Patent Grant
7388517
This invention relates to motor vehicle detection modules, in particular, to self-powered vehicular sensors supporting magnetic sensors in communication with a wireless sensor network, for placement upon pavement.
Today, there are vehicular sensor nodes using a magnetic sensor based upon a buried inductive loop in the pavement These prior art vehicular sensor nodes have several problems. First, to install them, the pavement must be torn up and the inductive coil buried. This installation process is not only expensive, but the quality of installation depends upon the proficiency of the installer. What is needed is a vehicular sensor node that is reliable and inexpensive to install without requiring a lot of training and/or experience.
Today, magnetic sensors, in particular magneto-resistive sensors, exist which can be used to sense the presence, and sometimes the direction, of a vehicle passing near them. Some significant elements of their use and installation are missing in the prior art. By way of example, how to mechanically package these sensors so they can be mounted on pavement and internally powered. Also, how to provide them an interface to traffic monitoring networks which can be pavement mounted and internally powered. And how to install the packaged sensors in a cost effective, reliable manner.
Today, there exist hard plastic shells which have been proven to withstand road use on pavement, but which have never been used for vehicular sensor nodes. These plastic shells have been used for road level traffic signals and traffic direction indicators, and are usually powered by an inductive coupling between a buried cable and an inductive power coupling to the electronics inside the plastic shell.
Today, there are many parking facilities and controlled traffic regions where knowing the availability of parking spaces on a given floor or region would be an advantage, but costs too much to implement. An inexpensive way to determine parking space availability is needed in such circumstances.
Today, many parking facilities and controlled traffic regions must identify and log vehicles upon entry and exit. This process is expensive, often requiring personnel. What is needed is an inexpensive mechanism providing this service. What is needed is a low cost, reliable mechanism for monitoring entry and exit from these facilities and regions.
Today, many traffic authorities use a radar based velocity detection approach to apprehend motorists driving vehicles at illegal speeds. These radar based systems are relatively inexpensive, but are detectable by motorists who equip their vehicles with radar detection devices. Consequently, these motorists often avoid detection of their illegal activities. While alternative optical speed detection systems exist, they have proven very expensive to implement. What is needed is a low cost, reliable mechanism for vehicle velocity detection identifying the vehicle violating the traffic laws.
This invention relates to motor vehicle detection modules, in particular, to self-powered vehicular sensors supporting magnetic sensors in communication with a wireless sensor network, for placement upon pavement.
The invention includes a vehicular sensor node, which is inexpensive, efficient, and reliable. It operates as follows: a clock count is maintained to create a task trigger and a task identifier. Power from a power source is controlled for delivery to a radio transceiver and a magnetic sensor based upon the task trigger and the task identifier. The radio transceiver and the magnetic sensor are operated based upon the task identifier, when the task trigger is active. The power source, the radio transceiver, and the magnetic sensor are enclosed in the vehicular sensor node, which is placed upon pavement and operates for at least five years without replacing the power source.
The invention includes a circuit apparatus for the vehicular sensor node. It includes the following. Means for maintaining the clock count to create the task trigger and the task identifier. Means for controlling the power from the power source delivered to the radio transceiver and the magnetic sensor based upon the task trigger and the task identifier. And means for operating the radio transceiver and the magnetic sensor based upon the task identifier, when the task trigger is active.
The means for maintaining the clock count preferably is powered and runs most if not all the time, whereas the means for controlling and the means for operating are preferably powered only when a task is triggered. When the means for controlling and/or the means for operating are powered, they tend to consume much more power than the means for maintaining the clock count. The invention preferably minimizes power dissipation using this apparatus and its method of operation.
One or more computers, field programmable logic devices, and/or finite state machines may be included to implement these means. Preferably, the means for controlling the power may minimize delivery of power to all circuitry when the task trigger is inactive, or the task identifier does not indicate the need for the circuitry, where the circuitry includes the radio transceiver, the magnetic sensor, the computer, as well as other circuits, such as memory. The power consumption of the minimized circuitry may preferably be less than 100 nano-watts (nw), further preferably less than 10 nw. The means for maintaining the clock count may be powered most of the time. The means for maintaining may couple with a clock crystal. The clock crystal may preferably operate at approximately 32K Herz (Hz), where 1K is 1024.
At least two of the means for maintaining, the means for controlling, and the means for operating may preferably be housed in a single integrated circuit. Preferably, all three means may be housed in the single integrated circuit. Also, the single integrated circuit may house the radio transceiver and/or the magnetic sensor. The circuit apparatus may include an antenna coupled with the radio transceiver. The antenna may preferably be a patch antenna.
The power source, may preferably include at least one battery, and may further preferably include at least one solar cell.
The magnetic sensor preferably uses a form of the magnetic resistive effect, and includes a more than one axis magneto-resistive sensor to create a magnetic sensor state. The magnetic sensor preferably includes a three axis magneto-resistive sensor.
The radio transceiver preferably implements a version of at least one wireless communications protocol, preferably the IEEE 802.15.4 communications standard. It uses at least one channel of the wireless communication protocol. It may use a second channel to communicate with a vehicle radio transceiver associated and/or attached to a vehicle.
The circuit apparatus may further include a light emitting structure, used to visibly communicate during installation and/or testing a vehicular sensor network. The circuit apparatus may also include a second light emitting structure used to communicate with vehicle operators and/or for pedestrians. In certain preferred embodiments, the previously discussed light emitting structure may implement the second light emitting structure. One important potential use is the indication of a traffic hazard.
The vehicular sensor may preferably be used in a vehicular sensor network providing traffic reports regarding parking space availability, logs of vehicular entry and exits, vehicular speeds, and photographs of license plates when needed.
The invention includes making a filled shell and the vehicular sensor node from the circuit apparatus, as well as the filled shell and the vehicular sensor node as products of that process.
The invention includes a vehicular sensor node, which is inexpensive, efficient, and reliable. The invention operates as follows: a clock count is maintained to create a task trigger and a task identifier. The power from a power source is controlled for delivery to a radio transceiver and a magnetic sensor based upon the task trigger and the task identifier. The radio transceiver and the magnetic sensor are operated based upon the task identifier, when the task trigger is active. The power source, the radio transceiver, and the magnetic sensor are enclosed in the vehicular sensor node, which is placed upon the pavement and operates for at least five years, and preferably at least ten years, without replacement of the power source or its components.
The invention as shown
The invention includes a circuit apparatus 100 for enclosure in a vehicular sensor node 500 as shown in
The means for maintaining 300 may preferably include a clock timer 22 controllably coupled to the computer 10 to deliver the task trigger 38 and the task identifier 34, and communicatively coupled with the computer to communicate said clock count 36, as shown in
The invention preferably includes a method of using the power source 60 of
Distributing the power 62 from the power source 60, preferably includes: Delivering the transceiver power 74 to the radio transceiver 20, when the task identifier 34 indicates that the radio transceiver is used. And delivering a sensor power 80 to the magnetic sensor 2, when the task identifier indicates the magnetic sensor is used. Delivering power to the radio transceiver and/or the magnetic sensor may preferably require starting to deliver power before performing the relevant operations with them.
The method of using the power source 60 of
The magnetic sensor 2 of
The magnetic sensor 2 has a primary sensing axis 4 for sensing the presence of a vehicle 6. Preferably, the magnetic sensor 2 may be first communicatively coupled 12 with a computer 10 and the magnetic sensor provides a magnetic sensor state 32 to the computer.
The radio transceiver 20 preferably implements a version of at least one wireless communications protocol, preferably the IEEE 802.15.4 communications standard. The wireless communications protocol may further preferably be the IEEE 802.15.4 communications standard. The radio transceiver uses at least one channel of the wireless communication protocol. It may use a second channel to communicate with a vehicle radio transceiver 8 associated and/or attached to the vehicle 6. The radio transceiver is preferably a CC2420 transmitter and receiver manufactured by ChipCon.
The radio transceiver 20 may include a receiver and a transmitter. Operating the radio transceiver often refers to operating exactly one of either the receiver or the transmitter. It may be preferred that when the receiver is being operated, power delivery to the transmitter is minimized. Similarly, when the transmitter is operated, power delivery to the receiver is minimized.
The means for operating 320 may preferably include the computer 10 controllably coupled 80 to the power circuit 70, controllably coupled 16 to the radio transceiver 20, and controllably coupled 12 to the magnetic sensor 2; and the computer accessibly coupled 14 with a memory 30 containing a program system 200, including the program steps of: operating said radio transceiver and said magnetic sensor based upon said task identifier 34, when said task trigger 38 is active, as shown in
Preferably, the computer 10 may also be second communicatively coupled 16 with the radio transceiver 20, as shown in
The circuit apparatus 100 may preferably include a light emitting structure 40, as shown in
The circuit apparatus 100 may further include the following. The computer 10 may be controllably coupled 80 with the power control 70 as shown in
Operating the vehicular sensor node 500 and/or the circuit apparatus 100 may preferably include using the light emitting structure 40 to visibly communicate, when the task identifier 34 indicates a feedback task. Using the light emitting structure 40 to visibly communicate preferably includes: receiving from the radio transceiver 20 a probe node address 54, and visibly communicating using the probe node address 54. The circuit apparatus, preferably further includes a node address 56. Visibly communicating using the probe node address further includes: visibly communicating when the node address equals the probe node address.
Alternatively, visibly communicating using the probe node address 54 may further include at least one the following: Visibly communicating when the node address 56 does not equal the probe node address. Visibly communicating when the node address is less than the probe node address. And visibly communicating when the node address is greater than the probe node address.
The circuit apparatus 100 may preferably include a second light emitting structure 140, as shown in
An example of a preferred circuit apparatus 100 is shown in
At least two of the means for maintaining 300, the means for controlling 310, and the means for operating 320 may preferably be housed in a single integrated circuit. Preferably, all three means may be housed in the single integrated circuit. Also, the single integrated circuit may house the radio transceiver 20 and/or the magnetic sensor 2. The circuit apparatus 100 may include an antenna 28 coupled 26 with the radio transceiver. The antenna may preferably be a patch antenna. In certain preferred embodiments, the computer 10 and the clock timer 22 may be housed in a single integrated circuit.
Some of the following figures show flowcharts of at least one method of the invention, which may include arrows with reference numbers. These arrows signify a flow of control, and sometimes data, supporting various implementations of the method. These include at least one the following: a program operation, or program thread, executing upon a computer; an inferential link in an inferential engine; a state transition in a finite state machine; and/or a dominant learned response within a neural network.
The operation of starting a flowchart refers to at least one of the following. Entering a subroutine or a macro instruction sequence in a computer. Entering into a deeper node of an inferential graph. Directing a state transition in a finite state machine, possibly while pushing a return state. And triggering a collection of neurons in a neural network. The operation of starting a flowchart is denoted by an oval with the word “Start” in it.
The operation of termination in a flowchart refers to at least one or more of the following. The completion of those operations, which may result in a subroutine return, traversal of a higher node in an inferential graph, popping of a previously stored state in a finite state machine, return to dormancy of the firing neurons of the neural network. The operation of terminating a flowchart is denoted by an oval with the word “Exit” in it.
A computer as used herein will include, but is not limited to, an instruction processor. The instruction processor includes at least one instruction processing element and at least one data processing element. Each data processing element is controlled by at least one instruction processing element.
The program system 200 of
Operation 232 of
Making the vehicular sensor node 500 from the circuit apparatus 100 and from a plastic shell 510 as shown in
One skilled in the art will also recognize that the steps of inserting 502 and filling 522 may be reversed in making the filled shell 540. These steps will be referred to hereafter as enclosing the circuit apparatus 100 in the plastic shell 510 filled with the filler 530 to create the filled shell.
The plastic shell 510 may resiliently deform while preserving the glued bond 552 when the vehicle 6 rests 556 on the plastic shell 510. The vehicle may further rest on the plastic shell for more than a day, an hour, a minute, and/or a second.
The plastic shell 510 preferably includes a polycarbonate compound, preferably a high impact polycarbonate compound. The plastic shell may further preferably be made from a Bayer high impact polycarbonate compound. The plastic shell may further preferably be a version of the SMARTSTUD™ plastic shell manufactured by Harding Systems as described at http:/www.hardingsystems.com/
The filler 530 preferably includes an elastomer, which further preferably includes a polyurethane elastomer. The gluing 542 preferably uses an adhesive, which preferably does not destructively interact with the plastic shell 510, and may further be manufactured by Harding Systems.
The invention includes a second circuit apparatus 1000 for an access point 1500 for wireless communicating 2202 with at least one vehicular sensor node 500 as shown in
The multiple vehicle sensor nodes wirelessly communicating with the access point 1500 are preferably configured to form a time division multiple access network, in which no more than one vehicle sensor node sends information to the access point across one channel in one time slot. The access point may send information to more than one, and in certain situations, all the vehicle sensor nodes on one channel during one time slot. By way of example, the access point may send the global clock count to all vehicular sensor nodes at essentially the same time.
The operations of the access point 1500 may be implemented by the second program system 1200, which may preferably include the following. When the second task identifier 1034 indicates distribute clock alignment, the second clock count 1036 is used to create the global clock count 52, and the second radio transceiver 1020 sends the global clock count 52 to at least one vehicular sensor node 500. When the second task identifier indicates access sensor state of the vehicular sensor node, the second radio transceiver is used to receive the received vehicular sensor state 1050 from the vehicular sensor node. When the second task identifier indicates update the second received vehicular sensor state 1052, the second received vehicular sensor state is updated based upon at least the received vehicular sensor state. When the second task identifier indicates calculate a vehicle velocity estimate 1054, the vehicle velocity estimate is calculated based upon the received vehicular sensor state and a second received vehicular sensor state 1052. When the second task identifier indicates a traffic network update, a traffic report 1056 is generated based upon the received vehicular sensor state and the second received vehicular sensor state, and the traffic report is sent using the network transceiver 1060 across the network-coupling 2502 to the traffic monitoring network 2500.
Installing the vehicular sensor node 500, wireless communicating 2202 with an access point 1500, as shown in
The traffic flow zone 2000 may include more than one primary traffic flow 2002, often indicating two-way traffic. The traffic monitoring zone 2200 may include more than one traffic flow zone. By way of example,
The first traffic flow zone 2000-1 includes a first primary traffic flow 2002-1. A first-first vehicular sensor node 500-1,1 and a first-second vehicular sensor node 500-1,2 are installed in the first traffic flow zone. The primary sensing axis 4 of these vehicular sensor nodes are aligned with the first primary traffic flow.
The second traffic flow zone 2000-2 includes a second primary traffic flow 2002-2. A second-first vehicular sensor node 500-2,1 and a second-second vehicular sensor node 500-2,2 are installed in the second traffic flow zone. The primary sensing axis 4 of these vehicular sensor nodes are aligned with the second primary traffic flow.
When a first vehicle 6-1 travels in the first primary traffic flow 2002-1 of the first traffic flow zone 2000-1, the following operations are performed by the first-first vehicular sensor node 500-1,1 and the first-second vehicular sensor node 500-1,2 installed in the first traffic flow zone. Both of the vehicular sensor nodes are time synchronized by the access point 1500 to within a fraction of a second, in particular, to fraction of a millisecond. The magnetic sensor state 32 of each vehicular sensor node is used to create a vehicle sensed state 50 within that vehicular sensor node. Both vehicular sensor nodes send their vehicle sensed state to at least partly create the received vehicular sensor state.
It is often preferred that the received vehicular sensor state 1050 includes a time synchronized sensor state for each magnetic sensor in the vehicular sensor nodes for the same traffic flow zone. One preferred method of determining a vehicle velocity estimate 1054 includes using at least two vehicle sensor nodes, such as the first-first vehicular sensor node 500-1,1 and the first-second vehicular sensor node 500-1,2. These vehicular sensor nodes are positioned a distance d apart. Each magnetic sensor 2 is synchronously used to determine the presence of the first vehicle 6-1. The time it takes for the first vehicle to travel from the first-first vehicular sensor node to the first-second vehicular sensor node is preferably known to a fraction of a millisecond. The vehicle velocity estimate is the ratio of the distance d traveled divided by the time to travel, and is typically accurate to a fraction of a percent.
The access point 1500 may integrate the number of vehicles sensed by a collection of vehicular sensor nodes to estimate availability of parking in a parking facility, or a region of the parking facility. The traffic report 1056 may include the estimated availability. The traffic monitoring network 2500 may present the estimated availability to a vehicle 6 trying to park. The vehicle may be operated by a human operator or directed by an automatic driving system.
This may preferably be implemented by a number of schemes. By way of example, each parking spot may be equipped with a vehicular sensor node 500. The access point 1500 may wirelessly communicate with vehicular sensor nodes throughout all or part of a parking facility, forming its estimated availability accurate to each parking spot. Another example scheme uses a vehicular sensor node in each traffic flow zone 2000 of each entrance and each exit to all or part of the parking facility. The estimated availability is then preferably accurate about the number of parking slots available, but not their exact location.
The access point 1500 preferably includes a network transceiver 1060, which may have several preferred embodiments. The network transceiver may include only a network transmitter. Alternatively the network transceiver may include the network transmitter and a network receiver.
The traffic monitoring network 2500 may include a Nema traffic control cabinet. The Nema traffic control cabinet may include a type 170 controller. Alternatively, the Nema traffic control cabinet may include a type 2070 controller. The network transmitter may interface to a relay drive contact, preferably through an opto-isolation circuit. The Nema traffic control cabinet may preferably employ an interface printed circuit board, which may support two relay drive contacts.
In
Alternatively, the traffic monitoring network 2500 may implement another embodiment of the network-coupling 2502. The network-coupling may include a wireline communications protocol. The wireline communications protocol may include at least one of the following: RS-232, RS-485, in particular, a TS-2 application layer on top of the RS-485 network layer. This application layer may support 19,200 to 600,000 bits per second transfer rates. The network-coupling may further include a version of Ethernet, possibly further supporting a version of High level Data Link Control (HDLC).
The second circuit apparatus 1000 may further include a video camera 1066 video-coupled 1064 with the second computer 1010, as shown in
Alternatively, the second memory 1030 may include a non-volatile memory component, which may store the traffic report 1056. The non-volatile memory component storing the traffic report may reside in a removable memory device. Alternatively, the second circuit apparatus 1000 may include a socket for a removable memory device. Traffic reports may be collected, by inserting a removable memory device in the socket, and transferring them to the removable memory device.
The video camera 1066 may be used to identify the vehicle 6 entering and/or leaving a parking structure or reserved entry area. Each time the access point 1500 determines the entry or exit of the vehicle in a traffic flow zone 2000, the video camera may be triggered to photograph the license plate 9. With an overall system strobe of once every millisecond, there is a highly probable, perceptible gap between vehicles entering or leaving.
The preceding embodiments provide examples of the invention and are not meant to constrain the scope of the following claims.
This application claims priority to Provisional Patent Application Ser. No. 60/549,260, filed Mar. 1, 2004 and Provisional Patent Application Ser. No. 60/630,366, filed Nov. 22, 2004, both of which are incorporated herein by reference.
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