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This paper proposes the application of a super twisting algorithm based control strategy for the position control of a Stewart platform. The conventional sliding mode controller is making use of a discontinuous feedback control, hence the control effort is discontinuous in nature. The discontinuity in feedback control induces the dangerous high frequency vibrations called chattering, which is highly...
This paper proposes the application of a continuous higher order sliding mode controller for the position control of a Stewart platform. The conventional integral sliding mode controller consists of a nominal control and a discontinuous feedback control hence the overall control is discontinuous in nature. The discontinuity in feedback control is undesirable for practical applications due to chattering...
Tracking a desired trajectory in joint space has been favored in several robot manipulators and end-effector control scheme due to the simplicity and high sampling rate offered by the joint space scheme. This usually require the trajectory conversion process, of the desired position, velocity, and acceleration, from Cartesian space to joint space using conventional inverse kinematics solutions which...
Robotic manipulators are the most important components in the present manufacturing industry for handling materials and manipulation. It is important to note that these manipulators are used in the complex planar and spatial work spaces to perform the task. Further, it is also very difficult to manipulate and dynamically control the manipulators when the degrees of freedom (DOF) of the manipulator...
Autonomous target capturing is the key for space robot to perform on-orbital servicing tasks. To meet the requirement of complex and long-term task, large flexible appendages, such as solar paddles and antenna reflectors are usually mounted on the base of a space robot. Due to the structure vibration, it is very challenging to capture a free-floating target satellite. In this paper, we derived the...
Learning motor skills for robots is a hard task. In particular, a high number of degrees-of-freedom in the robot can pose serious challenges to existing reinforcement learning methods, since it leads to a high-dimensional search space. However, complex robots are often intrinsically redundant systems and, therefore, can be controlled using a latent manifold of much smaller dimensionality. In this...
Living organisms are characterized by their smooth adaptability to environmental changes and their robustness against morphological modifications. To investigate the computational mechanisms behind such learning scheme, we proposed tacit learning as a novel learning method. In tacit learning, there are no clear distinctions between learning and motor control: learning is a simple accumulation process...
Space manipulator is an integral part of space station in its life stages including construction, operation and development, during which there are tasks for the manipulator as manipulating light camera and also assembling cabins of weight. Workload range is so wide that optimization is necessary to be considered to improve execution performance on all load conditions. Firstly, this paper details...
In this paper, geometric nonlinearity of a flexible link is considered for dynamic modeling of free-floating space manipulators. The system dynamics is derived by Lagrange theorem in conjunction with the assumed modes method. By reducing some parameters, dynamic equations of small deflection is obtained for control system design. For position control design, modified partial feedback linearization...
To verify and evaluate the performance of a space robot controller, kinematics and dynamics of the system have to be formed beforehand for computer simulation. The paper is devoted to develop a new kinematic notation for space robots and to come up with an open source of Matlab subroutines for the propose of obtaining the proper dynamics equations of space robots in symbolic forms automatically. For...
The vibration suppressive control problem is a challenge of flexible-joint space manipulators, which is settled by solving the energy optimal nonlinear control problem in this paper. Based on Legendre pseudo-spectrum method, the nonlinear model of optimal control problem is converted into the corresponding nonlinear programming problem. The complex and difficult two-point boundary value problem is...
In order to verify and test the dynamics characteristic of free-floating space robot, a hybrid dynamics simulation experiment based on hardware and software simulation is present in this paper. Firstly, a set of ground experiment system which consists of the joint electronic simulator, the central controller and dynamics simulation computer is built to simulate the motion of space manipulator and...
In this paper, a novel trajectory tracking method based on the optimal control is presented for space flexible manipulator with large payloads. According to the model of Euler-Bernoulli beam, the Lagrange equation and the assumed mode method are used to establish dynamic equation of flexible manipulator. Then the further dynamic equation of space flexible manipulator with large payloads is derived...
This paper presents a new trajectory generation algorithm for a space manipulator after capturing an uncooperative tumbling target. In particular, the previously developed Adaptive ReactionLess Control algorithm (ARLC) is extended to obtain minimum base reaction motion of the manipulator with consideration of joint limit constraints. A task-priority redundancy resolution technique is formulated within...
This paper discusses an unified method of the tracking and balancing controls for leg-wheel hybrid structures in an effort to improve the mobility over hard, flat surfaces. Preliminarily, we analyzed the contact constraint to formulate a dynamically decoupled model in the task space. Then, inequality constraints were determined to restrict the dynamic behavior of the system within the given bounds...
Dynamics and control of a space robotic system with flexible members during an object manipulation task is studied here. Flexible members such as solar panels of space free flying robotic systems and their flexible joints during a manoeuvre may get stimulated and vibrate. Therefore, such vibrations will cause some oscillatory disturbance forces on the moving base and manipulated object, which in turn...
Impedance control is well-suited to robot manipulation applications because it gives the designer a measure of control over how the manipulator to conforms to the environment. However, in the context of end-effector impedance control when the robot manipulator is redundant with respect to end-effector configuration, the question arises regarding how to control the impedance of the redundant joints...
This paper proposes an iterative learning control scheme in a task space for a musculoskeletal redundant planar arm model to accomplish a desired time dependent trajectory tracking task. In our previous work, we have proposed the iterative learning control scheme in a muscle length space for a two-link six-muscle planar arm model. This proposed method has been effective for performing a time dependent...
In this paper the servo problem in a 3-D robot manipulator based only on the visual measurements by following the dynamic visual servoing approach with a fixed camera configuration is considered. To model the whole visual servoing system, we consider the robot in an image space, reconstructed from the perspective projection of the robot space in the image plane. The manipulator dynamics is lifted...
A logging harvester for clear-cutting in plantation is introduced in this paper. A chassis of ZL-50 wheeled loader is adopted as its walking mechanism. A multi-functional articulated manipulator is mounted on the front of the chassis, which can do the felling, the limbing, the measuring and the bucking. Meanwhile the kinematics analysis of the manipulator is produced, a coordinate system and a kinematics...
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