Abstract:
Route planning for road vehicles is performed taking into account a ride quality that results from the roadway conditions along road segments on a route. A plurality of vehicles equipped with controlled suspensions calculate ride quality indices as the vehicles move over a plurality of road segments. The plurality of vehicles transmit the ride quality indices tagged with respective geographic coordinates to an aggregating server. The aggregating server determines a composite ride quality index for each road segment. A subscriber generates a route planning request identifying an origin and a destination. At least one potential route is identified between the origin and the destination comprised of selected road segments. A route ride quality index is determined in response to the selected road segments, and the potential route and the route ride quality index are presented to the subscriber for selection.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates in general to route planning and navigation for road vehicles, and, more specifically, to determining preferred routes in response to roadway conditions that affect the ride quality felt by occupants in a vehicle following a route. 
     Roadway vehicles such as cars and trucks utilize dampers between the wheels and vehicle body to improve the ride comfort for the vehicle occupants. In addition to static damping systems such as traditional shock absorbers, adaptive (a.k.a. continuously-controlled) dampers have been introduced in which the damping automatically adjusts to match the driving conditions, resulting in a smooth, comfortable ride experience. 
     The ride behavior of a vehicle (i.e., vibration within the suspension/body system) is composed of two main components known as primary ride and secondary ride. Primary ride refers to body motion caused by a large bump or discontinuity. The suspension motion corresponding to primary ride is characterized by high amplitude and low frequency, such as a frequency range from about one to two Hz. Secondary ride refers to suspension motion having a lower amplitude and a higher frequency, such as around ten Hz., caused by smaller scale but more numerous imperfections in a road surface. 
     Especially for vehicles without adaptive damping, the ride comfort along some roads may be undesirable or unacceptable to some drivers. Thus, if a particular roadway was known in advance to have rough surfaces creating significant primary and/or secondary ride issues, then some drivers might choose to avoid them whenever reasonably possible. 
     Navigation systems for performing route planning to drive a vehicle to a desired destination are known which optimize potential routes according to various factors, such as travel time, travel distance, and maximum or minimum use of freeways. Ride quality, however, has not been available as a parameter for evaluating the desirability of different potential routes. Moreover, the supporting data needed to evaluate the ride comfort associated with different segments of roadway does not exist and would be expensive and time consuming to create. 
     SUMMARY OF THE INVENTION 
     In one aspect of the invention, a route planning system for road vehicles comprises a ride quality database representing a plurality of road segments according to geographic coordinates. An agent is coupled to the ride quality database and is adapted to be coupled to a data network. The agent is configured to receive ride quality data via the data network from a plurality of vehicles traversing the road segments and to determine a composite ride quality index for each road segment according to the received ride quality data. The ride quality data and the composite ride quality indices are stored in the ride quality database in association with the respective road segments. The agent is configured to receive routing requests and to respond to the routing requests by retrieving composite ride quality indices corresponding to road segments identified by the routing requests. 
     In another aspect of the invention, a method of route planning for road vehicles is provided. A plurality of vehicles equipped with controlled suspensions calculate ride quality indices as the vehicles move over a plurality of road segments. The plurality of vehicles transmit the ride quality indices tagged with respective geographic coordinates to an aggregating server. The aggregating server determines a composite ride quality index for each road segment. A subscriber generates a route planning request identifying an origin and a destination. At least one potential route is identified between the origin and the destination comprised of selected road segments. A route ride quality index is determined in response to the selected road segments. The potential route and the route ride quality index are presented to the subscriber for selection. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing a vehicle having controlled dampers and a communication system for providing roadway-induced ride quality reconnaissance of the present invention. 
         FIG. 2  is a diagram showing the elements of a route planning system of the invention. 
         FIG. 3  is a plot showing a spectra of suspension displacement including primary ride and secondary ride. 
         FIG. 4  is a block diagram of a probe vehicle of the invention. 
         FIG. 5  is a flowchart of one preferred method performed by a probe vehicle of the invention. 
         FIG. 6  shows a network server according to one embodiment of the invention. 
         FIG. 7  is a block diagram of a subscriber vehicle for accessing the route planning of the present invention. 
         FIG. 8  is a flowchart of one preferred method for selecting a desired route based in part upon the expected ride quality associated with a route. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the present invention, a cloud-based server receives, processes (e.g., averages), classifies (e.g., on a scale between smooth and rough), and stores vehicle-generated data from multiple vehicles through “crowdsourcing” and makes the classified data available to other vehicles for purposes of route planning. Thus, properly equipped vehicles are used as data probes to evaluate ride quality associated with road segments. More specifically, a crowdsourcing agent receives data from individual vehicles along various roads and generates ratings based on aggregated data from many vehicles that can be used to rank the average ride quality that can be expected when traversing the same roads. The resulting ratings are used by the drivers of other individual vehicles to evaluate and select driving routes where they can obtain a desired ride comfort. 
     Disturbances (i.e., vibrations) induced in the vehicle body and suspension by road surface imperfections have constituent frequencies of two main types. Primary ride relates to road undulations causing body motion with frequency range from one to two Hz. Secondary ride relates to road roughness causing wheel vibration with a frequency around 10 Hz. Traditional suspension systems make a compromise between reducing the magnitude primary ride disturbances (i.e., ride control) and reducing the magnitude of secondary ride disturbances (i.e., ride comfort). If a particular driver is sensitive to driving on fine-scale road roughness, he might wish to avoid routes through rough terrain (i.e., to avoid poor secondary ride performance). If the driver is instead more sensitive to large bumps or potholes, he might prefer to avoid driving on roads with poor primary ride performance. While a vehicle with a continuously-controlled suspension (e.g., continuously-controlled dampers) would reduce the driver&#39;s perception of poor primary ride and secondary ride, it cannot totally eliminate the feel. Thus, some drivers might still prefer to avoid road segments with significant primary or secondary ride even though their vehicle is equipped with adaptive dampers. On the other hand, not all the vehicles are equipped with controlled suspensions. Information about the ride quality for various road segments can be particularly useful to those drivers whose vehicles do not have controlled suspensions. 
     Referring now to  FIG. 1 , a vehicle  10  which is suitable to be used as a data probe for obtaining ride quality data includes a controlled damper  11  coupled to a suspension controller  12 . A suspension sensor  13  and a wheel sensor  14  are likewise coupled to suspension controller  12  as known in the art. A human machine interface (HMI)  15  coupled to controller  12  allows a driver to manually adjust the suspension and to monitor performance. Any known type of suspension actuators and sensors may be employed for the present invention, wherein controller  12  is adapted to communicate with a modem or other wireless communication module  16  for transmitting ride quality data to a remote server via an antenna  17 . Suspension controller  12  continuously characterizes ride quality as vehicle  10  moves over a plurality of road segments based on signals from sensors  13  and  14  and on other computed variables as known in the art. In order to tag the ride quality data with geographic coordinates so that the ride quality data can be associated with particular pre-defined road segments, a GPS receiver  18  is preferably coupled to modem  16  and/or suspension controller  12 . 
     An overall system of the present invention is shown in  FIG. 2  which depicts vehicle  10  traversing a road segment  20 . As represented in a typical subscription navigation database, road segment  20  may have end points at  21  and  22 , for example. Vehicle  10  monitors signals from GPS satellites  23  to determine the geographic position of vehicle  10  and ascertain the identity of road segment  20 . Similarly equipped vehicles  24  and  25  traversing different road segments  26  and  27  may likewise gather ride quality data which may be tagged with respective geographic coordinates also obtained by monitoring GPS satellites  23  and then remotely uploaded to a crowdsourced data repository. 
     For providing communication between data-probing vehicles  10 ,  24 , and  25 , a wireless cellular network including a cell site  30  may be provided. A data network  31  provides a communication path to an aggregating server  32  which includes a supervisory agent  33  and a ride quality database  34 . A route planning function  35  utilizes the ride quality data from server  33  in order to identify the ride quality or comfort level associated with various potential routes. Route planning function  35  may be contained as a part of server  32 , located on-board an individual vehicle, or performed by other servers or resources as part of a navigation service provided to subscribing drivers, for example. 
       FIG. 3  shows an plot representing a spectrum of suspension displacement for a vehicle traversing a road segment having a particular ride quality. A trace  37  represents the magnitude of suspension displacement energy corresponding to respective frequencies of the frequency spectrum. Primary ride is characterized by energy spanning a range  38  between 1 and 2 Hz. Secondary ride is characterized by frequencies in a range  39  around 10 Hz. As used in the present invention, a ride quality index may be formed separately for each of the primary ride and secondary ride, or a single blended value or index based on both primary and secondary ride may be employed. Moreover, the values or combinations of values of the primary and secondary ride may be classified according to a driver-perceived comfort scale, e.g., from smooth to rough, or other characterizations such as slightly bumpy, moderately bumpy, moderate vibrations, etc. 
       FIG. 4  shows one preferred embodiment of an individual vehicle for performing as a data probe for determining both primary and secondary ride qualities. Thus, a plurality of on-board sensors and/or on-board computed values obtained in a block  40  provide the necessary parameters for calculating a primary ride quality index in a block  41  and a secondary ride quality index in a block  42 . Such calculations are well known in the art. The resulting indices are provided to a message controller  43  which also receives a current geographic position from a GPS receiver or a dead-reckoning system (not shown). Message controller  43  sends tagged ride quality data via a data network to an aggregating server as described below. 
     The vehicle system preferably operates according to a preferred method shown in  FIG. 5 . In step  45 , sensor data is collected from motion sensors within the suspension and wheels, and various variables are computed in a suspension controller for controlling variable damping parameters. Using the computed variables and sensor data, primary and secondary ride quality indices may be continuously calculated covering a predetermined distance in step  46 . In order to minimize the volume of network traffic associated with the collection of ride quality data from a large number of vehicles, a check is make in step  47  to determine whether a calculated index is greater than a predetermined threshold (i.e., has a value indicating a sufficiently noticeable degradation in ride quality). If a calculated index is not greater than the threshold then a return is made to step  45  for continuing to monitor ride quality. Otherwise, the index values above the threshold are tagged with geographic coordinates in step  48  and then sent to the cloud-based server in step  49 . 
       FIG. 6  shows the cloud-based aggregating server which collects the crowdsourced road quality data. Specifically, agent  33  receives and processes the new data. Based on the tagged geographic coordinates, it identifies a corresponding road segment. For each road segment within a region being covered by the route planning system, respective data records (such as record  50  and record  51 ) are maintained for storing the collected data points from all the respective vehicles together with a composite index formed by combining (e.g., averaging) these separate index value data points. In the event that no data points have been received for a particular road segment, a default value for the corresponding ride quality index may be used (e.g., a default value indicating a smooth road). Each composite index may correspond with a primary ride quality, a secondary ride quality, or a combination of the two. Either numerical or qualitative index values can be maintained. 
     Since ride quality on any particular surface depends in part on the speed of the vehicle, the use of crowdsourcing collection and aggregation of actual data from vehicles driving on the road segments in real time results in a highly useful and accurate database. 
     Once the road quality database is sufficiently built up, the data is used to support route planning by other vehicles.  FIG. 7  shows functional elements in a vehicle of a subscriber to a route planning service that uses the ride quality data stored on the aggregating server. A navigation system  55  is coupled to an HMI  56  through which a subscribing user can input a desired destination, identify a desired ride quality or comfort to be maintained across a route, and/or select between several potential routes that may be displayed with their corresponding ride quality indices. Navigation system  55  is coupled to a GPS receiver  57  for monitoring the geographic coordinates of the vehicle. A modem  58  is coupled to navigation system  55  for interacting with the aggregating server in order to generate routing requests and to receive ride quality-based routing information. 
     Returning to  FIG. 6 , agent  33  receives route requests from subscribers. Depending on which particular units perform the determination of potential routes (i.e., whether performed on-board the vehicle or off-board at the aggregating server or other sources in the network), the routing requests may identify specific road segments for which ride quality data is being requested or may identify a target ride quality and a destination so that agent  33  can identify the appropriate road segments for route planning. In a preferred embodiment, agent  33  collects relevant indices for road segments included in a potential route and then characterizes an overall route index for the complete route by combining the indices of the individual road segments. For example, an average value can be calculated. Alternatively, a worst-case comfort value along a potential route may be used as an overall route index. 
     A preferred method for route planning is shown in  FIG. 8 . In step  60 , an origination of a trip is identified (e.g., automatically by a vehicle-based GPS receiver) and a desired destination is identified by a subscribing user. Either an on-board or an off-board navigation system calculates potential routes to the identified destination in step  61 . In some embodiments, a subscribing user may also specify a desired ride quality in step  62  so that only potential routes satisfying the desired ride quality are identified in step  61 . During route generation (or alternatively after the potential routes have been assembled), ride quality indices are retrieved in step  63  for each segment in the potential routes. In step  64 , a route index is calculated for each potential route. The indices may be communicated to the subscriber&#39;s vehicle. In step  65 , a vehicle HMI displays each of the potential routes together with their respective route indices, thereby allowing the subscribing user to choose a desired route in step  66 . Thus, even though a particular vehicle may not include an adaptive suspension system, it obtains the benefits of being able to determine a route satisfying a desired comfort level based on data previously collected by other vehicles that do contain adaptive suspension systems.