Journal of Robotics The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . All rights reserved. Biologically Inspired Robotics Thu, 08 Oct 2015 06:58:41 +0000 Liwei Shi, Maki K. Habib, Nan Xiao, and Huosheng Hu Copyright © 2015 Liwei Shi et al. All rights reserved. Development and Motion Testing of a Robotic Ray Mon, 05 Oct 2015 08:56:25 +0000 Biomimetics takes nature as a model for inspiration to immensely help abstract new principles and ideas to develop various devices for real applications. In order to improve the stability and maneuvering of biomimetic fish like underwater propulsors, we selected bluespotted ray that propel themselves by taking advantage of their pectoral fins as target. First, a biomimetic robotic undulating fin driven propulsor was built based on the simplified pectoral structure of living bluespotted ray. The mechanical structure and control circuit were then presented. The fin undulating motion patterns, fin ray angle, and fin shape to be investigated are briefly introduced. Later, the kinematic analysis of fin ray and the whole fin is discussed. The influence of various kinematic parameters and morphological parameters on the average propulsion velocity of the propulsor was analyzed. Finally, we conclude that the average propulsion velocity generally increases with the increase of kinematic parameters such as frequency, amplitude, and wavelength, respectively. Moreover, it also has a certain relationship with fin undulating motion patterns, fin ray angle, fin shape, and fin aspect ratio. Jianhui He and Yonghua Zhang Copyright © 2015 Jianhui He and Yonghua Zhang. All rights reserved. Rolling Locomotion Control of a Biologically Inspired Quadruped Robot Based on Energy Compensation Mon, 05 Oct 2015 08:43:41 +0000 We have developed a biologically inspired reconfigurable quadruped robot which can perform walking and rolling locomotion and transform between walking and rolling by reconfiguring its legs. This paper presents an approach to control rolling locomotion with the biologically inspired quadruped robot. For controlling rolling locomotion, a controller which can compensate robot’s energy loss during rolling locomotion is designed based on a dynamic model of the quadruped robot. The dynamic model describes planar rolling locomotion based on an assumption that the quadruped robot does not fall down while rolling and the influences of collision and contact with the ground, and it is applied for computing the mechanical energy and a plant in a numerical simulation. The numerical simulation of rolling locomotion on the flat ground verifies the effectiveness of the proposed controller. The simulation results show that the quadruped robot can perform periodic rolling locomotion with the proposed energy-based controller. In conclusion, it is shown that the proposed control approach is effective in achieving the periodic rolling locomotion on the flat ground. Takuma Nemoto, Rajesh Elara Mohan, and Masami Iwase Copyright © 2015 Takuma Nemoto et al. All rights reserved. Action Selection and Operant Conditioning: A Neurorobotic Implementation Sun, 04 Oct 2015 12:21:28 +0000 Action selection (AS) is thought to represent the mechanism involved by natural agents when deciding what should be the next move or action. Is there a functional elementary core sustaining this cognitive process? Could we reproduce the mechanism with an artificial agent and more specifically in a neurorobotic paradigm? Unsupervised autonomous robots may require a decision-making skill to evolve in the real world and the bioinspired approach is the avenue explored through this paper. We propose simulating an AS process by using a small spiking neural network (SNN) as the lower neural organisms, in order to control virtual and physical robots. We base our AS process on a simple central pattern generator (CPG), decision neurons, sensory neurons, and motor neurons as the main circuit components. As novelty, this study targets a specific operant conditioning (OC) context which is relevant in an AS process; choices do influence future sensory feedback. Using a simple adaptive scenario, we show the complementarity interaction of both phenomena. We also suggest that this AS kernel could be a fast track model to efficiently design complex SNN which include a growing number of input stimuli and motor outputs. Our results demonstrate that merging AS and OC brings flexibility to the behavior in generic dynamical situations. André Cyr and Frédéric Thériault Copyright © 2015 André Cyr and Frédéric Thériault. All rights reserved. Bioinspired Tracking Control of High Speed Nonholonomic Ground Vehicles Sun, 04 Oct 2015 09:44:53 +0000 The behavior of nature’s predators is considered for designing a high speed tracking controller for nonholonomic vehicles, whose dynamics are represented using a unicycle model. To ensure that the vehicle behaves intuitively and mimics the biologically inspired predator-prey interaction, saturation constraints based on Ackermann steering kinematics are added. A new strategy for mapping commands back into a viable envelope is introduced, and the restrictions are accounted for using Lyapunov stability criteria. Following verification of the saturation constraints, the proposed algorithm was implemented on a testing platform. Stable trajectories of up to 9 m/s were achieved. The results presented show that the algorithm demonstrates significant promise in high speed trajectory tracking with obstacle avoidance. Adam Shoemaker and Alexander Leonessa Copyright © 2015 Adam Shoemaker and Alexander Leonessa. All rights reserved. Unified Switching between Active Flying and Perching of a Bioinspired Robot Using Impedance Control Sun, 04 Oct 2015 07:22:59 +0000 Currently, a bottleneck problem for battery-powered microflying robots is time of endurance. Inspired by flying animal behavior in nature, an innovative mechanism with active flying and perching in the three-dimensional space was proposed to greatly increase mission life and more importantly execute tasks perching on an object in the stationary way. In prior work, we have developed some prototypes of flying and perching robots. However, when the robots switch between flying and perching, it is a challenging issue to deal with the contact between the robot and environment under the traditional position control without considering the stationary obstacle and external force. Therefore, we propose a unified impedance control approach for bioinspired flying and perching robots to smoothly contact with the environment. The dynamic model of the bioinspired robot is deduced, and the proposed impedance control method is employed to control the contact force and displacement with the environment. Simulations including the top perching and side perching and the preliminary experiments were conducted to validate the proposed method. Both simulation and experimental results validate the feasibility of the proposed control methods for controlling a bioinspired flying and perching robot. Shanshan Du, Heping Chen, Yong Liu, and Runting Hu Copyright © 2015 Shanshan Du et al. All rights reserved. Development and Evaluation of Compact Robot Imitating a Hermit Crab for Inspecting the Outer Surface of Pipes Thu, 01 Oct 2015 12:33:41 +0000 Terrestrial hermit crabs which are a type of hermit crabs live on land, whereas typical hermit crabs inhabit the sea. They have an ability of climbing a tree vertically. Their claws allow them to hang on the tree. In this study, an outer-pipe inspection robot was developed. Its locomotion mechanism was developed in imitation of the terrestrial hermit crab’s claws. It is equipped with two rimless wheels. Each of the spokes is tipped with a neodymium magnet, which allows the robot to remain attached to even a vertical steel pipe. Moreover, the robot has a mechanism for adjusting the camber angle of the right and left wheels, allowing it to tightly grip pipes with different diameters. Experiments were conducted to check the performance of the robot using steel pipes with different diameters, placed horizontally, vertically, or obliquely. The robot attempted to move a certain distance along a pipe, and its success rate was measured. It was found that the robot could successfully travel along pipes with vertical orientations, although it sometimes fell from oblique or horizontal pipes. The most likely reason for this is identified and discussed. Certain results were obtained in laboratory. Further experiments in actual environment are required. Naoto Imajo, Yogo Takada, and Mikiji Kashinoki Copyright © 2015 Naoto Imajo et al. All rights reserved. Sparse Approximation for Nonrigid Structure from Motion Thu, 01 Oct 2015 12:32:45 +0000 This paper introduces applying a novel sparse approximation method into solving nonrigid structure from motion problem in trajectory space. Instead of generating a truncated traditional trajectory basis, this method uses an atom dictionary which includes a set of overcomplete bases to estimate the real shape of the deformable object. Yet, it still runs reliably and can get an optimal result. On the other hand, it does not need to consider the size of predefined trajectory bases; that is to say, there is no need to truncate the trajectory basis. The mentioned method is very easy to implement and the only trouble which needs to be solved is an -regularized least squares problem. This paper not only presents a new thought, but also gives out a simple but effective solution for the nonrigid structure from motion problem. Yaming Wang, Xiaomeng Yan, Junbao Zheng, and Mingfeng Jiang Copyright © 2015 Yaming Wang et al. All rights reserved. Unmanned Aerial Vehicle Navigation Using Wide-Field Optical Flow and Inertial Sensors Thu, 01 Oct 2015 12:31:29 +0000 This paper offers a set of novel navigation techniques that rely on the use of inertial sensors and wide-field optical flow information. The aircraft ground velocity and attitude states are estimated with an Unscented Information Filter (UIF) and are evaluated with respect to two sets of experimental flight data collected from an Unmanned Aerial Vehicle (UAV). Two different formulations are proposed, a full state formulation including velocity and attitude and a simplified formulation which assumes that the lateral and vertical velocity of the aircraft are negligible. An additional state is also considered within each formulation to recover the image distance which can be measured using a laser rangefinder. The results demonstrate that the full state formulation is able to estimate the aircraft ground velocity to within 1.3 m/s of a GPS receiver solution used as reference “truth” and regulate attitude angles within 1.4 degrees standard deviation of error for both sets of flight data. Matthew B. Rhudy, Yu Gu, Haiyang Chao, and Jason N. Gross Copyright © 2015 Matthew B. Rhudy et al. All rights reserved. Inverse Kinematic Analysis and Evaluation of a Robot for Nondestructive Testing Application Thu, 01 Oct 2015 08:59:17 +0000 The robot system has been utilized in the nondestructive testing field in recent years. However, only a few studies have focused on the application of ultrasonic testing for complex work pieces with the robot system. The inverse kinematics problem of the 6-DOF robot should be resolved before the ultrasonic testing task. A new effective solution for curved-surface scanning with a 6-DOF robot system is proposed in this study. A new arm-wrist separateness method is adopted to solve the inverse problem of the robot system. Eight solutions of the joint angles can be acquired with the proposed inverse kinematics method. The shortest distance rule is adopted to optimize the inverse kinematics solutions. The best joint-angle solution is identified. Furthermore, a 3D-application software is developed to simulate ultrasonic trajectory planning for complex-shape work pieces with a 6-DOF robot. Finally, the validity of the scanning method is verified based on the C-scan results of a work piece with a curved surface. The developed robot ultrasonic testing system is validated. The proposed method provides an effective solution to this problem and would greatly benefit the development of industrial nondestructive testing. Zongxing Lu, Chunguang Xu, Qinxue Pan, Xinyu Zhao, and Xinliang Li Copyright © 2015 Zongxing Lu et al. All rights reserved. Simulation of Octopus Arm Based on Coupled CPGs Thu, 01 Oct 2015 08:37:48 +0000 The octopus arm has attracted many researchers’ interests and became a research hot spot because of its amazing features. Several dynamic models inspired by an octopus arm are presented to realize the structure with a large number of degrees of freedom. The octopus arm is made of a soft material introducing high-dimensionality, nonlinearity, and elasticity, which makes the octopus arm difficult to control. In this paper, three coupled central pattern generators (CPGs) are built and a 2-dimensional dynamic model of the octopus arm is presented to explore possible strategies of the octopus movement control. And the CPGs’ signals treated as activation are added on the ventral, dorsal, and transversal sides, respectively. The effects of the octopus arm are discussed when the parameters of the CPGs are changed. Simulations show that the octopus arm movements are mainly determined by the shapes of three CPGs’ phase diagrams. Therefore, some locomotion modes are supposed to be embedded in the neuromuscular system of the octopus arm. And the octopus arm movements can be achieved by modulating the parameters of the CPGs. The results are beneficial for researchers to understand the octopus movement further. Juan Tian and Qiang Lu Copyright © 2015 Juan Tian and Qiang Lu. All rights reserved. A Framework for Multidisciplinary Optimization of a Balancing Mechanism for an Industrial Robot Mon, 27 Jul 2015 08:19:20 +0000 The paper presents a framework that can be used to design and optimize a balancing mechanism for an industrial robot. The framework has the capability to optimize three different concepts: a mechanical, a pneumatic, and a hydropneumatic. Several disciplines are included in the framework, such as dynamic and static analyses of the robot performance. Optimization is performed for each concept and the obtained optimal designs are all better than the reference design. This means that the framework can be used as a tool both to optimize the balancing mechanism and also to support concept selection. Johan A. Persson, Xiaolong Feng, Daniel Wappling, and Johan Ölvander Copyright © 2015 Johan A. Persson et al. All rights reserved. Visual Control System of a Spraying Robot for Hyphantria cunea Larva Nets Sun, 31 May 2015 11:53:07 +0000 In order to implement automatic spraying on Hyphantria cunea larva nets, a spraying robot system with monocular hand-eye coordination and smart targeting abilities was designed according to the target net features. The system realized spatial two-dimensional motions driven by step motors on linear guide rails. Images were processed in real-time to extract the net curtain targets defined using the border area, and the optimal spraying position was then determined. An identification algorithm based on the global net image to distinguish targets before and after spray was proposed. A simulation environment was designed to verify the correctness of this method. Results showed that the highest rate of over spray is 288.5%, and the spray miss rate is 0. Ying Zhao, Qun Sun, Chong Wang, and Cuihua Zhang Copyright © 2015 Ying Zhao et al. All rights reserved. Fixing Device for a Planar Object by Incorporating Jamming Transition Phenomenon and a Suction Unit Mon, 25 May 2015 13:51:19 +0000 This paper presents a versatile method to install a small machining robot onto a planar or slightly curved object. Normally, gripping tools provide a rigid connection between a robot and a target. However, if there is no graspable area on the target, the gripper cannot perform well. To overcome this problem, we proposed a deformable device that works as a universal suction pad and that can hold an ungraspable target by utilizing the jamming transition phenomenon. We determined the effect of the type of grains on the jamming transition phenomenon in terms of stability under jammed conditions. By comparing the four types of grains, we found that the tetrahedral-shaped grains performed the best. Subsequently, we evaluated the performance of the device. The suction force was 166-N when the proposed device was affixed to a curved target. Next, we evaluated the stiffness of the device. The average deformations of the device were 0.10 mm, 0.35 mm, and 0.04 mm, respectively, when 50-N downward vertical, horizontal, and upward vertical directional loads were applied to the device, which was affixed to the curved target. The results suggest that the proposed device performed well in affixing a robot onto a target. Akira Bekku and Yoshikazu Nakajima Copyright © 2015 Akira Bekku and Yoshikazu Nakajima. All rights reserved. Dynamic Modeling and Nonlinear Position Control of a Quadruped Robot with Theo Jansen Linkage Mechanisms and a Single Actuator Tue, 19 May 2015 11:19:02 +0000 The Theo Jansen mechanism is gaining widespread popularity among the legged robotics community due to its scalable design, energy efficiency, low payload-to-machine-load ratio, bioinspired locomotion, and deterministic foot trajectory. In this paper, we perform for the first time the dynamic modeling and analysis on a four-legged robot driven by a single actuator and composed of Theo Jansen mechanisms. The projection method is applied to derive the equations of motion of this complex mechanical system and a position control strategy based on energy is proposed. Numerical simulations validate the efficacy of the designed controller, thus setting a theoretical basis for further investigations on Theo Jansen based quadruped robots. Shunsuke Nansai, Rajesh Elara Mohan, Ning Tan, Nicolas Rojas, and Masami Iwase Copyright © 2015 Shunsuke Nansai et al. All rights reserved. Integrated Trajectory Planning and Sloshing Suppression for Three-Dimensional Motion of Liquid Container Transfer Robot Arm Mon, 18 May 2015 11:42:24 +0000 For liquid transfer system in three-dimensional space, the use of multijoint robot arm provides much flexibility. To realize quick point-to-point motion with minimal sloshing in such system, we propose an integrated framework of trajectory planning and sloshing suppression. The robot motion is decomposed into translational motion of the robot wrist and rotational motion of the robot hand to ensure the upright orientation of the liquid container. The trajectory planning for the translational motion is based on cubic spline optimization with free via points that produces smooth trajectory in joint space while it still allows obstacle avoidance in task space. Input shaping technique is applied in the task space to suppress the motion induced sloshing, which is modeled as spherical pendulum with moving support. It has been found through simulations and experiments that the proposed approach is effective in generating quick motion with low amount of sloshing. Wisnu Aribowo, Takahito Yamashita, and Kazuhiko Terashima Copyright © 2015 Wisnu Aribowo et al. All rights reserved. Omnidirectional Analysis of Spatial Manipulator Mon, 11 May 2015 08:22:34 +0000 Space manipulators are mainly used in the spatial loading task. According to problems of the spatial loading diversity, the testing loading installing position, and the utilization ratio of a test platform, the space manipulator is asked to evaluate the position and attitude of itself. This paper proposes the Point Omnidirectional Coefficient (POC) with unit attitude sphere/circle to describe attitude of the end-effector, which evaluates any points in the attainable space of the manipulators, in combination with the manipulation’s position message, and get relationships between its position and attitude of all points in the attainable space. It represents the mapping between sphere surface and plane for mission attitude constraints and the method for calculating volume of points space including attainable space, Omnidirectional space, and mission attitude space. Furthermore, the Manipulator Omnidirectional Coefficient based on mission or not is proposed for evaluating manipulator performance. Through analysis and simulation about 3D and 2D manipulators, the results show that the above theoretical approach is feasible and the relationships about link lengths, joints angles, attainable space, and Manipulator Omnidirectional Coefficient are drawn for guiding design. Yuquan Leng, Yang Zhang, Xu He, Wei Zhang, Haitao Luo, and Weijia Zhou Copyright © 2015 Yuquan Leng et al. All rights reserved. Disturbance Observer Based Control of Multirotor Helicopters Based on a Universal Model with Unstructured Uncertainties Sun, 22 Mar 2015 13:22:16 +0000 To handle different perspectives of unstructured uncertainties, two robust control techniques on the basis of a universal model are studied in this paper. Rather than building a model only applicable to a specific small-scale multirotor helicopter (MHeli), the paper proposes a modeling technique to develop a universal model-framework. Particularly, it is straightforward to apply the universal model to a certain MHeli because the contribution and allocation matrix is proposed in the model-framework. Based on the model uncertainties, the load perturbation of the rotor is the primary focus due to its indispensable importance in the tracking performance. In contrast to the common methods, it is proposed to take this unstructured uncertainty in that external disturbance and designs disturbance observer (DOB). In addition, a class of lead-compensator is specifically designed as for compensating phase lag induced by DOB. Compared with loop-shaping, greater robust tracking performance on rejecting load perturbation could be achieved as a tradeoff between robust stability and tracking performance which is successfully avoided with DOB-based control strategy. Ye Xie, Yunfeng Cao, Biao Wang, and Meng Ding Copyright © 2015 Ye Xie et al. All rights reserved. Dual Arm Free Flying Space Robot Trajectory Planning Using Polynomial Thu, 26 Feb 2015 10:20:00 +0000 The paper presents path planning of dual arm free flying space robot using smooth functions of time. Kinematic and dynamic modeling of dual arm free flying space robot is presented first. Using kinematic model, the Jacobian of the system has been derived, and using dynamic model, equations of motion are derived. A path planning methodology for planar system is developed using smooth function of time such as polynomials. Due to nonholonomic behaviour of the manipulator in the zero gravity environment linear and angular momentum is conserved. The proposed method yields input trajectories that drive both the manipulator and the base to a desired configuration. Joint torque curves can be obtained by introducing this joint trajectory curves in equation of motion of the space robot. Rishikesh Rathee and Pushparaj Mani Pathak Copyright © 2015 Rishikesh Rathee and Pushparaj Mani Pathak. All rights reserved. Passive Transparency Compensation for Bilateral Teleoperators with Communication Delays Wed, 25 Feb 2015 06:32:32 +0000 One of the main challenges in the realization of time-delayed bilateral teleoperators is the stable adaptation of transparency when the remote environmental dynamics are time-varying. In this paper, we propose a bilateral control strategy that passively adjusts the transparency of the system when the slave robot transitions between two different environments. The proposed controller exploits the effect that the wave impedance (a design parameter of the passivity-based scattering transformation) has on transparency without comprising closed-loop stability, regardless of time-varying communication delays. To properly adjust transparency, the control scheme smoothly switches the wave impedance parameter between a low value, ideal for free motion, and a sufficiently large value, suited for hard-contact tasks. We show that, by adopting this strategy, the transmitted impedance to the operator approximates more closely the environmental impedance value. Furthermore, we theoretically prove master-slave position coordination and force tracking under different scenarios. Simulation results illustrate the effectiveness of the proposed control strategy. Erick J. Rodríguez-Seda Copyright © 2015 Erick J. Rodríguez-Seda. All rights reserved. A Fast Learning Method for Multilayer Perceptrons in Automatic Speech Recognition Systems Mon, 23 Feb 2015 14:12:10 +0000 We propose a fast learning method for multilayer perceptrons (MLPs) on large vocabulary continuous speech recognition (LVCSR) tasks. A preadjusting strategy based on separation of training data and dynamic learning-rate with a cosine function is used to increase the accuracy of a stochastic initial MLP. Weight matrices of the preadjusted MLP are restructured by a method based on singular value decomposition (SVD), reducing the dimensionality of the MLP. A back propagation (BP) algorithm that fits the unfolded weight matrices is used to train the restructured MLP, reducing the time complexity of the learning process. Experimental results indicate that on LVCSR tasks, in comparison with the conventional learning method, this fast learning method can achieve a speedup of around 2.0 times with improvement on both the cross entropy loss and the frame accuracy. Moreover, it can achieve a speedup of approximately 3.5 times with only a little loss of the cross entropy loss and the frame accuracy. Since this method consumes less time and space than the conventional method, it is more suitable for robots which have limitations on hardware. Chenghao Cai, Yanyan Xu, Dengfeng Ke, and Kaile Su Copyright © 2015 Chenghao Cai et al. All rights reserved. The COMRADE System for Multirobot Autonomous Landmine Detection in Postconflict Regions Sun, 15 Feb 2015 10:33:44 +0000 We consider the problem of autonomous landmine detection using a team of mobile robots. Previous research on robotic landmine detection mostly employs a single robot equipped with a landmine detection sensor to detect landmines. We envisage that the quality of landmine detection can be significantly improved if multiple robots are coordinated to detect landmines in a cooperative manner by incrementally fusing the landmine-related sensor information they collect and then use that information to visit locations of potential landmines. Towards this objective, we describe a multirobot system called COMRADES to address different aspects of the autonomous landmine detection problem including distributed area coverage to detect and locate landmines, information aggregation to fuse the sensor information obtained by different robots, and multirobot task allocation (MRTA) to enable different robots to determine a suitable sequence to visit locations of potential landmines while reducing the time required and battery expended. We have used commercially available all-terrain robots called Coroware Explorer that are customized with a metal detector to detect metallic objects including landmines, as well as indoor Corobot robots, both in simulation and in physical experiments, to test the different techniques in COMRADES. Prithviraj Dasgupta, José Baca, K. R. Guruprasad, Angélica Muñoz-Meléndez, and Janyl Jumadinova Copyright © 2015 Prithviraj Dasgupta et al. All rights reserved. Self-Organized Fission Control for Flocking System Mon, 02 Feb 2015 09:41:36 +0000 This paper studies the self-organized fission control problem for flocking system. Motivated by the fission behavior of biological flocks, information coupling degree (ICD) is firstly designed to represent the interaction intensity between individuals. Then, from the information transfer perspective, a “maximum-ICD” based pairwise interaction rule is proposed to realize the directional information propagation within the flock. Together with the “separation/alignment/cohesion” rules, a self-organized fission control algorithm is established that achieves the spontaneous splitting of flocking system under conflict external stimuli. Finally, numerical simulations are provided to demonstrate the effectiveness of the proposed algorithm. Mingyong Liu, Panpan Yang, Xiaokang Lei, and Yang Li Copyright © 2015 Mingyong Liu et al. All rights reserved. Smart Tendon Actuated Flexible Actuator Thu, 29 Jan 2015 13:03:45 +0000 We investigate the kinematic feasibility of a tendon-based flexible parallel platform actuator. Much of the research on tendon-driven Stewart platforms is devoted either to the completely restrained positioning mechanism (CRPM) or to one particular type of the incompletely restrained positioning mechanism (IRPM) where the external force is provided by the gravitational pull on the platform such as in cable-suspended Stewart platforms. An IRPM-based platform is proposed which uses the external force provided by a compliant member. The compliant central column allows the configuration to achieve DOFs with tendons. In particular, this investigation focuses on the angular deflection of the upper platform with respect to the lower platform. The application here is aimed at developing a linkable module that can be connected to one another so as to form a “snake robot” of sorts. Since locomotion takes precedence over positioning in this application, a 3-DOF Stewart platform is adopted. For an arbitrary angular displace of the end-effector, the corresponding length of each tendon can be determined through inverse kinematics. Mathematical singularities are investigated using the traditional analytical method of defining the Jacobian. Md. Masum Billah and Raisuddin Khan Copyright © 2015 Md. Masum Billah and Raisuddin Khan. All rights reserved. Pose Self-Measurement of Noncooperative Spacecraft Based on Solar Panel Triangle Structure Mon, 26 Jan 2015 07:37:49 +0000 Aiming at the recognition and location of noncooperative spacecraft, this paper presents a monocular vision pose measurement method based on solar triangle structure. First of all, an autonomous recognition algorithm of feature structure based on sliding window Hough transformation (SWHT) and inscribed circle of a triangle is proposed, and the image coordinates of feature points on the triangle can be obtained relying on this algorithm, combined with the P4P algorithm and the structure of spacecraft, calculating the relative pose of target expressed by rotation and translation matrix. The whole algorithm can be loaded into the prewritten onboard program, which will get the autocomplete feature structure extraction and relative pose measurement without human intervention, and this method does not need to mount any markers on the target. Then compare the measured values with the accurate value of the laser tracker, so that a conclusion can be drawn that the maximum position error is lower than 5% and the rotation error is lower than 4%, which meets the requirements of noncooperative spacecraft’s pose measurement for observations, tracking, and docking in the final rendezvous phase. Jingzhou Song and Caixiu Cao Copyright © 2015 Jingzhou Song and Caixiu Cao. All rights reserved. Nonholonomic Motion Planning Strategy for Underactuated Manipulator Thu, 18 Dec 2014 00:10:19 +0000 This paper develops nonholonomic motion planning strategy for three-joint underactuated manipulator, which uses only two actuators and can be converted into chained form. Since the manipulator was designed focusing on the control simplicity, there are several issues for motion planning, mainly including transformation singularity, path estimation, and trajectory robustness in the presence of initial errors, which need to be considered. Although many existing motion planning control laws for chained form system can be directly applied to the manipulator and steer it to desired configuration, coordinate transformation singularities often happen. We propose two mathematical techniques to avoid the transformation singularities. Then, two evaluation indicators are defined and used to estimate control precision and linear approximation capability. In the end, the initial error sensitivity matrix is introduced to describe the interference sensitivity, which is called robustness. The simulation and experimental results show that an efficient and robust resultant path of three-joint underactuated manipulator can be successfully obtained by use of the motion planning strategy we presented. Liang Li, Yuegang Tan, and Zhang Li Copyright © 2014 Liang Li et al. All rights reserved. Humanoid Robot Head Design Based on Uncanny Valley and FACS Sun, 14 Dec 2014 11:55:58 +0000 Emotional robots are always the focus of artificial intelligence (AI), and intelligent control of robot facial expression is a hot research topic. This paper focuses on the design of humanoid robot head, which is divided into three steps to achieve. The first step is to solve the uncanny valley about humanoid robot, to find and avoid the relationship between human being and robot; the second step is to solve the association between human face and robot head; compared with human being and robots, we analyze the similarities and differences and explore the same basis and mechanisms between robot and human analyzing the Facial Action Coding System (FACS), which guides us to achieve humanoid expressions. On the basis of the previous two steps, the third step is to construct a robot head; through a series of experiments we test the robot head, which could show some humanoid expressions; through human-robot interaction, we find people are surprised by the robot head expression and feel happy. Jizheng Yan, Zhiliang Wang, and Yan Yan Copyright © 2014 Jizheng Yan et al. All rights reserved. Theory Analysis and Experiment Research of the Leg Mechanism for the Human-Carrying Walking Chair Robot Wed, 10 Dec 2014 08:10:48 +0000 For the high carrying capacity of the human-carrying walking chair robot, in this paper, 2-UPS+UP parallel mechanism is selected as the leg mechanism; then kinematics, workspace, control, and experiment of the leg mechanism are researched in detail. Firstly, design of the whole mechanism is described and degrees of freedom of the leg mechanism are analyzed. Second, the forward position, inverse position, and velocity of leg mechanism are studied. Third, based on the kinematics analysis and the structural constraints, the reachable workspace of 2-UPS+UP parallel mechanism is solved, and then the optimal motion workspace is searched in the reachable workspace by choosing the condition number as the evaluation index. Fourth, according to the theory analysis of the parallel leg mechanism, its control system is designed and the compound position control strategy is studied. Finally, in optimal motion workspace, the compound position control strategy is verified by using circular track with the radius 100 mm; the experiment results show that the leg mechanism moves smoothly and does not tremble obviously. Theory analysis and experiment research of the single leg mechanism provide a theoretical foundation for the control of the quadruped human-carrying walking chair robot. Lingfeng Sang, Hongbo Wang, Shuaishuai Wang, Na Chen, and Yuehua Wen Copyright © 2014 Lingfeng Sang et al. All rights reserved. Asymmetric Bellow Flexible Pneumatic Actuator for Miniature Robotic Soft Gripper Wed, 03 Dec 2014 06:39:53 +0000 The necessity of the soft gripping devices is increasing day-by-day in medical robotics especially when safe, gentle motions and soft touch are necessary. In this paper, a novel asymmetric bellow flexible pneumatic actuator (AFPA) has been designed and fabricated to construct a miniaturised soft gripper that could be used to grip small objects. The model of AFPA is designed using solid works and its bending motion is simulated in Abaqus software for optimisation and compared with experimental results. The actuator is fabricated using compression molding process that includes micromachining of the molds. Experiments conducted show the bending characteristics of the actuator at different pressures. The actuator shows excellent bending performance and the eccentricity in its design supports increased bending or curling motion up to a certain extent compared to normal bellows without eccentricity. The effects of profile shape and eccentricity on the actuator performance are analysed and the results are presented. Ganesha Udupa, Pramod Sreedharan, P. Sai Dinesh, and Doik Kim Copyright © 2014 Ganesha Udupa et al. All rights reserved. Kinematics and Dynamics of an Asymmetrical Parallel Robotic Wrist Mon, 01 Dec 2014 00:10:04 +0000 This paper introduces an asymmetrical parallel robotic wrist, which can generate a decoupled unlimited-torsion motion and achieve high positioning accuracy. The kinematics, dexterity, and singularities of the manipulator are investigated to visualize the performance contours of the manipulator. Using the method of Lagrange multipliers and considering all the mobile components, the equations of motion of the manipulator are derived to investigate the dynamic characteristics efficiently. The developed dynamic model is numerically illustrated and compared with its simplified formulation to show its computation accuracy. Guanglei Wu Copyright © 2014 Guanglei Wu. All rights reserved.