Short Intro: This project was a part of our credits for robotics. I have implemented proportional loop to control the speed of the robot. The speed of the robot wheel is measured using the optical IR wheel encoder. If the measured speed of the robot is less than the intended speed, the PWM of the motor is increased so that the robot reaches the intended speed.

Hardware:

• Microcontroller: AtMega328 - Arduino Uno.
• Motor driver: L298N.
• IR speed encoder: LM339 compactor based.
• Berg wires, LED's and Resistors.
• 300 RPM - motors - dual shaft.
• Lithium Ion batteries.

Working: The encoders are used to measure the speed of the wheel. The speed is measured by counting the encoder steps through hardware interrupts. The number of interrupts/pulses sent to the encoder is proportional to the speed of the robot. The number of pulses per 100 mSec are counted to measure speed. The intended speed of the robot wheels is set by the user. The difference between the intended speed and the measured speed of the encoder are amplified by gain and used to change the PWM of the motors.

Autonomous car is the recent trend and future of the Automobile sector.

Autonomous car also known as driverless car, robot car, self-driving car or autonomous vehicle.

In spite of all technical, political, infrastructural and personal (acceptance, cost) issues in autonomous car building, we are heading toward the innovation and believing in advanced new technologies.

•Such technologies will reduce human efforts and give more convenience, safe and luxurious experience.

•Safety concerns are addressed by technological advancements.

• These are communications of vehicles to other vehicles (V2V), vehicles to the road- side infrastructure (V2I), vehicles to pedestrians (V2P), and vehicles to the cellular network (V2N).

• Together, these use cases are known as vehicles to everything (V2X).

•Still there are many issues in this field which are pending in terms of solution.

• Here one such problem related to uneven road, referring to steep road is discussed and provided a solution for the same.

Problem statement

1) Speed control of autonomous vehicle on upward slope

2) Preventing roll back of vehicle, when starting a vehicle on steep Hill climbing.

SYSTEM COMPONENTS

ØRobotic Smart Car chassis 4wheel DIY kit

ØArduino Uno board

Motor Driver L298 module

ØOptical slot speed sensor

In the case of flat road, when no other vehicles are moving on the road then vehicle can keep moving with the same speed means need not to change the PWM of motor.

In case of upward slop, if current PWM is not sufficient to move the vehicle in forward direction then input PWM needs to be adjusted.

For this adjustment, the PID control is the solution.

Speed control of autonomous vehicle on upward slop

If the input PWM is insufficient to move the vehicle in forward direction then speed sensor gives the less output.

The input (speed) is compared with the actual speed of the motor, if there is an error then PWM will be increased/decreased and motor will rotate with more speed so that vehicle will move forward.

ØIn next feedback loop there is no error because sensor output is 1 now and vehicle will continue with its normal speed (using integral, derivative control).

2)Preventing roll back of vehicle on steep hill while staring the vehicle

In this scenario we are considering stopped vehicle state, because of some obstacle, pedestrian comes in or some forward vehicle got stop or we want to stop the car for a minute on the slop.

In this case we want derivative control to prevent the shootout condition.

Electrical braking also a solution for such condition.

In this option, the motor terminals are shorted with 0 Ohm resistance i.e infinite load.

In this configuration the motor will work as a generator. The vehicle will electrically brake because energy is dissipated in the motor armature.

So, we are addressing the problem of speed control on upward slope by PID loop control and electrical braking system.