Hakan Yavuz

Hybrid input shaping to suppress residual vibration of flexible systems

This paper presents a hybrid input shaping method to eliminate residual vibration of multi-mode flexible systems. This method, initially designed for one degree of systems, is modified to apply on linear and nonlinear multi-mode systems. In this method, firstly the flexible system is uncoupled using modal analysis method, and then the parameters of the decoupled system are used to shape the command template signal. A ramp plus ramped cycloid plus ramped versine is proposed as the command template signal to be preshaped. The template function is preshaped to yield zero residual vibration for point to point motion and then the resulting trajectory is convolved with a sequence of two impulses to obtain a twice shaped input. The proposed method is applied to eliminate residual vibration of a linear multimass and flexible joint manipulator types of systems. Simulation results show that the oscillations are considerably decreased with a high degree of robustness in the presence of system parameters uncertainty.

Quantized control settings based tuning of a heaving wave energy converter in irregular seas

ABSTRACT The increasing awareness of environmental issues attracts more attention on environmentally friendly energy sources. This leads to increasing research on effective use of renewable energy sources. Among them, wave energy offers a high potential. The wave energy converter systems used for transforming the wave energy into electrical energy have been a main research topic for decades. However, only a few of these systems has been successfully implemented. There seems to be some technical problems one of which is on their control applications. It has been reported that by means of appropriate control implementation, the performance of the wave energy converter system could be improved considerably. In literature, many different control techniques are reported. They appear to be weak due to implementation related restrictions. The present study proposes a novel control technique that is far more practical based on quantization of control settings. Various quantization levels and their effect on system power capture performance are studied. The technique assumes use of realistic off-the-shelf components with realistic features. The proposed method utilizes time-series-analysis technique with online parameter estimation feature. This new method does not require any knowledge of previous or future states of any of the system or sea state parameters, but only the currently available and measurable ones. The approach of the new control technique sets it apart from most of the previously reported ones. Therefore, the proposed technique is not only very much practical but also very much useful in improvement of the system power performance relative to passive techniques.

Effects of Rotor Material on Eddy Current Brake Performance

The eddy current brake(ECB) is built by corresponding motion between a coil and a metallic material. The eddy current and coil creates reverse magnetic fields w produces braking force and dissipated heat due to resistivity of rotor material. In this paper, an ECB system is offered and different rotor materials are investigated with respect to generated braking torque.

Dynamic Simulation of a Crankshaft

Crankshafts are one of the most important parts of a reciprocating engine. A°t basically connects driveline system to the pistons which gives the motion. Main aim of Crankshaft systems designs are to have lower bearing forces, lower torsional vibrations and higher fatigue strength. But, due to complexity of the geometry, lack of manufacturing quality and nonlinear forces, it is hard to analyze the characteristics of the crankshaft. In this paper, a 2D representation of a crankshaft model was built with load information from connecting rods and other specifications. The resultant bearing forces and harmonics of the crankshafts were calculated with given data. The AVL Excite software program was used to simulate the crankshaft of an engine.

Comparison of Robust Input Shapers for Elimination of Residual Vibrations

Input shaping is a feedforward control technique for improving the settling time and positioning accuracy, while minimizing residual vibrations. Shaped command profiles are generated by convolving a sequence of impulses. To design an input shaping controller, estimates of the system natural frequency and damping ratio are required. However, real systems cannot be modeled exactly, making the robustness to modeling errors an important consideration. Many robust input shapers have been developed, but robust shapers typically have longer durations that slow the system response. This creates a compromise between shaper robustness and rise time. This paper analyses the compromise between shaper duration and robustness for several robust input shapers