On the basis of only visual and odometer, a robust perception model is established to extract environmental features through effective fixed scale feature-transformation method, and updated feature by unscented Kalman...
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On the basis of only visual and odometer, a robust perception model is established to extract environmental features through effective fixed scale feature-transformation method, and updated feature by unscented Kalman filtering. The scale invariant feature transform (SIFT) is studied for 3D reconstruction, and a fast feature matching algorithm based on SIFT is proposed. A map representation method using SIFT features is also propounded, which is more convenient for environment recognition, robot localization and makes the data association map building much easier as well than the maps using simple features such as Harris corners and edges. The results of experiment show that this method can improve the success rate and precision of robot localization.
This paper firstly introduces the research status of gradient projection method (GPM) of redundant manipulator, then presents a 7-DOF (degree of freedom) redundant manipulator composes of a 3-DOF shoulder joint, a 1-D...
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This paper firstly introduces the research status of gradient projection method (GPM) of redundant manipulator, then presents a 7-DOF (degree of freedom) redundant manipulator composes of a 3-DOF shoulder joint, a 1-DOF elbow joint, and a 3-DOF wrist joint. Different from many other 7-DOF redundant manipulators, shoulder and wrist joints of the manipulator presented in paper are not spherical joints. The GPM is provided for inverse kinematics analysis. Scale factor is an important parameter in GPM, if the scale factor is utilized improperly, it can cause the GPM invalid or enable computational efficiency low. In this paper the improved scale factor is proposed in GPM. At last, the simulations of the GPM based on fixed scale factor, balanced scale factor and improved scale factor method are compared, the simulations demonstrated the improved scale factor method can overcome velocity impulses shortcoming of the fixed scale factor method, and rectify deficiency of the balanced scale factor method.
This paper presents that support vector machine (SVM) is used to classify three gait patterns: level walking, stair ascent and stair descent based on ground reaction force (GRF). The recognition process consists of th...
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ISBN:
(纸本)9781479973989
This paper presents that support vector machine (SVM) is used to classify three gait patterns: level walking, stair ascent and stair descent based on ground reaction force (GRF). The recognition process consists of three stages: i) a three layers wavelet packet analysis is used for feature extraction, with which squared and standard deviation of decomposition coefficients compose features; ii) with attributes distribution analysis of features (similar to principal component analysis), the feature set is cut down to contain six ones; and iii) the optimal feature set is input to the SVM classifier. Six healthy subjects were tested wearing the designed shoes. As a result, the accuracy is around 83.3%. Improved performance of the classifier was evident in ideal situation i.e. a constant walking velocity, no tilting et al., accuracy of SVM is nearly 100%. These results suggest that SVM system can function as an efficient classifier for recognition of three gait patterns.
In order to achieve large tolerance capture and high stiffness connection for space payload operations, a Chinese large-scale space end-effector (EER) was developed. Friction is a kind of strong nonlinear factor that ...
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ISBN:
(纸本)9781479973989
In order to achieve large tolerance capture and high stiffness connection for space payload operations, a Chinese large-scale space end-effector (EER) was developed. Friction is a kind of strong nonlinear factor that severely degrades performance of EER. To predict the friction amplitude and compensate the dynamic error, the friction model based Generalized Maxwell-Slip model (GMS) is built. In order to improve the parameters identification accuracy of friction model, and overcome the error effects of the low speed velocity measurement, the full-order speed observer is designed as feedback speed information. Experiments platform has been built and some dragging experiments on the EER have been done. Results of the experiments show that the precision of the position tracking can reach ±0.02mm by GMS compensation, increased more than 30% compared with Stribeck friction model.
Despite of many efforts by researches, real-time localization of mobile robot only using onboard sensor is still an open problem in mobile robotics. To contribute this research area, in this paper, a simple and effect...
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Chemical, biological, radiological, nuclear, and explosive (CBRNE) defense is a very critical issue in today's world and there is a trend to apply unmanned systems in such emergencies. Mobile manipulator is one ty...
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Chemical, biological, radiological, nuclear, and explosive (CBRNE) defense is a very critical issue in today's world and there is a trend to apply unmanned systems in such emergencies. Mobile manipulator is one typical representative and the performance of the manipulator matters a lot for the task. In this paper, the requirement of the manipulator for a sampling task is analyzed and a lightweight 5R manipulator is presented. As to get the best performance of the manipulator during the sampling process, the planar 3R manipulator's workspace is deeply looked into and an optimization method is proposed, which combines the condition number of the normalized Jacobian matrix and the end effector's orientation capability. And the optimum design is demonstrated through the simulation of a specific sampling task using rvc toolbox.
To segment gait phases of human locomotion tasks, such as level walking and stairway walking, ground reaction force (GRF) data during walking are collected. This paper presents a fuzzy logic inference (FLI) technique ...
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To segment gait phases of human locomotion tasks, such as level walking and stairway walking, ground reaction force (GRF) data during walking are collected. This paper presents a fuzzy logic inference (FLI) technique tuned by particle swarm optimization (PSO), which is used to find optimal triangular membership functions. To discriminate flexion and extension of swing leg, ground reaction force of the other foot is supplemented. As a result, a whole gait cycle is divided into five phases: heel strike(H-S), stance(S), heel off(H-O), swing one(Sw1), swing two(Sw2). The proposed method is simple and particularly suitable for human gait phases segmentation. Six healthy human were tested while maintaining a constant average walking velocity as far as possible. Results show that swing phase period accounts for around 31%, 41% and 42% in three gait motion patterns separately, which is nearly 40% in clinical gait analysis. After comparison, the proposed method is superior to conventional FLI(C-FLI) system. These results suggest that the proposed method can function as an efficient detector for gait phases.
A novel adaptive object impedance control strategy is presented for dual-arm cooperative humanoid manipulators. A general impedance scheme comprising internal impedance control and object impedance control is adopted,...
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A novel adaptive object impedance control strategy is presented for dual-arm cooperative humanoid manipulators. A general impedance scheme comprising internal impedance control and object impedance control is adopted, which aims at conferring a compliant behavior both in end-effector level and object lever. The adaptation law for the stiffness and damping of object impedance is derived from Lyapunov stability theory. In contrast with general object impedance, the proposed controller can exhibit different impedance characteristics according to the force exerted by environment on the object and can achieve minimizing the metabolic cost of the adaptation process. Simulation results show the object impedance controller exhibits explicit compliance behavior when the interaction with environment is weak and presents accumulation property of the stiffness and damping when the interaction is strong.
Application of hybrid robotics is a continuously developing field, as hybrid manipulators have demonstrated that they can combine the benefits of serial structures and parallel mechanisms. In this paper, a novel 5-deg...
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