MAGNETOELASTIC ELECTROMECHANICAL SYSTEMS FOR POWER HARVESTING FROM VIBRATION

The paper addresses the problem of vibration-to-electric energy conversion using magnetostrictive materials. Theoretical and experimental results of the study of the magnetostrictive electric transducers (MET) for power harvesting from vibration are presented. Both simulations and experimental data have confirmed functionality of the designed MET using giant magnetostrictive material TERFENOL-D

Vibration energy harvesting using Galfenol based transducer

In this paper the novel design of Galfenol based vibration energy harvester is presented. The device uses Galfenol rod diameter 6.35 mm and length 50mm, polycrystalline, production grade, manufactured by FSZM process by ETREMA Product Inc. For experimental study of the harvester, the test rig was developed. It was found by experiment that for given frequency of external excitation there exist optimal values of bias and pre-stress which maximize generated voltage and harvested power. Under optimized operational conditions and external excitations with frequency 50Hz the designed transducer generates about 10 V and harvests about 0,45 W power. Within the running conditions, the Galfenol rod power density was estimated to 340mW/cm3. The obtained results show high practical potential of Galfenol based sensors for vibration-to-electrical energy conversion, structural health monitoring, etc

Numerical Method for Optimization of Semi-Passively Controlled Dynamical Systems

Controlled dynamical systems with different type of actuators (e.g. external powered electromotors, magnetostrictive actuators, internal unpowered (passive) spring-damper-like drives, etc.) are considered. \ua0These systems are termed semi-passively controlled. Mathematical statement of optimization problem has proposed that is suitable both for modeling of optimal motion and for optimization of structure of semi-passively controlled dynamical systems with different degree of actuation. Numerical method for solving the proposed optimization problem is described. The method was successfully used for solving optimal control problems for several semi-passively controlled dynamical systems (industrial robots, human locomotor system with intelligent lower limb prosthesis, bipedal locomotion robots, others). The results obtained have confirmed the efficiency of the proposed numerical method for solving optimization problems for semi-passively controlled dynamical systems. Analysis of the results gives insight into the study of the role of inherent dynamics in controlled motion and how much a dynamical system should be governed by external drives and how much by a system’s inherent dynamics. It has been shown that complex goal-directed and cost-efficient controlled motion of underactuated dynamical system can be design using optimal interaction between external powered drives and internal unpowered spring-damper-like drives. This constitutes the powerful ability of semi-passively controlled dynamical systems

MAGNETOELASTIC ELECTROMECHANICAL SYSTEMS FOR POWER HARVESTING FROM VIBRATION

The paper addresses the problem of vibration-to-electric energy conversion using magnetostrictive materials. Theoretical and experimental results of the study of the magnetostrictive electric transducers (MET) for power harvesting from vibration are presented. Both simulations and experimental data have confirmed functionality of the designed MET using giant magnetostrictive material TERFENOL-D

Dynamic simulation of a human gait and design problems of the lower limb prostheses

In this paper the methodology and the numerical algorithm are proposed such as suitable both for the dynamic simulation of a human gait and for solving of the design problems of the lower limb prostheses. The methodology is based on the combination of the optimal control theory and the mathematical modeling with broad utilization of the data obtained from the biomechanical experiments. A special procedure is used for converting the initial optimal control problems for the highly nonlinear and complex bipedal locomotion system into the standard nonlinear programming problems. It is made by approximation of the independent variable functions using the combination of a spline and the Fourier series and the solution of the semi-inverse dynamics problem. The key feature of the algorithm proposed is its high numerical effectiveness and the possibility to satisfy many restrictions imposed on the phase coordinates of the system automatically and accurately. The proposed methodology is illustrated by the computer simulation of a human gait and the numerical results of solution of the design problems of the energy-optimal above-knee prostheses with several types of the structure of the knee mechanisms

Control and optimization of semi-passively actuated multibody systems

The controlled multibody systems are under the consideration. At the lecture special emphasis is put on the study of underactuated and overactuated systems having different type of actuators (external powered drives, unpowered spring-damper like drives, etc.). Several questions are addressed about the role of inherent dynamics, and how much multibody system should be governed by external powered drives and how much by the systems inherent dynamics. The lecture consists of the following parts: introduction to the subject in question; mathematical statement of the optimal control problems that are suitable for modelling of controlled motion and optimization of semi-passively controlled multibody systems with different degrees of actuation; description of the methodology and the numerical algorithms for solution of control and optimization problems for semi-passively actuated multibody systems. The solutions of several optimal control problems for different kind of semi-passively actuated multibody systems are presented. Namely, the energy-optimal control of planar semi-passively controlled three-link manipulator robot, the energy-optimal control of closed-loop chain semi-passively actuated SCARA-like robot; optimization of the hydraulic and pneumatic drives of the multibody system modelled the human locomotor apparatus with above-knee prostheses, and others. Future perspectives in area of control and optimization problems of the semi-passively actuated multibody systems are discussed

Controlled Multibody Systems with Magnetostrictive Electric Generators

The proposed paper addresses the problem of modeling and analysis of controlled multibody systems with embedded magnetostrictive transducers. Main emphasis is put on the modeling of the considered mechatronic systems for applications in the field of power harvesting from vibrations, namely vibration-to-electric energy conversion, using novel giant magnetostrictive materials. Mathematical model of the considered mechatronic system has been developed. It comprises the constitutive equations of magnetoelastic behavior of magnetostrictive rod (active element of transducers), standard formulae of electromagnetism for induced voltage and current in the pick-up coil due to variation of magnetic field intensity, and finally the equations of motion of multibody system itself. The last one can be derived using one of the well-known multibody dynamics formalism. Assuming that massinertia parameters of magnetostrictive transducers are negligible small the inverse dynamics based algorithm has been proposed for modeling the controlled motion of multibody systems with embedded transducers. This algorithm is also suitable to evaluate electrical power output of magnetostrictive electric generators for different controlled motions of the system and to optimize the generators design. The inverse dynamics based algorithm was implemented in Matlab/Simulink with user friendly interface. Its efficiency has been confirmed by simulation of performance of different magnetostrictive electric generators under the periodic excitations exerted by the hosting multibody system

Inverse dynamics and Fourier-based approach to solve optimal control problems for multi-link mechanisms

This paper is concerned with the investigation of multi-link mechanism controlled mo\uadtion between fixed boundary conditions and given constraints on the phase coordinates. The mo\uad\uadduli of the controlling moments at the hinges between the links are bounded. A com\uadpu\uadta\uadti\uado\uadnal method to the mathematical modeling of the optimal control laws which govern multi-link mechanism reaching motion is presented. This method is based on Fourier and spline appro\uadxi\uadma\uadtions of the independently variable functions and inverse-dynamics approach. The me\uad\uadthod proposed makes it possible to satisfy the boundary conditions and some constraints on the phase coordinates automatically and accurately. The efficiency of the proposed method is illustrated by the solution of the energy-optimal control problem of a plane mobile three-link manipulator with a load on the grip

Controlled Multibody Systems with Magnetostrictive Electric Generators

The proposed paper addresses the problem of modeling and analysis of controlled multibody systems with embedded magnetostrictive transducers. Main emphasis is put on the modeling of the considered mechatronic systems for applications in the field of power harvesting from vibrations, namely vibration-to-electric energy conversion, using novel giant magnetostrictive materials. Mathematical model of the considered mechatronic system has been developed. It comprises the constitutive equations of magnetoelastic behavior of magnetostrictive rod (active element of transducers), standard formulae of electromagnetism for induced voltage and current in the pick-up coil due to variation of magnetic field intensity, and finally the equations of motion of multibody system itself. The last one can be derived using one of the well-known multibody dynamics formalism. Assuming that massinertia parameters of magnetostrictive transducers are negligible small the inverse dynamics based algorithm has been proposed for modeling the controlled motion of multibody systems with embedded transducers. This algorithm is also suitable to evaluate electrical power output of magnetostrictive electric generators for different controlled motions of the system and to optimize the generators design. The inverse dynamics based algorithm was implemented in Matlab/Simulink with user friendly interface. Its efficiency has been confirmed by simulation of performance of different magnetostrictive electric generators under the periodic excitations exerted by the hosting multibody system