Date of Award

5-5-2025

Degree Type

Capstone Project

First Advisor

Bahram Nassersharif

Abstract

This capstone project, developed in collaboration with VATN Systems, resulted in the design, construction, and testing of a Stewart Platform to address the calibration challenges associated with IMUs in AUVSs. The goal was to create a precise and repeatable platform capable of actuating all 6 DOF—translation along and rotation about the x, y, and z axes—to correct internal sensor misalignments and improve overall AUV navigation performance.

Initial efforts focused on designing a gantry and tow tank system to calibrate an entire suite of onboard sensors including DVLs, GNSS modules, magnetometers, and IMUs. However, after sponsor guidance and reevaluation of project scope, the team pivoted toward developing a specialized calibration platform targeting the IMU as the primary source of sensor drift and orientation error. This refined objective enabled the creation of a more compact, efficient, and precise solution centered on VATN’s immediate operational needs.

The resulting Stewart Platform integrates six linear actuators arranged between a fixed base and a mobile top plate, allowing for full 6DOF motion control. The system architecture includes redundant feedback mechanisms through mounted IMUs and an external motion capture system to verify accuracy and orientation. A CAN-based control framework synchronizes all actuators and supports high-resolution, low-latency data transmission to microcontrollers and data acquisition modules. This infrastructure ensures precise actuation with tolerances within 0.001 inches and 0.01 radians, sufficient for accurate IMU calibration.

Preliminary tests confirmed the platform’s ability to reproduce consistent, controlled motion across all degrees of freedom. CAD models, system simulations, and hands-on testing supported the mechanical and electrical integration of all subsystems. Future work is proposed to improve actuator precision, expand data collection, and validate the system across more complex calibration routines involving multiple IMUs mounted simultaneously.

Ultimately, this project delivers a scalable, cost-effective calibration tool tailored to VATN’s AUV development pipeline. It reduces reliance on external vendors, enables rapid sensor alignment validation, and provides a foundation for further capabilities such as dynamic shock testing, full-vehicle mounting, and cooperative swarming calibration. The Stewart Platform represents a practical and forward-thinking solution to one of the most critical components of underwater navigation—IMU orientation and calibration.

Comments

Team Name: Team VATN (Team 14H)

Company Sponsor: VATN Systems

Sponsor Representative: Alex Jedsen

Document Reference: URI-MCE-402-014-2025

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