Assistive and rehabilitation devices are a promising and challenging field of recent robotics research. Motivated by societal needs such as aging populations, such devices can support motor functionality and subject training. The design, control, sensing, and assessment of the devices become more sophisticated due to a human in the loop. This paper gives a human–robot interaction perspective on current issues and opportunities in the field. On the topic of control and machine learning, approaches that support but do not distract subjects are reviewed. Options to provide sensory user feedback that are currently missing from robotic devices are outlined. Parallels between device acceptance and affective computing are made. Furthermore, requirements for functional assessment protocols that relate to real-world tasks are discussed. In all topic areas, the design of human-oriented frameworks and methods is dominated by challenges related to the close interaction between the human and robotic device. This paper discusses the aforementioned aspects in order to open up new perspectives for future robotic solutions.

In this paper, we provide a port-based mathematical framework for analyzing and modeling variable stiffness actuators. The framework provides important insights in the energy requirements and, therefore, it is an important tool for the design of energy efficient variable stiffness actuators. Based on new insights gained from this approach, a novel conceptual actuator is presented. Simulations show that the apparent output stiffness of this actuator can be dynamically changed in an energy efficient way.

In this paper, we present the prototype realization of the conceptual design of a fully-passive transfemoral prosthesis. The working principle has been inspired by the power flow in human gait so to achieve an energy efficient device. The main goal of this paper is to validate the concept by implementing in a real prototype. The prototype, in scale 1 : 2 with respect to the average dimensions of an adult human, is based on two storage elements, which are responsible for the energetic coupling between the knee and ankle joints during the swing phase and for the energy storage during the stance phase. The design parameters of the prototype are determined according to the human body and the energetic characteristics of the gait. The construction of the prototype is explained in details together with a test setup that has been built to evaluate the prototype.

This paper presents a general framework for optimization of haptic interfaces, in particular for haptic interfaces with closed kinematic chains, with respect to multiple design objectives, namely kinematic and dynamic criteria. Both performance measures are discussed and optimization problems for a haptic interface with best worst-case kinematic and dynamic performance are formulated. Non-convex single objective optimization problems are solved with a branch-and-bound type (culling) algorithm. Pareto methods characterizing the trade-off between multiple design criteria are advocated for multi-criteria optimization over widely used scalarization approaches and Normal Boundary Intersection method is applied to efficiently obtain the Pareto-front hyper-surface. The framework is applied to a sample parallel mechanism (five-bar mechanism) and the results are compared with the results of previously published methods in the literature. Finally, dimensional synthesis of a high performance haptic interface utilizing its Pareto-front curve is demonstrated.Keywords: Multi-criteria design optimization, dimensional synthesis of parallel mechanisms, optimal design of haptic interfaces, kinematic and dynamic performance of manipulators.

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