Simplifying ROS2 controllers with a modular architecture for robot-agnostic reference generation

TL;DR

This paper presents a modular architecture for ROS2 that separates reference generation from control laws, enhancing reusability and simplifying controller design across different robot platforms.

Contribution

A novel modular architecture for ROS2 that decouples reference handling from control laws, with dedicated reference generator components for improved reusability and simplified controller implementation.

Findings

References are tracked reliably in all tested scenarios.

Reference generators reduce duplicated code across controllers.

Controller implementations focus solely on control laws.

Abstract

This paper introduces a novel modular architecture for ROS2 that decouples the logic required to acquire, validate, and interpolate references from the control laws that track them. The design includes a dedicated component, named Reference Generator, that receives references, in the form of either single points or trajectories, from external nodes (e.g., planners), and writes single-point references at the controller's sampling period via the existing ros2_control chaining mechanism to downstream controllers. This separation removes duplicated reference-handling code from controllers and improves reusability across robot platforms. We implement two reference generators: one for handling joint-space references and one for Cartesian references, along with a set of new controllers (PD with gravity compensation, Cartesian pose, and admittance controllers) and validate the approach on simulated and real Universal Robots and Franka Emika manipulators. Results show that (i) references are tracked reliably in all tested scenarios, (ii) reference generators reduce duplicated reference-handling code across chained controllers to favor the construction and reuse of complex controller pipelines, and (iii) controller implementations remain focused only on control laws.