A mobile robot is one of the well-known nonholonomic systems. The integration of a kinematic controller and a torque controller for the dynamic model of a nonholonomic mobile robot has been presented (Fierro and Lewis, 1995). In this paper, an adaptive extension of the controller is proposed. If an adaptive tracking controller for the kinematic model with unknown parameters exists, an adaptive tracking controller for the dynamic model with unknown parameters can be designed by using an adaptive backstepping approach. A design example for a mobile robot with two actuated wheels is provided. In this design, a new kinematic adaptive controller is proposed, then a torque adaptive controller is derived by using the kinematic controller.

Adaptive tracking control of a nonholonomic mobile robot

Vehicle automation has been one of the fundamental applications within the field of intelligent transportation systems (ITS) since the start of ITS research in the mid-1980s. For most of this time, it has been generally viewed as a futuristic concept that is not close to being ready for deployment. However, recent development of “self-driving” cars and the announcement by car manufacturers of their deployment by 2020 show that this is becoming a reality. The ITS industry has already been focusing much of its attention on the concepts of “connected vehicles” (United States) or “cooperative ITS” (Europe). These concepts are based on communication of data among vehicles (V2V) and/or between vehicles and the infrastructure (V2I/I2V) to provide the information needed to implement ITS applications. The separate threads of automated vehicles and cooperative ITS have not yet been thoroughly woven together, but this will be a necessary step in the near future because the cooperative exchange of data will provide vital inputs to improve the performance and safety of the automation systems. Thus, it is important to start thinking about the cybersecurity implications of cooperative automated vehicle systems. In this paper, we investigate the potential cyberattacks specific to automated vehicles, with their special needs and vulnerabilities. We analyze the threats on autonomous automated vehicles and cooperative automated vehicles. This analysis shows the need for considerably more redundancy than many have been expecting. We also raise awareness to generate discussion about these threats at this early stage in the development of vehicle automation systems.

Potential Cyberattacks on Automated Vehicles

This brief proposes a sliding-mode control method for wheeled-mobile robots in polar coordinates. A new sliding-mode control method is proposed for mobile robots with kinematics in two-dimensional polar coordinates. In the proposed method, two controllers are designed to asymptotically stabilize the tracking errors in position and heading direction, respectively. By combining these controllers together, both asymptotic posture (position and heading direction) stabilization and trajectory tracking are achieved for reference trajectories at global regions except the arbitrary small region around the origin. In particular, constraints on the desired linear and angular velocities as well as the posture of the mobile robot are eliminated unlike the previous studies based on kinematics expressed in polar coordinates. Accordingly, arbitrary trajectories including a circle and a straight line in various forms can be followed even with large initial tracking errors and bounded disturbances. The stability and performance analyzes are performed and also simulations are included to confirm the effectiveness of the proposed scheme.

Sliding-mode tracking control of nonholonomic wheeled mobile robots in polar coordinates

In this paper, a control structure that makes possible the integration of a kinematic controller and an adaptive fuzzy controller for trajectory tracking is developed for nonholonomic mobile robots. The system uncertainty, which includes mobile robot parameter variation and unknown nonlinearities, is estimated by a fuzzy logic system (FLS). The proposed adaptive controller structure represents an amalgamation of nonlinear processing elements and the theory of function approximation using FLS. The real-time control of mobile robots is achieved through the online tuning of FLS parameters. The system stability and the convergence of tracking errors are proved using the Lyapunov stability theory. Computer simulations are presented which confirm the effectiveness of the proposed tracking control law. The efficacy of the proposed control law is tested experimentally by a differentially driven mobile robot. Both simulation and results are described in detail.

Design and implementation of an adaptive fuzzy logic-based controller for wheeled mobile robots

Optimization of interval type-2 fuzzy logic controllers for a perturbed autonomous wheeled mobile robot using genetic algorithms

This paper presents a model reference adaptive nonlinear control strategy for active steering of a two wheel steering car which is realized by steer-by-wire technology. The ideal fixed property of a steering system, which is provided by a reference model, is attained by D * control. The proposed method can treat the nonlinear relationships between the slip angles and the lateral forces on tires, and the uncertainties on the friction of the road surface, whose compensations are very important under critical situations. Some results of realtime simulation with a steering equipment show the effectiveness of the proposed method.

Active steering systems based on model reference adaptive nonlinear control

Image-based tracking control of an aerial blimp is proposed for surveillance systems. The controller is designed by backstepping techniques for underactuated systems. In our framework, only one camera on a blimp is used to control the blimp without the other sensors and to generate a reference trajectory from image information. After a commander sets a target, the blimp flies around it automatically. This image-based approach reduces to utilize the values estimated by a structure-from-motion algorithm. In this research an aerial blimp is used for indoor experiments, and image-based control are compared with position-based control.

Image-based tracking control of a blimp

An autonomous blimp for a surveillance system, which is circling around a specified target with only one camera, is designed in this paper. For this purpose, an extension of Lucas-Kanade algorithm for detection and tracking of features with rotation and scaling is provided, and a simplified structure-from-motion algorithm is applied to improve the accuracy of state estimation. A tracking controller is designed for the blimp which is an underactuated system. The desired path of the blimp is also generated from image information of a target. The blimp flies around the target automatically, after a commander sets it. Some experiments are performed indoors by using an aerial blimp.

Takanori Fukao

Papers

Adaptive tracking control of a nonholonomic mobile robot

Active steering systems based on model reference adaptive nonlinear control

Image-based tracking control of a blimp

An autonomous blimp for a surveillance system

Development of Autonomous Platooning System for Heavy-Duty Trucks