This paper is dedicated to vision-based modeling and control of large-dimension parallel robots driven by inextensible cables of non-negligible mass. An instantaneous inverse kinematic model devoted to vision is introduced. This model relies on the specificities of a parabolic profile hefty cable modeling and on the resulting simplified static analysis. By means of a kinematic visual servoing method, computer vision is used in the feedback loop for easier control. According to the modeling derived in this paper, measurements that allow the implementation of this visual servoing method consist of the mobile platform pose, the directions of the tangents to the cable curves at their drawing points and the cable tensions. The proposed visual servoing scheme will be applied to the control of a large parallel robot driven by eight cables. To this end, in order to obtain the aforementioned desired measurements, we plan to use a multi-camera setup together with force sensors.

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One of the main drawbacks of vision-based control that remains unsolved is the poor dynamic performances caused by the low acquisition frequency of the vision systems and the time latency due to processing. We propose in this paper to face the challenge of designing a high-performance dynamic visual servo control scheme. Two versatile control laws are developed in this paper: a position-based dynamic visual servoing and an image-based dynamic visual servoing. Both control laws are designed to compute the control torques exclusively from a sequential acquisition of regions of interest containing the visual features to achieve an accurate trajectory tracking. The presented experiments on vision-based dynamic control of a high-speed parallel robot show that the proposed control schemes can perform better than joint-based computed torque control.

Micro-manipulation plays a key role in the development of complex and assembled micro-systems. However, current micro-manipulation solutions are often limited to small rotation amplitudes and to simple shaped objects (such as cubes). Our approach consists in developing in-hand micro-manipulation techniques using dexterous micro-hands to manipulate arbitrary shaped objects and to perform large rotations. This paper focuses on the trajectory generation of a dexterous micro-hand to achieve automated repositioning by taking advantage of adhesion forces. The results on the generated trajectories show that adhesion forces can be exploited to enhance the manipulation possibilities. Moreover, experiments show that planed rotations are performed at more than 95% using an open loop control. Dexterous micro-manipulation is a promising way to perform complex manipulation tasks in micro-scale.

In many cases, soft and continuum robots represent an interesting alternative to articulated robots because they have the advantages of miniaturization capability, safer interactions with humans and often simpler fabricating and integration. However, these benefits are usually considered to arise at the expense of accuracy and precision because of the soft or flexible limbs. This paper demonstrates that, with a proper design, a planar parallel continuum robot is capable of great precision. Indeed, the proposed 3-Degrees-of-Freedom planar parallel continuum robot exhibits a precision of 9.13 nm in position and 1.2 µrad in orientation. In addition, the novel robotic design leverages the effect of the actuators' defects, making the robot more precise than its own actuators. Finally, the workspace of the proposed robot (62.3 mm 2 , 0.6452 rad) is significantly larger than most compliant mechanisms, which is particularly interesting when both very high precision and relatively large displacements are required.

This paper presents a new parallel robot with an integrated gripper. The grasping capability of the robot is obtained by a foldable platform that can be fully controlled by actuators located on the base of the seven degrees-of-freedom (DoF) parallel structure. This mechanism combines three key specificities in robotics which are compactness, rigidity, and high blocking forces. The paper presents the new structure, its kinematic modeling, and an analysis of its workspace and grasping force capabilities. In addition, a prototype is presented and tested in manipulation and insertion operations, which validates the proposed concept.

This paper presents the experimental validation of automatic dexterous in-hand manipulation of micro-objects. Currently, precise handling of micro-objects is still a challenge especially when large rotations are required. Indeed, the current dexterity of microgrippers is still very low and only some small range rotations have been shown. Although, the robotic hands in the macroscale have better capabilities, they are not able to manipulate micro-objects. The proposed approach extends the capabilities of dexterous macrohands to the microgrippers enabling dexterous micro-manipulation. Design rules of the microhand fingers and trajectories enabling micro-manipulation are proposed. The developed methods are validated by simulation and on an original experimental prototype having three fingers (7µm in diameter). Half turns of 220µm square objects demonstrates the relevance of the approach which opens the way to new advanced in-hand micro-manipulation and micro-assembly methods.

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