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Unit 4: Robot Mechanical Design Parameters - Practice Quiz

ECE244 — Elements Of Robotics 60 Questions
0 Correct 0 Wrong 60 Left
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1 What does robot kinematics study?

Introduction to robot kinematics Easy
A. The electrical wiring of robots
B. The strength of robot materials
C. The motion of robots without considering forces
D. The temperature of robot motors

2 What is the main purpose of a coordinate frame in robotics?

Coordinate frames and transformations Easy
A. To measure motor temperature
B. To store program instructions
C. To describe positions and orientations
D. To control battery voltage

3 What does a transformation between two coordinate frames usually describe?

Coordinate frames and transformations Easy
A. Sensor size and resolution
B. Relative position and orientation
C. Material weight and density
D. Motor power and current

4 What does the number of degrees of freedom of a robot indicate?

Degrees of Freedom (DOF) Easy
A. The number of batteries used
B. The number of independent motions
C. The number of sensors installed
D. The number of robot colors

5 Which type of motion is an example of one degree of freedom?

Degrees of Freedom (DOF) Easy
A. Changing three link lengths at once
B. Changing the robot's control software
C. Moving in every direction simultaneously
D. Rotation about one joint axis

6 Which pair is used to describe the pose of a robot end-effector?

Position and orientation of robots Easy
A. Position and orientation
B. Mass and temperature
C. Speed and battery level
D. Voltage and resistance

7 What is the input to a forward kinematics calculation?

Forward kinematics: Concept and applications Easy
A. End-effector force only
B. Camera brightness only
C. Joint variables and link dimensions
D. Motor temperature only

8 What is the usual output of forward kinematics?

Forward kinematics: Concept and applications Easy
A. The end-effector pose
B. The battery capacity
C. The controller brand
D. The motor material

9 What does inverse kinematics determine?

Inverse kinematics: Concept and applications Easy
A. The temperature of the workspace
B. Joint variables for a desired pose
C. The voltage of an external lamp
D. The color of each robot link

10 Why can inverse kinematics have more than one solution?

Inverse kinematics: Concept and applications Easy
A. Each joint has several colors
B. A pose may be reached by different joint configurations
C. A robot always has several batteries
D. Sensors measure different temperatures

11 What relationship does the robot Jacobian commonly describe?

Velocity kinematics and Jacobian (Introduction) Easy
A. Link mass and battery voltage
B. Tool shape and sensor brightness
C. Motor color and joint temperature
D. Joint velocities and end-effector velocity

12 What can occur when a robot reaches a kinematic singularity?

Velocity kinematics and Jacobian (Introduction) Easy
A. All motors stop receiving electricity permanently
B. The robot gains unlimited joint strength
C. The links automatically become longer
D. Some motions become difficult or unavailable

13 What is a robot path?

Robot trajectory and path planning (Basics) Easy
A. A sequence of positions to follow
B. A list of motor temperatures
C. A record of link colors
D. A map of electrical resistances

14 What additional information does a trajectory usually include compared with a path?

Robot trajectory and path planning (Basics) Easy
A. Paint thickness
B. Sensor packaging
C. Timing information
D. Battery manufacturer

15 What does robot dynamics study?

Introduction to robot dynamics Easy
A. Only the names of robot joints
B. Only the shape of control panels
C. Motion in relation to forces and torques
D. Only the colors of robot parts

16 Which laws form the basis of the Newton–Euler formulation?

Newton–Euler formulation (Concept) Easy
A. The laws of magnetic storage
B. The laws of optical reflection
C. Newton's laws of motion
D. The laws of chemical bonding

17 Which two types of energy are commonly used in the Lagrangian formulation?

Lagrangian formulation (Concept) Easy
A. Kinetic and potential energy
B. Electrical and chemical energy
C. Nuclear and magnetic energy
D. Light and sound energy

18 What is torque most closely associated with?

Forces and torques in robotic manipulators Easy
A. A measure of electrical insulation
B. A measure of color intensity
C. A turning effect of a force
D. A measure of air humidity

19 When is a robot in static balance?

Static and dynamic balance Easy
A. When all links are moving rapidly
B. When forces and torques are balanced at rest
C. When the robot has no control program
D. When every joint rotates continuously

20 Which industrial task commonly uses robot kinematics and dynamics?

Applications of kinematics and dynamics in industrial robots Easy
A. Measuring office lighting only
B. Planning and controlling welding motion
C. Selecting the factory wall color
D. Printing employee identification cards

21 A robot's joint variables are known, but the position of its end-effector relative to the base is required. Which branch of robot kinematics addresses this calculation?

Introduction to robot kinematics Medium
A. Trajectory optimization
B. Robot statics
C. Inverse kinematics
D. Forward kinematics

22 A point has coordinates in frame . The homogeneous transformation from frame to frame is . How is the point expressed in frame ?

Coordinate frames and transformations Medium
A.
B.
C.
D.

23 A planar robot has two revolute joints and one prismatic joint, all independently actuated. How many degrees of freedom does it have?

Degrees of Freedom (DOF) Medium
A. Three
B. Two
C. Six
D. One

24 A rigid robot end-effector operates in three-dimensional space. Which combination completely specifies its pose?

Position and orientation of robots Medium
A. Joint velocities and accelerations
B. Three orientation angles only
C. Three position coordinates only
D. Three position and three orientation parameters

25 For a planar two-link robot with link lengths and , which expression gives the end-effector -coordinate for joint angles and ?

Forward kinematics: Concept and applications Medium
A.
B.
C.
D.

26 A planar two-link robot is asked to reach a point beyond its maximum reach. What is the expected result of inverse kinematics?

Inverse kinematics: Concept and applications Medium
A. A unique joint solution is obtained
B. No real joint solution exists
C. Two valid joint solutions are obtained
D. The Jacobian becomes diagonal

27 A six-axis industrial robot reaches the same Cartesian target using two different joint configurations. This illustrates which property of inverse kinematics?

Inverse kinematics: Concept and applications Medium
A. The forward model is time-dependent
B. The target is dynamically unstable
C. The robot has zero degrees of freedom
D. The robot has multiple inverse solutions

28 The relationship between joint velocity and end-effector velocity is . What does the Jacobian represent?

Velocity kinematics and Jacobian (Introduction) Medium
A. The relation between torque and gravitational force only
B. The relation between path length and sampling time
C. The relation between joint velocities and Cartesian velocity
D. The relation between joint positions and mass

29 When a robot configuration causes its Jacobian to lose rank, what is the primary consequence?

Velocity kinematics and Jacobian (Introduction) Medium
A. The robot reaches every direction more easily
B. All joint torques become zero
C. Some Cartesian velocities become unattainable
D. The robot's link masses change

30 A robot must move from one configuration to another while limiting sudden changes in motor commands. Which trajectory property is most directly useful?

Robot trajectory and path planning (Basics) Medium
A. Continuous velocity and acceleration
B. Continuous position only
C. Discontinuous position
D. Random intermediate configurations

31 A collision-free path is found for a robot, but the path passes very close to an obstacle. Which planning modification generally improves operational safety?

Robot trajectory and path planning (Basics) Medium
A. Add a clearance margin around obstacles
B. Use larger joint accelerations
C. Ignore the robot's link geometry
D. Reduce the number of joints

32 Which statement best distinguishes robot dynamics from robot kinematics?

Introduction to robot dynamics Medium
A. Dynamics relates motion to forces and torques
B. Dynamics describes position without time
C. Kinematics calculates only collision forces
D. Kinematics requires motor mass properties

33 The Newton–Euler formulation derives manipulator equations primarily by applying which laws to each link?

Newton–Euler formulation (Concept) Medium
A. Thermodynamic equilibrium
B. Force and moment balance
C. Conservation of electrical charge
D. Geometric projection rules

34 A recursive Newton–Euler algorithm usually performs an outward recursion followed by an inward recursion. What is the purpose of these two passes?

Newton–Euler formulation (Concept) Medium
A. To determine path length and then obstacle locations
B. To calculate friction and then workspace volume
C. To propagate velocities and accelerations, then forces and torques
D. To compute joint angles and then link colors

35 In the Lagrangian formulation of robot dynamics, the Lagrangian is defined as:

Lagrangian formulation (Concept) Medium
A.
B.
C.
D.

36 For a generalized coordinate , the Euler–Lagrange equation used in robot dynamics is:

Lagrangian formulation (Concept) Medium
A.
B.
C.
D.

37 An end-effector applies a force to a workpiece. The corresponding joint torques can be estimated using which relation?

Forces and torques in robotic manipulators Medium
A.
B.
C.
D.

38 A robot holds a payload motionless with its arm extended horizontally. Compared with holding the same payload close to the shoulder joint, the required shoulder torque is generally:

Forces and torques in robotic manipulators Medium
A. Larger because the moment arm is longer
B. Zero because the payload is stationary
C. Smaller because the arm is extended
D. Unchanged because velocity is zero

39 A stationary robot carrying a load is statically stable when the projection of its combined center of mass lies:

Static and dynamic balance Medium
A. Inside the support polygon
B. Outside the support polygon
C. At the end-effector origin
D. On the robot's highest link

40 During rapid motion, a robot may tip even when its static center-of-mass projection is inside the support polygon. Which effect best explains this risk?

Static and dynamic balance Medium
A. Joint angles stop affecting the center of mass
B. The support polygon becomes infinitely large
C. Inertial forces shift the effective balance condition
D. Gravity becomes zero during acceleration

41 A serial manipulator has joint coordinates and task coordinates . Which statement correctly distinguishes kinematics from dynamics?

Introduction to robot kinematics Hard
A. Kinematics maps joint variables to pose without modeling mass or force effects.
B. Kinematics determines actuator torque directly from link inertia and gravity.
C. Kinematics applies only to revolute joints and excludes prismatic joints.
D. Kinematics maps external wrench, friction, and inertia to joint acceleration.

42 A point has coordinates in frame , and frame is related to frame by . Which expression gives the point coordinates in frame using homogeneous coordinates?

Coordinate frames and transformations Hard
A.
B.
C.
D.

43 Two transformations are given by and . What is the correct interpretation of their product?

Coordinate frames and transformations Hard
A.
B.
C.
D.

44 A rigid body moving freely in three-dimensional space requires six independent coordinates. If a manipulator's six joint axes become linearly dependent at a particular configuration, what is the most accurate consequence?

Degrees of Freedom (DOF) Hard
A. Its joint coordinates cease to be valid generalized coordinates everywhere.
B. Its number of physical joints immediately becomes smaller.
C. Its reachable workspace necessarily becomes completely disconnected.
D. Its instantaneous task-space mobility drops below six.

45 A planar mechanism contains four rigid links, including the ground, and four revolute joints. Using the planar Grübler criterion , what is its mobility, assuming no redundant constraints?

Degrees of Freedom (DOF) Hard
A.
B.
C.
D.

46 Which statement about representing orientation with roll-pitch-yaw angles is correct near a pitch angle of ?

Position and orientation of robots Hard
A. The orientation loses one physical degree of freedom permanently.
B. The representation can suffer a coordinate singularity.
C. The representation becomes more numerically stable than quaternions.
D. The rotation matrix ceases to represent a proper rotation.

47 A unit quaternion and its negative represent which relationship?

Position and orientation of robots Hard
A. They represent orientations separated by a rotation.
B. They are valid only when the quaternion has zero scalar part.
C. They represent the same physical orientation.
D. They represent rotations about opposite axes by equal angles.

48 For a two-link planar arm with link lengths and joint angles , which position equation follows from standard serial-chain geometry?

Forward kinematics: Concept and applications Hard
A.
B.
C.
D.

49 A constant tool transform is appended to a robot's flange transform. If the flange pose is and the tool transform is , which expression gives the end-effector pose?

Forward kinematics: Concept and applications Hard
A.
B.
C.
D.

50 For a two-link planar arm, a target satisfies . What does this condition imply when joint limits are ignored?

Inverse kinematics: Concept and applications Hard
A. Two distinct elbow configurations generally exist.
B. Infinitely many solutions exist because the arm is kinematically redundant.
C. No real joint solution exists because the target is inside the workspace.
D. Exactly one solution exists because the target lies on the workspace boundary.

51 Near a singular configuration, a damped least-squares inverse-kinematics update is preferred because it

Inverse kinematics: Concept and applications Hard
A. removes all dependence on the manipulator's geometric Jacobian.
B. limits excessive joint motion caused by small singular values.
C. guarantees an exact pose solution for every unreachable target.
D. converts every redundant manipulator into a uniquely solvable arm.

52 For a manipulator described by , what does a rank-deficient Jacobian imply at the current configuration?

Velocity kinematics and Jacobian (Introduction) Hard
A. Every joint velocity produces the same Cartesian velocity.
B. The manipulator has no reachable configurations outside the current pose.
C. Some task-space velocity directions cannot be produced instantaneously.
D. The forward-kinematics function is undefined for the current joint vector.

53 For a six-dimensional task with a square nonsingular Jacobian, a desired twist is converted to joint velocity by

Velocity kinematics and Jacobian (Introduction) Hard
A.
B.
C.
D.

54 A cubic joint trajectory is required to satisfy specified initial and final positions and velocities. Why is a cubic polynomial generally sufficient?

Robot trajectory and path planning (Basics) Hard
A. It guarantees constant Cartesian velocity even for nonlinear kinematics.
B. It minimizes torque for every robot regardless of its dynamics.
C. It has four coefficients matching the four boundary conditions.
D. It avoids all collisions because joint coordinates vary monotonically.

55 Why can a straight-line Cartesian path produce nonconstant joint speeds or even violate joint limits?

Robot trajectory and path planning (Basics) Hard
A. A straight Cartesian path has undefined velocity at every intermediate point.
B. The inverse-kinematic mapping is generally nonlinear and configuration dependent.
C. Cartesian straight lines are always longer than all feasible joint-space paths.
D. Joint limits affect only orientation and never affect position trajectories.

56 Which equation represents the standard rigid-manipulator dynamics, including inertia, velocity coupling, gravity, and applied joint torque?

Introduction to robot dynamics Hard
A.
B.
C.
D.

57 What is the defining computational structure of the recursive Newton–Euler algorithm for inverse dynamics?

Newton–Euler formulation (Concept) Hard
A. Backward recursion computes link accelerations from the base before forward propagation of velocities.
B. Forward recursion computes only potential energy; backward recursion computes joint positions.
C. Forward recursion computes velocities and accelerations; backward recursion computes forces and torques.
D. Both recursions propagate only homogeneous transforms and do not use force equations.

58 For generalized coordinates , the Lagrangian is . Which Euler–Lagrange equation gives the generalized force ?

Lagrangian formulation (Concept) Hard
A.
B.
C.
D.

59 An end-effector wrench is applied to a manipulator at configuration . Under virtual-work consistency, what joint torque results from this wrench?

Forces and torques in robotic manipulators Hard
A.
B.
C.
D.

60 A stationary manipulator supports a payload under gravity. Which condition best characterizes static equilibrium when joint friction is neglected?

Static and dynamic balance Hard
A.
B.
C.
D.
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