Search results

The purpose of this paper is to design a new trajectory error compensation method to improve the trajectory tracking performance and compliance of the knee exoskeleton in human–exoskeleton interaction motion.

A trajectory error compensation method based on admittance-extended Kalman filter (AEKF) error fusion for human–exoskeleton interaction control. The admittance controller is used to calculate the trajectory error adjustment through the feedback human–exoskeleton interaction force, and the actual trajectory error is obtained through the encoder feedback of exoskeleton and the designed trajectory. By using the fusion and prediction characteristics of EKF, the calculated trajectory error adjustment and the actual error are fused to obtain a new trajectory error compensation, which is feedback to the knee exoskeleton controller. This method is designed to be capable of improving the trajectory tracking performance of the knee exoskeleton and enhancing the compliance of knee exoskeleton interaction.

Six volunteers conducted comparative experiments on four different motion frequencies. The experimental results show that this method can effectively improve the trajectory tracking performance and compliance of the knee exoskeleton in human–exoskeleton interaction.

The AEKF method first uses the data fusion idea to fuse the estimated error with measurement errors, obtaining more accurate trajectory error compensation for the knee exoskeleton motion control. This work provides great benefits for the trajectory tracking performance and compliance of lower limb exoskeletons in human–exoskeleton interaction movements.

The purpose of this paper is to study the load capacity of nanoparticles-laden gas film (NLGF) in thrust bearing.

SiO₂ nanoparticles were added into gas to form an NLGF. The nanoparticles volume fraction in the film was controlled by a vibrator. The film thickness and the film pressure were measured by a micro cantilever displacement sensor and a membrane pressure sensor, respectively. The total load that makes the film thickness keeping constant was quantified, and then, the film load capacity was obtained.

The investigation shows that nanoparticles can enlarge the film load capacity remarkably; even a little amount of nanoparticles (0.01 per cent) could lead to a sharp rise. With the increase of nanoparticles volume fraction, load capacity increases. However, the increment of load capacity decreases gradually. In addition, the film pressure variation proves the enhancement effect of nanoparticles on the film load capacity.

The paper is restricted to the findings based on NLGF, which is formed by dispersing SiO₂ nanoparticles in gas film as an additive. The experimental results are applicable within the range of nanoparticles volume fraction of 0.01-0.33 per cent.

The fact that nanoparticles could enlarge the gas film load capacity is verified by experiment for the first time. This study reveals the corresponding relation between nanoparticles volume fraction and the film load capacity.

This study aims to identify appropriate strategies and actions adopted by business-to-business firms to cope with the ongoing COVID-19 crisis.

A review of business-to-business marketing responses to the COVID-19 crisis in China was conducted.

Nine marketing responses built on core business processes were classified into three categories: (1) embedded in product development management process (stretching product lines to meet urgent needs, expanding product lines to meet urgent needs and adjusting products proactively for emerging needs), (2) built on supply chain management process (coordinating suppliers to meet surging demand, migrating to digital distribution channels and solidarity with supply chain members) and (3) related to customer relationship management process (investing in advertising and promotion, cross-selling to existing customers and supporting customers).

This study contributes to the literature of marketing responses to COVID-19 by examining the cash flows effects of various marketing responses. It also contributes to the business processes based on marketing strategy framework by extending it to the crisis management context. In addition, it provides five practical suggestions for business-to-business firms to cope with the COVID-19 crisis.