Quadruped animals have high agility and grace skills in the motion over natural environment. An important feature of such animals is their abilities in the selection of appropriate gait in the response to the terrain ...
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ISBN:
(纸本)9781467372350
Quadruped animals have high agility and grace skills in the motion over natural environment. An important feature of such animals is their abilities in the selection of appropriate gait in the response to the terrain irregularities and also the smooth transition between them in order to increase the stability or conserve the energy. In this paper, a Cartesian CPG-based controller for the gait generation and the transition between them will be developed. The proposed approach uses nonlinear coupled oscillators for generating rhythmic signals. These patterns can be modulated by a programmed excitation signal and proportionally changing the frequency, amplitude and the coupling parameters among oscillators. According to these variations, the step length, duration of swing and stance phases of all legs, relative phase between the legs and the sequence of leg lifting can be adjusted smoothly especially by the duration of gait transition. Then, trajectories of swing legs along the z- and x-axeis will be computed through the data obtained form the CPG controller. The reference ZMP path will be desgined on the basis of the footprints of legs. Then, the COG trajectories will be calculated with a preview servo controller. Finally, some simulations are conducted to verify the effectiveness of the proposed approach both in the gait generation and smooth gait transition for a quadruped robot.
ability of quadruped robots for adjusting posture for crossing natural obstacles is an important issue. These robots should change their footholds to avoid any obstacles. In this paper, a gait planning algorithm based...
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ISBN:
(纸本)9781467372350
ability of quadruped robots for adjusting posture for crossing natural obstacles is an important issue. These robots should change their footholds to avoid any obstacles. In this paper, a gait planning algorithm based on Cartesian CPG-based controller for a quadruped robot in order to cross different planar obstacles will be developed. In proposed approach, the rhythmic patterns in central pattern generator are modulated by feedback signals which encode foothold positions in respect to the planar obstacles. By using these feedback signals the frequency of oscillation will be adjusted so that desired gait avoids the obstacles. The obtained gait results in the swing and stance sequences and also step length for each foot. Then, the trajectory of the swing legs in Cartesian space will be computed based on the CPG output data. So, the desired ZMP (Zero moment Point) trajectory will be obtained by using the footholds. Then, COG trajectory will be obtained by using a preview controller on the basis of the desired ZMP trajectory. Finally, proposed algorithm will be tested for crossing planar obstacles in different size and distance. Obtained results show the effectiveness of the proposed approach in crossing obstacles with different size and distance to each other.
Regarding robot interaction with moving objects and the necessity for robot controller to react in a timely manner having the objects current position, finding an efficient positioning method has always been a challen...
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ISBN:
(纸本)9781467372350
Regarding robot interaction with moving objects and the necessity for robot controller to react in a timely manner having the objects current position, finding an efficient positioning method has always been a challenge. As ball and plate system is considered to be a standard experimental system in controllaboratories. The system is consisted of the following pieces: a horizontal plate which gets tilted along each horizontal axes. The ball, which is located on the plate;is controlled by the system in a way to be placed in any point on the plate. In fact, the ball and plate system is an extension of the classical ball on beam experiment that is often used to study various types of control and stability problems.
One of the challenging issues in the robotic technology is to use robotics arm for surgeries, especially in eye operations. Among the recently developed mechanisms for this purpose, there exists a robot, called Eye-RH...
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ISBN:
(纸本)9781467372350
One of the challenging issues in the robotic technology is to use robotics arm for surgeries, especially in eye operations. Among the recently developed mechanisms for this purpose, there exists a robot, called Eye-RHAS, that presents sustainable precision in vitreo-retinal eye surgeries. In this work the closed-form dynamical model of this robot has been derived by Gibbs-Appell method. Furthermore, this formulation is verified through SimMechanics Toolbox of MATlab . Finally, the robot is simulated in a real time trajectory control in a teleoperation scheme. The tracking errors show the effectiveness and applicability of the dynamic formulation to be used in the teleoperation schemes.
In this paper, the desired configuration for installation of Delta robot is formulated as an optimization problem and has been solved to reach to the highest rate of pick and place operation. The optimization is perfo...
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ISBN:
(纸本)9781467372350
In this paper, the desired configuration for installation of Delta robot is formulated as an optimization problem and has been solved to reach to the highest rate of pick and place operation. The optimization is performed considering the actuators speed and acceleration limitation of the robot within the workspace. Furthermore, energy consumption is considered next as the other optimization objective, and it is shown that the optimal region for the first optimization problem lies within that of the latter one, and therefore, there is no need to propose a multi-objective optimization problem in this case. As a proof of concept, KNTU Delta robot is designed and implemented in practice by using the optimal configuration, and it is observed that the optimal design is very promising in practice.
In the problem of simultaneously localization and mapping (SLAM) for a mobile robot, it is required to detect previously visited locations so the estimation error shall be reduced. Sensor observations are compared by ...
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ISBN:
(纸本)9781467372350
In the problem of simultaneously localization and mapping (SLAM) for a mobile robot, it is required to detect previously visited locations so the estimation error shall be reduced. Sensor observations are compared by a similarity metric to detect loops. In long term navigation or exploration, the number of observations increases and so the complexity of the loop closure detection. Several techniques are proposed in order to reduce the complexity of loop closure detection. Few algorithms have considered the loop closure detection from a subset of sensor observations. In this paper, the compressed sensing approach is exploited to detect loops from few sensor measurements. In the basic compressed sensing it is assumed that a signal has a sparse representation is a basis which means that only a few elements of the signal are non-zero. Based on the compressed sensing approach a sparse signal can be recovered from few linear noisy projections by l_1 minimization. The difference matrix which is widely used for loop detection has a sparse structure, where similar observations are shown by zero distance and different locations are indicated by ones. Based on the multiple measurement vector technique which is an extension of the basic compressed sensing, the loop closure detection is performed by comparison of few sensor observations. The applicability of the proposed algorithm is investigated in some outdoor environments through some publicly available data sets. It has been shown by some experiments that the proposed method can detect loops effectively.
To obtain satisfactory performance for legged robots, they should be able to move on natural environment stably. In this article, the path planning of a quadruped robot in the motion over uneven terrains will be inves...
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ISBN:
(纸本)9781467372350
To obtain satisfactory performance for legged robots, they should be able to move on natural environment stably. In this article, the path planning of a quadruped robot in the motion over uneven terrains will be investigated. One of major problems for traversing uneven terrains is the robot stability. Thus, a condition to guarantee the robot stability over such terrains will be proposed. This condition defines a point with zero moment in 3D space. This condition makes it possible to vary of the height of main body stably during trotting which is a main issue for traversing uneven terrains. Based on this condition, a linear ZMP equation will be defined so that the main body acceleration acts as control input and the ZMP acts as output. A linear quadratic regulator with stability constraint and fixed final states will be proposed to obtain the COG path which results in minimum acceleration. The tip of swing foot path planning will be fulfilled so that the generated path leads to avoid any collision with environment. Furthermore, the path of tip of swing legs is designed with minimum acceleration. The simulation results confirm the validity of proposed methods in terms of stability and the improvement of the consumption energy over uneven terrains.
The purpose of this paper is to optimize dimensions of KNTU 6-DoF cable driven redundant parallel manipulators. This manipulator is under investigation for possible high-speed application such as object manipulator. U...
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ISBN:
(纸本)9781467372350
The purpose of this paper is to optimize dimensions of KNTU 6-DoF cable driven redundant parallel manipulators. This manipulator is under investigation for possible high-speed application such as object manipulator. Usage of cable parallel manipulator depends on kinematic characteristic and control algorithm. This optimization is based on different performance indices including the singularity measure, the kinematic sensitivity, the stiffness and free collision workspace. Stiffness of the cable is also taken into consideration because of its effect on kinematic stiffness of moving platform manipulators performance. Points with cable collision, singular or actuator wrench infeasible configuration characteristic are eliminating from entire workspace.
Gliomas are the most common primary brain malignancies, with different degrees of aggressiveness, variable prognosis and various heterogeneous histologic sub-regions, i.e., peritumoral edematous/invaded tissue, necrot...
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In this article, a method to obtain spatial coordinate of spherical robot's moving platform using a single camera is proposed, and experimentally verified. The proposed method is an accurate, flexible and low-cost...
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ISBN:
(纸本)9781467372350
In this article, a method to obtain spatial coordinate of spherical robot's moving platform using a single camera is proposed, and experimentally verified. The proposed method is an accurate, flexible and low-cost tool for the kinematic calibration of spherical-workspace mechanisms to achieve the desired accuracy in position. The sensitivity and efficiency of the provided method is thus evaluated. Furthermore, optimization of camera location is outlined subject to the prescribed cost functions. Finally, experimental analysis of the proposed calibration method on ARAS Eye surgery Robot (DIAMOND) is presented;In which the accuracy is obtained from three to six times better than the previous calibration.
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