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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 motion of robots without considering forces
C. The strength of robot materials
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 describe positions and orientations
C. To store program instructions
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. Material weight and density
C. Relative position and orientation
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 robot colors
B. The number of sensors installed
C. The number of independent motions
D. The number of batteries used

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. Rotation about one joint axis
C. Changing the robot's control software
D. Moving in every direction simultaneously

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. Speed and battery level
C. Voltage and resistance
D. Mass and temperature

7 What is the input to a forward kinematics calculation?

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

8 What is the usual output of forward kinematics?

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

9 What does inverse kinematics determine?

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

10 Why can inverse kinematics have more than one solution?

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

11 What relationship does the robot Jacobian commonly describe?

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

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

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

13 What is a robot path?

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

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

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

15 What does robot dynamics study?

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

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 chemical bonding
C. Newton's laws of motion
D. The laws of optical reflection

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

Lagrangian formulation (Concept) Easy
A. Electrical and chemical energy
B. Kinetic and potential 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 turning effect of a force
B. A measure of color intensity
C. A measure of air humidity
D. A measure of electrical insulation

19 When is a robot in static balance?

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

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. Printing employee identification cards
D. Selecting the factory wall color

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. Inverse kinematics
B. Forward kinematics
C. Robot statics
D. Trajectory optimization

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. Two
B. Three
C. One
D. Six

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 position and three orientation parameters
C. Three orientation angles only
D. Three position coordinates only

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 robot has zero degrees of freedom
C. The robot has multiple inverse solutions
D. The target is dynamically unstable

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 path length and sampling time
B. The relation between joint velocities and Cartesian velocity
C. The relation between torque and gravitational force only
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. The robot's link masses change
C. Some Cartesian velocities become unattainable
D. All joint torques become zero

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. Random intermediate configurations
B. Continuous velocity and acceleration
C. Discontinuous position
D. Continuous position only

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. Kinematics calculates only collision forces
B. Dynamics relates motion to forces and torques
C. Dynamics describes position without time
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. Conservation of electrical charge
B. Thermodynamic equilibrium
C. Force and moment balance
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 calculate friction and then workspace volume
B. To propagate velocities and accelerations, then forces and torques
C. To determine path length and then obstacle locations
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. Zero because the payload is stationary
B. Larger because the moment arm is longer
C. Unchanged because velocity is zero
D. Smaller because the arm is extended

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. At the end-effector origin
B. Inside the support polygon
C. On the robot's highest link
D. Outside the support polygon

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. Gravity becomes zero during acceleration
D. Inertial forces shift the effective balance condition

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 external wrench, friction, and inertia to joint acceleration.
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 joint variables to pose without modeling mass or force effects.

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

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

47 A unit quaternion and its negative represent which relationship?

Position and orientation of robots Hard
A. They are valid only when the quaternion has zero scalar part.
B. They represent the same physical orientation.
C. They represent orientations separated by a rotation.
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. No real joint solution exists because the target is inside the workspace.
B. Infinitely many solutions exist because the arm is kinematically redundant.
C. Exactly one solution exists because the target lies on the workspace boundary.
D. Two distinct elbow configurations generally exist.

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. converts every redundant manipulator into a uniquely solvable arm.
C. guarantees an exact pose solution for every unreachable target.
D. limits excessive joint motion caused by small singular values.

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

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

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 has four coefficients matching the four boundary conditions.
B. It minimizes torque for every robot regardless of its dynamics.
C. It guarantees constant Cartesian velocity even for nonlinear kinematics.
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. Joint limits affect only orientation and never affect position trajectories.
D. Cartesian straight lines are always longer than all feasible joint-space paths.

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

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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