robotic arrm

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ISSN-1997-2571 (Online)

J. Innov. Dev. Strategy 5(1):1-5(April 2011)

CONNIVING, MECHANIZED AND SCHEMING OF A PICK & PLACE AUTOMATON HAVING

BEST CONDITION

M.T. HAQUE1, A.A. ANAM2, M.K.A. HASAN3, M.A. SUFIYAN4 AND N. AFROZ5

1Production and development of the jute based blended fabrics in cotton processing system for textile uses. Bangladesh Jute Research

Institute (BJRI); 2Daudkandi Picking Power Plant, Bangladesh Power Development Board (PDB); 3Quality, Bangladesh Diesel Plant (BDP)

Ltd.; 4Operation &Maintenance (O&M), Business Management Unit (BMU). Energypac Confidence Power Venture Ltd., Hobigonj;

5Department of Textile Engineering, Southeast University, Dhaka.

Corresponding author & address: M.T. Haque, E-mail: [email protected]

Accepted for publication on 28 March 2011

ABSTRACT

Haque MT, Anam AA, Hasan MKA, Sufiyan MA, Afroz N (2011) Conniving, mechanized and scheming of a pick & place automaton

having best condition.J. Innov. Dev. Strategy 5(1), 1-5.

The Integration of Electronic engineering, Computer technology and Control engineering with Mechanical

engineering is increasingly forming a crucial part in the design, manufacture and maintenance of a wide range of

engineering products and processes. Here in this paper we take an opportunity to research concerning the different

parts of sophisticated computer controlled device Robot specially in the area of Infrastructure, Control system

(electrical & mechanical) and Gripper system. Unquestioningly, the design of robots is highly specialized and has its

particulars, not only in determining optimum specifications or representative loading conditions but also in the

selection of an appropriate configurations, component and material or analysis technique. The objective of this work

is to present a transparent comparison of different types of mechanical and electrical components used in this robot.

At the same time reasons have been mentioned why various components are used for the construction of this Robot.

The different arms of this Robot are manufactured from plastic & solenoid operated horizontal gripper is developed.

The gripper has object sensing activity with the help of sensor, by which it can grip only when the object will present

between the fingers. If there is no object it will discontinue its activity. This prevents the unnecessary movements. For

actuation of the movement of waist, first arm, second arm and gripper three stepper motor, one solenoid and some

mechanical mechanisms are used. Instead of using four separate driving circuits (three for stepper motor & one for

solenoid) for each driving system, we have use only one circuit, which simultaneously do the job of driving and

multiplexing. This robot is controlled according to the signal and data, which is sent to it from PC through Interface

from end to end LPT port and use C language for programming. The multipart control circuit formulated by us made

the programming very easy and small in size. While operating the robot, user can alter manual, automatic and variable

speed operations. The performance parameter and the accuracy test of the robot were carried out and the range of

loads carrying by the robotic arms was determined. This manufacturing process will help for studying basic structure

and the functions of a pick and place robot which has the great potential of endless uses in a developing country like

Bangladesh.

Key words: manufacturing process, gripper, Multiplexing and Driving (MD) circuit, computer interfacing

INTRODUCTIONThe term Robot has its origins in a Czech word robotnik meaning worker or serf. The playwright Karel

Capek in a 1920 play first introduce it. Isaac Asimov popularized the robot theme in science fiction in the late

1940`s and the early 1950`s, and subsequently by Hollywood movies. Although Capek introduced the word

robot to the world Isaac Asimov coined the term robotics in his short story Runaround, first published in

1942. This work is also notable because the so called Three rules (or laws) of Robotics are presented for the

first time: First, A robot may not injure a human being, or, through inaction, allow one to come to harm.

Secondly, A robot must obey the orders given it by human beings except where such orders would conflict with

the first law. Thirdly, A robot must protect its own existence as long as such protection does not conflict with

First or Second laws (Ayres and Miller, 1981).

Encyclopedia Britanica gives the following definition:

A Robot device is an instrumented mechanism used in science or industry to take the place of a human being. It

may or may not physically resemble a human or perform its task in a human way, and the line separating robotdevices from merely automated machinery is not always easy to define. In general, the more sophisticated and

individualized the machine, the more likely it is to be classed as a Robot device.

The Robotics Institute of America defines a Robot as follows:

A Robot is a reprogrammable multifunctional manipulator designed to move material, parts, tools or

specialized devices through variable programmed motions for the performance of a variety of tasks.

Robot:

A mechanical device, which can be programmed to perform some task of manipulation or locomotion under

automatic control.

Industrial Robot:

A programmable, multi-function manipulator designed to move material, parts, tools, or specialized devices

through variable programmed motions for the performance of a variety of tasks.

J. Innov. Dev. Strategy 5(1): April 20111 Co ri ht 2011 Green Global Foundation


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Haque et al.

Pick and Place Robot:

A simple robot, often with only two or three degrees of freedom, which transfers items from place to place by

means of point-to-point moves. Little or no trajectory control is available. Often referred to as bang bang

Robot.

We will not discuss here the problem of the possibility (or impossibility) of actually creating such a robot with a

human soul. The subject of our discussion will be limited mainly to industrial robots including those, which

belong to the family of bang-bang robots. The application of these robots in the modern world must meet the

requirements of industry, including functional and manufacturing demands. Obviously, esthetics and

environmental considerations are also involved. The mechanical component of the design of robotic systems

constitutes the main focus of our consideration (Karel 1923).

DESIGN & CONSTRUCTION OUTLINE OF THE ROBOT

Robot specificationsDegree of freedom: 4

Capacity: 500g (at any point within working envelop)

Repeatability: 0.5mm at the end of arm (fully extended)

Axis Capabilities:

Mechanical Assembly Maximum Angle() Speed (Degree/sec)

Waist 360 0-27

First Arm 270 0-10

Second Arm 90 0-10

Materials for the Robot Structure:

The material used for the manufacturing of the robot is plastic, which was 4mm thick. Plastic body makes the

robot light and aesthetic looking. Plates of the plastics were jointed with a special type of plastic dusts mixing

with chloroform. The driving force is important matter for the robot. Hence the weight should be taken care.

Some holes were drilled on the robotic arm body to make it comparatively lighter so that power required to

moves arms become less.

Figure 1. The Pick and Place Robot Structure

Different movements

We have employed mainly three different movements in our pick and place robot. They can be titled like

Waist Movement First Arm Movement Second Arm MovementWaist Movement:

The waist of the robot is controlled by the Spur Gear mechanism which is placed in the base of the pick and

place robot. The motor is directly coupled with a pinion having 20 teeth. The pinion is mashed with a gear

having 258 teeth. Hence the speed of the motor decreased by around 13 times and the torque is increased by the

same ratio. The Gear holds the total assembly on it so that the assembly can rotate according to the requirement

(Mark 1981).

First Arm Movement:

Another motor is coupled with a worm reducer, which has a reduction ratio of 40:1. The worm reducer will

transmit the power to one part of the combined shaft. The combined shaft is a combination of two different but

concentric. These two shafts are connected through ball bearings so that one can remain stationary while the

other one rotates. One of these shafts is fixed with the first arm. So the first arm can rotate by the rotation of theone part of the combined shaft (Roy 2001).

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Conniving, mechanized and scheming of a pick & place automaton having best condition

Second Arm Movement:

A third motor is coupled with another worm reducer, which transmits motion to the second part of the combined

shaft. This shaft is free with the first arm and has a toothed pulley in it. Through the toothed belt (timing belt), it

transmits movement to another shaft placed between the first arm and second arm. The timing belt and pulley

make it possible to position accurately. This shaft is fixed with the second arm and hence it can transmit power

to the arm. Figure 2 illustrates the postmortem view of the pick and place robot.

Fi ure 2. A Postmortem View of the Pick and Place Robot

Basis behind to decide on the system

Toothed belt gives constant speed ratio with accuracy. There is no slippage or creep. Available in the market. The worm reducer has a high transmission ratio as compare to the other transmission elements. The worm reducer takes smaller place as compare to the other conventional transmission elements.

Designing of Gripper

There are a variety of techniques for designing a gripper suitable for the pick and place robot. We can make use

of different kinematics device for the actuation of the finger movement of gripper. So there are a number of

alternatives among those we select Solenoid operated gripper.

Specifications:

The end effectors or gripper for our robot was made of plastics. Due to 4mm thick plastic material its weight has

been decreased (Leinecker and Archer, 2003).1. Material : Plastic 5. Total Width : 10cm

2. Degree of Freedom : 2 6. Finger Length : 8.5cm

3. Weight : 200g 7. Maximum Width of the object to Grip : 5.5cm

4. Total length : 5.5cm 8. Minimum width of the object to Grip : 1.5cm

Gripper finger

Tension wire

Solenoid

Figure 3. Assembly Drawing of the Gripper

ELECTRICAL SYSTEM

Electrical system includes mainly the followings:

Stepper Motor Solenoid Power Supply Control Circuit Sensor Circuit



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Stepper Motor

Stepper motors can be regarded as the main electrical component, which drives the base and arms. It is possible

to construct a motor in which the rotor is able to assume only discrete stationary angular positions. Rotary

motion occurs in a stepwise manner from one of these equilibrium positions to the next, and as a consequence

such a device is called a stepper motor. There are several general characteristics of a stepper motor that have

made it the actuator of choice in such a large number of applications. The device can be operated in an open-

loop manner with a positioning accuracy of 1 step (assuming that the rotor angular velocity is low enough sothat no steps are lost during a move). Thus if a certain angular distance is specified, the motor can be

commanded to rotate all appropriate number of steps, and the mechanical elements coupled to the shaft will

move the required distance. The motor exhibits high torque at small angular velocities. This is, of course, useful

in accelerating a payload up to speed (Rosenblatt 1982).

Motive for go for the stepper motor:

They are compatible with digital systems and not require digital to analog conversion at the input. While simple open loop control is good enough for the control of position and speed, it can also be used

in closed loop position and speed control system with either analog or digital system.

A wide range of step angle is available off the shelf from most manufactures, in the range of 1.8 to 90. Bi-directional control is available. Maximum torque occurs at low plus rates. Low speeds are possible without reduction gear. Moment of inertia is usually low. Multiple stepper motor driven from the same source can maintain perfect synchronization.

Motor Specifications:

Volt : 5V Current : 1.4A Step : 1.8/Step

Solenoid

Solenoid is very simple in principle. It has only two parts: a Coil and a Shaft. When current flows through the

coil, it is magnetized. The shaft will then give axial stroke. For our case the stroke is about 4mm, which is

enough for the actuation of the gripper fingers. For the transmission of power from solenoid shaft to gripper, a

transmission wire is used which is very much effective.

Power supply

The different components used in the pick and place robot has dissimilar power ratings according to their

specifications. A straight forward outline is presented below that shows the different power ratings for different

components.

Component Power Supply

Stepper Motor 5V

Solenoid 24V

IC (Latch) 74LS373 7.5V

Opto-Coupler (4N25) 17V

Control Circuit

Multiplexing and driving circuit and its operational principle:

If you observe control circuits for any mobile machine or manipulator using 2, 3 or more motors, definitely you

will find separate driving circuit for each driving system, concluding all to a single multiplexing circuit. But

dissimilarity will be observed in our case. We have used only one circuit, which simultaneously do the job of

driving and multiplexing. Even the solenoid also runs by the circuit. A schematic diagram of the circuit is

illustrated In figure 3.1 which is actually one forth (1/4) of the whole circuit. In the Multiplexing and Driving

(MD) Circuit, 74LS373 (Latch) is used which takes input from the LPT port and sends its output to Opto-

coupler (4N25) to initiate. As soon as the Opto-coupler is initiated, its output goes to Relay to trigger it. The

triggering of the Relay sends pulse to the motor. A stepper circuit requires four signals or pulse like 0011, 0101,

1010 to be actuated. So four Opto-couplers is used to trigger four Relays and finally four Relays send four

pulses, which is enough for the actuation of one motor. For the actuation of the solenoid, one Opto-coupler and

one Relay is engaged, where the Opto-coupler takes the input from any of the three latches (74LS373). Figure

3.1 illustrates whole circuit, which is manufactured for our pick and place robot, gives a transparent conception

about the MD circuit.



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Conniving, mechanized and scheming of a pick & place automaton having best condition

Sensor Circuit:

When the robot is under automatic operation, it performs the jobs endlessly in a cycle. In that case if the object

to be picked is finished, then what the robot will do? Will it stop or continuously doing its job except picking

and placing any object? To solve this problem we introduce a very small and effective circuit, which we named

`Object Sensor Circuit`. It will detect any object between the fingers. If there is no object between the fingers it

will discontinue its activity. This prevents unnecessary movements.

INTERFACE

The computer treats all its peripherals in identical way. It assigns an address to each of its peripherals and

transfers data to or from the peripheral by referring it with this address of the peripheral. A computer port is a

collection of registers, which is connected with the microprocessor through its interfacing circuit. The parallel

port is such a port and its interfacing circuit is already built in the motherboard. The original IBM-PC`s parallel

printer port has a total of 12 digital outputs and 5 digital input; accessed via 3 consecutive 8 bits ports in the

Processors 1/0 space.

8 output pins via the DATA port 5 input pins (one inverted) accessed via the STATUS port 4 output pins (three inverted) accessed via the CONTROL port. The remaining 8 pins are grounded.

Pc Controls The Pick And Place Robot:

Our pick and place robot is controlled according the signal and data, which is sent to it from PC through

Interface. We set up the interface through LPT port and make use of C language for programming that is

extensively bring into play for many such cases. The multipart control circuit formulated by us made the

programming very easy and small in size (Mass and Merriam, 1974).

Options:

While operating the robot the user may be desired to operate it in different line of attack and speed. We have

preserved some options for the user, which he can alter according to his requirement. The users have the

following opportunities while operating the robot;

Manually operation. Automatically Operation (cycle). Variable Speed.

CONCLUSION

Robot technology is extremely sophisticated and in fact it is only inborn condition in the country like

Bangladesh. In the vast area of robotics we attempted to develop a robot having basic characteristics with

optimum specification having the limited source locally available resources. Getting from the present to the

future will require much work in mechanical engineering, electrical engineering, computer Science, industrial

engineering, material technology & manufacturing system engineering. The purpose this work is to explore and

examine these areas, which constitute the technology, programming and application industrial robotics in arena

of transportation system, emergency disaster recovery, and precession control system, manufacturing

automation. Application of robotics in those fields may cause another industrial revolution, which may cause

replacing of human workers with a robot. To be sure there will be an impact on some workers, who,

unfortunately displaced by these machines. However, it is expected that in the longer term, more jobs will be

created as new and expanded industries are developed as a direct consequence of this new, more flexible form of

automation the robot.

REFERENCES

Ayres RU, Miller SM (1981) The Impact of Robotics on the Workforce and Workplace.Carnegie Mellon

University Report, Australia pp 60-66.

Karel C (1923) Rossum`s Universal Robot, English version by P. Selver and N. Playfaff, New York:

Doubleday, Page and Company, pp-52-60.

Mark T (1981) The Robot Market Explosion, Section 8, Publishers International Resource Development, Inc.,

Norwalk, Conn.`The push for Dominance in Robotics Gains Momentum,` Business Week, pp. 108-109.

Roy PK (2001) Microprocessor Data Hand Book, BPB Publications, B-14, Connaught Place, New Delhi-

110001, pp-101-120.

Leinecker RC, Archer (2003) Visual c++ Programming, John Wiley & Sons Inc., U.S.A. pp. 60-66.

Rosenblatt R (1982) The Robot Revolution. Editorial Research Reports, pp. 347364.

Mass G, Merriam C (1974) Webster`s New Collegiate Dictionary. Springfield., pp- 10-21.


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