rr420305-robotics.pdf

Code No: RR420305 Set No. 1

IV B.Tech II Semester Supplimentary Examinations, Apr/May 2009ROBOTICS

( Common to Mechanical Engineering and Production Engineering)Time: 3 hours Max Marks: 80

Answer any FIVE QuestionsAll Questions carry equal marks

1. Discuss a single station robotic assembly system with the help of an example. [16]

2. Describe the following basic configurations of robotic arms with neat sketches.Discuss the advantages and disadvantages of the configuration show also the workspace of the arms.

(a) Spherical configuration

(b) Articulated configuration. [8+8]

3. For the information given in the mechanical gripper design of figure 3. determinethe required actuating force if the gripper force is to be 150 N. [16]

Figure 3

4. For the figure 4, find the 4 4 homogenous transformation matrices i1Ai and0Ai

for i = 1, 2, 3, 4. [16]

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Figure 4

5. Consider the three-link articulated robot of figure 5. Derive the forward kinematicequations using the DH-convention. [16]

Figure 5

6. Determine the Jacobian of the 2-DOF RR manipulator with L1 6= L2 and showthat the significant Jacobian is [16]

J =

(

L1S1 L2S12 L2S12L1C1 + L2C12 L2C12

)

Determine the singularities and joint velocities of this manipulator.

7. Develop the expression for displacement, velocity and acceleration in joint space

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scheme considering the fifth order polynomial fit. [16]

8. (a) What are the five basic types of reasons sensors are used in a workcell?

(b) A resolver is used to indicate angular position of a rotational wrist joint. Theexcitation voltage to the resolver is 24 V. The resolver is directly connected tothe wrist joint. At a certain moment, the two pairs of stator terminals haveVS1 of 10.0V and VS2 of 21.82. Determine the angle of the rotational joint.

[6+10]

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1. (a) What are the sequence of operations of robot in the manufacturing cell? Ex-plain.

(b) What are the various components of the manufacturing cell? Explain thefunction of the components in the cell. [6+10]

2. Discuss the architectural considerations of robotic systems. [16]

3. (a) What are the three classifications of an end effector?

(b) A piston is to be designed to exert an actuation force of 750 pounds on itsextension stroke. The inside diameter of the piston is 50mm, and the ramdiameter is 18.75 mm.What shop air pressure will be required to provide thisactuation force? Use a safety factor of 1.5. [6+10]

4. In a roll-pitch-roll convention, roll stands for rotation () about z-axis, pitch forrotation () about new y-axis, and roll again () about new z-axis. The roll-pitch-roll geometry can be represented by Euler angles. Show that the overall rotationmatrix RRPR (, , ) is given by

RRPR (, , ) =

CCC SS CCS SC CS

SCC+ CS SCS+ CC SSSC SS C

where C = cos, C = cos, C = cos, S = sin, S = sin, and S = sin.[16]

5. Explain the method of Assignment of DH frames with the help of an example anddefine the link parameters. [16]

6. For the 6-DOF Stanford manipulator in figure 6. Obtain the Jacobian. [16]

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Figure 6

7. For a three-degree of freedom, cylindrical manipulator, design a linear trajectorywith parabolic blends. The initial position of the end-effector is expressed by thehomogeneous matrix Ts and the goal position by Tg as [16]

Ts =

0 1 0 2001 0 0 1000 0 1 1000 0 0 1

Tg =

1 0 0 500 1 0 2000 0 0 4000 0 0 1

8. A certain dc servomotor used to actuate a robot joint has a torque constant of 312.5cm-N/A, and a voltage constant of 1.5 V/Kr/min (1 Kr/min = 1000 rev/min).Thearmature resistance = 3.0 . At a particular moment during the robot cycle, thejoint is not moving and a voltage of 30 V is applied to the motor.

(a) Determine the torque of the motor immediately after the voltage is applied.

(b) Determine the back-emf and the corresponding torque of the motor at 500 and1000 rev/min.

(c) If there were no resisting torques and no inductance of the armature wind-ings operating to reduce the speed of the motor, determine the maximumtheoretical speed of the motor when the input voltage is 30 V.

(d) If the resisting torques due to friction and the payload being carried by therobot total 900 cm-N, determine the maximum theoretical speed of the motorwhen the input voltage is 30 V. Assume no effect of inductance from thearmature windings. [4+4+4+4]

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1. Discuss the following future applications of robots in service industries

(a) Bank Tellers

(b) Garbage collection and Waste disposal

(c) Fast food restaurants. [6+5+5]


(a) Cartesian configuration

(b) Cylindrical configuration. [8+8]

3. (a) In what ways do end effectors differ from the human hand ?

(b) A vaccum gripper is to be designed to handle flat plate glass in an automobilewindshield plant. Each plate weighs 175 N. A single suction cup will beused, and the diameter of the suction cup is 125 mm. Determine the negativepressure required to lift each plate. Use a safety factor of 2 in your calculations.

[4+12]

4. The homogeneous transformation matrices between frames {i} - { j} and {i} - {k}are : [16]

jTi=

0BBBBBB@

0.866 0.500 0 110.500 0.866 0 10 0 1 80 0 0 1

1CCCCCCA; kTi=

0BBBBBB@

1 0 0 00 0.866 0.500 100 0.500 0.866 200 0 0 1

1CCCCCCA

Determine jTk

5. For a simple elbow manipulator. Table presents the joint parameters. Find thecomplete set of inverse kinematics solutions. [16]Table:Joint d a1 1 90

0 0 02 2 0

0 0 a23 3 90

0 0 a34 4 90

0 0 a45 5 90

0 0 06 6 0

0 0 0

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6. Develop the expressions for the joint torques of a planar R-R manipulator usingNewton-Euler Formulation. [16]

7. A single-link robot with a rotary joint is motionless at = -50. It is desired tomove the joint in a smooth manner to = 800 in 4 seconds. Find the coefficientsof a cubic which accomplishes this motion and brings the arm to rest at the goal.Plot the position, velocity, and acceleration of the joint as a function of time. [16]






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1. Discuss a parallel robotic assembly system with the help of an example. [16]


(a) Spherical configuration

(b) Articulated configuration. [8+8]

3. (a) What are the two major categories of end effectors?

(b) A part weighting 75 N is to be grasped by a mechanical gripper using frictionbetween two opposing fingers. The coefficient of static friction is 0.35 and thecoefficient of dynamic friction is 0.20. The direction of the acceleration forceis parallel to the contacting surfaces of the gripper fingers. Which value ofcoefficient of friction is appropriate to use in the force calculations? Why?Compute the required gripper force by assuming a g factor of 2.0. [4+12]

4. Consider the coordinate frames O, A, B, and C shown in figure 4. where O is thereference frame. Determine the homogeneous transforms corresponding to framesA, B, and C with respect to O. [16]

Figure 4

5. (a) What do you mean by symbolic Notation? Explain.

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(b) Derive the Denavit and Hartenberg 44 transformation matrix. [6+10]

6. Develop the expressions for the joint torques of a planar R-R manipulator usingNewton-Euler Formulation. [16]

7. The motion of a joint from start to goal position is specified in terms of position,velocity and acceleration at the beginning and end of a path segment. Determinethe coefficients of the fifth-degree (quintic) polynomial for interpolating the smoothtrajectory in the segment. [16]






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rr420305-robotics.pdf

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