What is inverse kinematics?
Inverse kinematics works backward from a goal. Given where you want a robot's end-effector to be, it computes the joint angles that put it there. This is the reverse of forward kinematics, which goes from known joint angles to the resulting end-effector pose, and it is generally the harder direction.
It is fundamental to any robot that must reach a specific point in space, from a manipulator arm to a humanoid.
Key takeaways
- Inverse kinematics finds joint angles to reach a target end-effector pose.
- It is the reverse of forward kinematics and usually harder to solve.
- A target can have zero, one, or many valid joint solutions.
How it works
Given a target pose and the robot's geometry, solvers compute joint values either with closed-form equations for simple arms or with iterative numerical methods for complex ones. Depending on the robot's degrees of freedom, there may be no solution, a unique one, or infinitely many, so solvers often add preferences such as avoiding joint limits or staying close to the current pose. The chosen configuration then feeds motion planning and control.
Why it matters
Inverse kinematics is what translates a desired hand or tool position into commands a robot can execute, making it central to manipulation and teleoperation. Its handling of multiple solutions and constraints is a core reason robot control is more than just pointing at a target.
Frequently asked questions
How is inverse kinematics different from forward kinematics?
Forward kinematics computes the end-effector pose from known joint angles, while inverse kinematics computes the joint angles needed to achieve a desired pose.
Why can inverse kinematics have multiple solutions?
A robot with enough degrees of freedom can reach the same target in different ways, so several joint configurations may satisfy the same goal.
Related terms