CRE CRE Robot Kinematics & Mechanics 2

Question 1

The Newton-Euler dynamic formulation in robotics is primarily used to compute:

Accepted Answer

Joint torques and forces required to produce a desired motion

Answer

Newton-Euler formulation recursively applies Newton's laws to each link to calculate the joint forces and torques needed for a given trajectory.

Question 2

Which parameter quantifies a robot link's resistance to angular acceleration based on its mass distribution?

Accepted Answer

Moment of inertia

Answer

The moment of inertia captures how mass is distributed relative to the rotation axis, directly resisting changes in angular velocity.

Question 3

In a trapezoidal velocity profile for joint motion, the three phases are:

Accepted Answer

Accelerate, constant velocity, decelerate

Answer

A trapezoidal profile linearly increases velocity to a cruise speed, maintains it, then linearly decelerates to rest.

Question 4

Coulomb friction in robot joints primarily degrades:

Accepted Answer

Positional accuracy during slow or stop-start motion

Answer

Coulomb (sliding) friction creates stiction that makes precise positioning difficult, especially during low-speed or fine-adjustment motions.

Question 5

Gravity compensation in robot control works by:

Accepted Answer

Applying feedforward torques to counteract gravitational loads on each link

Answer

Gravity compensation feeds precomputed anti-gravity torques to each joint so the robot holds position without relying solely on feedback error.

CRE - Certified Robotics Engineer Practice Test