WO2017125925A1

WO2017125925A1 - Method and system for real-time detection and location of multiple independently moving objects

Info

Publication number: WO2017125925A1
Application number: PCT/IL2017/050071
Authority: WO
Inventors: Dror Barash
Original assignee: Speculo Systems Ltd
Priority date: 2016-01-19
Filing date: 2017-01-18
Publication date: 2017-07-27

Abstract

A system and method for determining the positions of multiple independent objects in real time is disclosed. The method comprises: (1) an initiation phase comprising transmitting a high speed initiation signal from a central control unit to a plurality of sensors, each of which incorporates at least one event timer; transmitting a unique low speed calibration signal from each sensor upon reception at said sensor of said initiation signal; receiving said calibration signals; determining the differences in time from the transmission of said initiation signal to the reception of each of said calibration signals; and, mapping the relative locations of said sensors from said differences; and, (2) a position determination phase comprising determining by triangulation positions of mobile devices that move with said objects, thereby determining positions of said objects. Systems for carrying out the method are also disclosed.

Description

METHOD AND SYSTEM FOR REAL-TIME DETECTION AND LOCATION OF MULTIPLE INDEPENDENTLY MOVING OBJECTS

FIELD OF THE INVENTION

[0001] This invention relates in general to methods for detecting and determining the locations of a plurality of moving objects in real time. In particular, it relates to systems and methods in which the objects communicate their positions to a central processor via a plurality of transmitters and detectors.

BACKGROUND OF THE INVENTION

[0002] In many applications, such as gaming and training, it is desirable to determine and record simultaneously and in real time the locations of a plurality of independently moving objects such as the participants in a game. A number of approaches to solving this problem have been disclosed in the literature.

[0003] U.S. Pat. No. 5346210 discloses an object locating system for locating a gaming ball relative to a playing field. The system comprises a calibration source that emits an ultrasonic signal that can be moved relative to the playing field and can receive a radio frequency (RF) signal; an object marking unit that emits an ultrasonic signal as well as an RF signal, the object marking unit also movable relative to the playing field and relative to the gaming ball, such that, when the calibration source receives the RF signal from the object marking unit, it discontinues emitting the ultrasonic signal; a plurality of sensors positionable relative to the playing field, each of which is designed to receive ultrasonic signals from the calibration source or object marking unit, and a processing unit operable to receive the electrical signals from each of the sensors and measure a time delay between ultrasonic signals received from at least two of the sensors.

[0004] U.S. Pat. No. 5544077 discloses a system for tracking a performer on a stage. A plurality of electromagnetic signal transmitters is positioned about the stage. Performers on the stage carry transponders which receive the electromagnetic signals and, responsive thereto, generate coded sound signals. Sound signal receivers positioned together with the signal transmitters receive the sound signals. A controller determines positions of the transponders and hence of the performers carrying the transponders, and causes spotlights to track the performers. [0005] U.S. Pat. No. 6292106 discloses a system for tracking personnel in rooms of a building. A radio frequency (RF) sync pulse is transmitted throughout a building having a plurality of rooms to be traversed by a plurality of players during, for example, an assault training exercise. Ultra-sound pulses are transmitted from fixed piezoelectric transducers mounted at each corner of each room. The ultra-sound pulses with encoded room identity information are generated in a predetermined timed sequence by different ultra-sound transducers after each RF sync pulse. Each player carries an RF receiver for receiving the RF sync pulses. Each player also carries multiple microphones for receiving the ultra-sound pulses transmitted in a room in which the player is currently located. Timing circuitry carried by each player generates signals representative of the delays between each RF sync pulse and the receipt of each of the ultra-sound pulses sequentially received thereafter. Each player carries an RF transmitter for transmitting an RF tracking signal representing an identity of the room, an identity of the player and the respective delays that each ultra-sound pulse is received after each RF sync pulse. A control facility receives all of the RF tracking signals from all of the players and determines each player's current position within one of the rooms based upon the room identity code and the delays that each ultra-sound pulse is received after each RF sync pulse for each player. The control facility displays the identity and current location of each player as each player moves within the rooms and moves from room to room. The azimuth and elevation of each player along with the articulation of a weapon held by each player can also be determined and displayed.

[0006] U.S. Pat. 6493649 discloses a detection system for determining positional information for objects. The position of each object is determined by determining the transit times of slowly propagating measurement energy transmitted from a measurement energy transmitter on each object to a plurality of fixed measurement energy receivers in the specified environment, the transmission of the measurement energy being triggered by a burst of high speed propagating trigger energy into the specified environment from a trigger energy transmitter, the measurement energy transmitter on each object being triggered by an object- mounted trigger energy receiver, each burst of trigger energy being encoded so as to trigger one only of the measurement energy transmitters, wherein a coordinating control system determines the order in which the measurement energy transmitters are triggered, in response to updatable information relating to service demands of the trigger energy transmitter and/or the objects. [0007] U.S. Pat. No. 7679997 discloses a method and system for determining the position of a robot. The method includes receiving a primary signal and a secondary signal transmitted from a predetermined signal transmitter using a sensor on a moving robot that receives the primary signal and three or more sensors that receive the secondary signal; calculating a transmission distance from a sensor that receives the secondary signal using time information extracted from the primary signal; and calculating a position of the signal transmitter from the distance, wherein the secondary signal comprises first and second secondary signals and each sensor that senses the secondary signal determines whether to amplify the second secondary signal based on the result of the measurement of the first secondary signal.

[0008] U.S. Pat. Appl. Pub. No. 2012/0274515 discloses a system and method for determining the position of an object. Two signals of different propagation velocities (e.g. ultrasound and radio frequency) are simultaneously sent out by an object; alternatively, the fast signal can be sent out from a central unit. The position of the object relative to the basic positions is determined from the time difference between the reception of the signals at two or more base receivers.

[0009] All of the systems and methods known in the prior art suffer from similar weaknesses. First, they are generally designed to track only a single object at a time rather than a plurality of objects, and are designed to treat the object as a single point in space rather than as an object that is made up of components that can move with respect to one another. In many cases, e.g. gaming in which the objects are humans, this oversimplification can limit the utility of the tracking system. Tracking systems known in the art also require a preliminary setup of a number of transmitters or receivers in known fixed locations, enabling them to determine absolute positions of objects relative to the space in which the tracked objects move, but not necessarily to determine only the relative positions of the object when a knowledge of the absolute positions of the objects is not necessary. These systems therefore require significant amounts of energy to use. Thus, a portable system in which there is no need for a permanent transmitter/receiver set up and which can track multiple objects in real time remains a long-felt, yet unmet, need.

SUMMARY OF THE INVENTION

[0010] The method and system disclosed herein are designed to meet this long-felt need. It is therefore an object of the present invention to disclose a method for determination of positions of multiple independent objects in real time, wherein said method comprises: (1) an initiation phase comprising transmitting a high speed initiation signal from a central control unit to a plurality of sensors, each of which incorporates at least one event timer; transmitting a unique low speed calibration signal from each sensor upon reception at said sensor of said initiation signal; receiving said calibration signals; determining the differences in time from the transmission of said initiation signal to the reception of each of said calibration signals; and, mapping the relative locations of said sensors from said differences; and, (2) a position determination phase comprising determining by triangulation positions of mobile devices that move with said objects, thereby determining positions of said objects.

[0011] It is a further object of this invention to disclose such a method, wherein said step of transmitting a unique low speed calibration signal from each sensor comprises transmitting from each sensor a low speed calibration signal characterized in that it is orthogonal to low speed calibration signals transmitted from other sensor.

[0012] It is a further object of this invention to disclose such a method, wherein said step of receiving said calibration signals comprises receiving said calibration signals at said central control unit.

[0013] It is a further object of this invention to disclose a method as defined in any of the above, wherein said step of receiving said calibration signals comprises receiving at each of said sensors at least one calibration signal transmitted by a different sensor.

[0014] It is a further object of this invention to disclose a method as defined in any of the above, wherein said high speed initiation signal is transmitted by a form of electromagnetic radiation selected from the group consisting of radio waves, microwaves, visible light, and infrared radiation.

[0015] It is a further object of this invention to disclose a method as defined in any of the above, wherein said low speed calibration signal is characterized by a propagation velocity less than or equal to that of sound.

[0016] It is a further object of this invention to disclose a method as defined in any of the above, wherein said low speed calibration signal is transmitted via ultrasound.

[0017] It is a further object of this invention to disclose a method as defined in any of the above, wherein each unique low speed calibration signal is orthogonal to low speed calibration signals transmitted by other sensors. [0018] It is a further object of this invention to disclose a method as defined in any of the above, wherein each unique low speed calibration signal is transmitted at a different frequency.

[0019] It is a further object of this invention to disclose a method as defined in any of the above, wherein each unique low speed calibration signal is transmitted along with a unique identifying code.

[0020] It is a further object of this invention to disclose a method as defined in any of the above, wherein said step of transmitting a unique low speed calibration signal from each sensor comprises transmitting from each sensor a low speed calibration signal characterized in that it is orthogonal to low speed calibration signals transmitted from other sensors.

[0021] It is a further object of this invention to disclose a method as defined in any of the above, wherein at least one of said high speed signal and said low speed detection signal carries information about said object. In some preferred embodiments of the method, said information is selected from the group consisting of information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and information about whether a particular switch associated with said object is in a predetermined position

[0022] It is a further object of this invention to disclose a method as defined in any of the above, wherein said position determination phase comprises: transmitting a unique fast detection signal and a unique slow detection signal from each of said mobile devices, wherein each unique fast detection signal and each unique slow detection signal is associated with a particular mobile device; receiving said detection signals at said plurality of sensors; decoding said detection signals; calculating a distance from each particular mobile device to each sensor that receives a fast and a slow detection signal associated with said particular mobile device; and, transmitting said calculated distances to a processing unit.

[0023] In some embodiments of the method, said processing unit is a part of said control unit. In some embodiments of the method, said step of calculating a distance comprises calculating a distance based on an approximation that said fast detection signal has an infinite propagation velocity. In some preferred embodiments of the method, said high speed detection signal is transmitted by a form of electromagnetic radiation selected from the group consisting of radio waves, microwaves, visible light, and infrared radiation. In some preferred embodiments of the invention, said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound. In some preferred embodiments of the invention, said low speed detection signal is transmitted via ultrasound. In some embodiments of the method, the method additionally comprises transmitting from at least one of said mobile devices to said control unit additional coded information. In some preferred embodiments of the method, said additional coded information comprises a Walsh code. In some preferred embodiments of the method, each unique detection signal is transmitted at a different frequency. In some preferred embodiments of the method, each unique detection signal is transmitted along with a unique identifying code. In some preferred embodiments of the method, each unique detection signal is orthogonal to the other detection signals. In some preferred embodiments of the method, at least one of said high speed signal and said low speed detection signal carries information about said object. In some preferred embodiments of the method, said information is selected from the group consisting of information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and information about whether a particular switch associated with said object is in a predetermined position.

[0024] It is a further object of this invention to disclose a method as defined in any of the above, wherein said position determination phase comprises: transmitting a fast detection signal from said control unit to each of said mobile devices and each of said sensors; transmitting from each of said mobile devices a unique slow detection signal associated with that particular mobile device upon reception of said fast detection signal at said particular mobile device, said slow detection signal having a particular signal level; receiving said slow detection signals at said sensors; for each slow detection signal received at a particular sensor: decoding said slow detection signal; and calculating a distance between said mobile device associated with said slow detection signal and said sensor from a difference in time between reception of said fast detection signal and said slow detection signal.

[0025] In some embodiments of the method, it additionally comprises transmitting an instruction from said control unit to each of said mobile devices whether or not to participate in said position determination phase. In some preferred embodiments of the method, it comprises putting each mobile device that is instructed not to participate in said position determination phase into sleep mode. In some preferred embodiments of the method, it comprises transmitting an instruction from said control unit to each of said mobile devices to alter said signal level. In some preferred embodiments of the method, it comprises transmitting a delay time from said control unit to each of said mobile devices, wherein said step of transmitting a slow detection signal comprises transmitting a slow detection signal said delay time after reception of said fast detection signal. In some preferred embodiments of the method, it comprises putting each of said mobile devices into a sleep mode after said transmitting a slow detection signal until reception of another fast detection signal. In some preferred embodiments of the method, said step of calculating a distance comprises calculating a distance based on an approximation that said fast detection signal has an infinite propagation velocity. In some preferred embodiments of the method, said high speed detection signal is transmitted by a form of electromagnetic radiation selected from the group consisting of radio waves, microwaves, visible light, and infrared radiation. In some preferred embodiments of the invention, said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound. In some preferred embodiments of the method, said low speed detection signal is transmitted via ultrasound. In some preferred embodiments of the method, each unique detection signal is transmitted at a different frequency. In some preferred embodiments of the method, each unique detection signal is transmitted along with a unique identifying code. It some preferred embodiments of the method, each unique detection signal is orthogonal to the other detection signals. In some preferred embodiments of the method, at least one of said high speed signal and said low speed detection signal carries information about said object. In some preferred embodiments of the method, said information is selected from the group consisting of information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and information about whether a particular switch associated with said object is in a predetermined position.

[0026] It is a further object of this invention to disclose a method as defined in any of the above, wherein said position detection phase comprises: transmitting a fast detection signal from said control unit; transmitting a unique slow detection signal from each of said sensors upon reception of said fast detection signal, each of said unique slow detection signals associated with a particular sensor; receiving said fast detection signal and at least one of said slow detection signals at each of said mobile devices; determining at each mobile device a difference in time between the reception of said fast detection signal and each of said unique slow detection signals; and, transmitting from each of said mobile devices to a processing unit said difference in time.

[0027] In some preferred embodiments of the method, it comprises putting each of said mobile devices into a sleep mode after said transmitting a slow detection signal until reception of another fast detection signal. In some preferred embodiments of the method, said step of calculating a distance comprises calculating a distance based on an approximation that said fast detection signal has an infinite propagation velocity. In some preferred embodiments of the method, said high speed detection signal is transmitted by a form of electromagnetic radiation selected from the group consisting of radio waves, microwaves, visible light, and infrared radiation. In some preferred embodiments of the invention, said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound. In some preferred embodiments of the method, said low speed detection signal is transmitted via ultrasound. In some preferred embodiments of the method, each unique detection signal is transmitted at a different frequency. In some preferred embodiments of the method, each unique detection signal is transmitted along with a unique identifying code. In some preferred embodiments of the method, each unique detection signal is orthogonal to the others. In some preferred embodiments of the method, at least one of said high speed signal and said low speed detection signal carries information about said object. In some preferred embodiments of the method, said information is selected from the group consisting of information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and information about whether a particular switch associated with said object is in a predetermined position.

[0028] It is a further object of this invention to disclose the method as defined in any of the above, wherein said mobile devices are attached to said objects.

[0029] It is a further object of this invention to disclose the method as defined in any of the above, wherein said mobile devices, sensors, and processing units are attached to said objects.

[0030] It is a further object of this invention to disclose the method as defined in any of the above, wherein said sensors are physically connected to said processing units. It is a further object of this invention to disclose a method as defined in any of the above, wherein said objects are human beings. In some preferred embodiments of the invention, said objects are players in a multi-player game.

[0031] It is a further object of this invention to disclose the method as defined in any of the above, wherein said step of transmitting a high speed initiation signal to a plurality of sensors comprises transmitting a high speed initiation signal to at least one predetermined subset of a plurality of sensors.

[0032] It is a further object of this invention to disclose a system for real-time detection and location of a plurality of independent objects, comprising: a control unit configured to transmit and receive high speed signals and low speed signals; a processing unit configured to process data received by said control unit; a plurality of sensors in communication with said control unit, each of which comprises at least one event timer; and, a plurality of mobile devices associated with said objects and in contact with said control unit.

[0033] In some preferred embodiments of the system, said sensors are portable. In some preferred embodiments of the system, said mobile devices are attached to said objects. In some preferred embodiments of the system, said processing unit is part of said control unit. In some preferred embodiments of the system, said sensors are physically connected to said processing units. In some preferred embodiments of the system, said sensors, detectors, and central control unit are all mobile.

[0034] It is a further object of this invention to disclose the system as defined in any of the above, wherein said high speed signals are transmitted by a form of electromagnetic radiation selected from the group consisting of radio waves, microwaves, visible light, and infrared radiation.

[0035] It is a further object of this invention to disclose the system as defined in any of the above, wherein said low speed signals are characterized by a propagation velocity less than or equal to that of sound.

[0036] It is a further object of this invention to disclose the system as defined in any of the above, wherein said low speed signals are transmitted via ultrasound.

[0037] It is a further object of this invention to disclose the system as defined in any of the above, wherein said sensors are in communication with one another.

[0038] It is a further object of this invention to disclose the system as defined in any of the above, wherein said sensors maintain their relative positions subsequent to activation of said system, but are not fixed in position prior to activation of said system.

[0039] It is a further object of this invention to disclose the system as defined in any of the above, wherein said sensors are configured to transmit unique low speed signals. [0040] It is a further object of this invention to disclose the system as defined in any of the above, wherein each of said mobile devices is configured to transmit at least one type of unique signal selected from the group consisting of unique high speed signals and unique low speed signals.

[0041] It is a further object of this invention to disclose the system as defined in any of the above, wherein at least one of said high speed signal and said low speed signal carries information about said object.

[0042] It is a further object of this invention to disclose the system as defined in any of the above, wherein said information is selected from the group consisting of: information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and, information about whether a particular switch associated with said object is in a predetermined position.

[0043] It is a further object of this invention to disclose the system as defined in any of the above, wherein said sensors are configured to receive at least one type of signal selected from the group consisting of high speed signals and low speed signals.

[0044] It is a further object of this invention to disclose the system as defined in any of the above, wherein each of said objects has at least one mobile device, at least one sensor, and at least one processing unit attached to it.

[0045] It is a further object of this invention to disclose the system as defined in any of the above, wherein said objects are human beings. In some preferred embodiments of the invention, said human beings are players in a multi-player game.

[0046] It is a further object of this invention to disclose the system as defined in any of the above, wherein said system comprises a plurality of sub-systems, each of said subsystems comprising a subset of said sensors. In some preferred embodiments of the invention, said control unit is configured to transmit to one subsystem at a time.

[0047] It is another object of the present invention to provide a method for determination of positions of multiple independent objects in real time, wherein said method comprises: an initiation phase comprising:

transmitting, for each of a plurality of sensors, a unique low speed calibration signal, each of said sensors associated with one of at least one mobile device; each of said at least one mobile device moving with at least a portion of one of said independent objects;

receiving said low-speed calibration signals;

determining, for each said low speed calibration signal, the difference in time from the transmission of said low speed calibration signal to the reception of said low speed calibration signal; and,

mapping the relative locations of said sensors from said time differences; and, a position determination phase comprising determining by triangulation positions of said at least one mobile device, thereby determining positions of said objects.

[0048] It is a further object of this invention to disclose such a method, additionally comprising step of initiating said transmission of said unique low speed calibration signal by member of a group consisting of: as determined by a clock internal to each said sensor, by a high-speed wake-up call received by each said sensor, or by a low-speed wake-up call received by each said sensor.

[0049] It is a further object of this invention to disclose such a method, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said unique low speed calibration signal, as determined by said internal clock and said receiving of said unique low speed calibration signal, as determined by said internal clock.

[0050] It is a further object of this invention to disclose such a method, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said high-speed wake-up call and said receiving of said unique low speed calibration signal.

[0051] It is a further object of this invention to disclose such a method, additionally comprising step of calculating said distance from said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

[0052] It is a further object of this invention to disclose such a method, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said low-speed wake-up call and said receiving of said unique low-speed calibration signal. [0053] It is a further object of this invention to disclose such a method, additionally comprising step of calculating said distance from half said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

[0054] It is a further object of this invention to disclose such a method, additionally comprising step of selecting said difference from a group consisting of: being orthogonal, being of different frequencies, being transmitted along with a unique identifying code, and any combination thereof.

[0055] It is a further object of this invention to disclose such a method, additionally comprising step of selecting a difference between said low-speed calibration signals from a group consisting of: being orthogonal, differing in frequency, being transmitted along with a unique identifying code, and any combination thereof.

[0056] It is a further object of this invention to disclose such a method, additionally comprising step of selecting said low-speed calibration signals to be orthogonal.

[0057] It is a further object of this invention to disclose such a method, additionally comprising step of sending said wake-up signal either to all of the sensors/mobile devices or to at least one subset of the units.

[0058] It is a further object of this invention to disclose such a method, additionally comprising step of selecting components of said wake-up signal from a group consisting of: a wake-up call, an identification code indicating which subset of said sensors is to be wakened, a time signal, a reset signal, a test signal, and any combination thereof.

[0059] It is a further object of this invention to disclose a system for determination of positions of multiple independent objects in real time, comprising: a plurality of sensors, each configured to transmit a unique low speed calibration signal, each configured to receive a low-speed calibration signal;

at least one processing unit configured to process data received from said sensors;

a plurality of mobile devices comprising said sensors and associated with said objects, said plurality of mobile devices in communication with said control unit wherein said processing unit is configured to determine, from said data received from said sensors, relative distances between said multiple independent objects. [0060] It is a further object of this invention to disclose such a system, wherein said transmission of said unique low speed calibration signal is initiatable by member of a group consisting of: as determined by a clock internal to each said sensor, by a high-speed wake-up call received by each said sensor, or by a low-speed wake-up call received by each said sensor.

[0061] It is a further object of this invention to disclose such a system, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said unique low speed calibration signal, as determined by said internal clock and said receiving of said unique low speed calibration signal, as determined by said internal clock.

[0062] It is a further object of this invention to disclose such a system, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said high-speed wake-up call and said receiving of said unique low speed calibration signal.

[0063] It is a further object of this invention to disclose such a system, wherein said distance is calculatable from said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

[0064] It is a further object of this invention to disclose such a system, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said low-speed wake-up call and said receiving of said unique low-speed calibration signal.

[0065] It is a further object of this invention to disclose such a system, wherein said distance is calculatable from half said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

[0066] It is a further object of this invention to disclose such a system, wherein a member of a group consisting of said high-speed wake-up call, said low-speed wake-up call and any combination thereof is selected from a group consisting of: either the same for all sensors, or differing between at least two subsets of sensors. It is a further object of this invention to disclose such a system, wherein said difference is selected from a group consisting of: being orthogonal, being of different frequencies, being transmitted along with a unique identifying code, and any combination thereof.

It is a further object of this invention to disclose such a system, wherein a difference between said low-speed calibration signals is selected from a group consisting of: being orthogonal, differing in frequency, being transmitted along with a unique identifying code, and any combination thereof.

It is a further object of this invention to disclose such a system, wherein said low-speed calibration signals are selected to be orthogonal.

It is a further object of this invention to disclose such a system, wherein said wake-up signal is transmittable either to all of the sensors/mobile devices or to at least one subset of the units.

It is a further object of this invention to disclose such a system, wherein components of said wake-up signal is selected from a group consisting of: a wake-up call, an identification code indicating which subset of said sensors is to be wakened, a time signal, a reset signal, a test signal, and any combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The invention will now be described with reference to the drawings, wherein

[0068] FIG. 1 illustrates schematically one embodiment of the method and system disclosed herein;

[0069] FIG. 2 illustrates schematically a second embodiment of the method and system disclosed herein;

[0070] FIG. 3 illustrates a method of triangulation according to the method and system disclosed herein; and,

[0071] FIG. 4 illustrates schematically an embodiment of the invention disclosed herein in which the sensors and mobile devices are attached to a single player; and,

[0072] FIG. 5 illustrates schematically a third embodiment of the method and system disclosed herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODFMENTS

[0073] In the following description, various aspects of the invention will be described. For the purposes of explanation, specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent to one skilled in the art that there are other embodiments of the invention that differ in details without affecting the essential nature thereof. Therefore the invention is not limited by that which is illustrated in the figures and described in the specification, but only as indicated in the accompanying claims, with the proper scope determined only by the broadest interpretation of said claims.

[0074] As used herein, the term "unique signal" is used to describe a signal that can be differentiated from other analogous signals produced by the system. All means known in the art for producing unique signals are thus contemplated by the inventor as being within the scope of the invention. Non-limiting examples of methods for producing unique signals include producing signals each of which is at a different frequency; producing signals that are encoded, e.g. with a unique code that precedes the signal of interest; or producing signals that are orthogonal to one another.

[0075] As used herein, with respect to signals in multiple-access communications schemes, the term "orthogonal" is used to describe signals that are characterized by the property that an ideal receiver can completely reject arbitrarily strong unwanted signals from the desired signal by using different basis functions.

[0076] As used herein, with respect to signals propagating in a communication system, the terms "high speed" and "low speed" are used as relative terms describing the propagation velocities of various signals. As used herein, the term "low speed" refers to a signal with a propagation velocity sufficiently slower than the "high speed" signal that a detector used in the communication can differentiate the times of arrival of a "high speed" signal and a "low speed" signal sent simultaneously from the same location.

[0077] The system and method disclosed herein use differences in timing between a high speed signal and a low speed signal to determine distances between a plurality of mobile devices and a plurality of sensors. In preferred embodiments of the invention, high speed signals are transmitted at the speed of light. In more preferred embodiments of the invention, the high speed signals are transmitted by electromagnetic radiation, non-limiting examples of which include radio frequency radiation, visible light, and infrared radiation. In preferred embodiments of the invention, the low speed signals are transmitted at a speed less than or equal to the speed of sound; in more preferred embodiments, ultrasound signals are used. Thus, in preferred embodiments of the invention, at the distances at which the invention is typically used, the difference in the propagation speeds of the high speed and low speed signals is sufficiently large that the propagation speed of the high speed signal can be treated as infinite (i.e. zero propagation time) without significantly compromising the accuracy of the distance determinations.

[0078] The system comprises a plurality of sensors, mobile devices associated with (and normally attached to) the objects whose location is to be determined; at least one detector, the detector typically being in a fixed position, and a control unit in communication with the detectors and mobile devices. Each detector can incorporate at least one event timer that can measure, record, and transmit the time of a given event or the difference in time between two successive events. In some embodiments of the invention, the mobile devices incorporate event timers as well. The system also includes a processing unit for converting the time- dependent data into distances and for performing triangulation for determining locations. The processing unit can be part of the control unit, or it can be a separate unit in communication with the control unit. In some embodiments of the invention, the central control unit is not a separate system, but rather one of the devices of the system that is configured to perform the actions of the control unit.

[0079] In some embodiments, the system can be used to determine the positions and movements of at least one player (typically a human) playing a game involving movement. For non-limiting example, the game can be tennis, baseball, table tennis, or basketball. In these embodiments, at least one mobile device is associated with each player, either as part of a game apparatus (bat, ball, racket, glove, etc.) or attached to some portion of the player's body such as, for non-limiting example, an arm, leg, head, neck, torso and any combination thereof. The movements of the player(s) and/or the game apparatus are determined, as described herein and are used to create a game emulation on a display unit such as, for non- limiting example, a display screen or a television. For non-limiting example, if the game being emulated is doubles tennis with four human players, each of the players would be equipped with at least one mobile device, as described above. The players' movements would enable the system to calculate the location of a virtual ball; the players' movements and the movements of the virtual ball would be shown on the display screen. In some embodiments, one, two, or three of the players in the double tennis game could be replaced by virtual players; the remaining humans then playing against virtual players appearing on the screen.

[0080] In some embodiments of the invention, the system is divided into subsystems, each of which comprises a subset of the sensors. In these embodiments, the control unit does not transmit to all of the subsystems simultaneously. As a non-limiting example, the control unit may, in some embodiments, transmit only to one subsystem. As further non-limiting examples of embodiments in which the system is divided into subsystems, in various such embodiments, the control unit can communicate with each subsystem sequentially, or not communicate with one or more of the subsystems at all, or can calculate the projected trajectories of objects in each subsystem and only transmit to a given subsystem when tracking of the objects associated with the sensors in that subsystem is deemed necessary, e.g. when the objects are projected to be on a collision course or when a subset of the players in a multi-player game are projected to be nearing a game objective.

[0081] In preferred embodiments of the method, the measurement phase is preceded by an initiation phase. In this initiation phase, the control unit sends a high speed initiation signal to the sensors. In preferred embodiments of the invention, this initiation signal may be preceded by a clock initiation signal to reset the internal clocks in the sensors to zero. Upon receiving the initiation signal, each sensor transmits a unique low speed calibration signal that is then received by the other sensors. Each sensor then transmits to the processing unit the difference in time between receiving the high speed signal and each low speed signal received from each of the other sensors. The processor then calculates the relative positions of the sensors by calculating the distance between each pair of sensors as the speed of propagation of the low speed signal multiplied by the time of propagation (approximating the time of propagation of the high speed signal to zero) and triangulating the resulting distances.

[0082] One consequence of the inclusion of an initiation phase in the method is that it enables construction of a system in which, in contrast to the prior art, the sensors need not be fixed in position prior to the use of the system. In systems known in the art, particularly those in which the absolute positions of the objects needs to be known, triangulation of the objects can only be performed if the absolute positions of the sensors are known a priori. In preferred embodiments of the system herein disclosed, the sensors are neither necessarily fixed in place nor are their positions (absolute or relative) measured beforehand. Rather, the ability of the central processing unit to calculate the relative positions of the sensors precludes the need to fix the sensors or their positions. In order to perform triangulation to obtain the relative positions of the objects, it is sufficient to know the relative positions of the sensors. This information is provided during the initiation phase.

[0083] In some embodiments of the invention, the control unit transmits a signal to wake up the mobile devices that are associated with (normally attached to) the objects of interest. If necessary, each mobile device can transmit a code or frequency information so that the processing unit can associate each unique signal with a particular mobile device.

[0084] Once the relative positions of the sensors are known and the mobile devices have been identified, the position determination phase can begin. Three preferred embodiments of a method of position determination are herein disclosed: fully active mode, semi-active mode, and passive mode. In some embodiments of the system, the mode of position determination can be set prior to the operation of the system. In other embodiments, a particular system is constructed to run in only one mode. In yet other embodiments, the system is configured such that it can switch in real time (either automatically or according to instructions provided by the operator) from one mode to another according to the needs of the moment.

[0085] Fully active mode

[0086] FIG. 1 schematically illustrates a fully active mode. In this mode, the mobile devices (130) transmit simultaneously unique high speed and low speed detection signals (300). These signals are received at the sensors (120) and the time differences between receiving a fast (high-speed) signal and a slow (low-speed) signal and the associated codes or frequencies are passed on to the processing unit (100), which then associates the timed signals with the mobile device that transmitted them. The processing unit then triangulates to find the relative location of each mobile device (FIG. 3), thereby determining the location of the object associated with the mobile device.

[0087] In some embodiments of the invention, the devices send additional information such as Walsh codes on either one or both of the signals.

[0088] In some embodiments of the invention, the devices send additional information such as: information about whether a particular button associated with said object has been pushed; information about whether a particular circuit associated with said object is open or closed; and, information about whether a particular switch associated with said object is in a predetermined position and any combination thereof. [0089] Semi-active mode

[0090] FIG. 2 schematically illustrates a semi-active mode. In this mode, the control unit (110) transmits a high speed detection signal (200). Each active device, upon receiving the high speed signal, transmits a unique low speed detection signal (210). The low speed signals are detected by the sensors which then send the timing and code information to the processing unit. The distances to the mobile devices are then calculated and their positions and the positions of the associated objects are then determined as above.

[0091] In the semi-active mode, the control unit can also transmit signals that include instructions to the devices. The instructions can be sent as part of the sync signal or as separate signals. For example, for a particular measurement, a subset of the devices can be instructed not to transmit a low speed detection signal; these non-participating devices can optionally be put into a "sleep" mode to save energy and battery use. Additionally or alternatively, the control unit can send an instruction to a given mobile device to alter its signal level depending on the strength of the signal received by the sensors. Some or all of the mobile devices can be put in sleep mode during the time between transmitting the low speed detection signal and receiving the next high speed detection signal from the control unit. As with the fully active mode, in the semi-active mode, the mobile devices can transmit additional information besides the signal used to determine their positions.

[0092] Passive mode

[0093] In the passive mode, the mobile devices include an event timer. The control unit sends a high speed detection signal that acts to reset the time counter in the mobile devices. Upon receiving the high speed detection signal, each sensor then transmits a unique low speed detection signal. The mobile devices determine the time at which each unique low speed detection signal is received after the time counter reset, and then transmit this information to the processing unit, optionally along with additional information as above. The processing unit then determines the distances from each sensor to each mobile device and determines the position of each mobile device by triangulation as above. In some embodiments of the invention, the mobile devices go into sleep mode after transmitting the information until the next time that a high speed detection signal is received.

[0094] FIG. 4 illustrates an additional embodiment of the invention in which the sensor system is attached to the object as well. Each object carries a set of sensors, mobile devices (e.g. attached to the limbs of a player), and a processing unit. If only one object is being tracked (e.g. in a single-player game), then the system works as described above. If more than one object is being tracked, as would be the case in a multi -player game, and determining and monitoring of the relative positions of the objects are desired, then fully active mode is preferably used, and each processing unit associated with an individual player must do a handshake with each other processing unit so that the relative positions of the players can be determined. In this embodiment, in the initiation stage, each set of sensors associated with a particular object acts as a mobile device relative to the sensors associated with the other objects. Thus, in this embodiment, the positions of the objects will be determined relative to one another rather than absolutely relative to the space in which the objects are moving.

[0095] In some embodiments, no high-speed initiation signal is needed; the locations of the objects can be found with only the low-speed calibration signal.

[0096] In some embodiments where the locations of the objects can be found with only the low-speed calibration signal, at least one member of a group consisting of the objects, the mobile devices, and the sensors is in a sleep mode until a wake-up signal is received. This wake-up signal can be a high-speed signal, a low-speed calibration signal and any combination thereof.

[0097] In embodiments where only low-speed calibration signals are used, the system can find the location of the sensor by calculating the time differences between emission of each calibration signal and its arrival at each sensor, as described above. As described above, the signals sent from each sensor arrive at each of the other sensors. From the differences in arrival times between a sending sensor and a receiving sensor, triangulation can be used to determine the relative locations of the sensors in space.

[0098] As shown in Fig. 5, the device comprises a plurality of mobile devices (130) (here, 3 mobile devices) and a plurality of detectors (here, 3 detectors). Each sensor comprises a transmitter and a receiver, the receiver configured to receive a wake-up call. Each detector is configured to receive the orthogonal signals from the transmitters. Each detector either comprises a clock/timer or is in communication with a clock/timer. The clock/timer or clock/timers are in communication with a processor configured to receive times from the clock and to process the times from the clocks in the plurality of detectors, as described hereinabove, to find relative distances between the sensors and, therefore, between the objects with which the sensors are associated. In some variants, as described hereinbelow, a wake-up call can be sent from the processor or the control unit to the sensors (120).

[0099] There are three main variants of these embodiments, each with sub-variants, all configured to ensure that the time of transmission for each low-speed calibration signal is accurately known.

[0100] In the first variant of these embodiments, each device sending a low-speed calibration signal transmits the signal based on its own internal clock. In one sub-variant of this first variant, each sensor comprises an accurate timer, with the various timers calibrated so that, for each sensor, the time of transmission of the signal is accurately known so that the time difference between transmission and reception can be accurately calculated.

[0101] In another sub-variant of this first variant, each sensor sends a high-speed signal at the same time as the low-speed calibration signal. Each sensor can then calculate a delay time from the difference between the time it receives the high-speed signal and the time it receives the low-speed calibration signal.

[0102] In the second variant, a high-speed wake-up signal is sent. This can be sent from the control unit, from a mobile device, or from a sensor. In the exemplary embodiment of Fig. 5, the wake-up signal is sent from the control unit. Since the wake-up signal is a high-speed signal, all the sensors will receive it at effectively the same time, therefore all of the orthogonal low-speed calibration signals will be sent at the same time; the delay time for each sensor will be the difference in time between the sensor receiving the wake-up signal and it receiving a low-speed calibration signal. From these delay times, as described above, triangulation can be used to determine the relative locations of the sensors.

[0103] For the second variant, the process is as follows:

1. A high-speed wakeup / sync signal is sent.

2. The detectors start counting time.

3. Each sensor receives the wakeup / sync signal and sends a low-speed calibration signal.

4. At least one of the detectors receives the low-speed calibration signal.

5. Each detector that receives a low-speed calibration signal determines the time the low-speed calibration signal is received. 6. The difference between the time the sync signal was sent and the time the detector received the low-speed calibration signal, minus the time needed for the sensors to respond (the system reaction time), is used to calculate the distance between the sensors and the detectors.

7. The distances between the sensors and the detectors are used to triangulate the sensors' locations.

[0104] In the third variant, a low-speed wake-up signal is sent. Preferably, this is sent from the control unit. Each mobile device receives the low-speed wake-up signal and sends an orthogonal low-speed calibration signal. At least one of the detectors will receive the low- speed calibration signal and, using the delay between when the low-speed wake-up signal was received and the low-speed calibration signal was received, the relative locations of the sensors can be found.

[0105] For the third variant, the process is as follows:

1. A low-speed wakeup / sync signal is sent.

2. The detectors start counting time.

4. At least one of the detectors receives the low-speed calibration signal.

5. Each detector that receives a signal determines the time the low-speed calibration signal is received.

6. The difference between the time the sync signal was sent and the time the detector received the low-speed calibration signal, minus a system reaction time (the time needed for the sensor to respond), is used to calculate the distance between the sensor and the detector. The distance between the sensor and the detector is the product of the speed of the low speed signal and half of the time difference.

7. The distances between the sensors and the detectors is used to triangulate the locations of the sensors.

[0106] The wake-up signal, either high speed or low-speed, can be the same for all sensors, or can be different for different subsets of sensors. If the wake-up signals are different for different subsets of sensors, they can differ in being orthogonal, in being of different frequencies, each can be transmitted along with a unique identifying code, and any combination thereof.

[0107] The low-speed calibration signals can be orthogonal, can differ in frequency, can be transmitted along with a unique identifying code, and any combination thereof. In preferred embodiments, the low-speed calibration signals are orthogonal.

[0108] The wake-up signal can send information to all of the sensors/mobile devices, or to at least one subset of the units. (The smallest possible subset being a single sensor; the largest possible subset being all the sensors.) The wake-up signal can comprise, in addition to the wake-up itself, an identification code indicating which subset of the sensors is to be wakened, a time signal, a reset signal, a test signal, and any combination thereof.

[0109] According to another embodiment of the present invention body emulation is provided by at least one wearable sensors.

[0110] It should be noted that combinations of the embodiments and variants disclosed hereinabove constitute further embodiments of the system and method disclosed herein.

[0111] The system and method disclosed herein can be used for any application in which location and tracking of a plurality of independent objects is desired. In preferred embodiments, the "objects" are players in a multi-player game, but the system and method could be used, as non-limiting examples, for locating people training in the same location but not necessarily participating in the same game or other training session, locating performers on a stage, locating moving inanimate objects moving in a given space, tracking goods along a production line in a factory, general inventory control, and so on.

[0112] It is another object of the present invention to provide a system and method for body emulation using at least one wearable sensor.

Claims

CLAIMS We claim:

1. A method for determination of positions of multiple independent objects in real time, wherein said method comprises:

an initiation phase comprising:

transmitting a high speed initiation signal from a central control unit to a plurality of sensors, each of said sensors comprising at least one event timer, each of said sensors associated with one of at least one mobile device; each of said at least one mobile device moving with at least a portion of one of said independent objects;

transmitting a unique low speed calibration signal from each said sensor upon reception at said sensor of said initiation signal;

receiving said low-speed calibration signals;

determining, for each said low speed calibration signal, the difference in time from the transmission of said initiation signal to the reception of said low speed calibration signal; and,

2. The method according to claim 1, wherein said step of transmitting said high speed initiation signal to said plurality of sensors comprises transmitting said high speed initiation signal to at least one predetermined subset of said plurality of sensors.

3. The method according to claim 1, wherein said step of transmitting said unique low speed calibration signal from each of said plurality of sensors comprises a step of selecting each said low speed calibration signal from each of said plurality of sensors, characterized in that the same is orthogonal to all of said low speed calibration signals transmitted from all others of said plurality of sensors.

4. The method according to claim 1, wherein said step of receiving a signal selected from a group consisting of said low-speed calibration signals, said high-speed initiation signals and any combination thereof comprises receiving said signal at said central control unit.

5. The method according to claim 1, wherein said step of receiving said low-speed calibration signals comprises receiving at each of said sensors at least one low-speed calibration signal transmitted by at least one different sensor.

6. The method according to claim 1, wherein said high speed initiation signal is transmitted by a form of electromagnetic radiation selected from a group consisting of radio waves, microwaves, visible light, and infrared radiation.

7. The method according to claim 1, wherein said low speed calibration signal is transmitted with a propagation velocity less than or equal to that of sound.

8. The method according to claim 1, wherein said low speed calibration signal is transmitted via ultrasound.

9. The method according to claim 1, wherein each said low speed calibration signal is transmitted at a frequency different from frequency of every other low speed calibration signal.

10. The method according to claim 1, wherein each unique low speed calibration signal is transmitted along with a unique identifying code.

11. The method according to claim 1, wherein at least one of said high speed signal and said low speed detection signal carries information about said object.

12. The method according to claim 11, wherein said information is selected from a group consisting of:

information about whether a particular button associated with said object has been pushed;

information about whether a particular circuit associated with said object is open or closed; and,

information about whether a particular switch associated with said object is in a predetermined position and any combination thereof.

13. The method according to claim 1, wherein said position determination phase comprises:

transmitting a unique high-speed detection signal and a unique low-speed detection signal from each of said at least one mobile device, wherein each unique high-speed detection signal and each unique low-speed detection signal is associated with a particular one of said at least one mobile device;

receiving said detection signals at said plurality of sensors;

decoding said detection signals;

calculating a distance from each particular one of said at least one mobile device to each sensor that receives a high-speed and a low-speed detection signal associated with said particular one of said at least one mobile device; and,

transmitting said calculated distances to a processing unit.

14. The method according to claim 13, wherein said processing unit is a part of said control unit.

15. The method according to claim 13, wherein said step of calculating a distance comprises calculating a distance based on an approximation that said high-speed detection signal has an infinite propagation velocity.

16. The method according to claim 13, wherein said high speed detection signal is transmitted by a form of electromagnetic radiation selected from a group consisting of radio waves, microwaves, visible light, infrared radiation and any combination thereof.

17. The method according to claim 13, wherein said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound.

18. The method according to claim 13, wherein said low speed detection signal is transmitted via ultrasound.

19. The method according to claim 13, comprising transmitting from at least one of said at least one mobile devices to said control unit additional coded information.

20. The method according to claim 19, wherein said additional coded information comprises a Walsh code.

21. The method according to claim 13, wherein each unique detection signal is transmitted at a different frequency.

22. The method according to claim 13, wherein each unique detection signal is transmitted along with a unique identifying code.

23. The method according to claim 13, wherein at least one of said high speed signal and said low speed detection signal carries information about said object.

24. The method according to claim 23, wherein said information is selected from a group consisting of:

25. The method according to claim 1, wherein said position determination phase comprises:

transmitting a high-speed detection signal from said control unit to each of said at least one mobile devices and each of said sensors;

transmitting from each of said at least one mobile devices a unique low-speed detection signal associated with that particular one of said at least one mobile device upon reception of said high-speed detection signal at said particular one of said at least one mobile device, said low-speed detection signal having a particular signal level; receiving said low-speed detection signals at said sensors; and,

for each low-speed detection signal received at a particular sensor:

decoding said low-speed detection signal; and,

calculating a distance between said at least one mobile device associated with said low-speed detection signal and said sensor from a difference in time between reception of said high-speed detection signal and reception of said low-speed detection signal.

26. The method according to claim 25, wherein said step of transmitting from each of said at least one mobile device said unique low-speed detection signal comprises selecting each of said low-speed detection signals to be orthogonal to all of said low-speed detection signals transmitted from all of said other sensors.

27. The method according to claim 25, comprising transmitting an instruction from said control unit to each of said at least one mobile device whether or not to participate in said position determination phase.

28. The method according to claim 27, comprising putting each of said at least one mobile device that is instructed not to participate in said position determination phase into sleep mode.

29. The method according to claim 25, comprising transmitting an instruction from said control unit to each of said at least one mobile device to alter said signal level.

30. The method according to claim 25, comprising transmitting a delay time from said control unit to each of said at least one mobile device, wherein said step of transmitting a low-speed detection signal comprises transmitting a low-speed detection signal said delay time after reception of said high-speed detection signal.

31. The method according to claim 25, comprising putting each of said at least one mobile device into a sleep mode after said transmitting of said low-speed detection signal until reception of another said high-speed detection signal.

32. The method according to claim 25, wherein said step of calculating a distance comprises calculating a distance based on an approximation that said high-speed detection signal has an infinite propagation velocity.

33. The method according to claim 25, wherein said high speed detection signal is transmitted by a form of electromagnetic radiation selected from a group consisting of radio waves, microwaves, visible light, and infrared radiation and any combination thereof.

34. The method according to claim 25, wherein said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound.

35. The method according to claim 25, wherein said low speed detection signal is transmitted via ultrasound.

36. The method according to claim 25, wherein each said low speed detection signal is transmitted at a different frequency.

37. The method according to claim 25, wherein each said low speed detection signal is transmitted along with a unique identifying code.

38. The method according to claim 25, wherein at least one of said high speed signal and said low speed detection signal carries information about said object.

39. The method according to claim 38, wherein said information is selected from a group consisting of: information about whether a particular button associated with said object has been pushed;

information about whether a particular switch associated with said object is in a predetermined position.

40. The method according to claim 1, wherein said position detection phase comprises: transmitting a high-speed detection signal from said control unit;

transmitting a unique low-speed detection signal from each of said sensors upon reception of said high-speed detection signal, each of said unique low-speed detection signals associated with a particular sensor;

receiving said high-speed detection signal and at least one of said low-speed detection signals at each of said at least one mobile device;

determining at each mobile device a difference in time between the reception of said high-speed detection signal and each of said unique low-speed detection signals; and,

transmitting from each of said at least one mobile device to a processing unit said difference in time.

41. The method according to claim 40, comprising putting each of said at least one mobile device into a sleep mode after said transmitting a low-speed detection signal until reception of another high-speed detection signal.

42. The method according to claim 40, wherein said step of calculating a distance comprises calculating a distance based on an approximation that said high-speed detection signal has an infinite propagation velocity.

43. The method according to claim 40, wherein said high speed detection signal is transmitted by a form of electromagnetic radiation selected from a group consisting of radio waves, microwaves, visible light, and infrared radiation.

44. The method according to claim 40, wherein said low speed detection signal is characterized by a propagation velocity less than or equal to that of sound.

45. The method according to claim 40, wherein said low speed detection signal is transmitted via ultrasound.

46. The method according to claim 40, wherein each said low speed detection signal is transmitted at a different frequency.

47. The method according to claim 40, wherein each said low speed detection signal is transmitted along with a unique identifying code.

48. The method according to claim 40, wherein at least one of said high speed signal and said low speed detection signal carries information about said object.

49. The method according to claim 48, wherein said information is selected from a group consisting of:

50. The method according to claim 1, wherein each of said at least one mobile device is attached to one said object.

51. The method according to claim 1, wherein each member of a group consisting of said at least one mobile device, said at least one sensor, said processing units and any combination thereof is attached to one said object.

52. The method according to claim 1, wherein said at least one sensor is physically connected to one said processing unit.

53. The method according to claim 1, wherein said object is a human being.

54. The method according to claim 53, wherein human being is a player in a multi-player game.

55. The method according to claim 1, wherein body emulation is provided by means of at least one wearable sensor.

56. A system for real-time detection and location of a plurality of independent objects, comprising:

a control unit (100) configured to transmit and receive high speed signals and low speed signals;

a processing unit (110) configured to process data received by said control unit;

a plurality of sensors (120) in communication with said control unit, each of which incorporates at least one event timer; and,

a plurality of mobile devices (130) comprising said sensors and associated with said objects, said plurality of mobile devices in communication with said control unit.

57. The system according to claim 56, wherein said sensors are portable.

58. The system according to claim 56, wherein said mobile devices are attached to said objects.

59. The system according to claim 56, wherein said processing unit is part of said control unit.

60. The system according to claim 56, wherein said sensors are physically connected to said processing units.

61. The system according to claim 56, wherein said sensors, said mobile devices, and central control unit are all mobile.

62. The system according to claim 56, wherein said high speed signals are transmitted by a form of electromagnetic radiation selected from a group consisting of radio waves, microwaves, visible light, and infrared radiation.

63. The system according to claim 56, wherein said low speed signals are characterized by a propagation velocity less than or equal to that of sound.

64. The system according to claim 56, wherein said low speed signals are transmitted via ultrasound.

65. The system according to claim 56, wherein said sensors are in communication with one another.

66. The system according to claim 56, wherein said sensors maintain their relative positions subsequent to activation of said system, but are not fixed in position prior to activation of said system.

67. The system according to claim 56, wherein said sensors are configured to transmit unique low speed signals.

68. The system according to claim 56, wherein at least one of said high speed signal and said low speed signal carries information about said object.

69. The system according to claim 68, wherein said information is selected from a group consisting of:

70. The system according to claim 56, wherein each of said mobile devices is configured to transmit at least one type of unique signal selected from a group consisting of unique high speed signals and unique low speed signals.

71. The system according to claim 56, wherein said sensors are configured to receive at least one type of signal selected from a group consisting of high speed signals and low speed signals.

72. The system according to claim 56, wherein each of said objects has at least one mobile device, at least one sensor, and at least one processing unit attached to it.

73. The system according to claim 56, wherein said objects are human beings.

74. The system according to claim 73, wherein said human beings are players in a multi- player game.

75. The system according to claim 56, wherein said system comprises a plurality of subsystems, each of said subsystems comprising a subset of said sensors.

76. The system according to claim 75, wherein said control unit is configured to transmit to one subsystem at a time.

77. The system according to claim 56, wherein body emulation is provided by means of at least one wearable sensor

78. A method for determination of positions of multiple independent objects in real time, wherein said method comprises:

an initiation phase comprising:

receiving said low-speed calibration signals;

79. The method of claim 78, additionally comprising step of initiating said transmission of said unique low speed calibration signal by member of a group consisting of: as determined by a clock internal to each said sensor, by a high-speed wake-up call received by each said sensor, or by a low-speed wake-up call received by each said sensor.

80. The method of claim 79, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said unique low speed calibration signal, as determined by said internal clock and said receiving of said unique low speed calibration signal, as determined by said internal clock.

81. The method of claim 79, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said high-speed wake-up call and said receiving of said unique low speed calibration signal.

82. The method of claim 81, additionally comprising step of calculating said distance from said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

83. The method of claim 79, additionally comprising step of calculating at least one distance between at least two of said plurality of sensors from a time difference between said transmitting of said low-speed wake-up call and said receiving of said unique low-speed calibration signal.

84. The method of claim 83, additionally comprising step of calculating said distance from half said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

85. The method of claim 79, additionally comprising step of selecting a member of a group consisting of said high-speed wake-up call, said low-speed wake-up call and any combination thereof from a group consisting of: either the same for all sensors, or differing between at least two subsets of sensors.

86. The method of claim 83, additionally comprising step of selecting said difference from a group consisting of: being orthogonal, being of different frequencies, being transmitted along with a unique identifying code, and any combination thereof.

87. The method of claim 78, additionally comprising step of selecting a difference between said low-speed calibration signals from a group consisting of: being orthogonal, differing in frequency, being transmitted along with a unique identifying code, and any combination thereof.

88. The method of claim 78, additionally comprising step of selecting said low-speed calibration signals to be orthogonal.

89. The method of claim 78, additionally comprising step of sending said wake-up signal either to all of the sensors/mobile devices or to at least one subset of the units.

90. The method of claim 78, additionally comprising step of selecting components of said wake-up signal from a group consisting of: a wake-up call, an identification code indicating which subset of said sensors is to be wakened, a time signal, a reset signal, a test signal, and any combination thereof.

91. The method according to claim 78, wherein body emulation is provided by means of at least one wearable sensor

92. A system for determination of positions of multiple independent objects in real time, comprising: a plurality of sensors (120), each configured to transmit a unique low speed calibration signal, each configured to receive a low-speed calibration signal;

at least one processing unit (110) configured to process data received from said sensors; a plurality of mobile devices (130) comprising said sensors and associated with said objects, said plurality of mobile devices in communication with said control unit wherein said processing unit is configured to determine, from said data received from said sensors, relative distances between said multiple independent objects.

93. The system of claim 92, wherein said transmission of said unique low speed calibration signal is initiatable by member of a group consisting of: as determined by a clock internal to each said sensor, by a high-speed wake-up call received by each said sensor, or by a low-speed wake-up call received by each said sensor.

94. The system of claim 92, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said unique low speed calibration signal, as determined by said internal clock and said receiving of said unique low speed calibration signal, as determined by said internal clock.

95. The system of claim 92, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said high-speed wake-up call and said receiving of said unique low speed calibration signal.

96. The system of claim 95, wherein said distance is calculatable from said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

97. The system of claim 89, wherein at least one distance between at least two of said plurality of sensors is calculatable from a time difference between said transmitting of said low-speed wake-up call and said receiving of said unique low-speed calibration signal.

98. The system of claim 97, wherein said distance is calculatable from half said time difference minus a system reaction time multiplied by a speed of sound of said unique low speed calibration signal.

99. The system of claim 92, wherein a member of a group consisting of said high-speed wake-up call, said low-speed wake-up call and any combination thereof is selected from a group consisting of: either the same for all sensors, or differing between at least two subsets of sensors.

100. The system of claim 99, wherein said difference is selected from a group consisting of: being orthogonal, being of different frequencies, being transmitted along with a unique identifying code, and any combination thereof.

101. The system of claim 92, wherein a difference between said low-speed calibration signals is selected from a group consisting of: being orthogonal, differing in frequency, being transmitted along with a unique identifying code, and any combination thereof.

102. The system of claim 92, wherein said low-speed calibration signals are selected to be orthogonal.

103. The system of claim 92, wherein said wake-up signal is transmittable either to all of the sensors/mobile devices or to at least one subset of the units.

104. The system of claim 92, wherein components of said wake-up signal is selected from a group consisting of: a wake-up call, an identification code indicating which subset of said sensors is to be wakened, a time signal, a reset signal, a test signal, and any combination thereof.

105. The system according to claim 92, wherein body emulation is provided by means of at least one wearable sensor