Experimental tests of the physical model were also carried out, demonstrating the feasibility of the prototype. In this collection of Special Issue articles, there is also one [5] which proposes a new selection criterion for linear pneumatic motors used to drive wearable assistive devices, namely, the energy-to-mass ratio. The requirements for a wearable assistive device are compactness, lightweightness, and energy efficiency. The authors propose a criterion for choosing an actuator that meets the above-mentioned requirements, namely, the energy-to-mass ratio. In the field of locomotor rehabilitation, prostheses are commonly required by people with trans tibial amputations. The authors of [6] propose the constructive solution of an ankle prosthesis based on an intelligent fluid joint (magneto rheological). Additionally, the sole of the prosthesis is equipped with eight pressure sensors which register the pressure between the sole and the ground, which is necessary to determine the kinematic and dynamic parameters of the person's gait. Robotic rehabilitation systems also involve the upper limbs. Upper limb exoskeletons are used for two types of activity: as an assistive system that provides physical support and reduces the wearer's strain at work, and as a robotic system for the rehabilitation of stroke patients. Thus, in [7], a dynamic analysis of a mechanism in the structure of an upper limb rehabilitation robot, called ParReEx, is presented. The dynamic analysis was performed in the first phase, considering the rigid kinematic elements, and later, the elasticity of the elements, as well as the friction in the kinematic couplings. A method of structural optimization of the constructive shape of the mechanism's elements is also presented, with the aim of reducing mechanical stress concentrators as well as minimizing the mass of the rehabilitation device. A similar system designed for upper limb rehabilitation is the ASPIRE robot, a dynamic study of which is presented in [8]. The purpose of this system is the rehabilitation of brachial monopensis. The dynamic analysis was performed using MSC_ADAMS software, a powerful tool for the study of mobile multibody systems. The robot is composed of three modules: the first providing the flexion/extension movement for the shoulder, the second providing the adduction/abduction movement, and the third providing forearm pronation/supination. The results obtained from the ADAMS simulation computed torque for the flexion/extension module and the adduction/abduction module are compared with those obtained experimentally. The similarity of these results validates the dynamic model, confirming that the connection forces determined from the dynamic simulation are valid. These data are used to study the mechanical strength of the flexion/extension modulus using the finite element method. The outstanding performance of exoskeleton robotic systems is evidenced by their use as assistive systems for stair ascent/descent, as presented in [9]. Stair climbing involves slow movements within the joints but with greater amplitudes than in normal walking. The objective of this study was to evaluate the biomechanics of a new robotic exoskeleton system intended for stair climbing. The results of the study show that an individual application of assistive force is required for adequate assistance when climbing stairs. Exoskeletons have also been developed that provide rehabilitation of a specific joint of the human lower limb. Thus, in [10], the energy consumption and torque control of such an exoskeleton are studied. The study focuses on sit-to-stand and walking activities. The constructive design of the exoskeleton hip robot was performed using Autodesk Inventor software, and the kinematic analysis was based on Denavit-Hartenberg parameters inputted into Matlab computational software. The Linear Quadratic Regulator (LQR) method was considered in order to obtain the optimum controller for energy consumption and walking activity.