This paper presents a practical real-time visual navigation system, including a vision system, a particle filter (PF) based localization system, and a path planning system, for humanoid robots in an indoor environment...
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Observer design for rigid body translational and rotational motion has important applications to unmanned or manned vehicles operating in air, underwater, or in space. An observer design for pose and velocity estimati...
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ISBN:
(纸本)9781467357159
Observer design for rigid body translational and rotational motion has important applications to unmanned or manned vehicles operating in air, underwater, or in space. An observer design for pose and velocity estimation for three-dimensional rigid body motion, in the framework of geometric mechanics, is presented here. Resorting to convenient defined Lyapunov function, a nonlinear observer on the Special Euclidean Group (SE(3)) is derived. This observer is based on the exponential coordinates, which are used to represent the group of rigid body motions. Exponential convergence of the estimation errors is shown and boundedness of the estimation error under bounded unmodeled torques and forces is established. Since exponential coordinates can describe uniquely almost the entire group of rigid body motions, the resulting observer design is almost globally exponentially convergent. The observer is then applied to the free dynamics of a rigid vehicle. Numerical simulation results are presented to show the performance of this observer, both in the absence and with unmodeled forces and torques.
This paper addresses the path following problem of a wheeled mobile robot with rhombic like kinematics (drivable and steerable wheels both at front and rear) operating in cluttered environments. Four path following co...
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ISBN:
(纸本)9789898565716
This paper addresses the path following problem of a wheeled mobile robot with rhombic like kinematics (drivable and steerable wheels both at front and rear) operating in cluttered environments. Four path following controllers are developed to steer the kinematic model of a rhombic like vehicle (RLV) along a desired path: three are based on feedback laws derived at a kinematic level with geometrical inspiration;the fourth is a nonlinear controller built upon a kinematic model of a RLV using Lyapunov functions. All the developed controllers are capable of performing under two situations: when both wheels follow the same path, or when each wheel follows a different path. The dynamic modelling of a RLV is lastly introduced. Simulated results present a comparative performance assessment of the controllers while dealing, or not, with vehicle dynamics. The main conclusions of these controllers are summarized, leading to a possible application in the actual vehicles that will operate in the remote handling missions of the International Thermonuclear Experimental Reactor (ITER).
Recent efforts in mission planning for underwater vehicles have utilised predictive models to aid in navigation, optimal path planning and drive opportunistic sampling. Although these models provide information at a u...
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ISBN:
(纸本)9781467356404
Recent efforts in mission planning for underwater vehicles have utilised predictive models to aid in navigation, optimal path planning and drive opportunistic sampling. Although these models provide information at a unprecedented resolutions and have proven to increase accuracy and effectiveness in multiple campaigns, most are deterministic in nature. Thus, predictions cannot be incorporated into probabilistic planning frameworks, nor do they provide any metric on the variance or confidence of the output variables. In this paper, we provide an initial investigation into determining the confidence of ocean model predictions based on the results of multiple field deployments of two autonomous underwater vehicles. For multiple missions of two autonomous gliders conducted over a two-month period in 2011, we compare actual vehicle executions to simulations of the same missions through the Regional Ocean Modeling System in an ocean region off the coast of southern California. This comparison provides a qualitative analysis of the current velocity predictions for areas within the selected deployment region. Ultimately, we present a spatial heat-map of the correlation between the ocean model predictions and the actual mission executions. Knowing where the model provides unreliable predictions can be incorporated into planners to increase the utility and application of the deterministic estimations.
Using Monte-Carlo simulations, the performance of three recently developed multiple-controller robust adaptive control methods is compared for different time-varying uncertain parameter waveforms, using a mass-spring-...
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Using Monte-Carlo simulations, the performance of three recently developed multiple-controller robust adaptive control methods is compared for different time-varying uncertain parameter waveforms, using a mass-spring-dashpot benchmark example. We further examine the performance of these different adaptive methods with that of the best possible robust nonadaptive design using the same physical example. Whenever possible, we also compare the adaptive methods' performance with that of the (unrealizable) “Perfect Model Identification (***)”. In order to have a “fair” comparison of the performance obtained with the different control laws we used the same bank of local controllers and tuned each approach for its best performance. The Monte-Carlo simulations highlight the strength and aptitude of each method as well as its shortcomings and drawbacks.
In this paper, a new hand exoskeleton device using a three-layered sliding spring mechanism is presented. In contrast to state of the art hand exoskeleton mechanisms (typically link, wire or pneumatically driven), the...
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ISBN:
(纸本)9781467356404
In this paper, a new hand exoskeleton device using a three-layered sliding spring mechanism is presented. In contrast to state of the art hand exoskeleton mechanisms (typically link, wire or pneumatically driven), the proposed mechanism is driven through large deformations of the compliant mechanism body. The mechanism can be made compact and lightweight by adequately positioning the compliant elements. In addition, the mechanism is designed to distribute 1-DOF actuated linear motion into three rotational motions of the finger joints, which translate into natural finger flexion/extension. The primary applicatoin of the proposed mechanism is to provide robotic support during physical therapy at the hospital (e.g. Continuous Passive Motion). However, thanks to its light and wearable structure, the proposed device could also be used at home as an assistive/therapeutic device to support activities of daily living. We introduce the mechanical structure of the three-layered sliding spring mechanism, present a prototype implementation as a hand exoskeleton device, and provide a preliminary evaluation.
There is increasing interest in the use of Autonomous Underwater Vehicles (AUVs) to substantially improve the means available for ocean exploration and exploitation. A key element in the operation of certain classes o...
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There is increasing interest in the use of Autonomous Underwater Vehicles (AUVs) to substantially improve the means available for ocean exploration and exploitation. A key element in the operation of certain classes of AUVs is the availability of good underwater positioning systems to localize one or more vehicles simultaneously based on information received on-board a support ship or a set of autonomous surface vehicles. In an interesting operational scenario, the set of autonomous surface vehicles carries a network of acoustic units that measure the elevation and azimuth angles between the target and each of the receivers. Motivated by these considerations, in this paper we address the problem of determining the optimal geometric configuration of an acoustic sensor network at the ocean surface that will maximize the angle-related information available for underwater target positioning. It is assumed that the angle measurements are corrupted by white Gaussian noise, the variance of which is distance-dependent. Using the Cramer-Rao lower bound inequality, the trace of the inverse of the Fisher Information matrix (also called the Cramer-Rao Bound matrix) for the problem at hand is used to determine the sensor configuration that yields the minimum possible covariance of any unbiased target estimator. It is shown that the optimal configuration lends itself to an interesting geometrical interpretation and that the spreading of the sensor configuration depends explicitly on the intensity of the measurement noise and the target depth. Simulation examples illustrate the key results derived.
This paper addresses the control of linear time-invariant plants whose dynamics are interconnected in an acyclic manner and are subject to unknown disturbances. Moreover, each plant's output is only measured at sa...
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ISBN:
(纸本)9781467320658
This paper addresses the control of linear time-invariant plants whose dynamics are interconnected in an acyclic manner and are subject to unknown disturbances. Moreover, each plant's output is only measured at sampling instants determined by a self-triggered strategy. In a self-triggered scenario, the controller is allowed to choose when the next sampling time should occur and does so based on a priori knowledge about the plant and on an estimate of the plant's state. We first address the single plant case where the proposed solution is a cascade interconnection of a state observer and a self-triggered controller designed for state feedback. We then consider the case where several plants are interconnected in an acyclic manner. In both cases, it is shown that the closed-loop system is input-to-state stable with respect to all bounded exogenous disturbances.
Based on HIT/DLR(Harbin Institute of Technology/Deutsches Zentrum für Luft-und Raumfahrt) Prosthetic Hand II,an anthropomorphic controller is developed to help the amputees use and perceive the prosthetic hands m...
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Based on HIT/DLR(Harbin Institute of Technology/Deutsches Zentrum für Luft-und Raumfahrt) Prosthetic Hand II,an anthropomorphic controller is developed to help the amputees use and perceive the prosthetic hands more like people with normal physiological *** core of the anthropomorphic controller is a hierarchical control *** is composed of a top controller and a low level *** top controller has been designed both to interpret the amputee's intensions through electromyography(EMG) signals recognition and to provide the subject-prosthesis interface control with electro-cutaneous sensory feedback(ESF),while the low level controller is responsible for grasp *** control strategies include the EMG control strategy,EMG and ESF closed loop control strategy,and voice control *** EMG signal recognition,10 types of hand postures are recognized based on support vector machine(SVM).An anthropomorphic closed loop system is constructed to include the customer,sensory feedback system,EMG control system,and the prosthetic hand,so as to help the amputee perform a more successful EMG *** results suggest that the anthropomorphic controller can be used for multi-posture recognition,and that grasp with ESF is a cognitive dual process with visual and sensory *** process while outperforming the visual feedback process provides the concept of grasp force magnitude during manipulation of objects.
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