This thesis is dealing with creation of computation model of energy harvestors. Harvestors based on translational motion and planar motion were modeled. These models were created in MSC Adams. Proposed harvestors are tranforming mechanical vibrations into electrical energy by electromagnetical induction. To achieve better electrical output, harvestors were tuned to natural frequency suitable for chosen aplication. First proposed harvestor is meant for railway track. For validation of its usability in intended application, model of railway track section is also proposed. Force generated by passing train is used for excitation of the track model. Second harvestor is nonlinear electromechanical oscilator proposed for use on unanchored sea buoy (drifter). After retuning previously proposed concept of energy harvestor to natural frequency 1.6 Hz, computation model for simulation purposes was created. After the simulation of sinusoidal excitation, the excitation based on real sea data was simulated. When excited by regular sea, the peak electric power 9 W was achieved. When excited by irregular sea the peak electrical power of the generator was 7.5 mW.