Vicente Milanés

A Review of Motion Planning Techniques for Automated Vehicles

Intelligent vehicles have increased their capabilities for highly and, even fully, automated driving under controlled environments. Scene information is received using onboard sensors and communication network systems, i.e., infrastructure and other vehicles. Considering the available information, different motion planning and control techniques have been implemented to autonomously driving on complex environments. The main goal is focused on executing strategies to improve safety, comfort, and energy optimization. However, research challenges such as navigation in urban dynamic environments with obstacle avoidance capabilities, i.e., vulnerable road users (VRU) and vehicles, and cooperative maneuvers among automated and semi-automated vehicles still need further efforts for a real environment implementation. This paper presents a review of motion planning techniques implemented in the intelligent vehicles literature. A description of the technique used by research teams, their contributions in motion planning, and a comparison among these techniques is also presented. Relevant works in the overtaking and obstacle avoidance maneuvers are presented, allowing the understanding of the gaps and challenges to be addressed in the next years. Finally, an overview of future research direction and applications is given.

Continuous Curvature Planning with Obstacle Avoidance Capabilities in Urban Scenarios

This paper presents a continuous curvature planning algorithm with obstacle avoidance capabilities. The automated system generates a collision free path that considers vehicles constraints, the road and different obstacles inside the horizon of view. The developed planning module was integrated in the RITS (former IMARA) autonomous vehicle architecture. The goal of this module is to obtain an accurate, continuous and safe path generation, by implementing parametric curves. To this end, a continuous curvature profile when calculating vehicle trajectory is introduced. It also permits to generate different speed profiles, improving the comfort by reducing lateral accelerations in the driving process. These algorithms have been implemented in simulated -ProSiVIC- and real platforms -Cybercars- showing good results in both cases. This approach is currently being implemented in the framework of the EU CityMobil2 project.

Low-Speed Cooperative Car-Following Fuzzy Controller for Cybernetic Transport Systems

This paper describes the development of a Cooperative Adaptive Cruise Control (CACC) for the future urban transportation system at low-speed. The control algorithm was evaluated using two Cybecars as prototype vehicles. A longitudinal response model for the vehicles was developed to design the CACC system. The control algorithm was implemented on a fuzzy logic-based controller that has been tuned to minimize a cost function in order to get a trade-off between a proper car-following gap error and the smoothness of the control signal. The controller was firstly tested in simulation using the developed model. Then, the CACC was implemented in two Cybecars to validate the controller performance in real scenarios.

Speed profile generation based on quintic Bézier curves for enhanced passenger comfort

Automated ground vehicles are becoming a reality for future deployment due to their potential improvement of safety, comfort or emission reductions. However, some challenges remain unsolved such as navigation in dynamic urban environments, where safety and comfort are paramount. In this paper, a novel speed profile generator, based on quintic Bézier curves, is presented. This approach permits to improve the comfort in automated vehicles by constraining the global acceleration in the whole ride. Moreover, a comparison with a Jerk limitation algorithm for continuous acceleration profile and a smooth speed profile is performed. The quintic Bézier curves assure continuity of velocity curves and therefore a smooth Jerk and acceleration profiles. The ISO 2631-1 standard, for evaluation of human exposure to whole-body vibration, is considered in both methods for lateral and longitudinal comfort constraints. Simulations show that this approach improves comfort by smoothing the acceleration and jerk profiles, while also constraining the total acceleration perceived by the passengers.

Using Plug&Play control for stable ACC-CACC system transitions

This paper examines the already commercially available Adaptive Cruise Controller (ACC) system, and its evolution by adding vehicle-to-vehicle communications: the cooperative ACC (CACC) version. The transition between ACC and CACC controllers will be done through the new control technique called Plug&Play. This technique is able to deal with living systems and the changes in its sensors and actuators to preserve the system stable. The aim is to ensure the system stability during transitions between controllers when the vehicle-to-vehicle communication link is changing from unavailable to available or vice versa.

Optimal energy consumption algorithm based on speed reference generation for urban electric vehicles

Power consumption and battery life are two of the key aspect when it comes to improve electric transportation systems autonomy. This paper describes the design, development and implementation of a speed profile generation based on the calculation of the optimal energy consumption for electric Cybercar vehicles for each of the stretches that are covering. The proposed system considers a commuter daily route that is already known. It divides the pre-defined route into segments according to the road slope and stretch length, generating the proper speed reference. The developed system was tested on an experimental electric platform at Inrias facilities, showing a significant improvement in terms of energy consumption for a pre-defined route.

Description and technical specifications of cybernetic transportation systems: an urban transportation concept

The Cybernetic Transportation Systems (CTS) is an urban mobility concept based on two ideas: the car sharing and the automation of dedicated systems with door-todoor capabilities. In the last decade, many European projects have been developed in this context, where some of the most important are: Cybercars, Cybercars2, CyberMove, CyberC3 and CityMobil. Different companies have developed a first fleet of CTSs in collaboration with research centers around Europe, Asia and America. Considering these previous works, the FP7 project CityMobil2 is on progress since 2012. Its goal is to solve some of the limitations found so far, including the definition of the legal framework for autonomous vehicles on urban environment. This work describes the different improvements, adaptation and instrumentation of the CTS prototypes involved in European cities. Results show tests in our facilities at INRIARocquencourt (France) and the first showcase at Léon (Spain).

Real-time planning for adjacent consecutive intersections

Real-time path planning constitutes one of the hot topics when developing automated driving. Different path planning techniques have been studied in both the robotics and automated vehicles fields trying to improve the trajectory generation and its tracking. In this paper, a novel local path planning algorithm combining both off-line and real-time generation for automated vehicles in urban environments is presented. It takes advantage of an off-line planning strategy to achieve a smooth and continuous trajectory generation with adjacent consecutive intersections. Therefore, this approach allows a smooth and continuous trajectory by means of planning consecutive curves concurrently, i.e., it will plan the upcoming curve and the following one in advance, taking into account the constraints of the infrastructure and the physical limitations of the vehicle. The real-time planning algorithm has been tested in simulation based on the INRIA-RITS vehicles architecture. The results obtained show an improvement in the smoothness, continuity and comfort of the generated paths.

Automated global planner for cybernetic transportation systems

Nowadays, the development of Intelligent Transportation System (ITS) is increasing due to its versatility, adaptability and use of clean energy. There are a number of pass and on-going projects worldwide dealing with the different challenges and approaches to solve road transport-related issues. Some of them are dealing with the Cybernetic Transportation Systems (CTS), which is an urban mobility concept based on the automation of door-to-door transport systems i.e. the Cybercars as a two-passenger CTS. This paper presents the functional architecture of the CTSs and the development of an automated global planner. Specifically, a new approach that considers the automatization of the global planner stage, which allows path calculations and modifications in real time, considering on-demand stopping points. The experimental tests show a proper behaviour in our facilities at INRIA-Rocquencourt (France).

An energy-saving speed profile algorithm for cybernetic transport systems

Cybernetic Transport Systems (CTS) are now available on some cities worldwide covering the so-called lastmile for people transportation. These electric vehicles are expecting to operate during several hours without interruptions. It implies that energy consumption plays a key role when it comes to extend its autonomy. This paper presents a new algorithm for reference speed generation of CTS with energy consumption considerations. It consists on a two layer controller: the first one is in charge of generating the speed reference based on an energetic model, and the second one is a high-level fuzzy system to improve some low-level undesirable behaviors. The designed system was compared with three other algorithms in a real platform, showing promising results in terms of energy saving.