The feedforward compensation of nonlinearities, i.e., hysteresis and creep, and unwanted vibrations in micromanipulators is presented in this paper. The aim is to improve the general performances of piezocantilevers dedicated to micromanipulation/microassembly tasks. While hysteresis is attenuated using the Prandtl-Ishlinskii inverse model, a new method is proposed to decrease the creep phenomenon. As no model inversion is used, the proposed method is simple and easy to implement. Finally, we employ an input shaping technique to reduce the vibration of the piezocantilevers. The experimental results show the efficiency of the feedforward techniques and their convenience to the micromanipulation/microassembly requirements.

Metamaterials have attracted wide scientific interest to break fundamental bounds on materials properties. Recently, the field has been extending to coupled physical phenomena where one physics acts as the driving force for another. Stimuli-responsive or 4D metamaterials have been demonstrated for thermo-elasticity, magneto-optics or piezo-electricity. Herein, a soft, ultra-compact and accurate microrobot is described which can achieve controlled motion under thermal stimuli. The system consists of an organized assembly of two functional structures: a rotational and a translational element. Both elements are designed basing upon the principle of the thermoelastic bilayer plate that bends as temperature changes. Samples are fabricated using gray-tone lithography from a single polymer but with two different laser writing powers, making each part different in its thermal and mechanical behaviors. Excellent motion-controllable, reversible and stable features in a dry environment are verified by simulations and experiments, revealing broad application prospects for the designed soft micro actuators.

At the microscale, small inertia and high dynamics of microparts increase the complexity of grasping, releasing, and positioning tasks. The difficulty increases especially because the position, the dimensions, and the stiffness of the micropart are unknown. In this paper, the use of a microgripper with integrated sensorized end effectors with high dynamic capabilities is proposed to perform stable and accurate grasps of multistiffness microcomponents. A dynamic nonlinear force/position model of the complete microgripper while manipulating a microcomponent is developed. The model takes into consideration not only free motion and constrained motion, but also, contact transitions which is a key issue at the microscale due to the predominance of surface forces. It enables us to estimate the position of the microgripper's end effectors, the contact position of the microcomponent, and the force applied on the microcomponent. Using the proposed microgripper and its model, both of the gripping forces are measured and the position of each of the microgripper's end effectors is estimated. This enables to perform a stable grasp of the micropart by providing force and position feedback. Moreover, using the developed microgripper and its model, the characterization of the microcomponent can be performed by estimating its dimensions and its stiffness.

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 mm2, 36.97 deg) is significantly larger than most compliant mechanisms, which is particularly interesting when both very high precision and relatively large displacements are required.