Data processing: vehicles – navigation – and relative location – Navigation – Employing position determining equipment
Reexamination Certificate
1999-12-19
2003-08-26
Black, Thomas C. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Navigation
Employing position determining equipment
C701S027000, C701S035000, C340S438000, C340S439000, C455S012100, C455S039000, C455S059000, C455S059000
Reexamination Certificate
active
06611755
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention disclosed herein broadly relates to asset management systems, and more particularly to a system for tracking the real-time location and status of vehicles of a fleet, and for communicating between the vehicles and a dispatcher or expediter in the fleet offices.
Operators of fleet vehicle businesses need to know where each vehicle in the fleet is located and what it is doing in order to make decisions on how to use the vehicles most efficiently. In recent years, vehicle locating systems have been developed using Global Positioning System (GPS) satellite information, and, for greater accuracy, differential GPS (DGPS) systems. These systems are highly accurate where line of sight (LOS) conditions exist, that is, where the vehicle (or more accurately, the vehicle's GPS receiver) has a clear LOS to the appropriate number of GPS satellites. But such conditions are typically unavailable or are at least less frequently available for a vehicle operating on city streets, particularly in areas where multi-story buildings are present, owing to the shielding that such buildings effect. In those circumstances an alternative navigation system such as dead reckoning (DR) navigation may be used to provide vehicle position and velocity data in urban canyons (i.e., streets bordered by tall buildings) where GPS measurements are only intermittently available. Or a map matching technique or navigation grid may be used as another or additional alternative.
Currently, wireless voice communication between dispatchers and drivers is the primary means of addressing the need of the fleet owner or operator to know what each vehicle is doing, i.e., its operations taking place at any given time, and where the vehicle is located when a particular operation is occurring. In industries where vehicles perform a repetitive sequence of events with each load, such as for ready mix concrete operations, “status boxes” have recently come into use. The status boxes require the driver to press a button at each stage of operation such as “load,” leave plant,” “arrive job,” “begin pour,” and so forth.
The primary problem with either wireless voice communication or status box systems is that data are manually provided to the dispatcher from the driver of the vehicle. This leads to untimely (late) and, perhaps worse, inaccurate data more than ninety percent of the time, according to analyses performed by the fleet owners/operators. The availability of timely, accurate data is essential if the fleet operator is to operate its business efficiently and economically.
Time Division Multiple Access (TDMA) wireless networks, which are in use for many applications including digital cellular telephones and wireless local area networks, may be used for the communication between dispatchers and drivers. A TDMA network allows multiple users of a single channel or frequency by assigning specific time slots to each user to use exclusively for transmission. For optimal performance of TDMA networks, precise time synchronization between members of the network is required. Efficient use of bandwidth in the network requires that the gap times between transmissions of each user, which is wasted time, be minimized. An important component to the gap time is uncertainty of time in all the participants in the network. Synchronization of wireless networks is often very coarse, requiring large gaps between transmissions, if specialized hardware is not used. Moreover, synchronization of network elements to a precise reference like GPS based timing information involves having a GPS receiver located on each network element, both mobile and fixed, increasing installation costs and complexity for both fixed network infrastructure and mobile network devices, especially if navigation data provided by GPS is not required.
Precise time synchronization between all of the wireless devices in the network can be performed in a number of ways. Typically, a precise, stable time reference, such as one based on the Global Positioning System (GPS) or other time distribution services, is located within each wireless device or within just the fixed infrastructure of the network, with synchronization information being transmitted to the mobile units. In these cases, device or infrastructure costs are increased because timing equipment has to be distributed among several locations or devices and installed where space and access for maintenance are limited.
Transmitting as much information as possible in a given amount of bandwidth is an important design goal in any communications network. This is especially true in wireless networks in which available bandwidth is very limited and customer requirements for data throughput are immense. Operation on most wireless bands is subject to occupied bandwidth constraints, requiring the data signal to be contained in a vary narrow region of the electromagnetic spectrum. In TDMA networks, a challenge is to minimize the gap times between transmissions and the overhead associated with each data packet in order to send as much information bearing data over the network as continuously as possible. The present invention addresses these two requirements with digital filtering to control occupied bandwidth and data recovery by the receiving system that requires no synchronization patterns to be transmitted.
SUMMARY OF THE INVENTION
The primary goal of the fleet management system of the present invention (sometimes in hereinafter called the PROTRAK system or the Galileo system (each of PROTRAK and Galileo, either alone or with various suffixes attached, is a trademark of Fleet Management Services, Inc. of Chandler, Ariz., to which the present patent application is assigned), the fleet management system, or simply the system) is to provide fleet management information to customers (i.e., the owners, operators, subscribers, or users of the fleet who seek to avail themselves of the advantages of a vehicle tracking, communication and fleet management system) to enable them to manage their assets more profitably. The system provides its customers with several means to accomplish this. First, the PROTRAK system gives the fleet operator the capability to locate vehicles of the fleet in real-time. Second, the system allows the operator to communicate with those vehicles over a very efficient and reliable wireless network—a time division multiple access (TDMA) wireless network. Third, the system enables the operator to receive timely, accurate data regarding what each vehicle of the fleet is doing, i.e., what operation(s) it is performing at any given time. Fourth, the system provides the operator with an ability to correlate the position and messaging information generated by the system with the operator's other management information systems to provide an integrated information source for improved fleet business management.
With respect to the latter, a fleet operator's existing management systems typically consist of accounting, human resources, inventory, and other systems which may not be well integrated. In addition, the operator may not have a reliable way to measure vehicle and driver performance which is critical to the operator's operations. The PROTRAK system provides the required vehicle and driver information together with a database management system that is capable of collecting such information and integrating it with data retrieved from the operator's other information systems in a database management application. This application can be used by the operator to generate reports that are tailored to its business and are based on all of the available data.
The PROTRAK system is particularly designed to operate in a market niche between cellular, specialized mobile radio (SMR), and paging services. The system may be used to track virtually any number of vehicles in a fleet across all metropolitan areas covered by the network.
Timely, accurate data can be made available to the fleet operator automatically by combining wireless data network technology, a wireless data c
Allen Robert F.
Billings Mark
Coffee John R.
Dye David A.
Kirchner Mark L.
Black Thomas C.
Blank Rome LLP
To Tuan C
Trimble Navigation Ltd.
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