Gravity compensation

What is Gravity Compensation?

Gravity compensation is a fundamental concept in robotic control that helps counteract the effects of gravity on a robot's joints and links. By applying the necessary motor current to balance this torque, the robotic joint can remain stationary at any position without additional external forces.

Why is it so important?

In robotics, a significant portion of motor power is consumed just fighting against gravity. Gravity compensation algorithms are standard in all industrial robots and collaborative robot arms because they provide: improved position accuracy and control, smoother motion planning, and more precise force control applications. The gravity compensation algorithm works as a feedforward component to the motor PID control loops, reducing their computational load and improving overall performance.

The Approach

In this example, we use the Robotics Toolbox for Python to model a "robotic arm" with a single revolute joint. We compute the required torque using the Recursive Newton-Euler Algorithm (RNEA) and convert this torque into a motor current/torque that the motor controller will command the motor. In this blog post we will explain in short pseudo code snippets how the algorithm works on a single DOF arm.

For more info check the full guide here: https://source-robotics.com/blogs/blog/gravity-compensation-in-robotics

Github repos with examples are here: Github repo, Github repo2