A novel distributed meta-module motion design for modular robotic systems based on grid partition method.

This article studies a meta-module motion design approach for homogenous modular robotic systems in self-configuration. By utilizing configuration diversity, scalability and unit-substitutability, homogenous modular robotic systems can be a promising approach to life detection and space exploration in the future. Based on the requirements of the potential applications, self-configuration can be considered as the precondition. As similar to swarm robotic systems, the distributed control strategy in which the modular robots are operated in a sequence of motion circles consist of 'detection'- 'decision'- 'execution' is of great significance. However, there is a limitation to the applicability of previously proposed work on the self-configuration topic, due to the fact that the self-configuration strategy execution suffers from the motion constraints of modular robots. In order to solve the problem, we propose a grid partition method that removes the gap between the locomotion of a single modular robot and the reconfiguration of the whole system. Under the analysis of the grid partition, the meta-module motion design is proposed to realize the distributed self-configuration strategy. We simulated the self-configuration in M-Lattice, a two-dimensional homogenous modular robotic system.

Adaptive Skid-Steering Control Approach for Robots on Uncertain Inclined Planes with Redundant Load-Bearing Mobility.

Climbing manufacturing robots can create a revolutionary manufacturing paradigm for large and complex components, while the motion control of climbing manipulation-oriented robots (CMo-Rs) is still challenging considering anti-slippage problems. In this study, a CMo-R with full-scenery climbing capability and redundant load-bearing mobility is designed based on magnetic adsorption. A four-wheel kinematic model considering the slipping phenomenon is established. An adaptive kinematic control algorithm based on slip estimation using Lyapunov theory is designed for uncertain inclined planes. For comparison, the traditional PID-based algorithm without slip consideration is implemented as well. Numeric simulations are conducted to tackle the trajectory tracking problems for both circular and linear trajectories on the horizontal plane (HP), 50° inclined plane (50° IP), 60° inclined plane (60° IP), and vertical plane (VP). The results prove that our approach achieves better tracking accuracy. It demonstrated applicability in various climbing scenarios with uncertain inclined planes. The results of experiments also validate the feasibility, applicability, and stability of the proposed approach.

MXene-based anode materials for high performance sodium-ion batteries.

As an emerging class of layered transition metal carbides/nitrides/carbon-nitrides, MXenes have been one of the most investigated anode subcategories for sodium ion batteries (SIBs), due to their unique layered structure, metal-like conductivity, large specific surface area and tunable surface groups. In particular, different MAX precursors and synthetic routes will lead to MXenes with different structural and electrochemical properties, which actually gives MXenes unlimited scope for development. In this feature article, we systematically present the recent advances in the methods and synthetic routes of MXenes, together with their impact on the properties of MXenes and also the advantages and disadvantages. Subsequently, the sodium storage mechanisms of MXenes are summarized, as well as the recent research progress and strategies to improve the sodium storage performance. Finally, the main challenges currently facing MXenes and the opportunities in improving the performance of SIBs are pointed out.

Effect of mechanical error on dual-wedge laser scanning system and error correction.

Compared with the traditional mechanical beam deflector in a beam-scanning system, the dual-wedge scanning system has several advantages, for example, compact structure, fast scanning speed, and low power consumption. High accuracy is the most important factor in dual-wedge scanning, but mechanical errors caused by machining or assembly errors adversely affect this scanning accuracy. Horizontal and angular mechanical errors appear between the incident light and the dual-wedge central optical axes. By building a mathematical model of an ideal dual-wedge scanning trajectory and a trajectory affected by mechanical errors, this paper analyzes the types and degree of influence on the scanning process, as well as the sensitivity of scanned images to different errors. Results show that the angular error has the most significant influence on the scanning image accuracy, in terms of trajectory shape and coverage. To correct the angular error, the two degrees-of-freedom flexible fine-tuning mechanism is customized based on the principle of the cantilever beam type. After finite element analysis and experimental validations, the fine-tuning mechanism can guarantee that the angular error in the dual-wedge central optical axes will be lower than 0.05 deg, thus ensuring scanning trajectory accuracy.