# Pune University Exam Paper

## ROBOTICS (Elective – II)

Time: 3 Hours]                                                                                                                    [Max.     Marks: 100

Instructions to the candidates:

1)                     Answer three questions from Section -1 and three questions from Section – II.

2)                                             Answers to the two sections should be written in separate books.

3)                     Neat diagrams must be drawn wherever necessary.

4)                     Figures to the right indicate full marks.

5)                     Use of logarithmic tables, slide rule, mollier charts, electronic pocket calculator is allowed.

SECTION – I

    

Ql) a) Write a note on Robot Generations.

b)                                                                                                                                                                                                                                                                                                                                                                                            Explain Robot Anatomy with the help of sketch.

c)                                                                                                                                                                                                                                                                                                                                                                                                                                              Explain difference between Repeatability and Accuracy.

d)                                                                                                                                                                                                                                                                                                                                                                                                                                             Explain the tenn “Exoskeleton” with suitable example.

OR

Q2) a) Following is a rotation matrix having only one incorrect element. Identify

and rewrite the matrix by correcting that element. 

0.7231 0.1636   – 0.1167

– 0.4289         0.8679   0.2506

0.5415 – 0.4690 0.6977

 

b)                        Referring Figure – I, write following transformation matrices;

A                                   C

T and Td

Assume orientation of Z-Axes so that all coordinate systems will be right handed.

P.T.O.

 Q3) a)
 Vision System,;.
 Object
 0.7543 -0.3936 0.5254 55 0.1921 0.8976 0.3967 -60 -0.6278 -0.1983 0.7527 35 0 0 0 1
 b)

 Detennine the new relation if the object is rotated by 35° with respect to its own X-axis and translated by 20 units along Z-axis of vision system.  Draw manipulator structure shown in Figure – 2 and attach coordinate frames at appropriate locations. List DH Parameters and determine transformation matrix between {Base} and {Gripper}.                                                                           

Relation between a vision system and an object is given by following transformation matrix;

OR

 Q4) a)

A 2R planar manipulator having link lengths LI = I25mm and L2 = 80mm is to be arranged in such a way that the free end will be located at (75, 75) with respect to the fixed end of the manipulator. State whether it is possible; if “yes” determine orientations of the links and if “no” state the reason.

Can the manipulator reach the same point if the link lengths are interchanged? If “yes” determine orientations of the links and if “no” state the reason.                                 

 b)

A 2R planar manipulator is required to locate its free end at (30, 25) with respect to the fixed end. State whether the point is reachable if the link lengths are LI = 180mm and L2 = 100mm. If “yes” determine orientations of the links and if “no” state the reason and suggest modification in the mechanism so as to reach the point.   

 Q5) a)

A planar manipulator shown in Figure – 3 is required to move in a straight line from (170, 0) to (110, 55) in 5 seconds. Determine third degree

 

polynomial equation for its rotary joint.

b)                   It is required to trace certain path by a planar manipulator shown in Figure – 4 in 7 seconds (linear path in 2.5 seconds and curved path in remaining duration with constant linear and rotational speeds respectively). List the joint parameters for each second staring from 0 to 7 seconds. 

OR

Q6) a)       Write a note on Control Law Partitioning.                                                           

b)     The characteristic equation of a second order control system is;

ms2 + bs + k = 0 where m = 1, b = 6 and k = 9.

Detennine position, speed and acceleration of mass in the system at time t = 0.5 seconds if it is initially at rest and displaced to a position x = 1.5. 

SECTION – II

Q7) a)  Explain mechanical grippers, what are the two ways of constraining the

part in the gripper.                              

b)                   Discuss various considerations for selection of a gripper systems. 

c)                    Explain typical vision system for a robot.        

OR

Q8) a)       Write short note on, continuous beam laser system.                                     

b)                   What is compliance? Explain active and passive compliance in brief. 

c)                    A vacuum gripper is used to lift flat steel plate of dimensions

7mm x 600mm x 900mm. The gripper uses to suction cups, 125 mm in diameter each, and they are located 450 mm apart for stability. Assume a factor of safety of 1.7 to allow for acceleration of the plate. Determine the negative pressure required to lift the plates if the density of steel is 8054.3 x 10 9kg/mm3.    

Explain with principle of operations, use of wrist force sensor for force sensing.  

 Q9 a) b) c) QIO) a) b) c) Qll)a) b) c) Q12)a) b) c)

Write a note on redundant Robot.                                                                   

Explain use of robot in spray painting.                                                          

OR

Explain different types of speed reduction 8 transmission systems used in robots.                                           

Explain use of robot in the welding.                                                               

Write various technical features required of robot for pick and place applications.           

Explain various performance characteristics of DC servo motors.  Write note on stepper motor.                                             

Compare hydraulic 8 electrical actuator based on weight, resolution, operating pressure and cost.                       

OR

Explain various methods used to enter the programming command into the controller memory.           

Explain generations of robot programming languages.                              

Explain WAIT, DELAY, SIGNAL command with suitable examples.