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Humanoid Kinematics Basics

Learning Objectives

  • Compute forward and inverse kinematics for humanoid limbs
  • Understand joint constraints and motion planning
  • Apply kinematics to robot arms, legs, and whole-body movements
  • Visualize humanoid movements in simulation

Humanoid robots rely heavily on kinematics to perform precise movements. Kinematics deals with the geometry of motion without considering the forces causing it.

Key Concepts​

Forward Kinematics​

  • Calculates the position of the robot’s end-effector given joint angles
  • Uses Denavit-Hartenberg (DH) parameters for limb modeling
  • Useful for simulation and visualization

💡 Tip: Forward kinematics is deterministic: joint angles → position of limb.

Inverse Kinematics​

  • Determines the joint angles required to reach a desired position
  • Often requires iterative solvers or numerical methods
  • Critical for motion planning and task execution

⚠️ Note: Multiple solutions may exist; constraints and joint limits must be respected.

Joint Constraints​

  • Each joint has a range of motion
  • Limits prevent mechanical damage and ensure safe operation
  • Must be considered during trajectory planning

Example: Humanoid Arm​

Shoulder → Upper Arm → Elbow → Forearm → Wrist → Hand