Ranajit Chatterjee

Augmented Stable Fuzzy Control for Flexible Robotic Arm Using LMI Approach and Neuro-Fuzzy State Space Modeling

Designing the control strategy for a flexible robotic arm has long been considered a complex problem as it requires stabilizing the vibration simultaneously with the primary objective of position control. A stable state-feedback fuzzy controller is proposed here for such a flexible arm. The controller is designed on the basis of a neuro-fuzzy state-space model that is successfully trained using the experimental data acquired from a real robotic arm. The complex problem of solving stability conditions is taken care of by recasting them in the form of linear matrix inequalities and then solving them using a popular interior-point-based method. This asymptotically stable fuzzy controller is further augmented to provide enhanced transient performance along with maintaining the excellent steady-state performance shown by the stable control strategy. The controller hence designed has been successfully implemented for a real robotic arm to operate over a long angular range of 180 with several payload conditions and, for situations where the system is operated for a long range and with a large variation in payload conditions, it could successfully outperform the recently proposed proportional derivative and strain controller.

Robot description ontology and disaster scene description ontology: analysis of necessity and scope in rescue infrastructure context

This work intends to identify the necessity and scope of developing ontology standards for describing rescue robot features and for describing disaster scenarios in the context of search and rescue effort coordination. In recent years robot platforms are being designed for aiding rescue operations through offering capabilities of sensing and manipulating remote regions by reaching far inside fragile and uncertain environments without risking the lives of the rescue workers. However, there is still no standard basis to describe the robot capabilities or to describe a disaster scenario in an unambiguous way to aid processing by human or machines for intelligent decision making or on-site rescue coordination purposes. Thus, the relative effectiveness of the available platforms for a particular situation cannot be compared on a rational basis. As a result, incorporation of robot platforms is likely to increase the complexity of the already difficult task of on-site decision making for rescue coordination. The current work identifies some of the necessities and benefits for developing such description standards. Suggested outlines of some necessary aspects of robot description ontology and scenario description ontology are also discussed.

Treaded control system for rescue robots in indoor environment

We developed a rescue robot system, which allows efficient utilization of the potentials of a robot, by effectively switching between tele-operation mode and autonomous mode based on the task and the operation environment. Rescue robots are mobile sytems which can perform search for human lives, on behalf of rescue personnel, in dangerous environments like earthquack disaster zones or areas with chemical hazards. As a pre-requisite of the system, we consider that the robot is equipped with capability of autonomous mobility, laser range finder for environment mapping and infra-red camera to detect victims. In situations when the remote operation of the robot is difficult due to un-suitable condition of wireless communication or the visibility is low, the autonomous mode based search operation is performed. In the autonomous mode, the locomotion is based on the distance sensor data and the infra-red camera to search and navigate towards a victim and inform the operator about the potion and condition of the victim. In the case of complex environmental situations, like a staircase, or in cases that the infrared camera information may not be reliable to detect a victim, the operators decisions become essential and the operation mode is switched to the tele-operation mode. In the case on tele-operation mode, the operator may use the information from the optical camera and operate the robot with a joystick. By switching between the tele-operation mode and autonomous mode the weak points of each mode can be compensated. We developed a robot, called KAMUI, which is equipped with the above mentioned pre-requisites. KAMUI is designed to have high mobility in uneven surface conditions and enhanced sensor systems for victim identification. We participated in RoboCupRescue league and evaluated the effectiveness of the developed system in real situations.

Development of Three-legged Modular Robots and Demonstration of Collaborative Task Execution

Our research perspective is to develop mechanisms for gathering information efficiently in disaster sites. Ideally this requires mechanisms with capabilities of flexible, on-site, adaptation of the overall shape and of the locomotion strategy to unknown and unstable environments. We have been developing three-legged modular robots which can be interconnected to cooperatively achieve multiple locomotion modes and collaboratively perform tasks that cannot be done by a single module. In this paper, we report the development of experimental modular robots and experimentations with their cooperative activities which evolve out of their various inter-connectivity options.

Development of modular legged robots: study with three-legged robot modularity

As an experimental platform for modular legged robots, generic limb modules are developed which are used to implement 3-limb robot units. Benefits of 3-limb modularity are discussed in the context of multi-legged robot assembly. A CPG network based locomotion gait generation approach for generic multi-leg formations is considered.

Robot description ontology and bases for surface locomotion evaluation

The current discussion intends to outline some aspects of a robot description ontology specifically focusing on the aspects related to describing the surface locomotion capabilities. Some necessary aspects to describe the relevant limitations are identified, which would form a basis of testing facility design as well as comparative evaluation of the on-surface locomotion features of ground robots.

Autonomous generation of behavioral trace maps using rescue robots

In the current research we consider the scenario of post disaster rescue operations using multiple robots inside damaged buildings where the damage is not very extreme. The objective the of the work is to develop systems to support efficient rescue missions involving creation and exchange of environment maps enriched with information important to rescue operations, among multiple robots and rescue workers. In current days many research institutes are developing robots with widely different types and capabilities to support rescue operations. In rescue missions involving multiple robots it is essential to have sharable map information for efficient search and navigation irrespective of the differences in the structures and capabilities of the participating robots. In this paper we address the above issue by proposing a map description which combines the geographical data as well as the information about robot behaviors called “Behavioral Trace Map”. We describe the algorithm for generation of such maps and we present experimental results using rescue robots developed in our laboratory.

Flexible interface for multiple autonomous and teleoperated rescue robots

Many natural hazards like earthquake and seismic sea waves happen every year all over the world. In addition, many manmade disasters happen in many countries. To deal with these disasters, rescue robots are being developed in many countries. These robots support the rescue workers to search for the victims in the disaster environments. In this paper, we propose a flexible and generic interface system for operating multiple rescue robots. The system can operate multiple heterogeneous robots from a common operation interface. The system also supports changing the operation mode of any robot between autonomous and tele-operation. As a demonstration, we used this system on actual robots in RoboCup Rescue league[1] and evaluated the proposed system.

Perception-based qualitative map building using autonomous mobile robots

In this paper, we propose a method of map building based on landmark and structural features in short period of time. It appears that human does not travel with an exact 3D map of environment in mind but moves by using only topological perception about the environment and landmark information. Similar to that of human perception, the map generated using mobile robots are represented as topological graph with nodes, links, landmark information, etc. which may be used for navigation as well as self localization by the same robot or other entities.

A stable state-feedback fuzzy controller employing linear matrix inequalities for flexible link robotic arm

The present paper proposes the design of a stable state-feedback fuzzy controller for a flexible robotic arm. The fuzzy controller is designed employing parallel distributed compensation philosophy where one local control rule is designed for each local fuzzy plant rule. A neuro-fuzzy architecture is employed to derive the approximate state-space model for the flexible robotic arm on the basis of experimental data collected from the real plant. A stable fuzzy controller is designed by recasting the stability conditions in form of linear matrix inequalities and hence deriving the appropriate control gains. The suitability of the control design strategy is successfully demonstrated by implementing it for the real robotic arm.