18-12-2012, 03:02 PM
robotic arm
[attachment=44226]
INTRODUCTION
By constructing a robotic arm we are making our first foot step in robotic world. It involves not only electronics but also programming and mechanics. Our aim is to construct a robotic arm which can move up to a load of 100gms to 30cm distance.
It will have a human arm like movements and 5 degrees of freedom so it replicates human arm to an extent. For more precision we are using servo motors and PIC microcontroller 18F4431 (8 channel PWM motor controller PIC). There are 7 servo motors we are using so that we could achieve 5 No of degrees of freedom. The entire body of the robotic arm will be connected using acrylic sheet and metal screws.
There are multiple approaches to design robotic arm. The designer can choose between cost precision and performance. The mechanical construction of a robot is an aspect highly influenced by the way one wishes to control it.
Various options are available from powerful DC geared motors to precision servo motors. Here we are using servo motors for higher precision and less amount of load is given.
The Servos are used for precision positioning. They are used in robotic arms and legs, sensor scanners and in RC toys like RC helicopter, airplanes and cars.
CIRCUIT DESCRIPTION
The figure 4 shows the circuit diagram of the Robotic arm. It contains 7 servo motors and 13 switches for the control of the robotic arm include one switch for memory reset. Twelve switches except reset switch will be mounted on a separate keypad for easy operation.
6V 4.7Ah BATTERY AND 7805 VOLTAGE REGULATORS
This 6V battery is the main power supply for the whole circuit. The 6V output from the battery will be regulated to 5V with the help of voltage regulators. Here five 7805 voltage regulators are used because the total load can be divided among them for easy usage.
SERVO MOTORS
The servo motors used here are 7 in number and it will be powered by the battery and regulators (except IC2). For base servo we gave separate regulator due to heavy load on it. There are 2 servos for the shoulder because it has to lift the whole structure. Others will share one regulator for each two servos. All servos are of the torque 6Kgcm (except gripper servo, it have only a torque of 1.5Kgcm).
SERVO MOTOR WIRING AND PLUGS
The Servo Motors come with three wires or leads. Two of these wires are to provide ground and positive supply to the servo DC motor. The third wire is for the control signal. These wires of a servo motor are colour coded. The red wire is the DC supply lead and must be connected to a DC voltage supply in the range of 4.8 V to 6V. The black wire is to provide ground. The colour for the third wire (to provide control signal) varies for different manufacturers. It can be yellow (in case of Hitec), white (in case of Futaba), brown etc.
[attachment=44226]
INTRODUCTION
By constructing a robotic arm we are making our first foot step in robotic world. It involves not only electronics but also programming and mechanics. Our aim is to construct a robotic arm which can move up to a load of 100gms to 30cm distance.
It will have a human arm like movements and 5 degrees of freedom so it replicates human arm to an extent. For more precision we are using servo motors and PIC microcontroller 18F4431 (8 channel PWM motor controller PIC). There are 7 servo motors we are using so that we could achieve 5 No of degrees of freedom. The entire body of the robotic arm will be connected using acrylic sheet and metal screws.
There are multiple approaches to design robotic arm. The designer can choose between cost precision and performance. The mechanical construction of a robot is an aspect highly influenced by the way one wishes to control it.
Various options are available from powerful DC geared motors to precision servo motors. Here we are using servo motors for higher precision and less amount of load is given.
The Servos are used for precision positioning. They are used in robotic arms and legs, sensor scanners and in RC toys like RC helicopter, airplanes and cars.
CIRCUIT DESCRIPTION
The figure 4 shows the circuit diagram of the Robotic arm. It contains 7 servo motors and 13 switches for the control of the robotic arm include one switch for memory reset. Twelve switches except reset switch will be mounted on a separate keypad for easy operation.
6V 4.7Ah BATTERY AND 7805 VOLTAGE REGULATORS
This 6V battery is the main power supply for the whole circuit. The 6V output from the battery will be regulated to 5V with the help of voltage regulators. Here five 7805 voltage regulators are used because the total load can be divided among them for easy usage.
SERVO MOTORS
The servo motors used here are 7 in number and it will be powered by the battery and regulators (except IC2). For base servo we gave separate regulator due to heavy load on it. There are 2 servos for the shoulder because it has to lift the whole structure. Others will share one regulator for each two servos. All servos are of the torque 6Kgcm (except gripper servo, it have only a torque of 1.5Kgcm).
SERVO MOTOR WIRING AND PLUGS
The Servo Motors come with three wires or leads. Two of these wires are to provide ground and positive supply to the servo DC motor. The third wire is for the control signal. These wires of a servo motor are colour coded. The red wire is the DC supply lead and must be connected to a DC voltage supply in the range of 4.8 V to 6V. The black wire is to provide ground. The colour for the third wire (to provide control signal) varies for different manufacturers. It can be yellow (in case of Hitec), white (in case of Futaba), brown etc.