waashk/dblp huggingface dataset:
on-line planning of nonholonomic trajectories in crowded and geometrically unknown environments. navigation of a car-like robot in environments with unknowns requires effective on-line planning of nonholonomic trajectories. we propose a set of basic maneuver patterns based on bezier curves that allow either forward or backward motion as building blocks to create nonholonomic trajectories quickly, given a sequence of knot positions/points (e.g., from some gps navigator). these maneuver patterns are particularly useful for generating feasible trajectories in crowded environments with many narrow passages. we embed the above techniques in a new planner suitable for on-line planning of nonholonomic and collision-free trajectories, called the on planner. our on planner enables that, given a sequence of rough knot points, a car-like robot can simultaneously plan and move in a geometrically unknown, crowded environment with local sensing towards a goal. simulation results demonstrate the planner's nice capabilities.
time-bounded lattice for efficient planning in dynamic environments. for vehicles navigating initially unknown cluttered environments, current state-of-the-art planning algorithms are able to plan and re-plan dynamically-feasible paths efficiently and robustly. it is still a challenge, however, to deal well with the surroundings that are both cluttered and highly dynamic. planning under these conditions is more difficult for two reasons. first, tracking and predicting the trajectories of moving objects (i.e., cars, humans) is very noisy. second, the planning process is computationally more expensive because of the increased dimensionality of the state-space, with time as an additional variable. moreover, re-planning needs to be invoked more often since the trajectories of moving obstacles need to be constantly re-estimated. in this paper, we develop a path planning algorithm that addresses these challenges. first, we choose a representation of dynamic obstacles that efficiently models their predicted trajectories and the uncertainty associated with the predictions. second, to provide real-time guarantees on the performance of planning with dynamic obstacles, we propose to utilize a novel data structure for planning - a time-bounded lattice - that merges together short-term planning in time with long-term planning without time. we demonstrate the effectiveness of the approach in both simulations with up to 30 dynamic obstacles and on real robots.
autonomous planetary exploration using lidar data. in this paper we present the approach for autonomous planetary exploration developed at the canadian space agency. the goal of this work is to autonomously navigate to remote locations, well beyond the sensing horizon of the rover, with minimal interaction with a human operator. we employ lidar range sensors due to their accuracy, long range and robustness in the harsh lighting conditions of space. irregular triangular meshes (itms) are used for representing the environment providing an accurate yet compact spatial representation. in this paper a novel path-planning technique through the itm is introduced, which guides the rover through flatter terrain and safely away from obstacles. experiments performed in csa's mars emulation terrain that validate our approach are also presented.
a novel control algorithm for wearable robotics using phase plane invariants. with microprocessing power greatly increasing, hardware is no longer a hurdle in the development of controllers for wearable robotic systems, specifically lower limb robots. the challenge remains in developing smart algorithms that are able to detect which task a person is about to perform and then determine the correct desired movements for the robotic system. this paper reflects on four existing control algorithms for the task of level ground walking, and then presents theory and test results of a novel control algorithm based on phase plane invariants. the goal of this paper is to produce the correct motor reference command in a continuous fashion rather than based on determining distinct states for a given task.
spectral clustering for feature-based metric maps partitioning in a hybrid mapping framework. hybrid maps combine metric and topological information for efficiently managing large-scale environments. in a feature-based mapping framework, this paper describes the application of a spectral clustering approach for automatically detecting the transitions between subsequently traversed local maps. contrary to recently proposed approaches, this algorithm considers each individual map feature as a node of a graph whose edges link two nodes if they are simultaneously observed. thus, given a sequence of observations, an auxiliary graph is incrementally built whose edges carry non-negative weights according to the locality of the features. given a feature, its locality defines the set of features that has been observed simultaneously with it at least once. at each execution of the mapping approach, the feature-based graph is split into two subgraphs using a normalized spectral clustering algorithm. if the graph partition is validated, the algorithm determines that the robot is moving into a new area and a new local map is generated. we have tested the proposed approach in real environments where features are obtained using 2d laser sensors or vision. experimental results demonstrate the performance of the proposal.
linescout technology: from inspection to robotic maintenance on live transmission power lines. power line inspection and maintenance practices are evolving as changing market regulations, significantly increased line loading and system availability requirements put pressure on grid owners to innovate. robotics is thus making its debut in that field. described in previous papers as an inspection tool, hydro-québec linescout technology is evolving into a teleoperated mobile robot capable of performing basic maintenance tasks. programmable pan-and-tilt camera (pptc) units were designed and implemented as the first step towards enhanced teleoperation control. linearm, a dual end effector robotic arm, was specifically designed for work on bundled conductors. design specifications and kinematics of these two subsystems are presented. implemented application modules to be mounted on linearm are also presented and their utilization is reported as a milestone in power line live maintenance. lastly, future work and challenges in applying robotics to transmission line maintenance are briefly discussed.
synchronized control in a large-scale networked distributed printing system. as engineered systems that have traditionally been controlled centrally become more modular, distributed, and autonomous, techniques are needed to maintain control coordination among independent elements, often across a network with delays and bandwidth limitations. in particular, manufacturing systems may require tight coordination, or synchronization, among components acting on the same physical object. this paper addresses the problem of controller synchronization in such a system. we present an implementation of exact controller synchronization for independent controllers in a highly modular printing domain. our approach, which allows networked controllers to join and leave a task dynamically, has produced excellent results on a high-speed printer prototype.
multi-robot plan adaptation by constrained minimal distortion feature mapping. we propose a novel method for multi-robot plan adaptation which can be used for adapting existing spatial plans of robotic teams to new environments or imitating collaborative spatial teamwork of robots in novel situations. the algorithm selects correspondences between previous and current spatial features by the application of pairwise constraints, and generates the transformation function with a fast regular grid approximation which minimizes distortion. the algorithm requires minimal domain knowledge, is capable of transforming the spatial aspects of collaborative team behavior and performs better in noisy problems with large displacements than the most generally used quadratic differences method. the algorithm can be utilized for rapid plan adaptation, plan generalization or team behavior imitation. methods are demonstrated on a multi-robot control problem in a random environment.
miniature soft hand with curling rubber pneumatic actuators. in medical and biotechnology fields, soft devices are required because of their high safety from low mechanical impedance. fma (flexible microactuator) is one of the typical soft actuators. it consists of fiber-reinforced rubber structure with multi air chambers and realizes bending motion pneumatically. it has been applied to robot hands, robot legs and so on. high potential of fma has been confirmed by many experiments reported in several papers. however in fabrication process of the actuator, it is difficult to embed the reinforced fiber in the rubber structure. in this study, we aim at development of a fiber less fma realizing quite large motion, which can be said curling motion, and a soft hand using the actuators. we design the actuator without fiber using nonlinear fem (finite element method) and derived efficient shape. the actuator is fabricated through micro rubber casting process including micro machining process for molds, micro vacuum rubber molding process and rubber bonding process with surface improvement by excimer light. basic driving experiments of the actuator showed that it realized curling motion which agreed well with fem results. and the actuator could grasp a fish egg without breaking. additionally, we made a soft hand consisting of three curling actuators. this hand also could be manufactured by simple casting process. the developed hand works opening and closing motions well.
kinematics and dynamics of a hybrid serial-parallel mobile robot. in this study, kinematics design, dynamics modeling and verification of a compounded serial-parallel wheeled mobile robot is elaborated. the proposed novel kinematic structure is best suited to fulfill stable motion of the robotic system when handling heavy objects by manipulators mounted on mobile platforms. the proposed system is made of a differentially-driven wheeled platform, a planar parallel manipulator, which is called here as star-triangle (st) mechanism, and a serial puma-type manipulator arm. the suggested structure adopts the advantages of both serial and parallel robots, to move the base point of the serial robot with respect to the mobile platform to fulfill the system stability after grasping heavy objects. in order to investigate the comprehensive kinematics model of the robot, after introducing its novel structure it is divided into three modules, i.e. a mobile platform, a parallel st mechanism, and a serial robot. next, a closed-form dynamics model is derived for the whole hybrid system based on a combined newton-euler and lagrange formulation. the proposed method presents the mutual dynamic interaction wrenches between the integrated platform and the serial manipulator which can be exploited for the tip-over stability analysis of the mobile robotic system. then, to verify the obtained mathematical model, several benchmark actuating inputs are applied to the model and the system responses are analyzed.
directionality control and flight stability of takeoff. flight initiation is an area that remains unexplored amongst today's nano-scaled, flapping-wing, robotic insects. to understand mechanical principles of ground-to-air transitions at this particular scale, we investigate the biomechanics of the fruit fly drosophila melanogaster during takeoff. building upon a prior framework [1], we analyze the insect's pre-flight motion, and its impact in directionality control. using a rigid multibody system comprised by one central body and six legs, we are able to estimate forces from joint kinematics. the approach provides a mathematical framework for studying tradeoffs between directionality control [1] and dynamic stability during flight initiation.
aerodynamics of dragonfly flight and robotic design. a pair of dynamically scaled robotic dragonfly model wings was developed to investigate the aerodynamic effect of wing-wing interaction in dragonfly flight. instantaneous aerodynamic forces were measured while forewing-hindwing phase difference (γ) was systematically varied. experimental results showed that, i) for hovering flight, γ=0° enhanced the lift force on both forewing and hindwing; γ=180° reduced the total lift force, but was beneficial for vibration suppression and body posture stabilization. in nature, 0° is employed by dragonflies in acceleration mode while 180° is usually in hovering mode. ii) for forward flight, wing-wing interaction enhances forewing lift while reduced hindwing lift at all phase differences. furthermore, the total lift was slightly reduced for γ= 0° to 90° and significantly reduced by 18% when γ=270°. the results consist well with the fact that, dragonflies usually employ 50° to 100° for forward flight, but seldom employ 270°. piv results are shown for wing-wing interaction analysis.
rollin' justin - design considerations and realization of a mobile platform for a humanoid upper body. research on humanoid robots for use in servicing tasks, e.g. fetching and delivery, attracts steadily more interest. with rollin' justin a mobile robotic system and research platform is presented that allows the implementation and demonstration of sophisticated control algorithms and dexterous manipulation. important problems of service robotics such as mobile manipulation and strategies for using the increased workspace and redundancy in manipulation task can be studied in detail. this paper gives an overview of the design considerations for a mobile platform and their realizations to transform the formerly table-mounted humanoid upper body system justin into rollin' justin, a fully self-sustaining mobile research platform.
a temptative to reach a visual singular configuration using halley's method. image-based visual servoing has been found to give satisfactory accurate and robust results. however, singularity and local minima may appear causing stability and convergence problems. in this paper, we present new control schemes based on halley's method as a temptative to obtain a robust system even when the desired configuration is singular. the new control scheme use the first and the second order derivatives of the error to be regulated to zero. hessian matrices of an image point are thus determined to be used in the control schemes. preliminary experimental results obtained on a 6 dof eye-in-hand system shows that a more accurate positioning can be obtained compared with classical methods.
the winch-bot: a cable-suspended, under-actuated robot utilizing parametric self-excitation. a simple, compact, yet powerful robotic winch, called "winch-bot," is presented in this paper. the winch-bot is an underactuated robot having only one controllable axis. although hanging a load with merely one cable, it is capable of moving it in a large workspace by swinging the load dynamically based on parametric self-excitation. the generated trajectories can be used for a variety of tasks, from moving material to cyclic inspection of surfaces. the basic principle and design concept of the winch-bot are first described, followed by dynamic modeling and analysis. two trajectory generation problems are solved. one is point-to-point transfer of a load, and the other is the tracking of a continuous path. it will be shown that the system can track a given geometric trajectory, although the tracking velocity cannot be determined arbitrarily due to the underactuated nature of dynamics. a prototype winch-bot is designed and built, and point-to-point, continuous path, and parametric excitation control are implemented.
robot force/position tracking with guaranteed prescribed performance. a control law is proposed that achieves predefined performance indices regarding the speed of response, the steady state and the allowed overshoot of the robot force/position tracking errors, ensuring no loss of contact of the robot end effector. the controller incorporates a transformed error, which includes the performance indices. the control objective is satisfied under parametric uncertainties in the robot dynamics and the elasticity model constant. simulation results confirm the theoretical findings and compare the proposed controller with a conventional one.
precise and robust large-shape reproduction using uncalibrated vision. the paper presents an alternative to cnc machining, based on a proposed method for creating very large and precise replicas of prototype shapes using material-removal and/or material-adding mechanisms that need not be calibrated. the method is based upon the creation of a "virtual mold", which is created in the two-dimensional image planes of two or more stationary, uncalibrated cameras. the cameras are placed so as to view portions of the prototype surface and remain stationary while multiple-beam laser pointers cast their light toward the prototype shape and the resulting laser-spot reflections are registered and matched among the cameras. large numbers of images can be acquired with slightly offset pan and tilt angles of laser-pointer-bearing units, resulting in collected laser-spot-centroid indications that may number in the thousands. the spot-centroid coordinates in camera space are matched in such a way that individual, physical spot-centroid indications are registered in memory in accordance with correspondence among those cameras able to view any one particular spot. this forms the basis of the "virtual mold". subsequent reproduction of the shape, as with a cnc machine, relies upon action of a robot to remove material from a blank. this blank is placed so as to occupy the region where the prototype had been during laser spot casting. camera-space manipulation is used to guide the robot in consecutive passes of material removal, with laser spots cast upon each newly revealed intermediate surface and reflected up into the original cameras. the paper presents the use of a fanuc m16-ib industrial robot, in order to obtain experimental evidence on how the original surface regions can be replicated with extremely high precision despite no need for calibration either of the cameras or the manipulator.
auxiliary models based multi-innovation gradient identification with colored measurement noises. for pseudo-linear regression identification models corresponding output error systems with colored measurement noises, a difficulty of identification is that there exist unknown inner variables and unmeasurable noise terms in the information vector. this paper presents an auxiliary model based multiinnovation stochastic gradient algorithm by using the auxiliary model technique and by expanding the scalar innovation to an innovation vector. compared with single-innovation stochastic gradient algorithm, the proposed approach can generate highly accurate parameter estimates. the simulation results confirm theoretical findings.
temporal stabilization of discrete movement in variable environments: an attractor dynamics approach. the ability to generate discrete movement with distinct and stable time courses is important for interaction scenarios both between different robots and with human partners, for catching and interception tasks, and for timed action sequences. in dynamic environments, where trajectories are evolving on-line, this is not a trivial task. the dynamical systems approach to robotics provides a framework for robust incorporation of fluctuating sensor information, but control of movement time is usually restricted to rhythmic motion and realized through stable limit cycles. the present work uses a hopf oscillator to produce discrete motion and formulates an on-line adaptation rule to stabilize total movement time against a wide range of disturbances. this is integrated into a dynamical systems framework for the sequencing of movement phases and for directional navigation, using 2d-planar motion as an example. the approach is demonstrated on a khepera mobile unit in order to show its reliability even when depending on low-level sensor information.
designing image trajectories in the presence of uncertain data for robust visual servoing path-planning. path-planning allows one to steer a camera to a desired location while taking into account the presence of constraints such as visibility, workspace, and joint limits. unfortunately, the planned path can be significantly different from the real path due to the presence of uncertainty on the available data, with the consequence that some constraints may be not fulfilled by the real path even if they are satisfied by the planned path. in this paper we address the problem of performing robust path-planning, i.e. computing a path that satisfies the required constraints not only for the nominal model as in traditional path-planning but rather for a family of admissible models. specifically, we consider an uncertain model where the point correspondences between the initial and desired views and the camera intrinsic parameters are affected by unknown random uncertainties with known bounds. the difficulty we have to face is that traditional path-planning schemes applied to different models lead to different paths rather than to a common and robust path. to solve this problem we propose a technique based on polynomial optimization where the required constraints are imposed on a number of trajectories corresponding to admissible camera poses and parameterized by a common design variable. the planned image trajectory is then followed by using an ibvs controller. simulations carried out with all typical uncertainties that characterize a real experiment illustrate the proposed strategy and provide promising results.
dynamically running quadrupeds self-stable region expansion by mechanical design. dynamic stability allows running animals to maintain preferred speed during locomotion over rough terrain. it appears that rapid disturbance rejection is an emergent property of the mechanical system. in running robots, simple motor control seems to be effective in the negotiation of rough terrain when used in concert with a mechanical system that stabilizes passively. in this paper, we show that a quadruped robot could be able to perform self-stable running behavior in significantly broader ranges of forward speed and pitch rate with suitable mechanical design. the results presented here are derived by studying the stability of passive dynamics of a quadruped robot running in the sagittal plane in a dimensionless context and can be summarized as: (a) the self-stabilized behavior of a quadruped robot for a particular gait is related to the magnitude of its dimensionless inertia, (b) the values of hip separation, normalized to rest leg length, and the leg relative stiffness of a quadruped robot affect the stability and should be in inverse proportion to its dimensionless inertia, and (c) the self-stable regime of quadruped running robots is enlarged at relatively high forward speeds.