Unlike traditional hard grippers, soft robotic grippers are commonly made of soft materials so that the soft grippers can produce motion via elastic deformations of their compliant components. The advantages of compliance allow soft grippers to effectively eliminate shocks caused by hard contact, which usually occurs when a hard robotic gripper manipulates a hard object. Until now, the soft robotic grippers are able to operate numerous objects with irregular geometries and different textures. Besides, with the help of embedded sensors, soft robotic grippers have facilitated the growing automation of many tasks, which are thought to be far too delicate for robotic manipulation. This paper reviews the advancement in soft robotic grippers. The paper first introduces the actuation technologies followed by the design and fabrication techniques. The use of 3D printing techniques in the fabrication of the soft gripper is also discussed. The Review then highlights the challenges and future outlook in the fabrication of soft grippers and sensors.

A B S T R A C T Corrosion is an electrochemical process in offshore pipelines where the material strength begins to decrease as corrosion advances. Numerous studies have been performed to determine the remaining strengths (failure pressure) of corroded pipelines. Currently the axial corrosions of the girth welded pipelines still leave much to be understood. This study attempted to simulate girth welded pipeline with various corroded depths and lengths in order to compare with offshore pipeline design manuals. Based on the numerical results, the influence of corrosion defects parameters on remaining strengths were investigated for girth welded pipelines. The investigation on the effect of strength mismatch revealed that in the cases of under-matched, higher failure pressures are obtained.Comparisons of current results with B31G-2012 and DNV-RP-F101 demonstrated that both codes may produce somewhat conservative predictions on the failure pressure. Furthermore, an equation was proposed to evaluate the corrosion progress across girth welded pipelines.B = a coefficient determined by the ratio of the corrosion depth to wall thickness d = depth of corrosion defect D = outer diameter of girth welded pipeline E = Young's modulus K = strength coefficient for weld metal L = length of corrosion defect M = a coefficient relevant to length of corrosion defect n = strain hardening coefficient P F = failure pressure calculated by B31G or DNV-RP-F101 P Failure = predicted failure pressure in this study Q = a coefficient related to length of corrosion defect S flow = flow stress S F = failure stress calculated by B31G or DNV-RP-F101 t = average wall thickness of girth welded pipeline α = an intermediate parameter α U = material strength factor γ d = partial safety factor for corrosion depth γ m = partial safety factor for offshore pipelines η = an intermediate parameter η d = the sensitivity factor for the corroded depth Correspondence: Z. M. Xiao.

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Under continuous loading conditions, small closely distanced cracks can grow and coalesce into a large one that may subsequently pose a threat to the integrity and safety of structures. Although many research works were carried out for predicting fatigue growth of multiple cracks, few papers focusing on nonlinear elastic–plastic analysis of multiple cracks' fracture behaviours can be referred to. In this study, 3‐D elastic–plastic investigation has been performed on fracture behaviours of two collinear cracks located in offshore pipelines. The influences of the cracks configuration, the separation distance and internal pressure of the pipeline on the crack behaviours are investigated. On the basis of the numerical results, a new strain‐based crack tip opening displacement estimation method is proposed for assessing the fracture behaviour of flawed pipelines with two interacting collinear cracks.

Accurate kinematic modelling is pivotal in the safe and reliable execution of both contact and non-contact robotic applications. The kinematic models provided by robot manufacturers are valid only under ideal conditions and it is necessary to account for the manufacturing errors, particularly the joint offsets introduced during the assembling stages, which is identified as the underlying problem for position inaccuracy in more than 90% of the situations. This work was motivated by a very practical need, namely the discrepancy in terms of end-effector kinematics as computed by factory-calibrated internal controller and the nominal kinematic model as per robot datasheet. Even though the problem of robot calibration is not new, the focus is generally on the deployment of external measurement devices (for open loop calibration) or mechanical fixtures (for closed loop calibration). On the other hand, we use the factory-calibrated controller as an ‘oracle’ for our fast-recalibration approach. This allows extracting calibrated intrinsic parameters (e.g., link lengths) otherwise not directly available from the ‘oracle’, for use in ad-hoc control strategies. In this process, we minimize the kinematic mismatch between the ideal and the factory-calibrated robot models for a Kinova Gen3 ultra-lightweight robot by compensating for the joint zero position error and the possible variations in the link lengths. Experimental analysis has been presented to validate the proposed method, followed by the error comparison between the calibrated and un-calibrated models over training and test sets.