Communications – electrical: acoustic wave systems and devices – Distance or direction finding – With electromagnetic wave
Reexamination Certificate
1999-09-29
2001-12-04
Lobo, Ian J. (Department: 3662)
Communications, electrical: acoustic wave systems and devices
Distance or direction finding
With electromagnetic wave
C342S055000
Reexamination Certificate
active
06327219
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a following system, and more particularly to a method and system for automatically directing a following device toward a movable object.
BACKGROUND OF THE INVENTION
Automatic following systems have wide applications in automobiles, sports, entertainment, and even toys. As an illustration, a following systems may be employed in a golf cart application. To play golf, a golfer always needs to bring a club bag around a golf course. While a club bag is necessary, it is often too heavy or cumbersome to be conveniently carried. Currently, a player has several choices. First, the player can pay for a caddie to carry the club bag. A drawback is that paying for a caddie is expensive. Second, the player can drive a golf car. This option is less expensive than hiring a caddie, but the golf car might be restricted from some areas. Third, the player can pull a golf cart or simply carry the club bag. However, pulling the golf cart or carrying the bag can make the game less enjoyable. Fourth, the player might use a battery-powered electronic cart.
Current electronic golf carts offer manual control buttons on the cart. A golfer can then set cart speed, and command it to move or stop. Some carts are even equipped with remote controllers so that a golfer can control a cart from a distance. However, none of the existing carts has automatic following capability. Therefore, these carts have the following drawbacks. First, a golfer still needs to worry about controlling the cart. Second, a golf cart may hit a person and cause injury. Third, a golfer may lose balls because of distractions caused by controlling the golf cart.
Automatic tracking, following, or positioning systems determine the position and moving characteristics of a moving object to be followed. Most of the systems use two methods to accomplish this. One method is a so-called “dead beacon” where multiple reference signals are transmitted at fixed locations and a moving object of interest detects the reference signals to compute its location. Such location information can then be made available to the following object. This is the method used in systems with Loran and GPS. The second method is to permit the moving object to transmit reference signals to the following object. The following object detects the reference signal to find out the position of the object to be followed. To find distance and orientation information, the following object usually has spatially distributed detectors. Signals received by the detectors can be used to compute the distance and orientation by triangulation.
There are several drawbacks to the above-mentioned approaches. The first approach requires the setup of a reference system. As a result, the system is expensive, hard to maintain and the working environment is limited. The GPS and Loran systems offer convenient global position reference, but they do not offer enough accuracy for real-time close following as required in certain applications such as golf carts. The second approach has in itself several drawbacks. First, a reference signal needs to be transmitted continuously from an object to be followed to the following object. This puts a strong restriction on its applications for portable use. Using a golf cart or luggage cart as an example, the object to be followed is a person and the following object is a cart. The person needs to carry a transmitter to send out a strong tracking signal. This transmitter which sends out strong signals has a high power consumption, and therefore would require a prohibitively large battery to energize the transmitter. It is therefore highly impractical to use this method for such applications. Secondly, this method puts a limitation on the use of directional signals (i.e., signals transmitting in small angles, such as infrared signals). This is because the body movement of the carrier may cause detection error. Third, in a multi-cart following case, the following carts may follow the wrong person. Fourth, the method does not offer obstacle detection capability.
Accordingly, it is an object of the present invention to provide an automatic following system which overcomes the above-mentioned drawbacks and disadvantages.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, an automated object following system includes a tracker associated with a following device, and a guider associated with an object to be followed. The tracker includes a first processor. At least two means for generating an encoded ultrasonic signal are provided, each having a control input communicating with the first processor for emitting an encoded ultrasonic signal generally toward the guider in response to a command signal from the first processor. The encoded ultrasonic signals carry signal source identification information. A radio frequency (RF) receiver communicates with the first processor for receiving from the guider an encoded RF signal carrying its identification and the time the ultrasonic signals were received by the guider for the first processor of the tracker to determine the distance and direction of the guider relative to the tracker for steering the following device toward the guider or object to be followed.
With respect to the guider, an ultrasonic detector detects the ultrasonic signals generated by the ultrasonic means of the tracker. A second processor communicates with the ultrasonic detector for generating its identification and the time the ultrasonic signals were received by the guider. An RF transmitter communicates with the second processor for transmitting the encoded RF signal carrying the identification and time information to the RF receiver of the tracker upon the reception of the ultrasonic signals by the ultrasonic detector.
Preferably, the tracker includes a plurality of infrared (IR) transmitters communicating with the first processor wherein each of the IR transmitters is oriented in a slightly different direction relative to an adjacent IR transmitter for emitting an encoded IR signal carrying source identification information generally toward the guider. The guider preferably includes an IR receiver communicating with the second processor for detecting at least one of the encoded IR signals generated by the IR transmitters. The second processor encodes information relating to its identification and which of the IR signals was detected by the guider in order to be transmitted back to the tracker by means of an encoded RF signal transmitted by the RF transmitter. The encoded RF signals are thus based on the time of reception of the encoded ultrasonic signals, and which of the encoded IR signals were received by the IR receiver such that the RF transmitter transmits the encoded RF signal to the RF receiver of the tracker based on both the information carried by the ultrasonic and IR signals.
Alternatively, instead of encoding an identification, the IR transmitters may transmit its signals in a predetermined sequence known by the tracker and the guider to permit the guider to identify which of the IR signals is received. Determining which of the IR signals is detected by the guider enables the guider to send back this information to the tracker via the encoded RF signal so that the tracker may precisely determine the heading angle of the guider relative to the tracker.
According to a second aspect of the present invention, a method of directing a following device associated with a tracker toward a movable, followed object associated with a guider is provided. At least two encoded ultrasonic signals directed generally toward the guider are generated at the tracker. Each encoded ultrasonic signal originates from a distinct source that is spaced from the other sources, and each encoded ultrasonic signal carries signal source identification information. The encoded ultrasonic signals are received at the guider, and thereupon an encoded RF signal is directed back to the tracker for directing the following device toward the followed object. The encoded RF signal carries it
Moh John
Zhang Ruiming
Lobo Ian J.
McCormick Paulding & Huber LLP
VI&T Group
LandOfFree
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