Why calibrate your industrial robot

Denavit–Hartenberg (DH) parameters and calibration form the mathematical foundation of how a robot understands its own geometry and motion. This page explains these core concepts at a practical level, helping you see how accurate models and calibration directly impact precision, consistency, and real-world performance.

Gravity and bending

Gravity and bending effects in a six-axis robot arise because each joint and link must support the weight of all components further along the kinematic chain. As gravity acts on the mass of the robot's links and tooling, it creates torque at each joint, causing small but measurable deflections. These loads also induce bending in the robot's arms, which manifests as slight rotations around preceding joint axes and compliance errors that accumulate toward the tool centre point. Together, these effects reduce positional accuracy and repeatability, especially under heavier payloads or extended reaches.

Two engineers looking at RCS product on industrial robot

Gravity-induced torque and link bending directly change how a six-axis robot actually moves compared with its ideal kinematic model. These effects introduce geometric error, reduce repeatability, and cause the TCP to deviate from its expected path. That's why advanced calibration sessions (like DH & Bending Calibration) explicitly measure and model bending caused by gravitational loads — because it materially affects the robot's accuracy and must be accounted for in high precision applications.

A FANUC six-axis robot in an automation cell using an RCS T-90 tri-ballbar system

In practical terms, if you don't account for gravity and bending, you can't fully trust your robot's geometric model, especially under heavy payloads or extended reach — leading to path deviations, offline to online mismatch, and poor accuracy. That's exactly why Renishaw calibration workflows include bending compensation as a core part of improving robot accuracy and ensuring repeatability in real-world conditions.

Fully calibrating a robot matters because it directly improves how accurately, consistently and reliably the robot understands and executes its own motion. Calibration updates the robot's geometric model (DH parameters), compensates for mechanical tolerances, and accounts for real-world effects like gravity-induced bending — all of which drift over time or vary between units. This introduces a host of benefits:

Maximises accuracy: Calibration fine-tunes parameters so the robot tool goes precisely where it is programmed to.
Enables offline programming: A calibrated robot's "digital twin" closely matches its physical positioning. This allows you to generate paths on a computer and load them onto the robot without spending hours manually teaching it individual points on the factory floor.
Prevents rework: Ensures operations like welding, drilling, or dispensing are performed perfectly, reducing waste and part rejection rates.

In short: full calibration restores the robot to a known, traceable, high-accuracy state so it performs as intended in demanding applications.

Discover RCS product series

Explore the RCS product series to see how each solution is designed to address specific challenges in robot accuracy, health, and calibration. Discover the tools that fit your needs and how they work together to support reliable, high-performance robotics.

Learn about the RCS product series

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