05-09-2014, 11:16 AM
ULTRASONIC HAPTIC VISION SYSTEM
VISION SYSTEM.docx (Size: 106.13 KB / Downloads: 22)
INTRODUCTION
The ultrasonic haptic vision system enables a person to navigate hallways and around large objects without sight, through the use of an ultrasonic rangefinder that hectically interfaces with the user via tiny vibrating motors mounted on the user’s head.
The idea behind this project was to construct a sixth sensory system that interacts with the body in an intuitive and user friendly fashion and enables the user to navigate without vision. We will also implement RF (Radio Frequency) transmission in order to provide feedback to a program running on the computer to keep track of the sensory data obtained from the mobile user mounted sensor system. 0
This enables the person sitting at the computer to observe all the distances between the surrounding obstacles and the user wearing the hat. The rangefinder rotated on a motor atop the hardhat in order to take the sensory data at discrete points around the user.
The hat and required hardware is all battery powered so that it is totally mobile and can be used as intended, so that movement is not restricted by the length of wires.
LOGICAL STRUCTURE
The basic logical structure of our project involves the sensory input from the ultrasonic rangefinder and its method of acquisition, the bipolar stepper motor that changes the sensor position to read ranges at different angles, the miniature vibrating motors that provides haptic feedback to the user and the microcontroller which enables the three major components to communicate effectively.
We will also have a base station which communicates with the mobile station via radio-frequency transmission, receives all of the hardware states and sensory information and displays it in an intuitive way for debugging and general informative display of the sensory information.
The motor atop the hard hat turns the ultrasonic sensor, which reads the distance to the nearest object at different angles and sends this information to the microcontroller which in turn sets the vibrator strength in that direction accordingly, to alert the user to the distance to the nearest object in that direction. At the same time the microcontroller relays this range information at the current angle back to the base station to display it on the computer
HARDWARE DESIGN
The following is a brief description of some of major components that we use in our hardware design of the system
Ultrasonic Range Sensor
We use ultrasonic sensor that has three different types of outputs, Pulse Width Modulation, Analog, and RS-232 making it a very versatile piece of hardware. The sensor is able to read at 20 Hz and reads in inch increments from 6 to 255
Full Bridge
The L298 is a very useful dual full bridge driver that can be used to guide and control the flow of current from the attached power supply using CMOS control signals. Thus using this dual bridge, we could drive our bipolar stepper motor using control signals to any desired voltage output. We will drive the bridge with a bipolar stepper motor pulse sequence generated by the microcontroller and a 5V regulated voltage rail for the power input
HARDWARE
• Soldered MCU boards
• Soldered controller boards, wires, etc
• Constructed hat, mounted motors and wired it all up
• Mounted hardware in plastic case and wired it
• Made heat sink, vibrating motor casings
• RF Hardware
• Hardware Testing
SOFTWARE
• MCU code for both mobile and base stations
• RF Encoding and Transmission Test
• Matlab Code on PC