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Inverse Kinematics Part 1: Finding θ2 First
Inverse Kinematics Part 1: Finding θ2 First
How does finding θ₂ before θ₁ give us the foundation for programming a robot to reach a specific target?
Learning Intentions:
Calculate θ₂ using the IK formula D = (x² + y² − L1² − L2²) ÷ (2·L1·L2) and perform a reachability check before solving.
Today's Concept:
Inverse kinematics is the reverse problem: you know where you want the tip to go. You need to find the angles that get it there.
You always find θ₂ first. Here's why: θ₂ — the elbow angle — depends only on the target location. θ₁ — the base angle — depends on both the target and θ₂. Solve them in the wrong order, and you're stuck. The formula for θ₂ comes directly from the Law of Cosines you used in Lesson 15. The formula has a new label, but it's the same math applied to the triangle formed by L1, L2, and the straight-line distance to the target.
Station Activity
Station Activity
Explore It – Finding θ2 First
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