forward kinematics
A calculation that determines where the end-effector (hand/gripper) is positioned in space based on knowing all the joint angles. Think: “If I know the angle of every joint, where is my hand pointing?”
The opposite of inverse kinematics.
What it is:
A mathematical calculation that determines the exact position and orientation of the robot's hand (end-effector) in 3D space when you know all the angles of every joint in the robot's arm.
The core question:
"If my shoulder is at 45°, my elbow at 90°, and my wrist at 120°, where exactly is my hand pointing in space?"
How it works:
Starting from the robot's base, you apply the Denavit-Hartenberg (DH) parameters for each joint sequentially:
- Start at the base (origin)
- Apply joint 1's angle → move to end of link 1
- Apply joint 2's angle → move to end of link 2
- Continue through all joints...
- Result: The exact 3D position (X, Y, Z) and orientation of the hand
The difference from inverse kinematics:
- Forward kinematics: Joint angles → Hand position (straightforward calculation)
- Inverse kinematics: Hand position → Joint angles (complex calculation, often with multiple solutions)
Why it matters:
- Visualization — You can predict where the hand will be before actually moving
- Collision detection — Check if the arm will hit obstacles
- Validation — Verify that inverse kinematics solutions are correct
- Feedback — Compare where the hand actually is versus where it should be
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