ISRN Robotics The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. An Improved ZMP-Based CPG Model of Bipedal Robot Walking Searched by SaDE Tue, 04 Mar 2014 12:45:32 +0000 This paper proposed a method to improve the walking behavior of bipedal robot with adjustable step length. Objectives of this paper are threefold. (1) Genetic Algorithm Optimized Fourier Series Formulation (GAOFSF) is modified to improve its performance. (2) Self-adaptive Differential Evolutionary Algorithm (SaDE) is applied to search feasible walking gait. (3) An efficient method is proposed for adjusting step length based on the modified central pattern generator (CPG) model. The GAOFSF is modified to ensure that trajectories generated are continuous in angular position, velocity, and acceleration. After formulation of the modified CPG model, SaDE is chosen to optimize walking gait (CPG model) due to its superior performance. Through simulation results, dynamic balance of the robot with modified CPG model is better than the original one. In this paper, four adjustable factors (, , , and ) are added to the joint trajectories. Through adjusting these four factors, joint trajectories are changed and hence the step length achieved by the robot. Finally, the relationship between (1) the desired step length and (2) an appropriate set of , , , and searched by SaDE is learnt by Fuzzy Inference System (FIS). Desired joint angles can be found without the aid of inverse kinematic model. H. F. Yu, E. H. K. Fung, and X. J. Jing Copyright © 2014 H. F. Yu et al. All rights reserved. Contextual Awareness in a WSN/RFID Fusion Navigation System Tue, 04 Mar 2014 12:19:03 +0000 We present insight into how contextual awareness can be derived from, and improve, a fusion algorithm combing a WSN and a passive RFID for autonomous mobile robot navigation. Contextual awareness of not where the robot is, but rather the context in which it exists in relation to the environment and human user serves to improve accuracy in navigation, alters the speed of the robot, and modifies its behavior. The WSN system, using a virtual potential field, provides fast general navigation in open areas and the RFID provides precision navigation near static obstacles and in narrow areas. We verified the effectiveness of our approaches through navigational and guidance experiments. Guillermo Enriquez, Sunhong Park, and Shuji Hashimoto Copyright © 2014 Guillermo Enriquez et al. All rights reserved. Design and Development of a Littoral AUV for Underwater Target Localization and Homing Using Vision and SONAR Module Wed, 18 Dec 2013 17:18:21 +0000 This paper presents the design and development of a modular littoral autonomous underwater vehicle called “ZYRA” having six degrees of freedom for performing the following tasks underwater: target (sound sources emitting frequencies between 1 Hz and 180 KHz) localization and homing, buoy detection. The development of the AUV has been divided into, namely, five sections: mechanical design and fabrication, embedded and power systems, control and software, image processing, and underwater acoustics. A fully functional AUV has been tested in a self-created arena with different tasks spread out in a shallow water environment. Two different kinds of experimental results have been presented: first the experimental results of the SONAR module and second based on the number of successful outcomes per total number of trials for each task. R. K. Sinha, Aayush Jha, Faheem Ahmad, Vivek Mishra, Prateek Murgai, Vatsal Rustagi, Raj Kumar Saini, and Akshay Jain Copyright © 2013 R. K. Sinha et al. All rights reserved. Internal and External Forces Measurement of Planar 3-DOF Redundantly Actuated Parallel Mechanism by Axial Force Sensors Wed, 09 Oct 2013 18:15:51 +0000 This paper proposes a method for measuring the internal and external forces of a planar 3-DOF (degree of freedom) redundantly actuated parallel mechanism. The internal forces, force acts inside the endplate and mechanism constraint force, and the external forces, forces act on the endplate and thrusts by actuators, were measured simultaneously using the axial forces of the rods. Kinetostatic equations of the parallel mechanism were used to derive algorithms for measuring the internal and external forces. A link axis force sensor was developed using a strain gauge sensor. To verify the actual internal force of the endplate, a force sensor was also installed on the endplate. A real-time system for measuring the forces of the parallel mechanism was developed using RT-Linux. The external and internal forces were measured accurately. Takashi Harada and Podi Liu Copyright © 2013 Takashi Harada and Podi Liu. All rights reserved. From the Human Spine to Hyperredundant Robots: The ERMIS Mechanism Sun, 08 Sep 2013 09:21:21 +0000 Mechatronics are occasionally inspired by nature for joint designs in order to exploit the advantages of the biological ones in terms of mobility and articulation. Within this context and based upon the human spine for structure and actuation, the authors will present a novel hyperredundant mechanism, named ERMIS. The muscle-skeletal system of the human trunk will be described and modelled, and the elements that are being replicated by the mechanical analog will be analysed. It will be shown that the vertebrae-intervertebral disk arrangement can be emulated by a spherical-type configuration, the proposed Disk-Ball-Disk joint. Furthermore, the muscle actuation system is being recreated by a system of wires and pulleys. The relevant kinematic models will be developed, and both simulation and experimental data to evaluate its operation will be demonstrated. Ioannis Georgilas and Vassilios Tourassis Copyright © 2013 Ioannis Georgilas and Vassilios Tourassis. All rights reserved. Biologically Inspired Perimeter Detection for Whole-Arm Grasping Tue, 03 Sep 2013 12:51:18 +0000 Grasping is a useful ability that allows manipulators to constrain objects to a desired location or trajectory. Whole-arm grasping is a specific method of grasping an object that uses the entire surface of the manipulator to apply contact forces. Elephant trunks and snakes and octopus arms are illustrative of these methods. One of the greatest challenges of whole-arm grasping in poorly defined environments is accurately identifying the perimeter of an object. Existing algorithms for this task use restrictive assumptions or place unrealistic demands on the required hardware. Here, a new algorithm (termed Octograsp) has been developed as a method of gaining information on the shape of the grasped object through tactile information alone. The contact information is processed using an inverse convex hull algorithm to build a model of the object’s shape and position. The performance of the algorithm is examined using both simulated and experimental hardware. Methods of increasing the level of contact information through repeated contact attempts are presented. It is demonstrated that experimentally obtained, coarsely spaced, contact information can result in an accurate model of an object’s shape and position. David Devereux, Robert Richardson, Arjun Nagendran, and Paul Nutter Copyright © 2013 David Devereux et al. All rights reserved. Nontumbling Gait for Multilegged Robots and Its Directional Normalized Energy Stability Margin Sun, 18 Aug 2013 08:07:59 +0000 This paper discusses the importance of a nontumbling gait, a gait that allows preventing complete tumbling of the robot. Nontumbling gait is made possible by the effect of the swing leg which may contact the ground even when the robot is affected by an external disturbance. Such an effect is present in both static walking and dynamic walking. Stability criterion required to maintain the nontumbling gait is then considered and proposed through generalized directional normalized energy stability margin. The validity of the introduced criterion is evaluated by a tumbling experiment with a simplified walking robot model. The concept is also applied to the gait control of the newly developed walking robot TITAN-XIII. Evgeny Lazarenko, Satoshi Kitano, Shigeo Hirose, and Gen Endo Copyright © 2013 Evgeny Lazarenko et al. All rights reserved. Mobile Robot Exploration by Using Environmental Boundary Information Thu, 18 Jul 2013 13:16:51 +0000 We present the method of exploration using environmental boundary information for an indoor map generation problem of a mobile robot. We introduce an exploration method by (i) integration of the exploration method with Reaction-Diffusion Equation on a Graph (RDEG) and connected components labeling and (ii) a replanning framework in updating exploration plan for the currently obtained sensor information. Our approach has been implemented in simulation environments and has been compared with two existing methods: frontier-based exploration method and zig-zag method. The results demonstrate the efficiency of our approach over others. Lastly, the approach was implemented and tested on an actual robot, demonstrating its efficiency in a real-world situation. Theeraphol Wattanavekin, Taiki Ogata, Tatsunori Hara, and Jun Ota Copyright © 2013 Theeraphol Wattanavekin et al. All rights reserved. Continuous Backbone “Continuum” Robot Manipulators Tue, 16 Jul 2013 14:03:01 +0000 This paper describes and discusses the history and state of the art of continuous backbone robot manipulators. Also known as continuum manipulators, these robots, which resemble biological trunks and tentacles, offer capabilities beyond the scope of traditional rigid-link manipulators. They are able to adapt their shape to navigate through complex environments and grasp a wide variety of payloads using their compliant backbones. In this paper, we review the current state of knowledge in the field, focusing particularly on kinematic and dynamic models for continuum robots. We discuss the relationships of these robots and their models to their counterparts in conventional rigid-link robots. Ongoing research and future developments in the field are discussed. Ian D. Walker Copyright © 2013 Ian D. Walker. All rights reserved. Application of Online Iterative Learning Tracking Control for Quadrotor UAVs Sun, 09 Jun 2013 19:13:31 +0000 Quadrotor unmanned aerial vehicles (UAVs) have attracted considerable interest for various applications including search and rescue, environmental monitoring, and surveillance because of their agilities and small sizes. This paper proposes trajectory tracking control of UAVs utilizing online iterative learning control (ILC) methods that are known to be powerful for tasks performed repeatedly. PD online ILC and switching gain PD online ILC are used to perform a variety of manoeuvring such as take-off, smooth translation, and various circular trajectory motions in two and three dimensions. Simulation results prove the ability and effectiveness of the online ILCs to perform successfully certain missions in the presence of disturbances and uncertainties. It also demonstrates that the switching gain PD ILC is much effective than the PD online ILC in terms of fast convergence rates and smaller tracking errors. Pong-in Pipatpaibul and P. R. Ouyang Copyright © 2013 Pong-in Pipatpaibul and P. R. Ouyang. All rights reserved. Unified Trajectory Planning Algorithms for Autonomous Underwater Vehicle Navigation Sun, 09 Jun 2013 13:58:08 +0000 This paper presents two efficient methods for obstacle avoidance and path planning for Autonomous Underwater Vehicle (AUV). These methods take into account the dynamic constraints of the vehicle using advanced simulator of AUV considering low level control and stability effects. We present modified visibility graph local avoidance method and a spiral algorithm for obstacle avoidance. The algorithms were tested in challenged scenarios demonstrating safe trajectory planning. Oren Gal Copyright © 2013 Oren Gal. All rights reserved. Hardware Architecture Review of Swarm Robotics System: Self-Reconfigurability, Self-Reassembly, and Self-Replication Fri, 24 May 2013 11:35:40 +0000 Swarm robotics is one of the most fascinating and new research areas of recent decades, and one of the grand challenges of robotics is the design of swarm robots that are self-sufficient. This can be crucial for robots exposed to environments that are unstructured or not easily accessible for a human operator, such as the inside of a blood vessel, a collapsed building, the deep sea, or the surface of another planet. In this paper, we present a comprehensive study on hardware architecture and several other important aspects of modular swarm robots, such as self-reconfigurability, self-replication, and self-assembly. The key factors in designing and building a group of swarm robots are cost and miniaturization with robustness, flexibility, and scalability. In robotics intelligence, self-assembly and self-reconfigurability are among the most important characteristics as they can add additional capabilities and functionality to swarm robots. Simulation and model design for swarm robotics is highly complex and expensive, especially when attempting to model the behavior of large swarm robot groups. Madhav Patil, Tamer Abukhalil, and Tarek Sobh Copyright © 2013 Madhav Patil et al. All rights reserved. Comparative Study between Robust Control of Robotic Manipulators by Static and Dynamic Neural Networks Wed, 08 May 2013 10:58:23 +0000 A comparative study between static and dynamic neural networks for robotic systems control is considered. So, two approaches of neural robot control were selected, exposed, and compared. One uses a static neural network; the other uses a dynamic neural network. Both compensate the nonlinear modeling and uncertainties of robotic systems. The first approach is direct; it approximates the nonlinearities and uncertainties by a static neural network. The second approach is indirect; it uses a dynamic neural network for the identification of the robot state. The neural network weight tuning algorithms, for the two approaches, are developed based on Lyapunov theory. Simulation results show that the system response, equipped by dynamic neural network controller, has better tracking performance, has faster response time, and is more reliable to face disturbances and robotic uncertainties. Nadya Ghrab and Hichem Kallel Copyright © 2013 Nadya Ghrab and Hichem Kallel. All rights reserved. Flight Control Laws Verification Using Continuous Genetic Algorithms Wed, 27 Mar 2013 10:57:16 +0000 This work is concerned with the application of a continuous genetic algorithm (CGA) to solve the nonlinear optimization problem that results from the clearance process of nonlinear flight control laws. The CGA is used to generate a pilot command signal that governs the aircraft performance around certain points in the flight envelope about which the aircraft dynamics were trimmed. The performance of the aircraft model due to pitch and roll pilot commands is analyzed to find the worst combination that leads to a nonallowable load factor. The motivations for using the CGA to solve this type of optimization problem are due to the fact that the pilot command signals are smooth and correlated, which are difficult to generate using the conventional genetic algorithm (GA). Also the CGA has the advantage over the conventional GA method in being able to generate smooth solutions without the loss of significant information in the presence of a rate limiter in the controller design and the time delay in response to the actuators. Simulation results are presented which show superior convergence performance using the CGA compared with conventional genetic algorithms. A. Al-Asasfeh, N. Hamdan, and Z. Abo-Hammour Copyright © 2013 A. Al-Asasfeh et al. All rights reserved. SPAM for a Manipulator by Best Next Move in Unknown Environments Thu, 21 Mar 2013 14:22:47 +0000 We propose a SPAM (simultaneous planning and mapping) technique for a manipulator-type robot working in an uncertain environment via a novel Best Next Move algorithm. Demands for a smart decision to move a manipulator such as humanoid arms in uncertain or crowded environments call for a simultaneous planning and mapping technique. In the present work, we focus more on rapid map generation rather than global path search to reduce ignorance level of a given environment. The motivation is that the global path quality will be improved as the ignorance level of the unknown environment decreases. The 3D sensor introduced in the previous work has been improved for better mapping capability and the real-time rehearsal idea is used for -space cloud point generation. Captured cloud points by 3D sensors, then, create an instantaneous -space map whereby the Best Next Move algorithm directs the local motion of the manipulator. The direction of the Best Next Move utilizes the gradient of the density distribution of the -nearest-neighborhood sets in -space. It has a tendency of traveling along the direction by which the point clouds spread in space, thus rendering faster mapping of -space obstacles possible. The proposed algorithm is compared with a sensor-based algorithm such as sensor-based RRT for performance comparison. Performance measures, such as mapping efficiency, search time, and total number of -space point clouds, are reported as well. Possible applications include semiautonomous telerobotics planning and humanoid arm path planning. Dugan Um and Dongseok Ryu Copyright © 2013 Dugan Um and Dongseok Ryu. All rights reserved. Classification of Clothing Using Midlevel Layers Thu, 07 Mar 2013 15:54:03 +0000 We present a multilayer approach to classify articles of clothing within a pile of laundry. The classification features are composed of color, texture, shape, and edge information from 2D and 3D data within a local and global perspective. The contribution of this paper is a novel approach of classification termed L-M-H, more specifically LC-S-H for clothing classification. The multilayer approach compartmentalizes the problem into a high (H) layer, multiple midlevel (characteristics (C), selection masks (S)) layers, and a low (L) layer. This approach produces “local” solutions to solve the global classification problem. Experiments demonstrate the ability of the system to efficiently classify each article of clothing into one of seven categories (pants, shorts, shirts, socks, dresses, cloths, or jackets). The results presented in this paper show that, on average, the classification rates improve by +27.47% for three categories (Willimon et al., 2011), +17.90% for four categories, and +10.35% for seven categories over the baseline system, using SVMs (Chang and Lin, 2001). Bryan Willimon, Ian Walker, and Stan Birchfield Copyright © 2013 Bryan Willimon et al. All rights reserved. New Volume Change Mechanism Using Metal Bellows for Buoyancy Control Device of Underwater Robots Mon, 21 Jan 2013 09:43:34 +0000 We propose a new volume change mechanism using a metal bellows for a buoyancy control device of underwater robots and vehicles. Our proposed buoyancy control method utilizes the volume change caused by the phase-change of materials. We chose paraffin wax as a phase-change material because its volume change exceeds other candidates. Our proposed device consists of a metal bellows and an aluminum housing that contains paraffin wax and water. The paraffin wax is heated and cooled by a nichrome wire and a peltier device. We conducted two experiments and confirmed that the heat sink in the aluminum housing increases the speed of the buoyancy change and that the thickness of the air layer is crucial for efficient insulating. Then, we built a prototype robot with the four devices and confirmed that the robot can change its buoyancy up to its maximum value. Koji Shibuya and Sho Yoshii Copyright © 2013 Koji Shibuya and Sho Yoshii. All rights reserved. Collision-Detecting Device for Omnidirectional Electric Wheelchair Thu, 29 Nov 2012 09:13:20 +0000 An electric wheelchair is the device to support the self-movement of the elderly and people with physical disabilities. In this paper, a prototype design of an electric wheelchair with a high level of mobility and safety is presented. The electric wheelchair has a high level of mobility by employing an omnidirectional mechanism. Large numbers of mechanisms have been developed to realize omnidirectional motion. However, they have various drawbacks such as a complicated mechanism and difficulty of employment for practical use. Although the ball wheel drive mechanism is simple, it realizes stable motion when negotiating a step, gap, or slope. The high level of mobility enhances the freedom of users while increasing the risk of collision with obstacles or walls. To prevent collisions with obstacles, some electric wheelchairs are equipped with infrared sensors, ultrasonic sensors, laser range finders, or machine vision. However, since these devices are expensive, it will be difficult for them to be widely used with electric wheelchairs. We have developed a prototype design of collision-detecting device with inexpensive sensors. This device detects the occurrence of collisions and can calculate the direction of the colliding object. A prototype has been developed to perform motion experiments and verify the accuracy of the device. The results of experiments are also presented in this paper. Shuichi Ishida and Hiroyuki Miyamoto Copyright © 2013 Shuichi Ishida and Hiroyuki Miyamoto. All rights reserved. An Adaptive -Based Formation Control for Multirobot Systems Tue, 27 Nov 2012 14:18:12 +0000 We describe a decentralized formation problem for multiple robots, where an formation controller is proposed. The network of dynamic agents with external disturbances and uncertainties are discussed in formation problems. We first describe how to design social potential fields to obtain a formation with the shape of a polygon. Then, we provide a formal proof of the asymptotic stability of the system, based on the definition of a proper Lyapunov function and technique. The advantages of the proposed controller can be listed as robustness to input nonlinearity, external disturbances, and model uncertainties, while applicability on a group of any autonomous systems with -degrees of freedom. Finally, simulation results are demonstrated for a multiagent formation problem of a group of six robots, illustrating the effective attenuation of approximation error and external disturbances, even in the case of agent failure or leader tracking. Faridoon Shabani, Bijan Ranjbar, and Ali Ghadamyari Copyright © 2013 Faridoon Shabani et al. All rights reserved. Flocking for Multiple Ellipsoidal Agents with Limited Communication Ranges Mon, 26 Nov 2012 09:11:34 +0000 This paper contributes a design of distributed controllers for flocking of mobile agents with an ellipsoidal shape and a limited communication range. A separation condition for ellipsoidal agents is first derived. Smooth step functions are then introduced. These functions and the separation condition between the ellipsoidal agents are embedded in novel pairwise potential functions to design flocking control algorithms. The proposed flocking design results in (1) smooth controllers despite of the agents’ limited communication ranges, (2) no collisions between any agents, (3) asymptotic convergence of each agent’s generalized velocity to a desired velocity, and (4) boundedness of the flock size, defined as the sum of all distances between the agents, by a constant. K. D. Do Copyright © 2013 K. D. Do. All rights reserved. Estimate a Flexible Link’s Shape by the Use of Strain Gauge Sensors Wed, 24 Oct 2012 13:58:51 +0000 This paper presents a method for estimating the flexible link’s shape by finite number of sensors. The position and orientation of flexible link are expressed as a function of curvature of the link. An interpolation technique gives this continuous curvature function from a finite set of the Wheatstone bridge made with strain gauges. For interpolation we can use different functions to find better way for estimation of link’s shape. Comparison between different types of function can show us best corresponding with nature of the link. Our case study is a single flexible link robot. A high-precision data logger is used as data acquisition instrument. M. H. Korayem, A. M. Shafei, and F. Absalan Copyright © 2013 M. H. Korayem et al. All rights reserved. A Theoretical and Experimental Approach of Fuzzy Adaptive Motion Control for Wheeled Autonomous Nonholonomic Vehicles Sun, 21 Oct 2012 15:42:32 +0000 A new fuzzy adaptive control is applied to solve a problem of motion control of nonholonomic vehicles with two independent wheels actuated by a differential drive. The major objective of this work is to obtain a motion control system by using a new fuzzy inference mechanism where the Lyapunov stability can be ensured. In particular the parameters of the kinematical control law are obtained using a fuzzy mechanism, where the properties of the fuzzy maps have been established to have the stability above. Due to the nonlinear map of the intelligent fuzzy inference mechanism (i.e., fuzzy rules and value of the rule), the parameters above are not constant, but, time after time, based on empirical fuzzy rules, they are updated in function of the values of the tracking errors. Since the fuzzy maps are adjusted based on the control performances, the parameters updating ensures a robustness and fast convergence of the tracking errors. Also, since the vehicle dynamics and kinematics can be completely unknown, dynamical and kinematical adaptive controllers have been added. The proposed fuzzy controller has been implemented for a real nonholonomic electrical vehicle. Therefore, system robustness and stability performance are verified through simulations and experimental studies. Maurizio Melluso Copyright © 2013 Maurizio Melluso. All rights reserved. An Introduction to Swarm Robotics Tue, 04 Sep 2012 10:10:37 +0000 Swarm robotics is a field of multi-robotics in which large number of robots are coordinated in a distributed and decentralised way. It is based on the use of local rules, and simple robots compared to the complexity of the task to achieve, and inspired by social insects. Large number of simple robots can perform complex tasks in a more efficient way than a single robot, giving robustness and flexibility to the group. In this article, an overview of swarm robotics is given, describing its main properties and characteristics and comparing it to general multi-robotic systems. A review of different research works and experimental results, together with a discussion of the future swarm robotics in real world applications completes this work. Iñaki Navarro and Fernando Matía Copyright © 2013 Iñaki Navarro and Fernando Matía. All rights reserved.