Climbing robots have attracted growing attention due to their mobility on vertical and nonplanar structural surfaces. However, the development of climbing robots capable of climbing on various complex surfaces remains elusive, especially on discontinuous surfaces. In nature, Parthenocissus climbs as it grows, having growing-climbing behaviors. Inspired by Parthenocissus , we propose a growing-climbing mechanism and report a soft climbing robot, which grows microstructured biofilms to enhance adhesion, similar to Parthenocissus growing suckers and adsorbing to the wall. The robot uses shape memory alloy contraction to achieve bending, similar to Parthenocissus using gelatinous fibers contraction to achieve hinge-like bending. In addition, to not damage the site, it can be fully contracted after completing tasks. The climbing robot can climb on various complex surfaces, especially discontinuous surfaces, verifying the effectiveness of Parthenocissus ’ growing-climbing mechanism. The growing-climbing mechanism is a universal climbing robot paradigm, opening a door for complex surface climbing robots.

Motivated by the agility of animal and human locomotion, highly dynamic bionic legged robots have been extensively applied across various domains. Legged robotics represents a multidisciplinary field that integrates manufacturing, materials science, electronics, and biology, and other disciplines. Among its core subsystems, the lower limbs are particularly critical, necessitating the integration of structural optimization, advanced modeling techniques, and sophisticated control strategies to fully exploit robots’ dynamic performance potential. This paper presents a comprehensive review of recent developments in the structural design of single-legged robots and systematically summarizes prevailing modeling approaches and control strategies. Key challenges and potential future directions are also discussed, serving as a reference for the future application of state-of-the-art manufacturing and control methodologies in legged robotic systems.

A heat exchanger is a device that transfers unneeded heat from one region to another, and transferred heat may be fully reused, thus improving energy efficiency. To augment this positive process, many studies and investigations on automation technologies have been performed. Inserts are widely used in pipe flow for heat transfer enhancement, since they can break the boundary layer and promote the heat exchange. Segmented twisted tape, which is applicable in 3D printing, is a novel insert and has potential in heat transfer enhancement. To clarify its advantages and disadvantages, this research presents a numerical investigation of vortex flow and heat enhancement in pipes containing one segmented twisted element. Flow state and heat transfer behaviour are obtained by simulation under constant wall temperature with different Reynolds numbers, ranging from 10,000 to 35,000. The effects of geometric parameters, including twist ratio (P/D = 2.0, 3.3 and 4.6) and length ratio (L/P = 0.3, 0.5 and 0.7), on the Nusselt number (Nu) and friction factor (f) are investigated. Streamline and temperature distribution are presented. Meanwhile, local and overall heat transfer performance is compared with those of a smooth tube, and the overall performance is evaluated by performance evaluation factor (η). The results indicate that the twist ratio (P/D) plays a dominant role in heat transfer enhancement while the length ratio (L/P) also has considerable influence. It is shown that a segmented tape insert can increase the overall heat transfer rate by 23.5% and the friction factor by 235%, while local improvement along the tube can be 2.8 times more than the plain tube.

Force monitoring or feedback on the end-effector is a key component for hydraulic manipulators to perform heavy-duty tasks such as handling and dismantling. However, the force sensors used in heavy-duty applications are expensive and fragile under complicated conditions. As an alternative, soft measurement methods are used to obtain the external force indirectly, but this is challenging for multi-DOF hydraulic manipulators due to the complex parallel-serial characteristics of the closed-chain structures with highly nonlinear frictions. To overcome the obstacles, a novel force soft measurement method for hydraulic manipulators is proposed using the cylinder decoupling model with LuGre friction compensation. In this method, the hydraulic manipulator is decoupled by the main chain consisting of manipulator links and several branch chains consisting of hydraulic cylinders, of which the inertia effect can be fully considered and modeled. The friction in each joint is also compensated by the LuGre friction model. Besides, the lumped inertia parameters and the LuGre friction parameters are acquired through the stepwise parameter identification method, which mitigates the complexity of the full model by first determining steady friction parameters and then solving the remaining parameters with different excitation trajectories. Compared with the traditional method without considering the closed-chain structures, the proposed force soft measurement method shows higher force estimation accuracy, which is conducive to the implementation of force-based strategies.

The dynamics of hydraulic robots are complicated due to the closed-chain joints formed by cylinder articulation. This article is focused on presenting a model-based control framework for rapid locomotion, integrating closed-chain dynamics without a substantial increase in computational costs. The virtual decomposition control (VDC) approach has been adapted and innovatively extended to a leg system for the first time, featuring a floating base and variable contact constraints. In this article, a position control framework is proposed, consisting of three VDC-based controllers designed specifically for the stance phase and the swing phase, respectively. During the stance phase, a constrained estimation model is developed to recursively compute the previously incalculable dynamic equations. Furthermore, the control laws are designed to ensure that the virtual power flows caused by contact constraints do not affect the stability. In the swing phase, a noninertial frame is established to transform the underactuated system into a fully actuated fixed-base system. Despite being position controlled, our framework enables the leg system to generate compliance by setting a separate low-gain VDC-based controller during the landing stage. Experiments reveal that the proposed framework exhibits better position trajectory tracking performance and jumping ability in highly dynamic motion compared with the state-of-the-art position controller. Additionally, the impedance characteristics of the leg system can be actively adjusted to adapt to uneven terrain.