Although it is well-established that exoskeletons as robots attached to the extremities of the human body increase their strength, limited studies presented a computer and mathematical model of a human leg hydraulic exoskeleton based on anthropometric data. This study aimed to examine lower limb joint angles during walking and running by using Inertial Measurement Units. The geometry and kinematic parameters were calculated. Twenty-six healthy adults participated in walking and running experiments. The geometric model of a human leg hydraulic exoskeleton was presented. Joint angle data acquired during experiments were used in the mathematical model. The position and velocity of exoskeleton actuators in each phase of movement were calculated using the MATLAB package (Matlab_R2017b, The MathWorks Company, Novi, MI, USA). The highest velocity of the knee actuator during walking and running was in the swing phase, 0.3 and 0.4 m/s, respectively. For the ankle and hip joints, the highest velocity of actuators occurred during the push-off phase. The results with 26 healthy subjects demonstrated that the system's compliance can be effectively adjusted while guiding the subjects walking in predefined trajectories. The developed mathematical model makes it possible to determine the position of lower limb segments and exoskeleton elements. The proposed model allows for calculating the position of the human leg and actuators’ characteristic points.

In the following paper, the dynamic modeling of a horizontal seat suspension which uses pneumatic muscles for the purpose of active vibration control is discussed. An original control system structure is proposed in order to improve the vibro-isolation properties of a horizontal seat suspension system. The presented control system design is based on inverse models of the pneumatic muscles and the primary controller that calculates the desired active force. By using the configurable control algorithm developed in this paper, it is possible to achieve a significant reduction in vibrations transmitted into the human body with just a slight increasing of the suspension travel. The active seat shows improved performance over the passive system in the 1–10 Hz frequency range. The results presented in this paper are useful in selecting the horizontal vibration control system for improving the comfort of a drive.

In this paper, a method for selecting the dynamic characteristics of seat suspension systems is presented. The basic principle of such a method consists in the shaping of nonlinear seat suspension dynamic behaviour for the different requirements defined by machine operators. A combined optimisation procedure has allowed to find the Pareto-optimal system configuration with simultaneous minimisation of conflicted optimisation criteria: the suspended body acceleration and suspension travel. As an example of the proposed method, the seat with a viscous-elastic passive suspension is investigated and its vibro-isolation properties are shaped by the air-spring and shock-absorber force characteristics.

In the paper, an innovative active control of a horizontal seat suspension system is discussed in context of realistic input vibration that occurs in the cabins of agricultural tractors. The vibration reduction system is represented by the state-space model and its numerical parameters are determined experimentally. For such a reliable mathematical representation of the system dynamics, the finite-time sliding mode controller is successfully designed for different spectral classes of the random excitation signal. A multi-objective control strategy is implemented in order to satisfy opposite requirements, that is, at the limited value of active force, a horizontal vibration of the seated human body is considerably reduced, but the suspension travel does not exceed unacceptable stroke of the system. Laboratory measurements of the seated human body have shown improved comfort of drivers under fore-and-aft vibrations.

This paper concerns the kinematics and dynamics of an arm exoskeleton used for human rehabilitation. The biomechanics of the upper arm was studied, and the nine degrees of freedom model of upper arm was obtained using Denavit–Hartenberg notation. The mass and inertial parameters were obtained from recent literature, and these parameters were used for modelling human arm in SolidWorks and MATLAB-Simulink packages. The inverse kinematics of the arm exoskeleton was solved in the previous paper Winter (Biomechanics and motor control of human movement. Wiley, New York, 2009 , and this model was implemented in this study. The arm angular velocity profile was selected within the time and speed restriction. By comparing three variants of motion with visualization, we indicated the change of joints angles. Then, the torques in each arm joints with and without exoskeleton were calculated. The obtained results demonstrate the efficiency of the proposed approach that can be utilized to analyse the kinematics and dynamics of exoskeletons for the purpose of selection of their actuators.