Showing 5 results for Sazgar
Volume 13, Issue 53 (5-2015)
Abstract
Investigation of quality characteristics of food products during different manufacturing stages such as storage, processing and consumption is important to reduce food loss. In recent years many researches have established for developing rapid and non-destructive techniques for quality control. In this study the potential of visible and near infrared spectroscopy (Vis/NIRS) in determining the quality parameters of lime including total soluble solid and acidity in reflection mode was investigated in the wavelength range of 400 to 1000 nm. The effects of different pre-processing techniques and spectral treatments, such as standard normal variable transformation (SNV), multiplicative scatter correction (MSC), median filter, Savitzky & Golay and the derivatives were evaluated. The model was developed based on partial least squares (PLS) regression. The correlation coefficient (R2) and root mean square error of prediction (RMSEP) for predictive model of soluble solids content was 0.949, 0.105 °Brix respectively. These parameters of the model predicting acidity was found to be 0.909 and 0.118 respectively. These results showed the high potential of Vis/NIRS and the important role of preprocessing techniques in developing precise models for the prediction of lime internal quality characteristics.
Volume 14, Issue 62 (4-2017)
Abstract
Hadi Sazgar, Shahram Azadi, Reza Kazemi,
Volume 18, Issue 2 (4-2018)
Abstract
The purpose of this research is to develop an advanced driver assistance system (ADAS) for the integrated longitudinal and lateral guidance of vehicles in high speed lane change maneuver. At the first step, the ADAS by considering the target vehicle position, the speed limit of the road and the available range of longitudinal acceleration produced several trajectories with different acceleration. Then, by considering vehicle and tire dynamics, the optimal trajectory is selected. Therefore, the chosen trajectory is collision free and feasible. Because the trajectory planning is carried out algebraically, its computational cost is low. This feature is very valuable in the experimental implementation. In the next step, using a combined longitudinal-lateral controller, the control inputs are calculated and transmitted to the brake/gas and steering actuators. The integrated controller design is based on sliding mode technique. Trajectory planning and controller design is based on a nonlinear tire model. Simulation results are presented and the results show the effectiveness of the integrated longitudinal and lateral guidance system.
Hadi Sazgar, Ali Keymasi Khalaji,
Volume 24, Issue 4 (April 2024)
Abstract
In recent years, advancements in driver assistance technology have significantly minimized the impact of human error on traffic accidents. The development of these systems is of great interest, especially for critical and accident-causing maneuvers such as critical lane change on the highway. One of the important parts of automatic lane change is the motion planning. In this research, taking into account the criteria of collision avoidance and feasibility of the path, an algorithm for the motion planning is proposed. The main innovation of the present research is that the dynamic limits and stability margins of the vehicle have been converted into quantitative criteria and considered in the motion planning. To evaluate the performance of the motion planning algorithm, the complete model of the car is used in the Carsim-Simulink software. Also, to follow the designed path, an integrated longitudinal-lateral control has been designed and implemented. The simulation results show that the proposed method provides a more accurate assessment of the trajectory dynamic feasibility in high-speed critical lane change maneuvers compared to the previous methods. This issue is especially evident for critical maneuvers where the lateral acceleration of the trajectory is more dominant than the longitudinal acceleration.
Hadi Sazgar, Ali Keymasi-Khalaji,
Volume 24, Issue 10 (October 2024)
Abstract
In many wheeled robot applications, in addition to accurate position control, dimensional and weight limitations are also important. The limitation of weight and dimensions means that it is not possible to use arbitrarily large actuators. On the other hand, accurate and fast tracking usually requires high control gains and, as a result, large control inputs. If the control input exceeds the saturation limit of the operator, in addition to increasing the tracking error, it may lead to robot instability in some cases. Therefore, it will be precious to provide a control method that can simultaneously provide high control accuracy and guarantee the robot's stability, taking into account the saturation limit of the actuators (speed and torque) in a predetermined manner. This issue has been addressed in the present study. The proposed control includes two parts: a kinematic controller and a dynamic controller. The kinematic control design is based on the Lyapunov approach, which can adjust the speed saturation limit of the actuators. For dynamic control, the robot velocity components are considered as control reference values and the robot wheel torque is considered as control inputs. In the dynamic control design, the torque saturation limit of the actuators is included in a predetermined way. To evaluate the performance of the proposed nonlinear control, various analyses were performed on the wheeled robot. The results showed that the proposed control algorithm while guaranteeing stability and following the path with high accuracy, has also fully met the requirements of the actuators’ saturation limits