Rodrigo Yassuda Yamashita

Application of Pattern Recognition for the Mitigation of Systematic Errors in an Optical Incremental Encoder

The accuracy and reliability in the measurement of the instantaneous angular speed (IAS) by incremental encoders are fundamental for speed and torque control systems. An error in the acquisition of this variable may cause instabilities or even render the system unfeasible. Many works deal with this problem, which in some cases is caused by the imperfections in the disk manufacturing or also shaft misalignments. Due to the systematic character of these type of error, in this work an error pattern in the encoder signal of a vehicle dynamometer was identified by means of a calibration process and detected along the experiment by minimizing the total variation of the corrected angular speed curve. By making use of this procedure, not only the measurement became more accurate, but also the direction of rotation and angular position of the rotary system could be detected with only one channel of the encoder sensor being acquired. After the application of this method, the measurement error was reduced by 84.22%, even in transient conditions, without the application of further filtering methods, which may unwantedly lead to phase shifting in the IAS signal.

Powertrain Optimization to Improve Vehicle Performance and Fuel Consumption

The available gearbox transmission ratios associated with gear shifting strategies influence the vehicle performance and fuel consumption because it changes the powertrain inertia and the engine operation point. However, the best configuration for the vehicle powertrain, according to a specific driving condition, is difficult to be determined. Therefore, this paper presents an Interactive Adaptive-Weight Genetic Algorithm to optimize the vehicle powertrain gear ratios and the gear shifting strategies to allow the vehicle to operate in the best compromise among fuel consumption and performance in the urban driving scenario provided by the FTP-72 cycle. The optimization process results in a fuel saving of 10.61% and 50.12% improvement in the vehicle performance when using the best-compromised configuration.

Multibody Model of a Small Tire Test Bench

In despite of the necessity to control the mobile robots, it is possible to observe the absence of tire models and experimental parameterization regarding small tires. This paper aims to collaborate with part of the fulfilment of this gap in the literature by proposing some updates to a test bench that focus on the parameterization of small tires. The multibody dynamics model including the updates of the test bench was executed in ADAMS/View in order to indicate whether these updates are feasible and whether the data acquired by the virtual load cells is correlated with the virtual tire contact loads. The resulting virtual tire contact loads are compared with the ones calculated directly by ADAMS/Tire routine and by Pacejka equations, demonstrating a good correlation.

Experimental Characterization of a Feedforward Control for the Replication of Moving Resistances on a Chassis Dynamometer

Dynamometers are devices that for long have been employed for acquiring power and torque outputting a prime mover, such as an engine. However, with the improvements in controllability, they may as well be applied nowadays to reproduce in laboratory conditions real operational loads, increasing the replicability of the tests and the reproducibility of the results. In this regard, the main goal of the present work is to describe the first outcomes of a project being carried in the Laboratory for Integrated Systems of Unicamp whose main goal is to further develop its chassis dynamometer for emulating real driving resistances, such as inclines and aerodynamic drag, upon the driveline of the vehicle being tested. In a first attempt to improve the control platform of the device, a lookup table was created in order to control an eddy-current brake and to verify its dynamical performance under voltage inputs. Compensation for the difference in inertia between the vehicle and the dynamometer and for the aerodynamic drag was also provided during the execution of an FTP-72 drive cycle. After the inclusion of the control structure, correlation coefficients of around 0.95 have been found when comparing the torque read at the torquemeter with the expected torque with compensation.