Introduction
A humanoid can have healthy hardware and still miss a grasp because its coordinate frames no longer agree. Calibration ties encoder zeros cameras IMUs force sensors hands and body geometry to the same physical robot. It is required after assembly and often after component replacement impacts or long term drift.
Key facts
- Joint zero errors can propagate into foot and hand pose errors.
- Camera calibration includes intrinsic parameters and the camera pose relative to the robot.
- Calibration should be followed by an independent validation task.
Joint calibration defines the body geometry
Joint zero offsets and kinematic parameters determine where the controller believes each link is located. Small offset errors can create larger endpoint errors across a long arm or leg. Calibration should cover the actual load and mechanical state because backlash can make one static pose misleading.
Vision needs both camera and robot frames
Intrinsic calibration describes how a camera forms an image. Extrinsic calibration connects the camera to the head wrist or body frame. Hand eye calibration is especially important when wrist cameras guide grasping because a few millimeters of frame error can move the final grasp away from the object.
Force sensing needs zero and scale checks
Wrist force sensors joint torque sensors and tactile devices can drift with temperature preload or mechanical changes. Calibration should define unloaded conditions reference loads and acceptable residual error. A force controlled task can become unstable when the sensor zero is wrong even if position control still looks normal.
Repairs should trigger known calibration recipes
Changing a hand camera joint or structural module should automatically call the required calibration workflow. The system should store calibration date technician tool version and resulting error metrics. This makes it possible to audit whether performance changed after maintenance.
Validation must be separate from fitting
A calibration procedure can overfit its own reference points. Use independent poses walking checks and manipulation targets to verify the result. The validation should include thresholds that block return to service when geometry or sensing remains outside tolerance.
Limitations and missing information
- Calibration procedures differ across hardware platforms.
- Some factory calibration requires special fixtures.
- Software compensation cannot correct every mechanical alignment problem.
Conclusion
Calibration is the bridge between the physical robot and the model inside its controller. Reliable humanoid deployment requires fast repeatable calibration that is integrated with maintenance and tested before the machine returns to work.
Sources and methodology
This guide separates published standards and official technical documents from engineering practice. Draft standards are described as work in progress. Product capability is not treated as verified unless a source supports it.
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