PTEM Based Moving Obstacle Detection and Avoidance for an Unmanned Ground Vehicle

Abstract

This study presents the development and implementation of an autonomous obstacle avoidance algorithm for an UGV (Unmanned Ground Vehicle). This research improves the prior work by enhancing the obstacle avoidance capability to handle moving obstacles as well as stationary obstacles. A mathematical representation of the area of operation with obstacles is formulated by PTEM (Probabilistic Threat Exposure Map). The PTEM quantifies the risk in being at a position in an area with different types of obstacles. A LRF (Laser Range Finder) sensor is mounted on the UGV for obstacle data in the area that is used to construct the PTEM. A guidance algorithm processes the PTEM and generates the speed and heading commands to steer the UGV to assigned waypoints while avoiding obstacles. The main contribution of this research is to improve the PTEM framework by updating it continuously as new LRF readings are obtained, on the contrary to the prior work with fixed PTEM. The improved PTEM construction algorithm is implemented in a MATLAB/Simulink simulation environment that includes models of the UGV, LRF, all the sensors and actuators needed for the control of the UGV. The performance of the algorithm is also demonstrated in real time experiments with an actual UGV system.

Forward and Inverse Dynamics of a Unicycle-Like Mobile Robot

“…In the field of robotics, stabilization and tracking problems of mobile robots have grown in importance in recent years, as testified by a large number of research projects devoted to the investigation of these topics [53][54][55]. Furthermore, the nonlinear control problem focused on mobile robots have recently attracted significant attention in the control community because of the wide scope of applications of these mechanical systems [56][57][58][59][60][61][62][63]. In several engineering applications, mobile robots are often treated as mechanical systems constrained by holonomic and/or nonholonomic algebraic equations, which can be modeled employing nonlinear dynamics techniques such as the multibody approach to the dynamics of mechanical systems.…”

“…The nonlinear control problem of wheeled mobile robots represents a challenging issue. Several effective methods were proposed in the literature for solving this problem [56][57][58][59][60][61][62][63]. However, the main difficulty associated with the nonlinear control approaches employed in the literature for wheeled mobile robots is that they rely on non-standard techniques which cannot be readily extended to other control problems [71][72][73][74].…”

A Monocular Vision Obstacle Avoidance Method Applied to Indoor Tracking Robot

“…In the research of the obstacle perception of ground unmanned vehicles, vision sensors, lidar sensors, and millimeter wave radar sensors are usually used to obtain obstacle information. Rajashekaraiah et al (2017) [5] used a laser rangefinder to obtain obstacle data and constructed a PTEM (probabilistic thread exposure map), which obtained obstacle information through lidar and updated PTEM in real time to guide unmanned vehicles to avoid obstacles. Similarly, using the radar sensor, Yang et al (2017) [6] proposed the sensor lidar to detect the obstacles in the front path.…”

Obstacle Avoidance System for Unmanned Ground Vehicles by Using Ultrasonic Sensors

“…Such a system was made of four controllers: two are used for angular velocity regulation for reaching the target position and the other two are used for obstacle avoidance [7][8][9][10]. Rajashekaraiah et al (2017) proposed the MATLAB/Simulink simulation environment as a powerful tool for implementing the PTEM algorithm (Probabilistic Threat Exposure Map) to improve the obstacle avoidance capability for moving and stationary obstacles [11]. Zhang and Jasiobedzki (2017) investigated safety issues for manned vehicles.…”