Most existing path following algorithms for middle-or large-sized underwater vehicles minimize yaw difference of the control object. Breaking the canonical manner, this paper presents a vision-based path planning and ...
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ISBN:
(数字)9781728137261
ISBN:
(纸本)9781728137278
Most existing path following algorithms for middle-or large-sized underwater vehicles minimize yaw difference of the control object. Breaking the canonical manner, this paper presents a vision-based path planning and following system for miniature robotic fish. As for path planning, the proposed system finds a gird path based on the AStar algorithm and selects a series of target points in the grid path. By connecting these points in order, a curve path can be planned. In terms of path following, the proposed system forgoes to give a specific yaw and only uses a global camera. It obtains coordinates of the robotic fish in real time by KCF tracking algorithm to calculate an approximate motion vector. A PID controller is employed to drive the difference angle between the motion vector and the target vector (the vector from the robotic fish to the target point) to zero. By swimming to target points one by one, the robotic fish can move to the terminus following the planned path. Finally, aquatic experiments are conducted to verify the effectiveness of the vision-based path planning and following system. The results reveal that the developed system can generate a safe and smooth path, and the robotic fish can follow the path with acceptable deviation.
This paper studies the finite-time control issue of semi-Markov jump systems with time-varying delays based under passivity framework. Firstly, sufficient criterion is derived to ensure that finite-time boundedness co...
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This paper studies the finite-time control issue of semi-Markov jump systems with time-varying delays based under passivity framework. Firstly, sufficient criterion is derived to ensure that finite-time boundedness condition can be satisfied and the desired passivity performance can be achieved simultaneously. Then, state-feedback controller procedure is presented with help of linear matrix inequalities(LMIs). Finally, a simulation example is provided for showing the applicability of the developed method.
Obstacle avoidance is one of the essential and indispensable functions for autonomous mobile robots. Most of the existing solutions are typically based on single condition constraint and cannot incorporate sensor data...
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This paper proposed an adaptive neural admittance control strategy for collision avoidance in human-robot collaborative tasks. In order to ensure that the robot end-effector can avoid collisions with surroundings, rob...
This paper proposed an adaptive neural admittance control strategy for collision avoidance in human-robot collaborative tasks. In order to ensure that the robot end-effector can avoid collisions with surroundings, robot should be operated compliantly by human within a constrained task space. An impedance model and a soft saturation function are employed to generate a differentiable reference trajectory. Then, adaptive neural network control with position constraint, based on integral barrier Lyapunov function (IBLF), is designed to achieve precise tracking while guaranteeing constrained satisfaction. Utilizing Lyapunov stability principles, we prove that semi-globally uniformly bounded stability is guaranteed for all states of the closed-loop system. At last, the effectiveness of the proposed algorithm is verified on a Baxter robot experimental platform. Collisions with surroundings can be avoided in human-robot collaborative tasks.
We have proposed an analytic compact model describing the drain current characteristics valid in all operating regions, for ultra-short channel cylindrical gate-all-around metal-oxide-semiconductor field-effect transi...
We have proposed an analytic compact model describing the drain current characteristics valid in all operating regions, for ultra-short channel cylindrical gate-all-around metal-oxide-semiconductor field-effect transistors considering source-to-drain tunnelling effect. The drain-induced barrier lowering had been incorporated from one two-dimensional analysis in our previous compact model. In this study, to represent the energy level profile along the device channel direction into the Wentzel-Kramers-Brillouin approximation by substituting a parabolic function, we can analytically derive the expressions of the transmission coefficients for source-to-drain tunneling. In the subthreshold region, the source-to-drain tunneling current then can be evaluated using the Landauer formula. Finally, a fully analytic compact model is proposed for representing the drain current in all operating regions. The results compared with non-equilibrium Green's function transport simulations can be obtained in a good agreement.
Soft robotics has several promising properties for aquatic applications, such as safe interaction with environments, lightweight, low cost, etc. In this paper, we proposed the kinematic modeling and hydrodynamics expe...
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Soft robotics has several promising properties for aquatic applications, such as safe interaction with environments, lightweight, low cost, etc. In this paper, we proposed the kinematic modeling and hydrodynamics experiments of a soft robotic arm with 3D locomotion capacity. We developed a mathematical model that incorporates the angle correction, as well as the open-loop model-based motion control. The model could precisely predict the three-dimensional (3D) movement, and the location error is less than 5.7 mm in different attitudes. Furthermore, we performed the hydrodynamic investigations and simultaneously measured the hydrodynamic forces and the wake flows at different amplitudes (50 mm, 100 mm, 150 mm, 200 mm) and frequencies (0.3 Hz, 0.4 Hz, 0.5 Hz) of the soft arm. Surprisingly, we found that the magnitudes of the hydrodynamic force (〈1 N) and the torques (〈0.08 N-m) of dynamically moving soft arm were tiny, which leads to negligible inertial effect for the underwater vehicle than those of the traditional rigid underwater manipulator. Finally, we demonstrated underwater picking and placing tasks of the soft manipulator by using a computer program that controls the tip attitude and velocity. This study may inspire future underwater manipulators that have properties of low-inertial, low power cost and can safely interact with the aauatic environments.
Optically induced electrokinetics(OEK)-based technologies,which integrate the high-resolution dynamic addressability of optical tweezers and the high-throughput capability of electrokinetic forces,have been widely use...
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Optically induced electrokinetics(OEK)-based technologies,which integrate the high-resolution dynamic addressability of optical tweezers and the high-throughput capability of electrokinetic forces,have been widely used to manipulate,assemble,and separate biological and non-biological entities in parallel on scales ranging from micrometers to ***,simultaneously introducing optical and electrical energy into an OEK chip may induce a problematic temperature increase,which poses the potential risk of exceeding physiological conditions and thus inducing variations in cell behavior or activity or even irreversible cell damage during ***,we systematically measure the temperature distribution and changes in an OEK chip arising from the projected images and applied alternating current(AC)voltage using an infrared *** have found that the average temperature of a projected area is influenced by the light color,total illumination area,ratio of lighted regions to the total controlled areas,and amplitude of the AC *** an example,optically induced thermocapillary flow is triggered by the light image-induced temperature gradient on a photosensitive substrate to realize fluidic hydrogel *** studies show that the projected light pattern needs to be properly designed to satisfy specific application requirements,especially for applications related to cell manipulation and assembly.
The space telescope stands for the highest level of a nation's aerospace industry, with its manufacturing and launch remaining a worldwide conundrum. The concept of modularized space telescope is proposed herein, ...
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The space telescope stands for the highest level of a nation's aerospace industry, with its manufacturing and launch remaining a worldwide conundrum. The concept of modularized space telescope is proposed herein, the main structure of the sub-mirror module is designed briefly and the assembly scheme of the main telescope is also provided. Besides, the kinematic equation and working conditions of the space robotic arm used for assembly are given, with the cubic B-spline curves formulating the joint space trajectory. Then, with minimizing the moving time as the objective of optimization, displacement, speed and acceleration as the constraint conditions, a mathematical model for time-optimal trajectory planning is established and the genetic algorithm is used to work out solutions. The emulation result shows that the joint space trajectory of the robotic arm obtained on the premise that all the restraint conditions are met can minimize the robotic arm's moving time.
Recognize an object and detect a good grasp in unstructured scenes is still a challenge. In this paper, the problem of detecting robotic grasps is expressed by a two-point representation in an unstructured scene with ...
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