Updated concrete construction robots are designed to optimize equipment operation, improve safety, enhance workspace awareness, and further ensure a proper working environment for construction workers. The importance of concrete construction robots has been constantly highlighted, as they have a profound impact on construction quality and efficiency. Autonomous vehicle driving monitoring has been widely employed in concrete construction robots; however, they lack clear relevance to the key functions in the building process. This paper aims to bridge this knowledge gap by systematically classifying and summarizing the existing concrete construction robots, analyzing their existing problems, and providing direction for their future development. The prescription criteria and selection of robots depend on the concrete construction process, which includes six common functional levels: distribution, leveling and compaction, floor finishing, surface painting, 3D printing, and surveillance. Misunderstood functions and the improper adjustment of construction robots may lead to increased cost, reduced effectiveness, and restricted application scenarios. Our review identifies current commercial and recently studied concrete construction robots to facilitate the standardization and optimization of robotic construction design. Moreover, this study may be able to guide future research and technology development efforts for autonomous robots in concrete construction.

Superhydrophobic microstructures (100 μm–1 mm) on a solid surface can change the droplet impact dynamics and reduce the contact time, both of which are potentially relevant for various industrial applications. In the study described here, the effects of two superhydrophobic microstructures are compared: a uniformly distributed convex hull structure and a striated structure. Droplet impact dynamics are simulated for a wide range of impact velocities (0.15 m/s–4.4 m/s) with the aim of quantitatively recording the morphological changes in droplets and the formation of splashed droplets using the curves of the spreading diameter and contact diameter vs time. Different types of bouncing behavior are also investigated. The results indicate that an increase in the impact velocity leads to a transition from rebound with full retraction, to a rebound without full retraction, then to a rebound with splashed droplets, and finally to a splashing phenomenon. The special morphologies during rebounding are also analyzed, in particular, pancake bouncing and bouncing in the flying-eagle configuration. The former had no significant change in contact time, owing to reattachment occurring, but the latter can reduce the contact time by 27.6% for an impact velocity of 1.4m/s. Finally, the dynamic behavior is quantitatively characterized, with a focus on the analysis of the maximum spread diameter, maximum retraction velocity, and contact time. As the impact velocity increases, the first two increase, but the third decreases. A sharp drop in the contact time at a high impact velocity is found to be due to the occurrence of the splashing phenomenon.

Tuning body stiffness like fish to improve swimming efficiency and speed has been adopted by many fish-inspired robotics. However, it is unknown whether the energy saved from improved efficiency can compensate for the energy consumption brought by tuning stiffness itself. To explore this issue, we develop a robotic fish with a tunable stiffness caudal peduncle (TSCP), simultaneously allowing for untethered swimming and online tunable stiffness, and conduct a series of tests. We first apply interchangeable caudal peduncles to our robot to explore the effect of a tunable stiffness mechanism and determine the optimal tunable stiffness interval. The results show that tunable stiffness can significantly improve the response of robot at different frequencies. Then we develop the TSCP by embedding shape memory alloy wire into a silicone matrix. TSCP can adjust the stiffness in real time through current and increase the initial stiffness by up to 57.4%. More importantly, we incorporate the cost of tunable stiffness into the total cost of transport compared to previous robots for the first time. The cost of maintaining medium and maximum stiffness accounts for 8.72% and 17.87% of the total cost of transport, respectively. As a result, TSCP increases the swimming speed by up to 35.5% and reduces the Strouhal number by up to 21.9% at high frequencies without extra power. This study supports the necessity of applying tunable stiffness to robotic fish and offers a novel idea for online tunable stiffness mechanism.