Available online at www.sciencedirect.com
ScienceDirect Procedia Technology 23 (2016) 4 – 6
3rd International Conference on Innovations in Automation and Mechatronics Engineering, ICIAME 2016
Autonomy for Robots: Design and Developmental Challenges (Keynote Address) Asokan Thondiyath* Department of Engineering Design Indian Institute of Technology Madras, Chennai Chennai 600036 India
Abstract Autonomy for robots is one of the key requirement in any field robotic applications. Design and development of autonomous robots raises many challenges to the engineers and full autonomy for robots is still an unfinished job. In this key note address, some of the design challenges and implementation issues will be presented. Along with this, the design of an autonomous underwater robot for surveillance application will be presented as a case study. © by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2016 2016Published The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). Selection and/or peer-review under responsibility of the Organizing Committee of ICIAME 2016. Peer-review under responsibility of the organizing committee of ICIAME 2016 Keywords: Autonomy, perception, sensing, control, underwater robots
1.0 Autonomous Robots Robots which can perform tasks without human intervention are termed as autonomous robots. However, the degree of autonomy depends on the tasks to be performed and fully autonomous robots are expected to have a very high degree of autonomy. An operating region defined by a set of parameters within which the system can decide and act on its own towards the goalset can be termed as the degree of autonomy. Robots with full autonomy are preferred in many applications such as space exploration, defence warfare etc. In order to have autonomy, the robot should be
* Corresponding author. Tel.: +0-000-000-0000 ; fax: +0-000-000-0000 . E-mail address:
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2212-0173 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the organizing committee of ICIAME 2016 doi:10.1016/j.protcy.2016.03.066
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capable of collecting information from surroundings, perceive the environment, localize itself, decide on actions, and execute the necessary motion. These steps are called Perception, Localisation, Cognition, and Motion Control [1].
Position Global Map
Localization
Cognition
Environment Model
Perception
Environment
Motion Control
Figure 1: General Control Scheme for Autonomous Operation (adapted from [1]) Some of the challenges in implementation of autonomous operation are: 1. The real world is difficult to model 2. The level of uncertainty in sensing is very high 3. Unstructured environments will give inconsistent information and 4. Computational requirements are very high. Navigation, Guidance and Control are the three important modules in any robot that provides autonomy to it. The degree of autonomy depends on the capability of these three systems in achieving the four steps in autonomous operation mentioned earlier. The implementation of these three modules for an autonomous underwater robot [2,3,4] is briefly described in the following sections. 2.0 Design of Autonomous Underwater Robot The general building blocks for an autonomous robot is shown in Fig. 2. For an autonomous underwater robot, the design of navigation, guidance and control systems is much more complex than its terrestrial counterparts as the robot has six degrees of freedom and most of the times the robot will be underactuated [5,6]. It is necessary to identify navigation sensors and systems to ensure that the vehicle position and orientations are continuously monitored and conveyed to the mission controller. Guidance algorithms for path planning and obstacle avoidance have been specifically developed for underwater robots [3,5].
Data logging
Sensors
Vehicle Safety
Communications
Navigation
Mission Control
Actuator Control
Vehicle Guidance and Control
Fig. 2 Building blocks for an autonomous robot
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As shown in Figure 3, the control system plays the important role of providing the necessary control forces to propel it towards its intended goal position. Thrusters and control planes provide the control forces. Design of controllers and control algorithms [4, 6] play a major role in achieving the desired targets without major deviations.
Fig. 3 Implementation of autonomous control for underwater robot References [1] Roland S., Illah R. N., Davide S., Introduction to Autonomous Robots, PHI Learnig Private Limited, 2011.
[2] Saravanakumar S, Thomas George, Asokan T (2014), Real-Time obstacle avoidance for an underactuated flat-fish type autonomous underwater vehicle in 3D space, International Journal of Robotics and Automation (ACTA Press), Vol. 29, No. 4, 2014 [3] Saravanakumar S., Asokan T. (2013), Multipoint Potential Field Method for Path Planning of Autonomous Underwater Vehicles in 3D Space, Intelligent Service Robotics: Volume 6, Issue 4 (2013), Page 211-224 [4]Santhakumar Mohan, Asokan T.(2012), Power Efficient Dynamic Station Keeping Control of a flat-fish type Autonomous Underwater Vehicle through Design Modifications of Thruster configuration, Ocean Engineering 58 (2012) 11–21 [5] Saravanakumar Subramanian and Asokan Thondiyath (2012), An Improved Guidance Algorithm for Smooth Transition at Way-Points in 3D Space for Autonomous Underwater Vehicles, Int. Nat. Journal of Ocean Systems Engineering, Vol. 2(3), 2012 [6]Santhakumar Mohan, and Asokan Thondiyath (2011), A nonlinear tracking control scheme for an underactuated autonomous underwater robotic vehicle, Int. Nat. Journal of Ocean Systems Engineering 1(3), (2011) 120-135.
