Linear Dynamic Modeling of Parallel Kinematic Manipulators from Observable Kinematic Elements.

International audienceThis paper presents a linear method for kinematic and dynamic modeling of parallel kinematic manipulators. This method is simple, compact and clear. One can write all the equations from the beginning till the end with pen and paper. It is thus well suited to mechanical understanding and computer implementation. We can apply it to many parallel robots. This method relies on a body-oriented representation of observable rectilinear kinematic structures (kinematic elements) which form the robot legs

On the adequation of dynamic modelling and control of parallel kinematic manipulators.

International audienceThis paper addresses the problem of controlling the dynamics of parallel kinematic manipulators from a global point of view, where modeling, sensing and control are considered simultaneously. The methodology is presented through the examples of the Gough-Stewart manipulator and the Quattro robot

Vector-based dynamic modeling and control of the quattro parallel robot by means of leg orientations.

International audienceOne of the key steps in high-speed control of a parallel robot is to define an efficient dynamic model. It is usually not easy to have such a model for parallel robots, since many of them have complex structures. Here, we propose a vector-based approach, which employs the robot leg orientations, to obtain a simplified inverse dynamic model. At the least, this vector-based methodology is pioneering, when combined with the observation of orientations by a calibrated camera, in the sense of solving the entire control-oriented (hard) modeling problem, both kinematics and dynamics, in an almost algebraic manner through the knowledge of only a nominal set of image features: the edges of the robot legs and their time derivatives. Proposed method is verified on a simulator of the Quattro robot with a computed torque control where the leg orientations are steered

A vision-based generic dynamic model of PKMs and its experimental validation on the Quattro parallel robot.

International audienceIn this paper, we present a dynamic modeling method for parallel kinematic manipulators. This method is built upon the postures (i.e., 3D orientation vectors, lengths and self rotations) of the kinematic elements which form the kinematic chains of the robot. Regarding the structure of the above method, computer vision emerges as a good option to obtain the postures of these kinematic elements. This method is then validated experimentally on the commercial Adept Quattro parallel robot

Dynamic Control of the Quattro Robot by the Leg Edges

International audienceThis paper discusses variable selection for the efficient dynamic control of the Quattro parallel robot through an inverse dynamic model expressed by means of leg orientations. A selection is made within a group of variables where each can imply the state of the robot. Besides, in this work, steering a parallel robot dynamically using its self-projection onto the image plane (where the edges of the lower-legs are exploited in control) is proposed and validated for the first time. In the light of the realistic control simulation, the formative points of better control of the Quattro robot are figured out

Kinematic modeling and control of a robot arm using unit dual quaternions

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The effect of densification temperature on some physical and mechanical properties of Scots pine (Pinus sylvestris L.)

As wood’s density increases, strength properties tend to increase due to a decrease in cavity volume. This study aimed to determine the effect of temperature levels in the densification process with an open-system thermomechanical method on the density, bending, modulus of elasticity in bending, compression, shear strength, and Brinell hardness in radial/tangential directions of Scots pine. The densification process significantly increased the strength properties of Scots pine. This increase stemmed from the decrease in the rate of cavities with the densification process, which also resulted in an increase in cell wall elements that have load-bearing properties per unit volume. An increase in densification temperature decreased strength properties. The decrease in the strength values can be explained by increasing chemical degradation with a rise in the temperature level. The most suitable temperature level was 120ºC for a higher bending, shear, and compression strength, and it was 140ºC for a higher radial and tangential hardness in the densification of Scots pine. Increases of 42% in the bending strength, 20% in the shear strength, 47% in the compression strength, 242% in the radial hardness, and 268% in the tangential hardness were obtained after densification

A Study on Dexterous Grasps via Parallel Manipulation Analogy

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Parking objects by pushing using uncalibrated visual servoing

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High Speed Parallel Kinematic Manipulator State Estimation from Legs Observation.

International audienceTo control dynamics of a parallel robot, we should measure the state feedback accurately and fast. In this paper, we show how to estimate positions and velocities simultaneously (i.e., the state feedback) at a reasonable accuracy and speed. We did this using only the sequential visual contours of the legs. A single-iteration virtual visual servoing scheme regulates rapidly an error of these contours. We validated this theory, a step to control parallel robots at high speed by their leg kinematics, with simulations and experiments