This project is designed from consumer products such as brake or acceleration pedal to medical applications such as surgical instruments. I am going to focus on the problem of our current brake/acceleration pedal system, and design a solution to address this problem. Nowadays, the current brake hydraulic system that we have, has some limitation which one of the limitations is when the footbrake pedal is push too hard in immediate time, this causes the wheel to lock-up instead of gradually slow down in a shortest amount of time. In fact, this can cause the car sliding which means longer distance to stop, make a screeching sound when it stop, and we do not have as much control when this situation takes place. This project will focus more to solve the problem by replacing the current hydraulic system with the brake/acceleration by-wire pedal. Having brake/acceleration by-wire pedal designed; this design device has a lot of benefits to offer. The by-wire pedal design advantages are:

The main objective is to design and construct a electromechanical pedal that can control a motor speed, and another electromechanical brake control pedal. The input sent by a sensor in a pedal will be converted from analog to digital before entered as input of a microcontroller. A written algorithm in the microcontroller will process and send output to motor controls. The output of the microcontroller will be converted from digital to analog before being sent as input to the motor controls. The motor activates based on the given output of the microcontroller and performs one degree of freedom (DOF). Then, feedback from the motor will be measured by accelerometer or tachometer and send back to the microcontroller. Feedback from the motor will be used to compensate with the input given by the force sensor. The figure below is the block diagram of the force feedback motor control project that I am working on.

These are the tasks that I will progressively perform during my senior design II for this Spring 08' semester:

For demonstration unit, the objectives of the device are to show one degree of freedom with speed control, direction control and brake control. The Flexiforce sensor will take input by putting three different load pressures. The Flexiforce sensor does the A/D conversion and then sends signal to the microcontroller to process the signal. Once processed, the microcontroller produces pulses and sends the pulse signals to the stepper motor driver. When the stepper motor driver receives every pulse, it will sequence the stepper motor by one step. For three different load pressures will have three different speed levels. Another demonstration is to show the device with brake control by gradually increasing the pressure of the load from no load to full load pressures on the pedal. The more pressure the pedal gives as an input, the less amount of rotation the stepper motor operates. Thus, the amount of rotation of the stepper motor is inversely proportional to the amount of braking being called for. There are two pedals as inputs to show the speed control and brake control of the device, and two motors as outputs of the motor control.