Accurate acquisition of interactive information is crucial for the effective execution of rehabilitation training. However, due to model and sensor errors, it is difficult to obtain interactive information accurately and quickly. To overcome these challenges, a novel accurate and fast estimation method for the human–robot interaction torques (HRITs) is proposed in this article. First, the HRIT model with order adaptive adjustment ability (HMOAA) is constructed. The polynomial order of HMOAA can be adaptively adjusted based on the partial state estimation, which is more consistent with the dynamic time-varying characteristics of HRIT. Second, the Sage–Husa adaptive strong tracking Kalman filter (SHASTKF) is designed based on the modified Sage–Husa adaptive Kalman filter (SHAKF) and strong tracking Kalman filter (STKF). The SHASTKF can quickly track the abrupt HRIT changes when the subject suddenly exerts active torques in rehabilitation training. Moreover, it also has the ability to recursively estimate the noise characteristics, and can stably complete the HRIT estimation task when the noise characteristics are unknown. Finally, simulations and experiments are conducted to validate the proposed method, and the comparison results demonstrate that the proposed method has good torque estimation precision and fast tracking ability of abrupt changes in HRITs.

Human–robot interaction has been widely studied, where compliant and safe human–robot interaction of continuum manipulators in the constrained environment is one of the key issues that have not been well addressed. In this study, finite-time observer-based variable impedance control of cable-driven continuum manipulators (CDCM) is proposed to overcome the limitation of existing methods. First, the pseudo-rigid modeling method is utilized to establish the kinematics and dynamics of the CDCM. Then, a variable impedance controller with selected controller parameters for the CDCM is designed to realize compliant and safe human–robot interaction operations with force–position coupling constraint, which is rarely studied in the literature. In order to realize the closed-loop variable impedance controller, a finite-time observer is designed to estimate acceleration feedbacks, which can avoid the difficulty of directly sensing the interaction forces and shows excellent robust stability in noisy environments. On this basis, by combining the advantages of the variable impedance controller and finite-time observer, the finite-time observer-based variable impedance controller is proposed, and the stabilities of the proposed method are analyzed. Finally, the feasibility of the proposed control scheme for the CDCM is demonstrated by some numerical simulations.

The present study focuses on summarizing the recent advancements in the field of fish swimming mode research and bionic robotic fish prototypes based on smart materials. It has been widely acknowledged that fish exhibit exceptional swimming efficiency and manoeuvrability compared to conventional underwater vehicles. In the pursuit of developing autonomous underwater vehicles (AUVs), conventional experimental methods often prove to be complex and expensive. Hence, the utilization of computer simulations for hydrodynamic modelling provides a cost-effective and efficient approach for analysing the swimming behaviour of bionic robotic fish. Additionally, computer simulations can provide data that are difficult to obtain through experimental methods. Smart materials, which integrate perception, drive, and control functions, are increasingly being applied to bionic robotic fish research. However, the utilization of smart materials in this field is still an area of ongoing research and several challenges remain unresolved. This study provides an overview of the current state of research on fish swimming modes and the development of hydrodynamic modelling. The application of four distinct types of smart materials in bionic robotic fish is then reviewed, with a focus on analysing the advantages and disadvantages of each material in driving swimming behaviour. In conclusion, the paper highlights the key technical challenges that must be addressed for the practical implementation of bionic robotic fish and provides insights into the potential future directions of this field.

Highly conductive multilayer graphene nanosheet films are self-assembled for tattoo dry electrodes and strain sensors, which can be used for detecting human electrocardiogram, electromyogram, wrist pulse and breath.