. 1 , the remote controller  30  is swing by a player (not shown) in a desired direction  32  from a first position  30   b  (shown in dashed box) to a second position  30   a  (shown in dashed box) and to the current position  30 . The remote controller  30  is able to sense its motions including: tilting and rotation up and down, tilting and rotation left and right, rotation along the main axis (as with a screwdriver), acceleration up and down, acceleration left and right, and acceleration toward and away from the sensor bar  40 , or the video display  50  if the sensor bar  40  is placed near the display  50 . The information of motions is sent to the console  20  for displaying on the display  50  and for calculating possible hit of an object. 
         [0024]    In the embodiment of  FIGS. 1 and 2 , two wires  60 ,  70  are set up around the playing environment with a first wire  60  set up on the front side and a second wire  70  set up on the rear side. In other words, the first wire  60  is located between the video display  50  and the remote controller  30  while the remote controller  30  is located between the first wire  60  and the second wire  70 . 
         [0025]    The first wire  60  can have four segments that a first segment  62  is generally extended vertically from the ground to a position that is higher than the height of the player&#39;s hand when his or her arm is raised. A second segment  64  is generally extended horizontally from the top-right side of the player to the top-left side of the player. The second segment  64  can be fixed on its position by hangers. Alternatively, the second segment  64  can be fixed to the ceiling of the room where the video game system  10  is set up. A third segment  66  is extended generally vertically from where the second segment  64  ends to the ground. A fourth segment  68  goes horizontally and can be placed on the ground. 
         [0026]    The second wire  70  can have a similar setting as the first wire  60 . The second wire  70  also has four segments  72 ,  74 ,  76 ,  78  that placed around the playing environment. The second wire  70  is placed in parallel with the first wire  60  so that the distance between the first wire  60  and the second wire  70  is about the same between each corresponding segments. For demonstration purpose, the wires  60 ,  70  in  FIG. 2  are shown in skewed positions. They are preferred to be placed at the same level for each segment. Especially, the fourth segments  68 ,  78  can both be placed on the ground. The way it shows that segment  68  is higher than wire  78  is just for demonstration purpose. 
         [0027]    In the embodiment of  FIGS. 1-2 , the wires  60 ,  70  are set up as a square and the distance between the two wires is about one half of the side length of the square. For example, assuming that the height of the first segments  62  is two meters, it is preferred that all other segments  64 ,  66 ,  68 ,  72 ,  74 ,  76 ,  78  are also about two meters long and the distance between the first wire  60  and the second wire  70  is about one meter. 
         [0028]    In another embodiment, the first wire  60  and the second wire  70  can each be shaped as a circle. In that case, it is preferred that the first wire  60  and the second wire  70  have the same radius and the distance between the first wire  60  and the second wire  70  is about the same as the radius of the circles. 
         [0029]    The current generator  80  has input ports and output ports. The first segment  62  of the first wire  60  is electrically coupled to one of the output ports of the current generator  80  and the fourth segment  68  of the first wire  60  is electrically coupled to one of the input ports of the current generator  80 . Similarly, the first segment  72  of the second wire  70  is electrically coupled to one of the output ports of the current generator  80  and the fourth segment  78  of the second wire  70  is electrically coupled to one of the input ports of the current generator  80 . 
         [0030]      FIG. 3  shows a magnetic field distribution of  FIG. 1  when impulse electrical current is applied to wires  60 ,  70  by the current generator  80 .  FIG. 4  shows a magnetic field distribution of  FIG. 2  when impulse electrical current is applied. The direction of impulse electrical current flow is shown by arrows on wires  60 ,  70 . In the first wire  60 , the impulse electrical current is flow out from the current generator  80  to the first segment  62 , the second segment  64 , the third segment  66 , the fourth segment  68 , and finally flow back to the current generator  80 . Similarly, in the second wire  70 , the impulse electrical current is flow out from the current generator  80  to the first segment  72 , the second segment  74 , the third segment  76 , the fourth segment  78 , and flow back to the current generator  80 . 
         [0031]    Based on the Ampere-Maxwell equation, induced magnetic field can be produced by the change of electrical field, which can be produced by an electrical current, as shown in the second term on the right hand side of the following equation: 
         [0000]      curl( B )=μ 0   J+μ   0 ε 0             E/             t    
         [0000]    where curl(B) is the curl of the magnetic field in teslas, μ 0  is the permeability constant (4π×10 −7  Tm/A), ε 0  is the vacuum permittivity, and E is the electric field. 
         [0032]    Arrows in  FIG. 3  represent magnetic field vectors in a plane bisecting the wires  60 ,  70 . Note that the magnetic field is approximately uniform between the wires  60 ,  70 . In  FIG. 4 , the magnetic field vectors pointing out of the page are denoted by double circles when they are within the loop of wires. The magnetic field vectors pointing into the page are denoted by an x in circle when they are outside the loop of wires. Therefore, once the current is turned on, a temporarily magnetic field will be generated by the impulse electrical current. The timing of when and how much magnetic field needed to be generated will be described below with the interaction of the remote controller  30 . 
         [0033]      FIG. 5  shows an enlarged perspective view of the remote controller  30  of  FIGS. 1-4 . The remote controller  30  has a handle  31  with a first permanent magnets  32  and a second permanent magnets  36  attached thereto. The second permanent magnet  36  longitudinally perpendicular to the first permanent magnet  32 . The handle  31  has a front face  42 , a rear face  44 , a left face  46 , and a right face (not shown). The first permanent magnet  32  has a first pole  33  and a second pole  34  while the second permanent magnet  36  has a first pole  37  and a second pole  38 . The face of the first pole  33  of the first permanent magnet  32  is parallel to the front face  42  of the handle  31 . The face of the second pole  34  of the first permanent magnet  32  is parallel to the rear face  44  of the handle  31 . The face of the first pole  37  of the second permanent magnet  36  is parallel to the left face  46 . The face of the second pole  38  of the second permanent magnet  36  is parallel to the right face  48  of the handle  31 . The orientation as well as the strength of the permanent magnets  32 , 36  are calibrated and stored in the console  20  by, for example, the manufacturing. 
         [0034]    When a user turns on the video game system  10 , the system  10  detects the position of the wires  60 ,  70 . This detection can be made by placing sensor tabs on the four comers of each wire  60 ,  70 . Based on the placement of the wires  60 ,  70 , the magnitude of induced magnetic field at each point in space between the loop of wires  60 ,  70  can be calculated when a known impulse electrical currents are applied to wires  60 ,  70  by the current generator  80 . Therefore, when a user is playing, the system  10  detects the relative acceleration and direction of the movement between the remote controller  30  and a target. The position of both the remote controller  30  and the target are shown on the display  50  as they move. The system  10  predicts the timing and location a strike or a hit will occur. The system  10  then utilizes vector arithmetic to calculate the amount and direction of an impact reaction force that will be occurred by such a hit based on the speed, acceleration, and direction of the remote controller  30  and also the target. Once the desired impact reaction force is known, the current generator  80  generates a suitable impulse currents to both wires  60 ,  70 . The impulse currents then generate a desired induced magnetic field as shown in  FIGS. 3 and 4 . 
         [0035]    The calculation of magnetic field is briefly described below. A pair of two identical cylindrical wires are placed side-by-side one on each side of the environment as shown in  FIGS. 1-4  and  6 - 7 , and separated by a distance h equal to one half of the side or radius R of the wire. Each wire carries an equal electrical current flowing in the same direction. Setting h=R, minimizes the non-uniformity of the magnetic field at the center of the wires, in the sense of setting d 2 B/dx 2 =0, but leaves a small amount of variation in field strength between the center and the planes of the wires. A slightly larger value of h reduces the difference in field between the center and the planes of the wires, at the expense of decreasing the field&#39;s uniformity in the region near the center, as measured by d 2 B/dx 2 . 
         [0036]    The calculation of the magnetic field at central point along the axis of the pair of wires is described below. It is convenient to think about the Taylor series expansion of the field strength as a function of x, the distance from the central point of the wire-pair along the axis. By symmetry the odd order terms in the expansion are zero. By separating the wires so that x=0 is an inflection point for each wire separately, it can be expected that the order x 2  term is also zero, and hence the leading non-uniform term is of order x 4 . The inflection point for a simple wire is R/2 from the wire center along the axis. As a result, the location of each wire at x=±R/2. If the current flowing through the wires is I, then the magnetic flux density, B at the midpoint between the wires will be given by B equals to (4/5) 3/2  μ 0 I/R, where μ 0  is the permeability constant (1.26×10 −6  Tm/A), and R is in meters. The calculation of the exact magnetic field at any point in space is more complicate since it involves Bessel functions. The mathematical functions can be programmed into software form and stored in a memory that can be accessed by the microprocessor of the console  20 . Alternatively, the mathematical functions can be implemented in hardware so the exact magnetic field at any point in space can be calculated in a “real-time” fashion. 
         [0037]    The generated induced magnetic field thus generates a force on the permanent magnets  32 ,  36  of the remote controller  30 . The system  10  emulates the impact reaction force by creating a magnetic field that generates a force in a direction against the direction of the movement of the remote controller  30 . The magnetic field that can be changed dynamically according to the movement of the remote controller  30 . The timing, direction and magnitude of the magnetic field are determined by the microcontroller embedded in the console  20  based on the information about the relative movement between the player and an object, the way the player holds the remote controller, and the setting of the pair of wires  60 ,  70 . The player therefore senses the impact reaction force when he or she strikes a ball. 
         [0038]    The remote controller  30  connects to the console  20  using Bluetooth and features rumble as well as an internal speaker. When there is a hit between objects such as a baseball bat and a baseball, the system  10  produces a “pop” sound and makes an impact reaction force on the remote controller  30 . The synchronized sound and the impact reaction force make the video game system  10  “real” to a player by emulating the real-life experiences. 
         [0039]    Following is an example of a tennis game played by a right-handed player on the video game system  10 . The player holds the remote controller  30  use the right hand as if he or she is holding a tennis racquet. Video display  50  displays a player holding a tennis racquet that represents the player while the opponent can be another human player or the computer. For a right-handed player, to play a forehand, the player moves the racquet from the right side of the player&#39;s body, continues across the body as contact is made with the ball, and ends on the left side of the body. To play a backhand, the player moves the racquet from the left side of the body, continues across the body as contact is made with the ball, and ends on the right side of the body. 
         [0040]    When the player plays a forehand, the face of the first pole  33  of the permanent magnet  32  will first face the display  50  and then the face of the second pole  38  will face the display  50 . The system  10  detects the acceleration and direction of the relative movement between the remote controller  30  and the target tennis ball served by the opponent. The position of both the remote controller  30  and the target tennis ball are shown on the display  50  as they move. The system  10  predicts the timing and location of a strike or a collision between the tennis racquet and the target tennis ball will occur. The system  10  then calculates the amount and direction of an impact force and its reaction force that will be produced by such a hit based on the speed, acceleration, and direction of the remote controller  30  and the target tennis ball. 
         [0041]    Just before the face of the first pole  33  is going to face the display  50 , the system  10  creates an impulse current that induces a suitable magnetic field in a direction as shown of  FIGS. 3 and 4  based on the desired impact reaction force. The magnetic field therefore creates a magnetic force emulating the impact reaction force on the permanent magnet  32  and the player can feel it. The system  10  keeps on monitoring the direction and position of the remote controller  30 . When the motion continues for a 90° turn and just before the face of the second pole  38  of the permanent magnet  36  is facing the display  50 , the system  10  turns off the current from the current generator  80 . This current change in wires  60 ,  70  then generates a magnetic field in the opposite direction as shown in  FIGS. 3 and 4 . Since the face of the second pole  38  is now facing the display  50 , the magnetic force emulating the impact reaction force is also acting on the permanent magnet  36  and the player will be able to feel it. 
         [0042]    Thus, when the hand of a player is moving around his or her body, the system  10  detects the swing and generates magnetic force two times within a 90° turn of the remote controller  30 . These two consecutive forces happened in a short period of time that the player may “feel” just like one hit of a tennis ball with an elastic tennis racquet. 
         [0043]    When the player plays a backhand, the face of the second pole  34  of the permanent magnet  32  will first face the display  50  and then the face of the first pole  37  will face the display  50 . Just before the face of the second pole  34  is going to face the display  50 , the system  10  generates an impulse current that generates a suitable magnetic field in a direction opposite to the arrows shown of  FIGS. 3 and 4 . The magnetic field therefore creates a magnetic force emulating the impact reaction force on the permanent magnet  32  of the remote controller  30  and also the player&#39;s hand. When the motion continues for a 90° turn and just before the face of the first pole  37  of the permanent magnet  36  is facing the display  50 , the system  10  turns off the current from the current generator  80 . This current change is then generates a magnetic field that is in the same direction as shown in  FIGS. 3 and 4 . Since the face of the first pole  37  is now facing the display  50 , the magnetic force emulating the impact reaction force is also acting on the permanent magnet  36  of the remote controller  30  and also the player&#39;s hand. 
         [0044]      FIG. 6  shows a top view of major components and magnetic field distribution in a second exemplary video game system  110  of the present invention.  FIG. 7  shows a front view of major components and magnetic field distribution in the embodiment of  FIG. 6 . For purpose of demonstration, not all components in  FIG. 6  are shown in  FIG. 7 . 
         [0045]    The main difference between  FIG. 6  and  FIG. 3  is that in  FIG. 6 , a steady DC current is generated by the current generator  180  so that there is a steady magnetic field within the wire loops  160 ,  170 . Referring to  FIGS. 6 and 7 , the video game system  110  has a console  120 , a remote controller  130 , a sensor bar  140 , a video display  150 , a plurality of electrical wires  160 ,  170 , and a DC current generator  180 . 
         [0046]    The console  120  has a built-in microprocessor to execute software programs that stored in a disk and can be read by a disk drive of the console  120 . The console  120  is electronically coupled to the sensor bar  140  which contains a plurality of LEDs. The console  120  is also electronically coupled to the video display  150 . Typically, the sensor bar  140  is placed on top of the display without movement. When there is a movement between the remote controller  130  and the sensor bar  140 , the video game system  110  detects and reflects the movement by showing that movement on the video display  150 . The video game system  110  also makes a reaction based on the algorithm stored in the console  120  and shows that on the display  150  accordingly. 
         [0047]    The remote controller  130  is the primary controller for the console  120 . The remote controller  130  has built-in accelerometers and gyroscopes. When the remote controller  130  is using with the LEDs within the sensor bar  140 , the infrared detection is able to sense its position in  3 D space. Users control the game by using physical gestures as well as pressing buttons. The remote controller  130  is able to sense its motions including: tilting and rotation up and down, tilting and rotation left and right, rotation along the main axis (as with a screwdriver), acceleration up and down, acceleration left and right, and acceleration toward and away from the sensor bar  140 , or the video display  150  if the sensor bar  140  is placed near the display  150 . 
         [0048]    In the embodiment of  FIGS. 6 and 7 , two wires  160 ,  170  are set up around the playing environment with a first wire  160  set up on the front side and a second wire  170  set up on the rear side. In other words, the first wire  160  is located between the video display  150  and the remote controller  130  while the remote controller  130  is located between the first wire  160  and the second wire  170 . 
         [0049]    The first wire  160  can have four segments that a first segment  162  is generally extended vertically from the ground to a position that is higher than the height of the player&#39;s hand when his or her arm is raised. A second segment  164  is generally extended horizontally from the top-right side of the player to the top-left side of the player. The second segment  164  can be fixed on its position by hangers. Alternatively, the second segment  164  can be fixed to the ceiling of the room where the video game system  110  is set up. A third segment  166  is extended generally vertically from where the second segment  164  ends to the ground. A fourth segment  168  goes horizontally and can be placed on the ground. 
         [0050]    The second wire  170  can have a similar setting as the first wire  160 . The second wire  170  also has four segments  172 ,  174 ,  176 ,  178  that placed around the playing environment. The second wire  170  is placed in parallel with the first wire  160  so that the distance between the first wire  160  and the second wire  170  is about the same between each corresponding segments. Although  FIG. 7  is a front view and the wires  160 ,  170  are shown in skew. Especially, the fourth segments  168 ,  178  can be both placed on the ground. The way it shows that segment  168  is higher than wire  178  is just for demonstration purpose. 
         [0051]    In the embodiment of  FIGS. 6-7 , the wires  160 ,  170  are set up as a square and the distance between the two wires is about one half of the side of the square. For example, assuming that the height of the first segments  162  is two meters, it is preferred that all other segments  164 ,  166 ,  168 ,  172 ,  174 ,  176 ,  178  are also about two meters and the distance between the first wire  160  and the second wire  170  is about one meter. 
         [0052]    In another embodiment, the first wire  160  and the second wire  170  can each be shaped as a circle. In that case, it is preferred that the first wire  160  and the second wire  170  have the same radius and the distance between the first wire  160  and the second wire  170  is about the same as the radius of the circles. 
         [0053]    The current generator  180  has input ports and output ports. The first segment  162  of the first wire  160  is electrically coupled to one of the output ports of the current generator  180  and the fourth segment  168  of the first wire  160  is electrically coupled to one of the input ports of the current generator  180 . Similarly, the first segment  172  of the second wire  170  is electrically coupled to one of the output ports of the current generator  180  and the fourth segment  178  of the second wire  170  is electrically coupled to one of the input ports of the current generator  180 . 
         [0054]      FIG. 6  also shows a magnetic field distribution when steady DC electrical currents are applied to wires  160 ,  170  by the current generator  180  while  FIG. 7  shows the front view. The direction of DC electrical current flow is shown by arrows on wires  160 ,  170 . In the first wire  160 , the steady electrical current is flow out from the current generator  180  to the first segment  162 , the second segment  164 , the third segment  166 , the fourth segment  168 , and then flow back to the current generator  180 . Similarly, in the second wire  170 , the impulse electrical current is flow out from the current generator  180  to the first segment  172 , the second segment  174 , the third segment  176 , the fourth segment  178 , and flow back to the current generator  180 . 
         [0055]    Based on the Ampere-Maxwell equation, magnetic field can be produced by the steady electrical current as shown in the first term on the right hand side of the following equation: 
         [0000]      curl( B )μ 0   J+μ   0 ε 0             E/             t    
         [0000]    where J is the current density in amperes per square meter. 
         [0056]    Arrows in  FIG. 6  represent magnetic field vectors in a plane bisecting the wires  160 ,  170 . Note that the magnetic field is approximately uniform in between the wires  160 ,  170 . In  FIG. 7 , the magnetic field vectors are point out from the page and denoted by double circles when they are within the loop of wires. The magnetic field vectors are point into the page and denoted by an x in circle when they are outside the loop of wires. Therefore, a steady magnetic field is generated by DC electrical currents. 
         [0057]      FIG. 8  shows an enlarged perspective view of the remote controller  130  of  FIGS. 6-7 . The remote controller  130  has a handle  131  with two electromagnets  132 ,  136  attached. The handle  131  has a front face  142 , a rear face  144 , a left face  146  and a right face  148  (not shown). The first electromagnet  132  has a first end  133  and a second end  134  while the second electromagnet  136  has a first end  137  and a second end  138 . The face of the first end  133  is parallel to the front face  142 . The face of the second end  134  is parallel to the rear face  144 . The face of the first end  137  is parallel to the left face  146 . The face of the second end  138  is parallel to the right face  148 . The orientation as well as the strength of the electromagnets  132 ,  136  are stored in the console  120  by manufacturing. 
         [0058]    When a user turns on the video game system  110 , the system  110  detects the position of the wires  160 ,  170 . This detection can be made by placing tabs on the four comers of each wire  160 ,  170 . Based on the placement of the wires  160 ,  170 , the magnitude of magnetic field within the loop of wires  160 ,  170  can be calculated when electrical currents are applied to wires  160 ,  170  by the current generator  180 . Therefore, when a user is playing, the system  110  uses the acceleration and direction of the movement of the remote controller  130  to calculate the amount of force required and the timing to produce the impact reaction force. Once the desired impact reaction force is known, the system  110  creates a temporary magnet on the electromagnets  132 ,  136 . The steady magnetic field thus generates a magnetic force emulating the impact reaction force on the electromagnets  132 ,  136  of the remote controller  130 . The user therefore senses the impact reaction force when he or she strikes a ball. 
         [0059]    Following is an example of a tennis game played by a right-handed player with the system  110 . When the player plays a forehand, the face of the first end  133  of the electromagnet  132  will first face the display  150  and then the face of the second end  138  will face the display  150 . Just before the face of the first end  133  is going to face the display  150 , the controller  130  set the first end  133  as the north pole with a desired magnitude based on the calculation previously described. The magnetic field generated by the wires  160 ,  170  creates a magnetic force on the electromagnet  132  of the remote controller  130  to emulate the calculated impact reaction force. When the motion continues for a 90° turn and just before the face of the second end  138  of the electromagnet  136  is facing the display  150 , the controller  130  set the second end  138  of the electromagnet  136  as the north pole with a desired magnitude. The magnetic force created by magnetic field generated by the wires  160 ,  170  acting on the electromagnet  136  of the remote controller  130  to emulate the calculated impact reaction force. 
         [0060]    Therefore, when the hand of a player is moving around his or her body, the system  110  detects the swing and generates magnetic force two times within a 90° turn of the controller  130 . These two consecutive forces happened in a short period of time that the player may “feel” just like one hit of a tennis ball with an elastic tennis racquet. 
         [0061]    When the player plays a backhand, the face of the second end  134  of the electromagnet  132  will first face the display  150  and then the face of the first end  137  of the electromagnet  136  will face the display  150 . Just before the face of the second end  134  is going to face the display  50 , the controller  130  set the second end  134  of the electromagnet  132  as the north pole with a desired magnitude based on a calculation described previously. The magnetic field generated by the wires  160 ,  170  creates a magnetic force on the electromagnet  132  of the remote controller  130  to emulate the impact reaction force. When the motion continues for a 90° turn and just before the face of the first end  137  of the electromagnet  136  is facing the display  150 , the controller  130  set the first end  137  of the electromagnet  136  as the north pole with a desired magnitude so that a magnetic force is also applied on the electromagnet  136  of the remote controller  130  to emulate the impact reaction force. 
         [0062]    In the exemplary embodiments described previously, although tennis is used as example, it is understandable that the exemplary embodiments also applied to other games such baseball, golf, or boxing. 
         [0063]    Although the remote controller  30 ,  130  shown previously is in a shape like a traditional TV remote control, it can be embedded in any shape as desired. For example, the remote controller  30 ,  130  can be embedded in a boxer glove so that when a player is playing a box game with the system  10 ,  110 , he or she can feel the impact reaction force when he or she strikes the opponent shown on the display  50 ,  150 . 
         [0064]    Various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates are also contemplated and included within the scopes of the invention described and claimed herein.