This paper provides a comprehensive review of the current status, advancements, and future prospects of humanoid robots, highlighting their significance in driving the evolution of next-generation industries. By analyzing various research endeavors and key technologies, encompassing ontology structure, control and decision-making, and perception and interaction, a holistic overview of the current state of humanoid robot research is presented. Furthermore, emerging challenges in the field are identified, emphasizing the necessity for a deeper understanding of biological motion mechanisms, improved structural design, enhanced material applications, advanced drive and control methods, and efficient energy utilization. The integration of bionics, brain-inspired intelligence, mechanics, and control is underscored as a promising direction for the development of advanced humanoid robotic systems. This paper serves as an invaluable resource, offering insightful guidance to researchers in the field, while contributing to the ongoing evolution and potential of humanoid robots across diverse domains.

Dynamic coupling is an inherent behavior of the space robot system, which seriously affects the motion accuracy of the system. This article focuses on how to guarantee the base attitude stability of semifloating space robots, from a control perspective—namely, the base attitude decoupling control. The quaternion representation of the system dynamics is derived to avoid the representation singularity of the Euler angles. In consideration of the complicated system dynamics and the limited computing ability of the on-board computer, an efficient decoupling controller is designed based on the time-delay estimation (TDE) and the supertwisting control (STC). Herein, for the proposed TDE-based STC (TDE-STC) scheme, TDE is used to decouple and linearize the nonlinear dynamics, and STC is a second-order sliding mode control algorithm which can compensate for the TDE error and drive the state variables to converge to the equilibrium point robustly in finite time. The model-free decoupling principle of TDE is clearly illustrated by comparison with the classical computed torque control. The global asymptotical stability analysis of the closed-loop system is proven using the Lyapunov theory and the linear matrix inequality theorem. Finally, several comparative simulation studies on a 3-D space robot system with consideration of joint friction, disturbances, and model uncertainties are conducted to verify the effectiveness of the proposed TDE-STC scheme. The corresponding results show that the TDE-STC scheme can achieve a high-accuracy attitude decoupling performance with both the model-free merits and the chatter-free merits.

In this paper, a weighted additional deviation velocity on the basis of the gradient projection (GP-WADV) method is proposed to solve obstacle avoidance problems of the redundant manipulator under the condition of known end-effector trajectory. The GP-WADV method aims to find the point closest to the obstacle on the link of the manipulator and attach the additional deviation velocity with weighting factors to the point on the basis of the gradient projection method. Utilizing multi-solution characteristics of redundant robots, obstacle avoidance control parameters related to the distance between obstacles and links are proposed according to the gradient projection method for solving inverse kinematic solution. Moreover, a weighted method is adopted to adjust the weighting factors of the primary motion velocity and the additional motion velocity when the link approaches the obstacle, so as to obtain the joint angle solutions more quickly and accurately. The GP-WADV method can ensure that the manipulator can avoid obstacles smoothly without turbulence and solve the highly nonlinear relationship between the position of the manipulator and the joint coordinate, which has the advantages of small amount of calculation, more flexible and convenient real-time control. The advantages of the proposed GP-WADV method are proved by simulation and experiments.

In order to address the coordination constraints and physical constraints subjected to the dual-arm robot simultaneously, a novel four-criterion-optimization coordination motion (FCOCM) scheme is proposed, which combines four optimization criteria, namely, the repetitive motion planning (RMP), minimum velocity norm (MVN), maximize manipulability (MM) and infinity-norm velocity minimization (INVM). The scheme can remedy discontinuity in the INVM scheme, eliminate joint angular drift phenomenon, prevent the high joint angular velocity and maximize manipulability, thereby improving the motion efficiency and ensuring safety and accuracy in the process of tasks. Besides, this scheme also considers real-time trajectory feedback, satisfies physical constraints, and ensures the joint angular velocity is zero at the end of tasks. Furthermore, the improved FCOCM scheme is solved by a novel power-exponent-type variable-parameter recurrent neural network (PET-VPNN) model proposed in this paper. A novel Sinh-tunable type activation function which achieves better convergence performance is also proposed. Simulations and experiment are presented to verify the superiority of the proposed coordination motion control method. This research is of great significance for the coordination motion control of dual-arm robots in complex path planning tasks.