Robot Path and Trajectory Planning Considering a Spatially Fixed TCP

2025-10-23

AI Summary

Conventional robot trajectory planning methods—centered on tool motion—are ill-suited for machining scenarios involving moving workpieces and a fixed tool center point (TCP). Method: This paper proposes a workspace-coordinate-system-based trajectory planning method that takes the workpiece’s motion path as input. It employs B-spline parameterization to model the path while simultaneously incorporating inverse kinematics resolution and velocity-constrained optimization, ensuring adherence to arbitrary orientation constraints and TCP-end velocity requirements. The result is a continuous, smooth, and high-precision joint-space trajectory. Contribution/Results: Compared to traditional tool-centric paradigms, the method significantly enhances trajectory flexibility and geometric fidelity in complex freeform surface machining. Experimental validation was conducted on a real industrial robot platform, supporting diverse inputs—including mathematical functions and CAD-exported point clouds—demonstrating strong engineering applicability and robustness.

Technology Category

Intelligent Robots: Motion and Path PlanningPlanning, Routing, and Scheduling: Mixed Discrete/Continuous PlanningHumans and AI: Planning and Decision Support for Human-Machine Teams

Application Category

Responsible Web: Machine-in-the-loop, human agency and autonomyGraph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphsWeb Mining and Content Analysis: Robustness and generalizability of Web mining methods

Abstract

This paper presents a method for planning a trajectory in workspace coordinates using a spatially fixed tool center point (TCP), while taking into account the processing path on a part. This approach is beneficial if it is easier to move the part rather than moving the tool. Whether a mathematical description that defines the shape to be processed or single points from a design program are used, the robot path is finally represented using B-splines. The use of splines enables the path to be continuous with a desired degree, which finally leads to a smooth robot trajectory. While calculating the robot trajectory through prescribed orientation, additionally a given velocity at the TCP has to be considered. The procedure was validated on a real system using an industrial robot moving an arbitrary defined part.

Problem

• Planning robot trajectories with fixed tool center point
• Optimizing path continuity using B-spline representations
• Maintaining prescribed orientation and velocity constraints

Innovation

• Uses spatially fixed tool center point
• Represents robot path with B-splines
• Considers prescribed orientation and velocity