Wednesday, March 16, 2016

Accelerometer Based Hand Gesture Controlled Robot using 8051

Robots are playing an important role in automation across all the sectors like construction, military, medical, manufacturing, etc. After making some basic robots like line follower robot, computer controlled robot, etc, we have developed this accelerometer based gesture controlled robot by using arduino uno. In this project we have used hand motion to drive the robot. For this purpose we have used accelerometer which works on acceleration.

Required Components

1.     8051 Microcontroller
2.     DC Motors
3.     Accelerometer
4.     HT12D
5.     HT12E
6.     RF Pair
7.     Motor Driver L293D
8.     9 Volt Battery
9.     Battery Connector
10. USB cable
11. Robot Chasis

A gesture controlled robot is controlled by using hand in place of any other method like buttons or joystick. Here one only needs to move hand to control the robot. A transmitting device is used in your hand which contains RF Transmitter and accelero-meter. This will transmit command to robot so that it can do the required task like moving forward, reverse, turning left, turning right and stop. All these tasks will be performed by using hand gesture.

Here the most important component is accelerometer. Accelerometer is a 3 axis acceleration measurement device with +-3g range. This device is made by using polysilicon surface sensor and signal conditioning circuit to measure acceleration. The output of this device is Analog in nature and proportional to the acceleration. This device measures the static acceleration of gravity when we tilt it. And gives an result in form of motion or vibration.

According to the datasheet of adxl335 polysilicon surface-micromachined structure placed on top of silicon wafer. Polysilicon springs suspend the structure over the surface of the wafer and provide a resistance against acceleration forces. Deflection of the structure is measured using a differential capacitor which incorporate independent fixed plates and plates attached to the moving mass. The fixed plates are driven by 180° out-of-phase square waves. Acceleration deflects the moving mass and unbalances the differential capacitor resulting in a sensor output whose amplitude is proportional to acceleration. Phase-sensitive demodulation techniques are then used to determine the magnitude and direction of the acceleration.

Pin Description of accelerometer
1.     Vcc        5 volt supply should connect at this pin.
2.     X-OUT  This pin gives an Analog output in x direction
3.     Y-OUT  This pin give an Analog Output in y direction
4.     Z-OUT   This pin gives an Analog Output in z direction
5.     GND      Ground
6.     ST          This pin used for set sensitivity of sensor

Circuit Diagram and Explanation

Gesture Controlled Robot is divided into two sections:
1.     Transmitter part
2.     Receiver part

In transmitter part an accelerometer and a RF transmitter unit is used. As we have already discussed that accelerometer gives an analog output so here we need to convert this analog data in to digital. For this purpose we have used 4 channel comparator circuit in place of any ADC. By setting reference voltage we gets a digital signal and then apply this signal to HT12E encoder to encode data or converting it into serial form and then send this data by using RF transmitter into the environment.

At the receiver end we have used RF receiver to receive data and then applied to HT12D decoder. This decoder IC converts received serial data to parallel and then read by using 8051. According to received data we drive robot by using two DC motor in forward, reverse, left, right and stop direction.


Gesture controlled robot moves according to hand movement as we place transmitter in our hand. When we tilt hand in front side, robot start to moving forward and continues moving forward until next command is given.
When we tilt hand in backward side, robot change its state and start moving in backwards direction until other command is given.
When we tilt it in left side Robot get turn left till next command.
When we tilt hand in right side robot turned to right.
And for stopping robot we keeps hand in stable.

Circuit Diagram for Receiver Section

Circuit for this hand gesture controlled robot is quite simple. As shown in above schematic diagrams, a RF pair is used for communication and connected with microcontroller . Motor driver is connected to microcontroller to run the robot. Motor driver’s input pin 2, 7, 10 and 15 is connected to microcontroller digital pin number 6, 5, 4 and 3 respectively. Here we have used two DC motors to drive robot in which one motor is connected at output pin of motor driver 3 and 6 and another motor is connected at 11 and 14. A 9 volt Battery is also used to power the motor driver for driving motors.

GSM based Fire Detection System

The fig shows block diagram of SMS based fire detection system.
It consists of following blocks.
Power Supply:
Power supply is used to provide voltage to the Microcontroller, LCD, sensors, ADC, buzzer etc.

Sensor are basically use to convert physical quantity (eg. Temp, smoke etc) in electrical form (voltage, current etc.)
there are different sensors available for various physical quantity.

For FIRE detection we use Smoke sensor MQ2, Temp. Sensor LM35 & fire sensor.
If smoke is detected, then smoke sensor (MQ2: smoke to analog voltage) give signal to the ADC. The temp sensor LM35 (temp to analog voltage) sense the temp if it exceeds the max temp level then it sends the signal to the ADC. If fire is detected, then fire sensor gives signal to the microcontroller.

ADC is used to convert analog signal into digital form. In our project we use ADC0808. ADC receive signal from temp sensor & smoke sensor & convert it into digital form & this digital signal sends to the microcontroller.

Microcontroller is the main control unit of project. Once microcontroller gets signal from sensors (via ADC), if fire is detected then it will immediately turn on the buzzer & send the signal to the GSM modem.

GSM modem:
In project we used GSM modem for message sending.
When microcontroller detects fire then it sends information to the GSM modem, then GSM modem sends this information via SMS. GSM modem is used to send the message to the fire stations well as to the responsible person.

16x2 LCD: 
Display is used to display the system status.
Buzzer is used for notification regarding fire detection.

If fire is detecting, then microcontroller sends signal to the buzzer.