waashk/dblp huggingface dataset:
neural virtual sensors for terrain adaptation of walking machines. when walking in realistic conditions, accurate, reliable sensorial information is critical to ensure the safe operation of legged robots. that means a large number of sensors, cabling, and electronic systems must be used, complicating the robot. on the other hand, the great complexity of the hardware of walking machines is one of the main obstacles preventing the introduction of this kind of vehicle in real applications; consequently this hardware should be simplified. these antagonistic requirements can be reconciled by the use of what are called virtual sensors. this paper addresses the design of virtual sensors for terrain adaptation developed with the aims of simplifying the hardware of the walking machine or increasing the reliability of the sensorial information available. these virtual sensors are based on neural networks and can estimate the forces exerted by the feet from data extracted from joint-position sensors, which are mandatory in all robotic systems. the force estimates are used to detect foot&#x002f;ground contact. some experiments carried out with the silo4 walking robot are reported to prove the efficacy of this method. &copy; 2005 wiley periodicals, inc.
a new revolute robot manipulator adapting the closed-chain mechanism. conventional robot manipulators actuated by motors with conventional speed reducers such as the harmonic drive or rv have weakness in the load capacity since the speed reducers are not stiff enough. to overcome this, we propose a four-bar-link actuator driven by the ball screw, which has a high stiffness and high torque transmission ability, and propose a new type of four degree-of-freedom revolute robot manipulator adapting the proposed actuators. the base joint of the robot is actuated by the motor with the conventional speed reducer, and the other joints are actuated by the proposed actuators. the kinematics and dynamics of the robot are analyzed in the joint coordinate and in the cartesian coordinate. for the performance tests of the robot, a four degree-of-freedom revolute robot was built. through the performance tests, the results of superior load capacity and positioning accuracy are presented. &copy; 2005 wiley periodicals, inc.
a new family of hybrid 4-dof parallel mechanisms with two platforms and its application to a footpad device. this paper proposes a new family of 4-degrees-of-freedom (dof) parallel mechanisms with two platforms and its application to a footpad device that can simulate the spatial motions of the human foot. the new mechanism consists of front and rear platforms, and three limbs. two limbs with 6-dof serial joints ( <und>p</und>-s-p-p) are attached to each platform and are perpendicular to the base plate, while the middle limb is attached to the revolute joint that connects the front and rear platforms. the middle limb is driven by the 2-dof driving mechanism that is equivalent to active serial prismatic and revolute joints ( <und>pe</und>- <und>re</und>), or prismatic and prismatic joints ( <und>pe</und>- <und>pe</und>) with two base-fixed prismatic actuators. since the middle limb perpendicular to the base plate has 3-dof serial joints ( <und>pe</und>- <und>re</und>-r or <und>pe</und>- <und>pe</und>-r), two new 4-dof parallel mechanisms with two platforms can generate pitch motion of each platform, and roll and heave motions (1t-3r) or pitch motion of each platform and two translational motions (2t-2r) at both platforms, according to the type of the 2-dof driving mechanism. kinematic analyses of the 1t-3r mechanism were performed, including inverse and forward kinematics and velocity analysis. based on the 1t-3r mechanism, a footpad device was designed to generate foot trajectories for natural walking. &copy; 2005 wiley periodicals, inc.
visual map-less navigation based on homographies. we introduce a method for autonomous robot navigation based on homographies computed between the current image and images taken in a previous teaching phase with a monocular vision system. the features used to estimate the homography are vertical lines automatically extracted and matched. from homography, the underlying motion correction between the reference path and the current robot location is computed. the proposed method, which uses a sole calibration parameter, has turned out to be especially useful to correct heading and lateral displacement, which are critical in systems based on odometry. we have tested the proposal in simulation, and with real images. besides, the visual system has been integrated into an autonomous wheelchair for handicapped, working in real time with robustness. &copy; 2005 wiley periodicals, inc.
a natural redundancy-resolution for 3-d multi-joint reaching under the gravity effect. a simple control method for 3-dimensional multi-joint reaching movements under redundancy of degrees of freedom (dof) is proposed, which need neither introduce any performance index to solve inverse kinematics uniquely nor calculate pseudo-inverse of the jacobian matrix of task coordinates with respect to joint coordinates. the proposed control signal is composed of linear superposition of three terms: (1) angular-velocity feedback for damping shaping, (2) task-space position error feedback with a single stiffness parameter, and (3) compensation for gravity force on the basis of estimates for uncertain parameters of the potential energy without calculation any inverse joint position to the target in task space. through a theoretical analysis of the closed-loop dynamics and a variety of computer simulations by using a whole arm model with five dofs, the importance of synergistic adjustments of damping factors as well as its relation to selection of the stiffness parameter is pointed out. it is shown that if damping factors are chosen synergistically corresponding to the inertia matrix at the initial time and the stiffness parameter then the endpoint converges asymptotically to the target position and reaches it smoothly without incurring any self-motion. &copy; 2005 wiley periodicals, inc.
online robotic experiments for tele-education at the university of pisa. in this paper we describe work being done at our department to make the robotics laboratory accessible to students and colleagues to execute and watch real-time experiments at any time and from anywhere. we describe a few different installations and highlight the underlying philosophy, which is aimed at enlarging the lab in all the dimensions of space, time, and available resources, through the use of internet technologies. in particular, four experimental setups with hardware and software architecture description are presented: the dc motor, the magnetic levitator, the nonholomonic motion planner (nhmp), and the graphic environment tool. &copy; 2005 wiley periodicals, inc.
collision-free control of robotic manipulators in the task space. this paper addresses the problem of position control of robotic manipulators in the task space with obstacles. a computationally simple class of task space regulators consisting of a transpose jacobian controller plus an integral term including the task error and the gradient of a penalty function generated by obstacles is proposed. the lyapunov stability theory is used to derive the control scheme. through the use of the exterior penalty function approach, collision avoidance of the robot with obstacles is ensured. the performance of the proposed control strategy is illustrated through computer simulations for a direct-drive arm of a scara type manipulator operating in both an obstacle-free task space and a task space including obstacles. &copy; 2005 wiley periodicals, inc.
analyzing unidentified locked-joint failures in kinematically redundant manipulators. robots are frequently used for operations in hostile environments. the very nature of these environments, however, increases the likelihood of robot failures. common failure-tolerance techniques rely on effective failure detection and identification. since a failure may not always be successfully identified, or, even if identified, may not be identified soon enough, it becomes important to consider the behavior of manipulators with unidentified failures. this work investigates the behavior of robots experiencing unidentified locked-joint failures in a general class of tasks characterized by point-to-point motion. based on the analysis, a procedure for workspace evaluation is developed that allows for the identification of regions in the manipulator's workspace in which tasks may be completed even with such failures. &copy; 2005 wiley periodicals, inc.
range error detection caused by occlusion in non-coaxial ladars for scene interpretation. when processing laser detection and ranging (ladar) sensor data for scene interpretation, for example, for the purposes of feature extraction and&#x002f;or data association in mobile robotics, most previous work models such devices as processing range data which follows a normal distribution. in this paper, it is demonstrated that commonly used ladars suffer from incorrect range readings at changes in surface reflectivity and&#x002f;or range discontinuities, which can have a much more detrimental effect on such algorithms than random noise. most ladars fall into two categories: coaxial and separated transmitter and receiver configurations. the latter offer the advantage that optical crosstalk is eliminated, since it can be guaranteed that all of the transmitted light leaves the ladar and is not in any way partially reflected within it due to the beam-splitting techniques necessary in coaxial ladars. however, they can introduce a significant disparity effect, as the reflected laser energy from the target can be partially occluded from the receiver. as well as demonstrating that false range values can result due to this occlusion effect from scanned ladars, the main contribution of this paper is that the occurrence of these values can be reliably predicted by monitoring the received signal strength and a quantity we refer to as the &ldquo;transceiver separation angle&rdquo; of the rotating mirror. this paper will demonstrate that a correct understanding of such systematic errors is essential for the correct further processing of the data. a useful design criterion for the optical separation of the receiver and transmitter is also derived for noncoaxial ladars, based on the minimum detectable signal amplitude of a ladar and environmental edge constraints. by investigating the effects of various sensor and environmental parameters on occlusion, some advice is given on how to make use of noncoaxial ladars correctly so as to avoid range errors when scanning environmental discontinuities. &copy; 2005 wiley periodicals, inc.
dynamic virtual environment to test teleoperated systems with time delay communications. this paper presents a dynamic virtual environment tool for training operators and to prove different control schemes in telerobotic systems, and describes virtual reality environments used in teleoperated robotic systems. in the presented tool, the kinematic and dynamic model of the remote environment which is manipulating the operator is considered. the paper also describes how time delays in the communication channel can be easily added to the simulator, in order to analyze their effects in the teleoperated system. finally, some experimental results achieved with this virtual teleoperated system are shown. with the presented dynamic simulator, different control schemes designed to overcome the time delay problem could be tested. &copy; 2005 wiley periodicals, inc.
projective virtual reality as a basis for on-line control of complex systems-not only-over the internet. already in 1994 the term projective virtual reality was coined and a first implementation was used to control a complex multirobot system in germany over the internet from california. building on this foundation, the general aim of the development of virtual reality technology for automation applications at the institute of robotics research (irf) today is to provide the framework for projective virtual reality for a broad range of applications. the general idea of projective virtual reality is to allow users to &ldquo;project&rdquo; actions carried out in the virtual world into the real world by means of robots or other means of automation. the framework is based on a task-oriented approach which builds on the &ldquo;task deduction&rdquo; capabilities of a newly developed virtual reality system and a task planning component. the advantage of this approach is that robots which work at great distances from the control station can be controlled as easily and intuitively as robots that work right next to the control station. robot control technology now provides the user in the virtual world with a &ldquo;prolonged arm&rdquo; into the physical environment, thus paving the way for intuitive control of complex systems over the internet&mdash;and in general for a new quality of user-friendly man-machine interfaces for automation applications. lately, this work has been enhanced by a new structure that allows one to distribute the virtual reality application over multiple computers on a network. with this new feature, it is now possible for multiple users to share the same virtual room, although they may physically be thousands of miles apart. they only need an internet connection to share this new experience. lately, the network distribution techniques have been further developed to not just allow users to cooperate over networked pcs but also to be able to set up a panorama projection or a cave running of a networked cluster of pcs. this approach cuts down the costs for such a high-end visualization environment drastically and allows for a new range of applications. &copy; 2005 wiley periodicals, inc.
the optimum design of 6-dof isotropic parallel manipulators. how to obtain 6-dof parallel manipulators with optimum global isotropy is investigated in this paper. a systematic method is first presented to get isotropic parallel designs. a measure for spatial isotropy is then proposed to evaluate and compare the global isotropy of obtained manipulators. efficient methods to find the minimum and maximum singular values of matrices are developed to facilitate the evaluation process. &copy; 2005 wiley periodicals, inc.
analytical identification of limb structures for translational parallel manipulators. a systematic analytical method, based on the theory of screws, is presented for identification of limb structures of general and over-constrained 3-degree-of-freedom (dof) translational parallel manipulators. given a system of wrenches of constraint, the corresponding reciprocal basis screws are determined. then, the joint screws of a limb are obtained by a linear combination of these basis screws. feasible limbs that can be used for construction of translational platforms are enumerated according to the type of constraint and the number of joints making up the limbs. &copy; 2004 wiley periodicals, inc.
the synthesis of three-degree-of-freedom planar parallel mechanisms with revolute joints (3-rrr) for an optimal singularity-free workspace. in this paper, a method is presented for the synthesis of 3-<und>r</und>rr planar parallel mechanisms. the method uses a genetic algorithm while considering three different design criteria: the optimization of the mechanism workspace to approach a prescribed workspace, the maximization of the mechanism's dexterity, and the avoidance of singularities inside the mechanism workspace. it is shown that, for a given mechanism, some working modes do not have any corresponding singularity curves located inside the mechanism workspace. furthermore, a case is presented where, for a given orientation range of the mechanism's end-effector, there are no parallel singularities located inside the workspace. finally, two methods are described and compared to deal with the nonuniform units of the mechanism's jacobian matrix during the dexterity computation. &copy; 2004 wiley periodicals, inc.
vision based intelligent wheel chair control: the role of vision and inertial sensing in topological navigation. this paper describes ongoing research on vision based mobile robot navigation for wheel chairs. after a guided tour through a natural environment while taking images at regular time intervals, natural landmarks are extracted to automatically build a topological map. later on this map can be used for place recognition and navigation. we use visual servoing on the landmarks to steer the robot. in this paper, we investigate ways to improve the performance by incorporating inertial sensors. &copy; 2004 wiley periodicals, inc.
dynamics modeling and analysis of a biped walking robot actuated by a closed-chain mechanism. we developed a new type of human-sized biped walking robot (bwr) driven by the closed-chain type of joint actuator. each leg of the robot is composed of three pitch joints and one roll joint. in all, a 15 degree-of-freedom robot including four arm joints and three joints for the head was developed. the bwr was developed to walk autonomously such that all leg joints are actuated by small 90 w dc motors&sol;drivers and dc batteries and controllers which are boarded. the joint actuator for the bwr is composed of the four-bar-link mechanism driven by the ball screw which has high strength and high gear ratio. a dynamics modeling of the developed bwr for forward walking is presented in which the revolute joint dynamics are transformed into the prismatic joint dynamics of the ball screw. also, an analysis on the four-bar-link mechanism applied to the joint actuator and on the structure of the bwr is shown. the design specification of the actuating motor for the bwr is analyzed through the torque analysis of the four-bar-link actuator. through walking experiments of the bwr, the walking performance and trajectory tracking ability is shown. &copy; 2004 wiley periodicals, inc.
a new 6-dof parallel robotic structure actuated by wires: the wiro-6.3. this paper describes a novel parallel robotic structure with six degrees of freedom, whose end effector is driven by nine wires operated by motors: the wiro-6.3. the ideas that led to the conception of the robot are thoroughly discussed and analyzed. the workspace of wiro-6.3 has been numerically analyzed, and it is significantly larger than the one of other analogous seven-wire structures. the forward and inverse kinematics are both solved in closed form. &copy; 2004 wiley periodicals, inc.
optimal path planning of mobile robots for sample collection. in this paper, the problem of path planning for sample collection using single or multiple mobile robots such as mars rovers is formulated as a mathematical optimization problem involving a performance metric based on the scientific values of the collected rock and soil samples. the posed optimization problem is np-hard and more complex than the well-known traveling salesman problem. algorithms are proposed for obtaining near-optimal solutions for both single and multiple robots. their application is illustrated using real mars surface data. the dependence of the optimal performance on the number of mobile robots is studied numerically. &copy; 2004 wiley periodicals, inc.
vision based robotic control. the university of colorado at denver robotics society is constructing an autonomous ground vehicle (agv) capable of accomplishing the association of unmanned vehicle systems international (auvsi) competition objectives. the design presented features an engineering focus on a statistical, vision based discrete-time control system optimized for an exterior robotic vehicle. a simple robust strategy incorporates ultrasonic ranging to make this vehicle capable of negotiating the features presented in the autonomous challenge. &copy; 2004 wiley periodicals, inc.
minimum jerk motion planning for a prosthetic finger. in this paper we propose a method, based on both physiologic and engineering considerations, for the motion planning of a prosthetic finger. in particular, we exploit a minimum jerk approach to define the trajectory in the cartesian space. then, cubic splines are adopted in the joint space. the redundancy problem arising from the presence of three links is solved by assuming that there is a constant ratio between the second and the third joint motion. the value of the proportional constant is determined by minimizing the maximum jerk in the joint space. it is found that this constant value can be suboptimally but effectively set to one for all the movements. this approach guarantees a natural movement of the finger as well as reduced vibrations in the mechanical structure and increased control performances. &copy; 2004 wiley periodicals, inc.
modeling and control for a gough-stewart platform cnc machine. in this paper, a complete dynamic model on task space for a 6 degrees of freedom (dof) gough-stewart platform-type computer numerical control (cnc) machine is derived. the rotation terms of the legs are included for those inertia effects cannot be negligible in the machine tool applications. the formulation derived by means of the euler-lagrange method is convenient for designing the adaptive control law. also, the average-type force model for end milling process is derived and included in the dynamic model and control. a composite adaptive control scheme is developed by use of filtering dynamics technique. an appropriate estimator gain is designed in the parameter adaptation law that is useful for estimating the selected important cutting parameters. experimental results verify the proposed adaptive control scheme can achieve good tracking performance. &copy; 2004 wiley periodicals, inc.
navigation aided image processing in uav surveillance: preliminary results and design of an airborne experimental system. this paper describes an airborne reconfigurable measurement system being developed at swedish defence research agency (foi), sensor technology, sweden. an image processing oriented sensor management architecture for uav (unmanned aerial vehicles) ir&sol;eo-surveillance is presented. some preliminary results of navigation aided image processing in uav applications are demonstrated, such as slam (simultaneous localization and mapping), structure from motion and geolocation, target tracking, and detection of moving objects. the design goal of the measurement system is to emulate a uav-mounted sensor gimbal using a stand-alone system. the minimal configuration of the system consists of a gyro-stabilized gimbal with ir and ccd sensors and an integrated high-performance navigation system. the navigation system combines dgps real-time kinematics (rtk) data with data from an inertial measurement unit (imu) mounted with reference to the optical sensors. the gimbal is to be used as an experimental georeferenced sensor platform, using a choice of carriers, to produce military relevant image sequences for studies of image processing and sensor control on moving surveillance and reconnaissance platforms. furthermore, a high resolution synthetic environment, developed for sensor simulations in the visual and infrared wavelengths, is presented. &copy; 2004 wiley periodicals, inc.