Goran Vasiljevic

Slip-based traction control system with an on-line road condition estimation for electric vehicles

In this paper a slip-based traction control system (TCS) with an on-line road condition estimation is presented. The system is designed for a car with in-wheel electric motors, so that estimation and control are implemented independently for each wheel thus enabling the optimal friction coefficient for every wheel, even if they are on different surfaces or have different tire characteristics. A road condition is approximated using a function which is estimated in the real-time and used as the input to the TCS. The design of the presented TCS is based on the wheel slip ratio, controlled to its optimal value by a PI controller and with the addition of a feedforward branch for the transition response speed up. The non-linear model of a small three-wheeled electric car, comprising the hardware in the loop, is used for the system testing.

Decentralized Control of Multi-AGV Systems in Autonomous Warehousing Applications

In this paper, we present an algorithm for decentralized control of multiple automated guided vehicles performing transportation tasks within industrial and warehousing environments. By running on each vehicle in the system, the algorithm provides vehicles with capabilities for autonomous path planning and motion co-ordination. The path planning part of the algorithm implements a free-ranging motion scheme by determining the shortest feasible paths considering nonholonomic vehicle constraints. The motion co-ordination part of the algorithm ensures safe vehicle motions by reliable detection and resolution of different conflict situations with other vehicles in the shared workspace. Conflict resolution is based on a vehicle priority scheme and results in temporary stopping or removal of the lower priority vehicles taking part in the conflict. Removal action is always performed within the vehicles private zone, i.e., the pre-allocated local region of the workspace surrounding the vehicle. By encoding information on the vehicle size and its kinematic constraints, the introduced private zone mechanism provides the necessary physical space required for successful execution of every removal action. We also analyze the stability of the presented algorithm and discuss its deadlock-free and livelock-free properties. Algorithm performance has been validated by simulation using ten vehicles and experimentally on two different setups-a laboratory setup comprising five Pioneer 3DX vehicles and by two state-of-the-art autonomous forklifts in industrial-like operating conditions.

Experimental testing of a traction control system with on-line road condition estimation for electric vehicles

In this paper experimental results of testing slip-based traction control system (TCS) with an on-line road condition estimation are presented. TCS is designed for a car with in-wheel electric motors, so that estimation and control are implemented independently for each wheel thus enabling the optimal friction coefficient for every wheel, even if they are on different surfaces or have different tire characteristics. A road condition is approximated using a function which is estimated in the real-time and used as the input to the TCS. The design of the presented TCS is based on the wheel slip ratio, controlled to its optimal value by a PI controller and with the addition of a feedforward branch for the transition response speed up. System is tested on a newly developed experimental setup consisting of the wheel with embedded (in-wheel) motor rolling on the metal drum loaded by the second motor simulating car behaviour.

Kinect-based Robot Teleoperation by Velocities Control in the Joint/Cartesian Frames

Abstract In this paper we present a new concept of robot teleoperation by tracking the pose of the human operators body with the Kinect motion capture sensor. Instead of controlling robot joint positions, positions of operators hands and legs are used to control robot velocities. In the first method operators movements control velocities of individual robot joints, while in the second, velocities of a robot tool in the Cartesian space are controlled in the same manner. In the latter case the joint coordinates are obtained directly from robots inverse kinematics equations. The methods were demonstrated on a five degrees of freedom (5-DOF) articulated robot arm Mitsubishi Movemaster EX.

Design and control of a four-flipper tracked exploration & inspection robot

We describe the design and control of a prototype of an exploration and inspection robot built as a four flipper/track mobile robot. It is equipped with on-board sensors including standard and thermovision cameras, gas and temperature detectors, etc. The robot maintains wireless video and audio communication with the operator. Its principal aim is to explore buildings, locate people caught in the accidents and detect potential sources of danger in abnormal conditions caused by flood, fire, earthquake or other natural and nonnatural disasters. The robot construction complies to the ATEX norms in order to minimize the risk of interventions of professional units (e.g. fire fighting, civil guard, police, military). Having four independently controlled tracks/flippers, the robot allows easy maneuvering and overtaking of obstacles (including steps). Although dominantly designed as a remote-controlled robot device, advanced control features such as roll-angle compensation and corridor/steps/door centering algorithms help the operator to navigate robot in a much easier and safer way.

Dynamic modeling and simulation of a three-wheeled electric car

We present a non-linear model of a small three wheeled electric car with one rear wheel and two front steered wheels. Each wheel is actuated by a permanent magnet synchronous in-wheel motor. The model was created for development and testing of advanced control algorithms for increasing the cars performance and safety. It includes models of electric motor, non-linear tire-road characteristics, longitudinal and lateral dynamics, a realistic suspension system and the option to influence cars weight and its distribution.

Multi-layer mapping-based autonomous forklift localization in an industrial environment

In this paper a forklift (mobile robot) localization method in an industrial environment is presented. The presented method is based on an adaptive Monte Carlo localization using three laser range scanners, where two safety lasers are located at the ground level and one laser is located at the top level of the vehicle. Each level(layer) has its own independent map acquired by mapping algorithms prior to the localization. The proposed localization method is based on two independent localizations at each level (layer) and their fusion. Presented method is tested in the realistic industrial environment and compared to the marker-based localization that is accurate enough to be considered a ground truth.

Model predictive control based torque vectoring algorithm for electric car with independent drives

We present torque vectoring algorithm for the electric car with four independent drives using the model predictive control (MPC). The presented method uses the linearized model of the car in every step of the simulation to create the quadratic problem with criteria selected in such a way that distribution of torques to each wheel causes the best achievable behavior of the car. The presented algorithm is tested in the simulation environment and compared with the results obtained by distributing torques symmetrically to each wheel.

Harmonization of Research and Development Activities towards Standardization in the Automated Warehousing Systems

In this chapter, we describe some ideas of robotic system standardization based on ongoing research and development processes in a European FP7 project named EC-SAFEMOBIL, which is focused on estimation and control technologies for safe, wireless, high-mobility cooperative systems. Strongly influenced by the European Commission, demand has been to commercialize as many project results as possible, EC-SAFEMOBIL researchers and developers needed some standards to follow for the main project application areas—unmanned aerial systems (UAS) and automated warehousing systems (AWS). Although many aspects of UAS are covered by adequate standards, this does not hold true for automated warehouses. In the given analysis of possible standardization of automated warehousing systems, we elaborate on ideas on how to overcome evident gaps between academic achievements and viable industry practice. Paying particular attention to process and development standards, as well as function-specific standards, we describe our view of reaching new standards in automated warehousing systems, particularly with a number of deployed automated guided vehicles (AGVs). This involves adopting or extending existing standards from other application areas (UAS), creating new ones, and defining standard benchmark tests. We have proposed a few benchmark scenarios for testing two system functionalities—marker-less indoor localization and distributed control.