Microprocessor based robotics arm

Abstract

Robotic arm has become popular in the world of robotics. The essential part of the robotic arm is a programmable microprocessor. The microprocessor based brick capable of driving basically three stepper motors design to form an anthropomorphic structure. The first design was for experimental use on a human-size industrial robot arm called PUMA 560 which stands for Programmable Universal Machine for Assembly. This human size robot was used to explore issues in versatile object handling and compliance control in grasp actions it was done in Bejczy city & in the Jan, 1986. This paper explains the method of interfacing the robotic arm stepper motors with the programmed 8051-based microprocessor which are used to process and control the robot operations. We have employed the assembly language in programming our microcontroller of the microprocessor. A sample robot which can grab by magnetizing and release small objects by demagnetizing is built for demonstrating the method explained.

1. Introduction

A robotic arm is a robot manipulator which is programmable and its functions are almost similar to that of human arm. The links of such a manipulator are connected by joints allowing either rotational motion or translational displacement. Kinematic chain can be formed by the links of the manipulator. The business end of the kinematic chain of the manipulator is called the end effecter and it is analogous to the human hand. The end effecter can be designed to perform any desired task such as welding, gripping, spinning etc., depending on the application. The robot arms can be autonomous or controlled manually and can be used to perform a variety of tasks with great accuracy. The robotic arm can be fixed or mobile (i.e. wheeled) in the nature and can be designed for industrial or home applications.

2. Robotic Arm

The word robotics, the meaning and the study of robots was done by a famous foreign scientist Isaac Asimov. Robotics is a branch which involves elements of mechanical and electrical engineering in it, as well as control theory, computing and now artificial intelligence in it by which we can implement it in the different fields. According to the Robot Institute of America, “A robot is a reprogrammable, multifunctional manipulator designed to move materials, parts, tools or specialized devices through variable programmed motions for the performance of a variety of tasks”. The way in which we are going to use robotic term in the form of arm is called as robotics arm. In order to perform any useful task the robot must interface with the environment, which may comprise feeding devices, other robots, and most importantly people. As the robot with which we are going to deal with work as arm and is therefore known as robotic arm

3. Types Of Robotic Arm

There are various kinds of the robotic arm available in the market for the different tasks these are as follows.

i. Cartesian Robot / Gantry Robot.

ii. Cylindrical Robot.

iii. Spherical Robot / Polar Robot.

iv. SCARA Robot.

v. Articulated Robot.

vi. Parallel Robot.

4. Block Diagram For Robotic Arm

The method employed in designing and construction of the robotic arm is based upon the operational characteristics and features of the microcontrollers of the microprocessor, stepper motors, the electronic circuit diagram and most importantly the programming of the microcontroller of the microprocessor and mainly the stepper motors.

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This work is able to successfully accomplish the defined functionality means it defines all the functions of the robotic arm. A sample robot which can rotate, magnetize an object, lower and raise its arm, by being controlled by the 8051 microcontroller of a microprocessor is built successfully and it was named as robotic arm. The 8051-development board is soldered and it used the required procedure for the correct operation of the controller. The 8051 development board has been interfaced to the stepper motors such that the anthropomorphic like structure can be controlled from the buttons at the base of the structure which is robotic arm. These buttons help to control the whole system of the robotic arm. These four buttons have the uncommon task from each other which is explained as follows.

On/Off

The ON button puts on the system while the OFF button puts off the system. This is only the task allotted to them just to ON and to OFF the robotic arm.

Start/Stop

The START button starts the initial movement of the whole arm from its reset point, while the STOP button takes the arm back to its reset button after completion of its movement applied for the required task.

Right-Left/Left-Right

When this button is switched to the RIGHT-LEFT part it causes movement from right to left, while the LEFT-RIGHT part causes movement from left to right. It is used only for the right and left movement.

Rotation Of 180/90

When the button is on 180, it causes a rotation of 180 degree of the base stepper motor, but when put on 90 degrees, it causes rotation of 90 degrees. It means it is used for the 90 and 180 degree rotations.

5. Mechanical Structure Of The Arm

For the construction of any kind of the robot we must have any kind of the idea over which we have to work for its construction. Same is the case of the robotic arm for its construction we need its mechanical structure. In constructing our robotic arm, we made use of three stepper motors and gears since our structure is a three dimensional structure. A typical prototype that we employed for the construction of our robotic arm. There is a stepper motor at the base of the arm, which is used for circular movement of the whole structure for the easiness of the task; another stepper is at the shoulder which allows for upward and downward movement of the arm again used according to the task given to the robotic arm; while the last stepper motor is used at the wrist which allows for the picking of objects by the magnetic hand.

6. Robotic Arm Design Process

It includes various points related to the designing of the microprocessor based robotics arm. All those points which explain them are as follows:

Defining The Problem

i. Identifying the purpose of a construction.

ii. Identifying specific requirements.

A community wants to construct a robotic arm. Design and build a prototype device which could satisfy this need. Design and build a prototype device which could satisfy this need. You need to determine what problem you are trying to solve before you attempt to design and build a robotic arm to solve a problem.

Researching And Designing

i. Gathering information.

ii. Identifying specific details of the design which must be satisfied.

iii. Identifying possible and alternative design solutions.

iv. Planning and designing an appropriate structure which includes drawings.

Creating A Prototype

i. Testing the design.

ii. Troubleshooting the design.

Building Your Robot

Construction work can now begin. Here are some sites that help with:

i. Structure.

ii. Gear combinations.

iii. Arm mechanisms.

iv. Placing sensors.

v. Hints and tricks.

vi. The Art of LEGO Design by Fred Martin – an excellent resource for building very strong structures.

Programming And Testing Your Robot

Now it is time to program your robot. This can be achieved in many different ways. Use can achieve rudimentary intelligence in your robot by using only relays, potentiometers, bump switches and some discrete components. You can increase complexity in intelligence in your robot by adding more sensors and continuing in the same vein of using hardwired logic. By introducing a more sophisticated control element, the microprocessor, you introduce a significant new tool in solving the robot control problem.

Evaluating Your Robot

i. Evaluate the design.

ii. Evaluate the planning process.

As building and programming work progresses, and the design begins to take shape, you will automatically carry out tests on the design. You will also need to complete systems tests at various stages of the construction. If any of the tests show that you have failure in a joint, or that part of your structure is not meeting specifications, then you will have to make modifications in your plan. When building and programming is complete, the entire project must be tested to see if it does the job for which it was designed. An evaluation needs to then be written. This should be a statement outlining the strengths and weaknesses in your design. It should describe where you have succeeded and where you have failed to achieve the aims set out in the specifications.

7. Overall Arm Design

The two arms used both have six degrees of freedom, and are mounted on the humanoid robot cog. The arms are mirror image of one another. The kinematics of the arm is designed to be similar as that of the human arm. There are two joints each at shoulder, elbow and wrist although the axis of the first elbow joint is coincident with the co-axes of the shoulder joints. The arms has length same as that of the length of the human arm.

8. Market Applications Of Robotics Arm

Applications of robotic arm are very effective in the market world. There are various fields where there is a deemed need of the robotic arm these can be explained as follows.

Automotive

Robotic arm can be used in different ways in the automotive field.

i. Power train Control

ii. Body Electronics

iii. Driver Information Systems

iv. Chassis

v. Safety

vi. Automotive Networking

Consumer

Robotic arm can be used in different ways in the consumers.

i. Mobile Consumer Electronics

ii. Home Electronics

Industrial

Robotic arm can be used in different ways in the industrial field.

i. Factory Automation

ii. Building Control

iii. Metering

iv. Medical

v. Point of Sale/Kiosks

vi. Home Appliances

Medical

Robotic arm can be used in different ways in the medical field.

i. Home Portable

ii. Diagnostics and Therapy

iii. Imaging

iv. Intelligent Hospitals

Networking

Robotic arm can be used in different ways in the networking field.

i. Network Security

ii. Home and SOHO Networking

iii. Network Storage

9. Future-Scope

The scope of this work for manufacturing of robotics arm involves confirming the 8051 micro-controller of microprocessor. Input/output (I/O) signals are compatible with that of the robotic arm stepper motors and testing of the robot’s motor signals through programming the 8051 microcontroller of the microprocessor. Assembly programming is used to develop the programs for the EPROM 2732 on the 8051 micro-controller of the microprocessor platform that takes robot’s motor signal as I/O and controls the robot operation programmatically. We have assumed that after figuring out the interface issues for the Robot with the 8051 microcontroller, the same knowledge can be extended to make very complex robots with enhanced functionality. With the technique used in the manufacturing of the robotic arm we can also make other robots for the different tasks.

Conclusion

Finally from this topic we can conclude a robotic arm is an instrument by means of which we can do any kind of the task and use it in the way in which manner we want to solve the task. The controlling software used in this robotic arm can be general for any kind of robot arm and set of sensors. This paper introduces a set of design principles which seek to reduce robotic applications design and implementation time so reducing the errors present in any practical implementation as well. Experiments show that the solution presented in this paper, although its limitations, allow the robotic applications designer to save development time while keeping the overall complexity low. There exists open-source applications which handle similar problems but they are not well fitted for small control applications. We have learnt that because of limitations in the programming language used to develop the application and the final application itself is highly sensitive to implementation issues. Also, to completely verify the design principles it would be necessary to evaluate the effort required to design a control application for multiple and heterogeneous platforms.

Acknowledgement

I thank GOD almighty for guiding me throughout the term paper. I would like to thank all those who have contributed to the completion of the term paper and helped me with valuable suggestions for improvement. I am extremely grateful to Mr. JAGDEEP SINGH, Department of ELECTRONICS AND COMMUNICATIONS, for providing me with best facilities and atmosphere for the creative work guidance and encouragement. I thank all my friends for extending their cooperation during my term paper. Above all I would like to thank my parents without whose blessings; I would not have been able to accomplish my goal.

References

The references for the term paper given to me are as follows:

www.robotics.com (Robotics history, background)

www.orca-robotics.com (Robot controlling)

www.wikipedia.com (microprocessor based robotics arm)

www.google.com (Seminar Report on robotic arm)

www.google.com (applications of robotics arm)