The six possible degrees of freedom in physics and mechanical engineering, especially when related to rigid body motion, are usually divided into two categories: translation and rotation.
1. Translation:
- Translational motion refers to the movement of an object in a straight line in space without changing its direction or attitude.
- A rigid body can translate in three degrees of freedom: forward/backward (X-axis direction), up/down (Y-axis direction, assuming the ground is horizontal), left/right (Z-axis direction, perpendicular to the X-axis and Y-axis).
2. Rotation:
- Rotational motion refers to the circular motion of an object around a point or axis, which changes its direction or attitude.
- A rigid body can also rotate in three degrees of freedom: pitch (rotation around the Y-axis), roll (rotation around the X-axis), and yaw (rotation around the Z-axis).
Therefore, the six possible degrees of freedom can be divided into two categories: translation and rotation. These two degrees of freedom together describe the complete motion capabilities of a rigid body in three-dimensional space. Whether it is a simple mechanical component or a complex robotic system, its movement can be accurately described and controlled by a combination of these six degrees of freedom.
It should be noted that the degree of freedom classification here is based on the motion characteristics of a rigid body in three-dimensional space, which may be different from the degree of freedom classification of the human body or other non-rigid body systems.
In human kinematics, degrees of freedom are usually used to describe the flexibility and range of motion of joints, but also involve two types of motion: translation and rotation.
However, in specific applications, it is necessary to select the appropriate degree of freedom classification and description method based on the actual situation and field characteristics.