> ## Documentation Index
> Fetch the complete documentation index at: https://aegean.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Why robots move

> Relate a robot's motion to its causes, the masses, forces and torques that act on it.

Kinematics describes how a robot moves. Dynamics explains why it moves that way. The equations of motion relate the masses, forces and torques acting on a robot to the accelerations they produce. This chapter builds them for one rigid body and then for a whole robot arm.

<CardGroup cols={2}>
  <Card title="Rigid-body dynamics" icon="weight-hanging" href="/aiml-common/lectures/dynamics/rigid-body-dynamics/index">
    Form equations of motion with twists and wrenches. Content is planned for December 2026.
  </Card>

  <Card title="Inverse dynamics" icon="arrow-rotate-left" href="/aiml-common/lectures/dynamics/inverse-dynamics/index">
    Compute the joint torques for a desired motion with the recursive Newton-Euler algorithm. Content is planned for December 2026.
  </Card>

  <Card title="Forward dynamics" icon="play" href="/aiml-common/lectures/dynamics/forward-dynamics/index">
    Determine the motion produced by given joint torques and simulate the result. Content is planned for December 2026.
  </Card>

  <Card title="Constrained dynamics" icon="link" href="/aiml-common/lectures/dynamics/constrained-dynamics/index">
    Form equations of motion under Pfaffian constraints. Content is planned for December 2026.
  </Card>
</CardGroup>

## References

* [Cross product and torque](https://www.khanacademy.org/science/in-in-class11th-physics/in-in-class11th-physics-motion-in-a-plane/x7183bffa9768c609:scalar-and-vector-product-of-vectors/v/cross-product-and-torque) (Khan Academy). A short video on torque as the cross product of the lever arm and the force. Watch it before the wrenches on the rigid-body dynamics page.

***

<Callout icon="bug" iconType="regular">
  Found an error on this page? [Report an issue](https://github.com/aegean-ai/eaia-feedback/issues/new?template=page-issue.yml\&page=/book/dynamics).
</Callout>


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.