Robotics & Autonomous Systems Car


This is an independent project course from the Electrical Engineering department. The goal of the course is to create a small autonomous vehicle from the ground up that can navigate around a race track with obstacles as fast as possible. This project is currently in progress, expected to be completed May 2021

Figure 1: Autonomous Systems Car

We design, fabricate, solder, and code almost everything except the chassis and PSoC (programmable logic). This includes designing our own powertrain, power distribution boards, hall effect sensor, electronic speed controller, closed-loop PID feedback controls, and video boards.

The course is entirely self-taught, all that is provided to us is a lab with 24/7 access, a vast array of components and parts, and general tasks that the robot must be able to complete.

As a mechanical engineer, I normally wouldn't be able to take this course, but given my passion and intended career path I was able to get special permission to enroll.

Electronic Subsystems

Subsystems include:

  • Power distribution

  • Programmable System on a Chip (PSoc)

  • Hall Effect Sensor and Board

  • Motor Controller

  • Camera and Video Board (coming soon)

  • XBee (wireless communication b/w robot and computer)

Figure 2: Block Diagram of System

Power Distribution:

  • The vehicle is powered by two separate batteries since the PSoC requires a very constant input voltage

  • A 7.2V battery is used to power the motors

  • A 9.6V battery is used to power everything else

  • The PSoC uses 9.6V directly

  • All other electronics run at 5V or 3.3V, so I designed a power board to step down and deliver the appropriate voltage to various subsystems.

  • The power board uses MC78XX series voltage regulators in the TO-220/D-PAK package

Figure 3: Diagram showing system level power distribution. Circuits RT3 and RT6 are connected to share a common ground

Figure 4: Soldered power board. Takes 9.6V and steps it down to 5V to be used by other subsytems

Programmable System on a Chip (PSoC)

  • PSoC is a microcontroller IC featuring a core, configurable analog and digital blocks, programmable routing, and interconnect.

  • Programmed using software called PSoC creator which features hardware component layout and C code

Figure 5: PSoC development board overview

Figure 6: PSoC schematic

Figure 7: PSoC Creator software

Hall Effect Sensor and Board

  • In order to control vehicle speed, an accurate way to measure speed is required.

  • To do this, I decided to use a hall effect sensor.

  • I glued 5 small magnets in even intervals to the inside of the rear wheel. The hall effect sensor is mounted in such a way that it will detect the magnetic fields of the magnets as they pass by allowing me to calculate the RPM of the wheel.

  • To convert the analog signal of the sensor to a digital signal, I used a Schmitt trigger.

  • When the magnetic field exceeds a threshold value, the output will be 0V, otherwise 5V

  • By detecting and counting the rising edges of this signal in a given time period, I can easily calculate the vehicle's true speed

Figure 8: Functional Block Diagram for sensor

Figure 9: The Allegro™ A1104 Hall-effect switch

Motor Control Board

  • The PSoC can output a PWM signal to control the speed of the brushed DC motor

  • The +5v PWM signal is used as a gate voltage for an n-type MOSFET which can provide power to the motor

  • To protect the FET from back EMFs, I used a flyback diode in parallel with the motor

  • To protect the PSoC, I used a gate resistor

Figure 10: Hand sketch of motor board diagram

Figure 11: Prototype build of motor board

Camera and Video Board

coming soon!