IC 1005- ROBOTICS & AUTOMATION2 Marks Question & Answer

1. Define a Robot?RIA defines arobot as a “programmable , multifunction manupulator designed to

Move materials, parts ,tools or special devices through variable programmed motions for the performance of the variety of tasks “.

2. What is meant by actuator.Most actuation uses electro-magnetic motors and gears but there have been

frequent questions regarding other forms of actuation including 'muscle-wires' and inexpensive RC-servos.

3. What other types of actuation are there? Types of motors:

Synchronous Stepper AC servo Brushless DC servo Brushed DC servo

4. What are the types of hydraulic actuators ?The types of hydraulic actuators are

Linear hydraulic actuatorSingle acting cylinderDouble acting cylinderDouble acting double rod cylinderHydraulic rotary actuatorGear motorVane motorPiston motor

5. What is meant by workspace?The space in which the end point of the robot arm is capable of operating is called

as workspace in other words reachability of robot arm is known as workspace.

6. What is meant by work volume?The volume of the space swept by the robot arm is called work volume.

7. What is meant by work envelope ?The work envelop is described by the surface of the work space.

8. Define End effector.End effector is a device that is attached to the end of the wrist arm you perform

specific task .

9. Give some examples of tool as Robot End effectorSpot Welding Tools Arc welding Torch Spray painting nozzle Water jet cutting tool

10. W hat are the methods of Robot programming : a. Lead through methodsb. Texual robot languagesc. Mechanical Programming

11. List some application of robot in loading and unloading a. Die castingb. Injection mouldingc. Forming ,stamping d. Trimming process

12. List some advantages vs Disadvantages of Robots

¨ Robots work continuously without experiencing fatigue of problem.

¨ Robots have repeatable precision at all times.

¨ Robots can be much more accurate than human.

¨ Robots replace human workers creating economic problems.

¨ Robots lack capability to respond in emergencies.

¨ Robots, although superior in certain senses, have limited capabilities in Degree of

freedom, Dexterity, Sensors, Vision system, real time response.

¨ Robots are costly, due to Initial cost of equipment, Installation costs, Need for Peripherals,

Need for training, Need for programming.

13. Classify Robot based on JIRA Class1: Manual-Handling Device

Class2: Fixed Sequence Robot

Class3: Variable Sequence Robot

Class4: Playback Robot

Class5: Numerical Control Robot

Class6: Intelligent Robot

14. What are the various types of AFR (Association FranÇaise de Robotique)

Type A: Manual Handling Devices/ telerobotics

Type B: Automatic Handling Devices/ predetermined cycles

Type C: Programmable, Servo controlled robot, continuous point-to-point trajectories

Type D: Same type with C, but it can acquire information

15. Mention classes of RIA (Robotics Institute of America).

Variable Sequence Robot(Class3)

Playback Robot(Class4)

Numerical Control Robot(Class5)

Intelligent Robot(Class6)

16. Define Robots degrees of freedom

Number of independent position variables which would has to be specified to

locate all parts of a mechanism. In most manipulators this is usually the number of joints.

17. Name the commonly used robot configuration system ?The commonly used robot configuration system are• Cartesian coordinate system• Cylindrical coordinate system• Polar or spherical coordinate system• Revolute coordinate system

18. What is forward kinematics?It is a scheme to determine joint angles of a robot by knowing its position in the world coordinate system

19. What is reverse kinematics?It is a scheme to determine the position of the robot in the world coordinate system by knowing the joint angles and the link parameters of the robot.

20. List the various actuating mechanisms used in mechanical grippers.Linkage actuation gripperGear and rack actuation gripperCam actuated gripperScrew actuated gripper

21. Sketch the revolving joint and show the relative joint motions?

22. What is meant by right hand co-ordinate system.In a right handed coordinate system, if you know the directions of two out of the three

axes, you can figure out the direction of the third. Let’s suppose that you know the directions of the x and y axes. For example, suppose that x points to the left, and y points out of the paper, as shown in Fig.

23. What is a Homogeneous TransformationsA transformation matrices must be in square form.

• It is much easier to calculate the inverse of square matrices.• To multiply two matrices, their dimensions must match.

24. Write the procedure for Denavit-Hartenberg representationStart point:

Assign joint number n to the first shown joint. Assign a local reference frame for each and every joint before or after these joints.

Y-axis does not used in D-H representation. Procedures for assigning a local reference frame to each joint:

All joints are represented by a z-axis. (right-hand rule for rotational joint, linear movement for prismatic joint)

.The common normal is one line mutually perpendicular to any two skew lines ٭ .Parallel z-axes joints make a infinite number of common normal ٭

F=[nx ox ax Px

n y oy a y P y

nz oz az P z

0 0 0 1]

Intersecting z-axes of two successive joints make no common normal between ٭them(Length is 0.).

25. Define Degeneracy The robot looses a degree of freedom and thus cannot perform as desired. When the robot’s joints reach their physical limits, and as a result, cannot move any further.

In the middle point of its workspace if the z-axes of two similar joints becomes colinear.

26. Define Dexterity: The volume of points where one can position the robot as desired, but not orientate it.

27. Write the Programming of inverse kinematic of robots

A robot has a predictable path on a straight line, Or an unpredictable path on a straight line. A predictable path is necessary to recalculate joint variables. (Between 50 to 200 times a second) To make the robot follow a straight line, it is necessary to break the line into many small

sections. All unnecessary computations should be eliminated.

28. What is meant by (D-H) model.A commonly used convention for selecting frames of reference in robotics applications is the Denavit and Hartenberg (D-H) conventional In this convention, each homogeneous transformation is represented as a product of four basic transformations. The common normal between two lines was the main geometric concept that allowed Denavit and Hartenberg to find a minimal representation.

29. Define Jacobian Jacobian is a representation of the geometry of the elements of a mechanism in

time.

30. List the differential motion of a frame Differential translations, Differential rotations, Differential transformations(translations and rotations).

31. Define Differential Translations & rotation & its representation.Differential Translations

¨ Definition: A translation of a frame at differential values. ¨ Representation : Trans(dx, dy, dz)

Differential rotations ¨ Definition: A small rotation of a frame at differential values.

¨ Representation: Rot(k, dq)

32. How to relate the jacobian and the differential operator The differential motions of the robot’s joints are ultimately related to the hand frame of the robot.

Method 1 ¨ Jacobian calculate [D] matrix¨ [D] contains differential motions of the hand, dx, dy, dz, dx, dy, dz.¨ Used to calculate dT

Method 2¨ Jacobian calculate [T6D] matrix

¨ [D] contains differential motions of the hand T6dx, T6dy, T6dz, T6dx, T6dy, T6dz.

¨33. What is Lagrangian mechanics

Lagrangian mechanics is based on the differentiation energy terms only, with respect to the system’s variables and time.

34. Define Robot’s Equations of Motion

The Lagrangian is differentiated to form the dynamic equations of motion. The final equation of motion for a general multi-axis robot is below.

35. What is the kinetic energy of a rigid body with motion in three dimension ?

36. Write the kinetic energy of a rigid body in planar motion?

37. What is meant by Euler angles? Any orientation of one frame with respect to another may be written as a single rotation about a fixed axis

38. Define Trajectory planning,

It “interpolate” or “approximate” the desired path by a class of polynomial

functions and generates a sequence of time-based “control set points” for the

control of manipulator from the initial configuration to its destination.

K=12

mV 2+ 12

ω__

hG

K=12

mV 2+ 12

I ω2

39. Differentiate Path Vs trajectoryPath: A sequence of robot configurations in a particular order without regard to the timing of these configurations. Trajectory: It concerned about when each part of the path must be attained, thus specifying timing.

40. Compare Joint-space Vs Cartesian-space descriptions Joint-space description:

- The description of the motion to be made by the robot by its joint values. - The motion between the two points is unpredictable.

Cartesian space description: - The motion between the two points is known at all times and controllable.

- It is easy to visualize the trajectory, but is is difficult to ensure that singularity.

41. State Cartesian-space trajectories.

Cartesian-space trajectories relate to the motions of a robot relative to the Cartesian reference frame.

In Cartesian-space, the joint values must be repeatedly calculated through the inverse kinematic equations of the robot.

42. What is 4-3-4 trajectory?

43. Illustrate the Linear Segments with Parabolic Blends

Linear segment can be blended with parabolic sections at the beginning and the end of the motion segment, creating continuous position and velocity. Acceleration is constant for the parabolic sections, yielding a continuous velocity at the common points A and B.

44. Sketch out the trajectory planning

45. What is the need of continuous trajectory recording?

46. State the Linearization Techniique:

The most widely used are based on feedback linearization, that is,

cancellation of the known non-linearities that are replaced by a linear, time invariant and

decoupled model, for which classical control design techniques can be employed. In order

to ensure insensitivity to model uncertainties, parameter variations and external

disturbances, adaptive and robust control schemes are often employed in conjunction with

the non-linear decoupling feedback.

47. Sketch the variety of automatic and robotized system as functions of productivity level &

product demand

48. What is meant by manipulator dynamics .It is concerned with the equations of motion, the way in which the manipulator moves in response to torques applied by the actuators or external forces.

49. State the 2 problems relating to manipulator dynamics Inverse Dynamics in which the manipulator’s equations of motion are solved for

given motion to determine the generalized forces.Direct Dynamic in which the equations of motion are integrated to determine the

generalized coordinate response to applied generalized forces50. What are the types of Grippers?

Magnetic GripperMechanical GripperHooking Gripper

Vacuum Gripper