Hybrid iterative learning control of a flexible manipulator

This paper presents an investigation into the development of a hybrid control scheme with iterative learning for input tracking and end-point vibration suppression of a flexible manipulator system. The dynamic model of the system is derived using the finite element method. Initially, a collocated proportional-derivative (PD) controller using hub angle and hub velocity feedback is developed for control of rigid-body motion of the system. This is then extended to incorporate a non-collocated proportional-integral-derivative (PID) controller with iterative learning for control of vibration of the system. Simulation results of the response of the manipulator with the controllers are presented in the time and frequency domains. The performance of the hybrid iterative learning control scheme is assessed in terms of input tracking and level of vibration reduction in comparison to a conventionally designed PD-PID control scheme. The effectiveness of the control scheme in handling various payloads is also studied

Implementing active force control to reduce vibration of a short length drive shaft

Vibration is a physical phenomenon involving repeated oscillatory movements or fluctuations at certain frequency and typically undesirable in many applications since it may cause undue failure or damage to the system. In this paper, the vibration of a three degree-of-freedom (DOF) model representing a short length drive shaft has been effectively and robustly suppressed through the implementation of a novel Active Force Control (AFC) used in conjunction with a classic proportional-integral-derivative (PID) controller. The shaft vibration caused by its support and constraint during its operation was simulated using MATLAB and Simulink considering a number of operating and loading conditions. The results proved that when a pure PID controller was implemented, the vibration is indeed reduced but at the expense of longer execution time and producing noticeable frequency oscillation with slight offset. On the other hand, when the AFC loop was engaged by adding it directly in series with the PID controller (PID+AFC) to produce a 2 DOF controller without any need to further tune the PID controller gains, the vibration is significantly reduced with the amplitude hovering a zero datum without any offset and yielding an extremely low frequency trending

Single phase Unified Power Flow Controller (UPFC) : simulation and construction.

Unified Power Flow Controller (UPFC) is used to control the power flow in the transmission systems by controlling the impedance, voltage magnitude and phase angle. This controller offers advantages in terms of static and dynamic operation of the power system. It also brings in new challenges in power electronics and power system design. The basic structure of the UPFC consists of two voltage source inverter (VSI); where one converter is connected in parallel to the transmission line while the other is in series with the transmission line. The main scope of this paper involves the designing of a single phase UPFC using Matlab and Simulink software, and constructing a lab scale model of the UPFC. A microcontroller program has been developed to provide the required phase shift. The experimental result which has been obtained from a lab scale system showed a good agreement with the simulation result

Effects of high power converter on power line carrier signal

Power line carrier (PLC) systems are used in transmission of signals for teleprotection, teletripping, telecontrol and speech communication. The signal to noise ratio (SNR) of the PLC is based on the noise level at the input of the carrier's receiver. The interference due to large power converter will be superimposed on the background noise at lower level. It has reduced the SNR to an unacceptable value. This paper deals with analysis of high frequency (HF) harmonics (higher than 20 kHz) produced from the converters, and the methods used to reduce the noise imposed on the PLC communication signal. The experimental and simulation results have been obtained for both processes

Simulation of lightning surges on tower transmission using PSCAD/EMTDC: a comparative study

This paper describes the analytical and the experimental responses of the surges strike on the transmission line towers. A new method of calculating transmission tower surge response has been proposed. It has been found that the tower surge response calculated by the proposed method has a close agreement with the measured tower surge response obtained from scale model and field tests. Without the use of simulation program, this topic might be difficult to understand. PSCAD/EMTDC has been selected as the software used to generate the appropriate data needed to graphically demonstrate this phenomenon

Development of hand-arm model rig for tremor excitation

This paper describes the development of a handarm model rig to simulate human tremor behaviour. The experimental rig is designed as an apparatus to induce vibration along a hand-arm model. An Intra Vernacular (IV) Training arm is used as the handarm model. Displacement and acceleration behaviour at three selected points along the handarm model were recorded by mean of piezoelectric accelerometer. The data from the experiment can be used for further analysis of the human hand-arm tremor especially for Parkinson's disease (PD) patients. Results from the experiments are raw data which can later be used in designing an appropriate instrument that can suppress the hand tremor

Enhancing disturbance rejection capability and body jerk performance of a twin-rotor helicopter model using intelligent active force control

This paper presents a study on the effectiveness of utilizing an innovative control approach based on an intelligent active force control (IAFC) strategy to stabilize a twin-rotor helicopter model and improve its ability to effectively reject external disturbances via a simulation work. A detailed mathematical model of a two-degree-of-freedom (DOF) helicopter was derived using the Euler-Lagrange method taking into account the effects of coupling and disturbances. In this developed model, a Proportional–Integral–Derivative (PID) controller was designed and combined with the proposed IAFC strategy to yield an intelligent hybrid control architecture known as a PID-IAFC scheme that can improve system performance and reject various types of applied disturbances. The intelligent algorithms used in the schemes are based on iterative learning (IL) and fuzzy logic (FL). In this work, different types of external disturbances in the form of sinusoidal waves, pulsating, and random noise disturbances were applied to the helicopter system to verify the sensitivity and durability of the proposed control schemes and consequently, a comparative study was performed to analyze the system characteristics. Notably, the efficacy of the IAFC based control unit was investigated to improve the body jerk performance in the presence of external disturbances. The acquired results reveal the effectiveness and robustness of the IAFC based controller in stabilizing the dual-rotor helicopter, rejecting the applied disturbances, and improving the body jerk performance by at least 54% for pitching and 19% for yawing motions in the presence of the pulsating disturbance, and 60% and 54%, respectively, for the random noise disturbance

Practical real-time implementation of a disturbance rejection control scheme for a twin-rotor helicopter system using intelligent active force control

This paper centers around an experimental investigation into the effectiveness of an innovative hybrid control approach based on an intelligent active force control (IAFC) strategy to stabilize a twin-rotor helicopter model and improve its ability to reject external disturbances efficiently. The intelligent algorithm was based on an iterative learning (IL) method integrated into the main control loop to estimate control parameters automatically while on-line. A mechatronic test rig with the IAFC-based control algorithm was incorporated into a Quanser Aero twin-rotor model in a laboratory setting as a verification platform to evaluate the applicability and efficacy of the proposed control algorithm via a practical real-time implementation. The hybrid IAFC-based control design was rigorously examined to test its feasibility and durability in countering various forms of external disturbances while executing the trajectory tracking tasks. Notably, the efficiency of the IAFC-based control unit was mainly studied and compared with other control plans under different operating conditions for benchmarking. The experimental results show the ability of the controller based on the IAFC strategy to effectively improve the disturbance rejection capability compared to the other control schemes considered in the study. About 27% improvement of the system performance in terms of lowering the root mean square error (RMSE) was observed compared to the other control systems counterparts

Static Synchronous Series Compensator (SSSC) with low harmonic inverter.

Static Synchronous Series Compensator (SSSC) is one of the two converters of the Unified Power Flow Controller (UPFC). It provides the main function of UPFC in controlling the amount and direction of power flow in the transmission lines by varying the additional voltage magnitude, Δv and additional voltage phase shift, Φ. In this worlç the SSSC has been constructed using 3-level Neutral-Point-Clamped (NPC) structure in order to reduce the harmonics. The effect of the variation of additional voltage magnitude, Δv and additional voltage phase shift, Δ to the sending end voltage, V2 has been investigated. From the results obtained from simulation and laboratory models, a small THD of less of 2% has been obtained

Effects of high power electronics converters on PLC signals

The harmonics are generated by the switching operation of large power converters, such as Static Compensator (STATCOM), Static Reactive Power Controller (SVC) and UPFC. These harmonics may cover a wide range of frequencies and it can cause problems of interference with communication systems. Power Line Carrier (PLC) system is one of the systems used in transmission of signals for Tele-potations, Tele-tripping, Tele-control and speech communications. The Signal to Noise Ratio (SNR) of the PLC is based on the noise level at the input of the carrier receiver. These effects of harmonics result in overheating, extra losses in electric machines and capacitors; and over voltage due to excited resonance in the power system. The main source of disturbances resulting from harmonics has been proved to be from a high power converter. This problem becomes more complicated when harmonics are originating in many single source. These harmonics can be propagated throughout the entire interconnected power network. The interference due to large power converter will be superimposed on the background noise at lower levels causing it to reduce the SNR to an unacceptable value. This study deals with the analysis of the waveform of the converters and the methods used to reduce the noise imposed on PLC communication signal. © 2006 Asian Network for Scientific Information