Multi-Objective Optimization-Based Assist-as-Needed Controller for Improved Quality of Assistance in Rehabilitation Robotics.

Assist-as-needed (AAN) is a paradigm in rehabilitation robotics based on the fact that more active participation from human users promotes faster recovery of motor functions. Moreover, the patients and public engaged and involved in our research design stressed that in order to provide safe and patient-friendly assistance, rehabilitation robotics should be equipped with different constraints while giving minimal assistance where required. Most of the current constraint-based AAN methods are only capable of providing position or velocity constraints which limit the quality of assistance that the robotic systems could provide. In this paper, we propose a multi-objective optimization (MOO) based controller which can implement both linear and non-linear constraints to improve the quality of assistance. This MOO-based proposed controller includes not only position and velocity constraints but also a vibration constraint to subside the tremors common in rehabilitation patients. The performance of this controller is compared with a Barrier Lyapunov Function (BLF) based controller with task-space constraints in a simulation. The results indicate that the MOO-based controller behaves similarly to the BLF-based controller in terms of position constraints. It also shows that the MOO-based controller can improve the quality of assistance by constraining the velocity and subsiding the simulated tremors.

Developments in circular external fixators: A review.

Circular external fixators (CEFs) are successfully used in orthopedics owing to their highly favorable stiffness characteristics which promote distraction osteogenesis. Although there are different designs of external fixators, how these features produce optimal biomechanics through structural and component designs is not well known. Therefore, the aim of this study was to conduct a review on CEFs following the PRISMA statement. A search for relevant research articles was performed on Scopus and PubMed databases providing the related keywords. Furthermore, a patent search was conducted on the Google Patent database. 126 records were found to be eligible for the review. Different designs of CEFs were summarized and tabulated based on their specific features. A bibliometric analysis was also performed on the eligible research papers. Based on the findings, the developments of CEFs in terms of materials, automation, adjustment methods, component designs, wire-clamping, and performance evaluation have been extensively discussed. The trends of the CEF design and future directions are also discussed in this review. Significant research gaps include a lack of consideration towards ease of assembly, effective wire-clamping methods, and CEFs embedded with online patient-monitoring systems, among others. An apparent lack of research interest from low-middle and low-income countries was also identified.