Question

What is a degree-of-freedom in the context of kinematics?
1. Minimum dependent coordinates to describe the configuration
2. Maximum independent coordinates to describe the configuration
3. Maximum dependent variables specified to describe the configuration
4. Minimum independent variables specified to fix the configuration

Answer 1

Correct Answer - Option 4 : Minimum independent variables specified to fix the configuration

Explanation:

In kinematics:

Degree of Freedom: The degree of freedom (DOF) of a mechanical system is the minimum number of independent variables required to define the position or motion of the system. 

For a simple mechanism, the degree of freedom (F) is given by Grubler’s criterion:

F = 3 (n - 1) - 2j - h

Where, j = number of revolute joints, n = number of links, h = number of higher pairs

If F > 1 ⇒ more than 1 input required to obtain a definite motion of links

if F = 1 ⇒ Only 1 input required to obtain a definite motion of links ⇒ Kinematic chain

If F = 0 ⇒ It has zero mobility ⇒ Frame

If F < 0 ⇒ It is a redundant frame.