Aerial Tele-Manipulation with Passive Tool via Parallel Position/Force Control

This paper addresses the problem of unilateral contact interaction by an under-actuated quadrotor UAV equipped with a passive tool in a bilateral teleoperation scheme. To solve the challenging control problem of force regulation in contact interaction while maintaining flight stability and keeping the contact, we use a parallel position/force control method, commensurate to the system dynamics and constraints in which using the compliant structure of the end-effector the rotational degrees of freedom are also utilized to attain a broader range of feasible forces. In a bilateral teleoperation framework, the proposed control method regulates the aerial manipulator position in free flight and the applied force in contact interaction. On the master side, the human operator is provided with force haptic feedback to enhance his/her situational awareness. The validity of the theory and efficacy of the solution are shown by experimental results. This control architecture, integrated with a suitable perception/localization pipeline, could be used to perform outdoor aerial teleoperation tasks in hazardous and/or remote sites of interest.

Design and Modeling of Series-Parallel Compliant Device for Reliable Assembly Under Position/Angle Deviation

Automatic assembly using manipulator has attracted increasing attention due to low cost and high quality of assembly. As the manipulator is entirely rigid, it often causes assembly failure and even damages the manipulator when there is a position or angle deviation. A series-parallel compliant device is developed here to realize the reliable assembly under the position or the angle deviation and does not produce a significant contact force. Its core idea is that when the contact force exceeds a specific value, this device becomes compliant and can move in a particular direction. It guarantees that this assembly allows a relatively significant misalignment and produces a small force, protecting parts and manipulators. This device has two compliant components, and these two components are connected using a rigid block. Each compliant component consists of the rigid frame, the four elastic limbs with a similar ‘n’ shape, and the square block. Due to using the elastic material, each elastic limb is equivalent to a compliant hinge (or spring), making this designed device equal to a series-parallel compliant structure. In this way, this device becomes compliant and can move in a particular direction when the contact force exceeds a specific value. On this basis, the desired compliance of the device is realized in various directions depending on the compliant device, and an optimization method is designed to achieve the parameters of this device based on the kinematic model and the stiffness analysis. Experiments under different working conditions are carried out and demonstrate the reliable assembling performance of this designed device even if there exists the position deviation or the angle deviation.

Microscale sensor solution for data collection from fibre-matrix interfaces

Especially the applications of fibrous composites in miniature products, dental and other medical applications require accurate data of microscale mechanics. The characterization of adhesion between single filament and picoliter-scale polymer matrix usually relies on the experiments using so-called microbond (MB) testing. The traditional MB test systems provide unitary data output (i.e., converted force) which is enigmatic in resolving the fracture parameters of multi-mode interface cracks. As a fundamental basis, the momentary reaction force and respective local strain at the location of a non-ambiguous gradient are needed for a mechanical analysis. In this paper, a monolithic compliant based structure with an integrated Fiber Bragg Grating (FBG) sensor is developed and analysed. The stiffness of the compliant structure is estimated by using mathematical and finite element (FE) models. Qualification experiments are carried out to confirm the functional performance: MB testing of synthetic (carbon and glass) and natural (flax) single filaments are successfully performed. Quasi-static and dynamic analysis of the MB testing is carried out by using the FE method to interpret the response of the compliant structure. The developed strain-sensing CBPM-FBG holder shows excellent sensitivity during the MB tests for both synthetic and natural filaments, even at a low filament diameters as low as $$7\,\upmu \hbox {m}$$ 7 μ m , making the monolithic compliant structure the first instrument capable of force-strain data output for bonded filament-droplet specimens.

Safety-enhanced control strategy of a power soft robot driven by hydraulic artificial muscles

Power soft robots—defined as novel robots driven by powerful soft actuators, achieving both powerfulness and softness—are potentially suitable for complex collaborative tasks, and an approach to actuating a power soft robot is the McKibben artificial muscle. This study aims to show the potential of hydraulic artificial muscles to be implemented in a power soft robot with high safety, including higher stability against sudden load separation or impact disturbance, and appropriate dynamic compliance. The stability of a manipulator arm driven by hydraulic muscle actuators is experimentally proven to be higher than that of pneumatic muscle actuators when the stored elastic energy is instantaneously released. Therefore, the hydraulic muscle actuator is a better candidate for actuating a power soft robot. By taking advantage of the incompressible liquid medium and the compliant structure of a hydraulic muscle, a second-order impedance control strategy with a braking method is proposed to improve dynamic compliance without sacrificing the safety features of hydraulic muscles. The results show that the manipulator can be easily shifted by a several-kilogram-level external force and react safely against sudden load change with low angular velocity by the proposed impedance control.

Multiobjective Optimization for the Aero-Structural Design of Adaptive Compliant Wing Devices

The design of morphing structures must combine conflicting structural requirements and multiple load conditions that are related to the aerodynamic shapes aimed at optimizing aircraft performance. This article proposes a multilevel approach for the design of adaptive compliant wing devices. A set of aerodynamic shapes, and associated their loads, is defined by a shape optimization, coupled with a three-dimensional parametric technique, that can identify only feasible shape changes due to the morphing. A topology and sizing multiobjective optimization drives the Pareto-optimal structural design of the compliant structure, which is able to deform itself to match, once actuated, all of the previously defined aerodynamic shapes. Next two design levels produce a more detailed solution which is extended until the definition of the complete device. A 90 pax, twin prop green regional aircraft is used as an innovative aircraft demonstration platform for the design of the morphing droop nose to be installed on the wing. The results show the structural capabilities of this device in terms of the external shape quality and the strain requirements. This work enables the validation of the design method and prove the functionality of compliant structures when accounting for the aeroelastic effects due to the interaction with the wing-box.

Acutely ruptured basilar artery bifurcation aneurysm, treated with simultaneous Cascade and Comaneci temporary-assisted coiling

Temporary stent-assisted coiling is an eligible approach for the treatment of acutely ruptured complex cerebral aneurysms. Improved material properties and industrial advances in braiding technology have led to the introduction of new stent-like devices to augment endovascular coil embolization. Such technology includes the Cascade and Comaneci neck-bridging devices. Both devices are manually controlled, non-occlusive and fully retrievable neck-bridging temporary implants. The braided nature and the ultra-thin wire, compliant structure of their bridging meshes helps maintain target vessel patency during coil embolization. In this video (video 1) we demonstrate the straightforward combination of two temporary neck-bridging devices for the embolization of an acutely ruptured aneurysm of the basilar artery. Technical success and complete embolization of the aneurysm were recorded at the final angiography. In this technical video we discuss the technical nuances of the Comaneci and Cascade coil embolization.Video 1

Experimental Assessment of a 3D-Printed Stainless Steel Gas Foil Bearing

Gas foil bearings (GFBs) are a key enabling technology for high-speed turbomachinery. The manufacturing of GFBs relies mainly on sheet metal forming techniques in order to conceive the compliant structure (e.g., bump foil) and the top foil. Such techniques require the development of a special know-how and most importantly, limit the design creativity to what is manufacturable using sheet metal forming. Additive manufacturing (AM) is a disruptive technology in prototyping and fabrication. This paper accesses the feasibility of AM in the fabrication of GFBs using selective laser melting (SLM) technology. A stainless steel GFB is 3D-printed in one piece, including the sleeve, the bump, and top foils. The bearing is assessed geometrically and statically before being tested on a gas bearing test rig, where it supported a ø40 mm rotor (m = 2 kg). The bearing performed similar to a conventional GFB, showing rotordynamically stable and repeatable operation up to 37.5 krpm. Such result highlights the potentials of AM as a viable alternative for foil bearing manufacturing.

Characteristic Behavior of PVDF-Compliant Structure as an End Effector Using Creo Element/Pro Release 5.0

The tremendous area of application of microprocessors and microcontrollers has exhausted the demand for polymers as sensors among the fastest growing technologies of the $18 billion sensor market worldwide. This chapter presents the study of characteristic behavior of a compliance structure made of PVDF (Poly Vinylidene Fluoride) material which is acting as an actuator and sensor, too. The inverse piezoelectric nature of PVDF has been used to produce the required amount of force by applying the voltage at a specific point at the base of the structure which is generating the opening and closing of the end effector. The displacement of the tip of the end effector can be sensed by generated voltage of piezoelectric effect of PVDF.

Augmented Aircraft Performance with the Use of Morphing Technology for a Turboprop Regional Aircraft Wing

This article presents some application of the morphing technology for aerodynamic performance improvement of turboprop regional aircraft. It summarizes the results obtained in the framework of the Clean Sky 2 AIRGREEN2 program for the development and application of dedicated morphing devices for take-off and landing, and their uses in off design conditions. The wing of the reference aircraft configuration considers Natural Laminar Flow (NLF) characteristics. A deformable leading edge morphing device (“droop nose”) and a multi-functional segmented flap system have been considered. For the droop nose, the use of the deformable compliant structure was considered, as it allows a “clean” leading edge when not used, which is mandatory to keep natural laminar flow (NLF) properties at cruise. The use of a segmented flap makes it possible to avoid external flap track fairings, which will lead to performance improvement at cruise. An integrated tracking mechanism is used to set the flap at its take-off optimum setting, and, then, morphing is applied in order to obtain a high-performance level for landing. Lastly, some performance improvements can be obtained in climb conditions by using the last segment of the flap system to modify the load distribution on the wing in order to recover some extended laminar flow on the wing upper surface.