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Reinforcement learning in the high-dimensional, continuous spaces typical in robotics, remains a challenging problem. To overcome this challenge, a popular approach has been to use demonstrations to find an appropriate initialisation of the policy in an attempt to reduce the number of iterations needed to find a solution. Here, we present an alternative way to incorporate prior knowledge from demonstrations...
Robotics research tends to focus upon either non-contact sensing or machine manipulation, but not both. This paper explores the benefits of combining the two by addressing the problem of classifying unknown objects, such as found in service robot applications. In the proposed approach, an object lies on a flat background, and the goal of the robot is to interact with and classify each object so that...
Measuring the contact force between a robotic foot and the ground can play an important role in the implementation of biped motion. In this paper, one possible implementation of a contact force measurement system is given. The possibilities of this system are simulated on a motor-powered pendulum. Experiment results are also given.
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...
This paper proposes an output based adaptive iterative learning control (OBAILC) scheme for robotic systems. The idea of using OBAILC is to improve the tracking performance iteratively with relatively smaller values of observer-controller gains by assuming that the system tracks the same task iteratively. The design combines proportional-derivative controller with an adaptive term that iteratively...
Complex mechatronic systems with a number of independently driven elements generally employ an equal number of drive elements. Commonly, these systems are actuated by electric motors and hence electric energy is transmitted through them. In various systems, however, mechanical energy may be distributed through the system instead of electrical energy and may be used directly to drive output elements...
Modeling and simulation of multi-fingered robot hand (MFRH) is increasingly gaining importance amongst researchers for industrial and medical applications. In this paper, a MFRH with five fingers is modeled and simulated for grasping task. This was done using a CAD tool known as Solidworks, and an analytical tool known as SimMechanics of MATLAB. The simulation results show that the improved performance...
Most industrial robots nowadays still employ strategies that neglect or minimize the effects of task dynamics. Some tasks, however, are intrinsically dynamic and can only be accomplished by considering their dynamic aspects. We address ball catching as a prominent and widely studied example for such a task. The paper follows a special approach to accomplish the task: the nonprehensile catching, which...
High performance control of robotic systems, including the new generation of humanoid, assistive and entertainment robots, requires adequate knowledge of the dynamics of the system. This can be problematic in the presence of modeling uncertainties as the performance of classical, model-based controllers is highly dependant upon accurate knowledge of the system. In addition, future robotic systems...
In state of the art robotics, high positioning accuracy is achieved by using solid and stiff components as well as powerful drive units which have no backlash. In contrast, human beings are able to achieve remarkable high positioning accuracy despite of low mass, low power consumption and relatively simple mechanics. One approach to obtain this accuracy is to temporarily create additional supporting...
This paper presents a method for vision based estimation of the pose of human hands in interaction with objects. Despite the fact that most robotics applications of human hand tracking involve grasping and manipulation of objects, the majority of methods in the literature assume a free hand, isolated from the surrounding environment. Our hand tracking method is non-parametric, performing a nearest...
We consider a class of linear flexible mechanical systems arising from the dynamics of animal locomotion. A distinctive property of such systems is that the stiffness matrix is asymmetric. Extending the standard notion to this class, we define the natural oscillation as a free response under the damping compensation to achieve marginal stability. As a benchmark, a link chain system in a fluid environment...
In the face of large scale parametric uncertainties, the single model (SM)-based classical adaptive control approach demands high observer, controller and adaptation gains in order to achieve good tracking performance. The well known problem of having high-gain based design is that it amplifies the input and output disturbance as well as excites hidden unmodeled dynamics causing poor tracking performance...
Usually, the identification of the dynamic parameters of robot makes use of the inverse dynamic model which is linear with respect to the parameters. This model is sampled while the robot is tracking exciting trajectories. This allows using linear least squares (LS) techniques to estimate the parameters. The efficiency of this method has been proved through experimental identifications of a lot of...
In this work, we propose an output feedback sliding mode control (SMC) method for trajectory tracking of robotic manipulators. The design process has two steps. First, we design a stable SMC approach by assuming that all state variables are available for feedback. Then, an output feedback version of this SMC design is presented which incorporates a model-free linear observer to estimate unknown velocity...
Recent efforts to develop virtual environments for the study of robot hands and grasping have been limited. The general approach to modeling the hand has overlooked many fundamental aspects that relate to the mechanical design of robot hand prototypes. In particular, resulting motions of hands due to tendon action have not been simulated in any existing virtual environment, to our knowledge. Furthermore,...
This project is focusing on the development of robot-assisted stroke rehabilitation system of human upper limb and hand elbow movements. Realizing the complexity of human upper limb, the study is limited to human upper limb, consisting of 3 glenohumeral joints (abduction-adduction, flexion-extension, and rotation) and elbow joint (flexionextension). In this paper the rehabilitation robotic system...
Aiming to structurally and functionally replace missing or damaged tissues, regenerative medicine can offer revolutionary therapeutical solution in addressing musculoskeletal conditions. Translation from basic research to affordable cost effective therapeutic procedures implies using advanced robotic and automatized technology for research, processing, quality control and future development. This...
The optimal trajectory planning is an important function in a robot control area. Generally, the operating function of manipulators requires the highest performance such as minimum time, minimum energy, and no damage to the system. This paper proposes a minimum time trajectory planning that is clamped with cubic splines and uses Harmony Search (HS) algorithm for solving the optimization problem. Minimum...
Coordination in multi-robot systems is a very active research field in artificial intelligence and robotics, since through coordination one can achieve a more effective execution of the robotspsila tasks. We achieve collaboration between agents through introducing roles into the situation calculus. Homogeneous agents can flexibly switch roles according to pre-defined triggers to be evaluated at run-time...
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