Road Grade Estimation Using Crowd-Sourced Smartphone Data

Integration of information on road transverse geometric features such as cross slope and superelevation in digital maps can widen the scope of its applications, which is primarily navigation, by enabling driving safety and efficiency applications such as Advanced Driver Assistance Systems (ADAS). The huge scale and dynamic nature of road networks make sensing such road geometric features a challenging task. Traditional methods oftentimes suffer from high cost, limited scalability and update frequency, as well as poor sensing accuracy. To overcome these problems, we propose a cost-effective and scalable road transverse slope estimation framework using sensor data from smartphones. Based on error characteristics of smartphone sensors, we intelligently combine data from accelerometer, gyroscope and GPS to estimate road transverse slope profile of a road segment. To improve accuracy and robustness of the system, the estimations of road transverse slope from multiple sources/vehicles are crowd-sourced to compensate for the effects of varying quality of sensor data from different sources. Extensive experimental evaluation on a test route of 9km demonstrates the superior performance of our proposed method, achieving 350% improvement on road transverse slope estimation accuracy over existing methods, with 90% of errors below 0.5°.

Road grade estimation for look-ahead vehicle control using multiple measurement runs

<div class="section abstract"><div class="htmlview paragraph">A variety of vehicle controls, from active safety systems to power management algorithms, can greatly benefit from accurate, reliable, and robust real-time estimates of vehicle mass and road grade. This paper develops a parallel mass and grade (PMG) estimation scheme and presents the results of a study investigating its accuracy and robustness in the presence of various noise factors. An estimate of road grade is calculated by comparing the acceleration as measured by an on-board longitudinal accelerometer with that obtained by differentiation of the undriven wheel speeds. Mass is independently estimated by means of a longitudinal dynamics model and a recursive least squares (RLS) algorithm using the longitudinal accelerometer to isolate grade effects. To account for the influences of acceleration-induced vehicle pitching on PMG estimation accuracy, a correction factor is developed from controlled tests under a wide range of throttle levels. The estimation approach is applied to data collected while driving on public roads under a variety of driving conditions, replicating several noise factors associated with daily driving. Thresholds are developed to isolate driving events that are likely to result in quick and accurate mass estimates, and an averaging filter is then applied to these converged values. The algorithm is shown to rapidly deliver estimates within 3% of true vehicle mass.</div></div>

Accurate and reliable global positioning system (GPS)-based vehicle use data are highly valuable for many transportation, analysis, and automotive considerations. Model-based design, real-world fuel economy analysis, and the growing field of autonomous and connected technologies (including predictive powertrain control and self-driving cars) all have a vested interest in high-fidelity estimation of powertrain loads and vehicle usage profiles. Unfortunately, road grade can be a difficult property to extract from GPS data with consistency. In this report, we present a methodology for appending high-resolution elevation data to GPS speed traces via a static digital elevation model. Anomalous data points in the digital elevation model are addressed during a filtration/smoothing routine, resulting in an elevation profile that can be used to calculate road grade. This process is evaluated against a large, commercially available height/slope dataset from the Navteq/Nokia/HERE Advanced Driver Assistance Systems product. Results will show good agreement with the Advanced Driver Assistance Systems data in the ability to estimate road grade between any two consecutive points in the contiguous United States.

Long haulage road transport consumes considerable amounts of energy in today's world. Predictive control strategies based on digital maps can significantly lower the portion being wasted in traditional cruise control operated highway driving. Such control strategies rely on high quality stored road grade information. This paper describes a newly developed method to estimate the road grade using sensors commonly found on standard heavy duty vehicles. The method utilizes a piecewise linear road model derived from highway design methodologies. The estimation method has been implemented and evaluated experimentally, and is shown to give better results compared to an existing method.

<div class="htmlview paragraph">Digital maps have large potential to enhance or enable Advanced Driver Assistance Systems (ADAS) by extending driver horizon and therefore to contribute to safer, smarter and cleaner road transport. As a predictive sensor called ADAS Horizon, in-vehicle digital maps are an important source of information providing look-ahead capability for ADAS applications and providing further information for on-board sensors to enhance environment perception.</div> <div class="htmlview paragraph">This paper reports on results from the European Commission project MAPS&ADAS, part of PReVENT Integrated Project, dedicated to the development, test and validation of a standardized interface (ADAS Interface) between ADAS applications and ADAS map data sources for accessing map data regarding vehicle position.</div>

Vehicle specific power (VSP) is useful for estimation of vehicle emissions. Previous research has indicated that vehicle specific power and emissions are sensitive to variation of road grade. Several methods have been used for acquisition of road grade data in earlier studies, but all have certain limitations such as insufficient accuracy, complicated data processing, or requirements for devices or data that are not easily available. The objective of this study was to develop and verify a road grade measurement framework based on an electronic pressure sensor. The method includes atmospheric pressure acquisition using electronic sensors, determination of the pressure-altitude relationship based on meteorological station data, filtering of altitude data by Fourier transform, and grade calculation combined with the onboard diagnostics distance. Road grades and vehicle specific power calculated based on atmospheric pressure were found reliable and accurate, which also improved the accuracy of vehicle emission rates calculation.

Modern automobiles are increasingly equipped with Advanced Driver Assistance Systems (ADAS), which improve passenger safety and comfort. Each of these ADAS can rely on a multitude of environmental sensors, which creates the need of cross-linking ADAS with respect to their access to environment information. This idea is reflected in the so-called environment model (EM) that centralizes the access of all ADAS functions to the perceived but not yet interpreted scene in the vehicle environment. In this paper, we propose an architectural framework that concretizes the EM in terms of separate modules for signal processing and sensor data fusion, as well as well-defined generic input and output interfaces. Moreover, we extend the EM by including additional components and output interfaces for centralized scene interpretation (CSI). The architectural framework allows streamlining the development process and increasing computational efficiency, as software modules for scene interpretation can be shared among multiple ADAS. In addition, the consistency of the overall ADAS behavior is improved, as all ADAS functions rely on the same scene information and scene interpretation. We illustrate our concept of centralized scene interpretation using the case study of a module for the detection of directional roadways, a generalization of motorways. The algorithm we present analyzes multiple perceptual indicators in favor or against a directional roadway and computes an overall decision, along with a foresight value for the expected duration of the directional roadway, to be used in various ADAS functions.

<div class="section abstract"><div class="htmlview paragraph">The testing of vision sensor-based Advanced Driver Assistance (ADA) systems and Electronic Control Units (ECUs) is quickly becoming a major requirement in the automotive industry. ADA ECU development teams require a verification and validation (V&V) infrastructure early in the development cycle, and traditional approaches are not suitable for this purpose. This paper proposes the design of an integrated test suite for the functional and real-time testing of ADA algorithms and ECUs. The proposed test suite consists of a hardware bridge built using a Field Programmable Gate Array (FPGA), a Universal Serial Bus (USB) 3.0 interface, and a software application running on the Personal Computer (PC). By using an FPGA to build the hardware bridge, we get a compact, real-time, and reconfigurable platform to support the desired test requirements. The USB3.0 interface is specifically proposed to support the high data rates evident in ADA systems based on multiple vision sensor and sensor fusion technologies. The PC-based software application has a modular, extensible, and scalable architecture to support current and future test requirements, as well as several features that improve the end user's productivity. The proposed test suite can be used for: (a) acquisition and storage of sensor data (recording mode), (b) visualization of stored sensor data (replay mode), (c) offline evaluation and improvement of ADA algorithms (functional test mode), (d) online testing of advanced driver assistance system (ADAS) ECUs (real-time test mode). The major contribution of this paper is the design proposal for supporting the real-time test mode for laboratory testing of ADA ECUs, and it concludes with a qualitative discussion of potential enhancements.</div></div>

Up-to-date map data is a must for current and future navigation and advanced driver assistance system (ADAS) applications. Today, digital maps are normally stored on DVDs or hard disks, with periodic updates only available on replacement disks. However, new mechanisms for updating maps have been investigated and some of them already reached the market. As the real world is changing every day, detecting changes to the road network quickly and at a low cost is a challenge. Although mapmakers continuously survey the European road network for changes, map information is not always up-to-date or accurate. This paper presents the test and validation results and two example applications from the FeedMAP project and how they can be used for increasing driving safety by integrating map deviation detection and incremental update technology into ADAS applications using the ADAS Horizon concept.

Portable emissions measurement systems (PEMS) are useful for quantification of real-world vehicle activity, energy use, and emissions. However, there is no standard methodology for processing PEMS data; this can lead to errors in reported results. PEMS typically include tailpipe exhaust gas and particle analyzers, Global Positioning System (GPS) receivers, engine sensors, and electronic control unit (ECU) data loggers. The sensitivity of estimated emission rates to random errors in measurements is quantified. Methods are evaluated for identification and correction of improper synchronization of PEMS, ECU, and GPS data streams and for road grade estimation. Estimated fuel use and emission rates for light- and heavy-duty vehicles are sensitive to errors in intake manifold absolute pressure and engine revolutions per minute values and in indicators of air-to-fuel ratio including carbon dioxide and oxygen concentrations. Synchronization can be aided by maximizing the Pearson correlation coefficient between two indicator variables and confirming the result by matching concurrent increases in indicator variables. The effect of improper synchronization on estimated modal emission rates is quantified. Modal average emission rates based on vehicle-specific power (VSP) are more sensitive to improperly synchronized engine versus GPS data. Improperly synchronized data streams result in decreased variability between the lowest and highest modal average emission rates. Estimation of road grade from a linear least squares slope of elevation over a specified distance is demonstrated. VSP-based modal fuel use and pollutant emission rates are less sensitive to differences in road grade than to errors in synchronization.

An advanced driver-assistance system (ADAS), based on lane detection technology, detects dangerous situations through various sensors and either warns the driver or takes over direct control of the vehicle. At present, cameras are commonly used for lane detection; however, their performance varies widely depending on the lighting conditions. Consequently, many studies have focused on using radar for lane detection. However, when using radar, it is difficult to distinguish between the plain road surface and painted lane markers, necessitating the use of radar reflectors for guidance. Previous studies have used long-range radars which may receive interference signals from various objects, including other vehicles, pedestrians, and buildings, thereby hampering lane detection. Therefore, we propose a lane detection method that uses an impulse radio ultra-wideband radar with high-range resolution and metal lane markers installed at regular intervals on the road. Lane detection and departure is realized upon using the periodically reflected signals as well as vehicle speed data as inputs. For verification, a field test was conducted by attaching radar to a vehicle and installing metal lane markers on the road. Experimental scenarios were established by varying the position and movement of the vehicle, and it was demonstrated that the proposed method enables lane detection based on the data measured.

Advanced Driving Assistance Systems (ADAS) consist out of many electronics applications that assist drivers and take over safety critical functions. Reliable sensor data (e.g. Rain, ambient light, tire pressure, Radar, LiDAR, ultrasonic park-assist, etc.) are crucial in safety applications and might be a challenge under the existing and emerging radio fields to avoid systematic failure of the ADAS. The sensor data from some EMI sensitive ADAS sensor might not be reliable under foreseeable intended and unintended use. At that moment it's important to be able to detect the radio field that causes inaccurate/incorrect sensor data. This paper describes an integrated, accurate, frequency flat RF detector with programmable RF-immunity acceptance threshold and state of the art resolution. The EMI-detector is integrated in a Rain & Light-ADAS sensor IC that decides on the activation of the vehicle head lights and wipers. The design of the EMI detector allows to share pin-resources (it reuses the light sensor input pin and allows concurrent operation with the light sensor). To avoid availability issues the RF-immunity acceptance threshold - triggering safe state in this IC - can be programmed above the minimal EMI level for which the ADAS sensor is designed.

The “ROADSCANNER” project addresses the need for increased accuracy and integrity Digital Maps (DM) utilizing the latest developments in GNSS, in order to provide the required datasets for novel applications, such as navigation based Safety Applications, Advanced Driver Assistance Systems (ADAS) and Digital Automotive Simulations. The activity covered in the current paper is the feasibility study, preliminary tests, initial product design and development plan for an EGNOS enabled vehicle probe. The vehicle probe will be used for generating high accuracy, high integrity and ADAS compatible digital maps of roads, employing a multiple passes methodology supported by sophisticated refinement algorithms. Furthermore, the vehicle probe will be equipped with pavement scanning and other data fusion equipment, in order to produce 3D road surface models compatible with standards of road-tire simulation applications. The project was assigned to NIKI Ltd under the 1st Call for Ideas in the frame of the ESA - Greece Task Force.

This paper presents a look-ahead road grade determination method for use in energy management of hybrid electric vehicles. Data that is gathered from a digital map and vehicle sensors is used to predict the future road grade and longitudinal forces. The predicted information is employed to specify the near future traction force demand. A simulation is carried out using data associated with a 50 km section of a real highway for a typical vehicle. The results are presented and discussed.