DOI: 10.5281/zenodo.16081095
title: GRIPIT Ohwaboo measurement: flight data of a passive EDS magnetic levitation vehicle propelled by pressurized over heated water rocket

description: These are the measurement data recorded during testing of the OHWABOO prototype vehicle of the GRIPIT project.

The GRIPIT project was funded by HES-SO Switzerland as a flagship multidisciplinary research project from 2021 to 2024; the project is described here: https://www.hes-so.ch/recherche-innovation/projets-de-recherche/detail-projet/gripit-groupe-de-recherche-interdisciplinaire-en-projet-innovant-de-transport

THe OHWABOO demonstrator is a passive EDS type maglev vehicle that was built to study flight dynamics and stability. In particular, we were interested in measuring the dynamic evolution of air gaps and forces between magnets and rail, the flight stability (oscillations, possible impacts) and the response of & rail misalignment conditions.

The OHWABOO vehicle consists of 4 permanent magnet levitation pods sliding in a I shaped aluminium rail (or H shaped rotated 90°). Each levitation module is linked to the main body of the vehicle with independent vertical and lateral mechanical suspension. The vehicle is accelerated with a powerfull over heated water booster aka POWHARO (hence the name) and reaches ~120 km/h in ~1s while 4 pneumatic breaks stops the vehicle before it reaches the end of the 100m test track. The vehicle was equipped with laser distance sensors (lateral and vertical) & accelerometers for each levitation modules, as well as triaxial force sensors on 1 module.

The  corresponding simulation models have been published on GitHub (https://github.com/jcugnoni-heig/GRIPIT_Ohwaboo_simulations ) and where successfully matched with the measurement results obtained during our test campaign in Sion HEI-VS in fall - winter 2024.

Published files & info:



Projet_GRIPIT_V2:



Project description / overall presentation; in French



GRIPIT OHWABOO_Sensors_Control_Datalogger_v7b :



description of the full data logger & control system

 most usefull data are the description of the sensors, calibration of sensors, data files & header / channel order



Mesure entre-fer et cotes aimants GRIPIT OHWABOO & Airgaps and magnet dimensions GRIPIT OHWABOO DeepL en-US:



definition of the air gaps and laser distance measurement offsets



DataRecords_GRIPIT.zip:



Archive of 4 test runs, with different conditions




Dataset short description:

One folder for each test run. Each folder contains the analog sensor data in data0.csv and data1.csv and the digital records of 5 IMUs in log_ttyAMCxx.txt

The analog data in data0.csv contain the laser distance measurements for each levitation module, in lateral and vertical direction (2kHz sampling rate, sensor data in Volt). The description of the channels (column) and calibration of the sensors is in the "GRIPIT OHWABOO_Sensors_Control_Datalogger_v7b" document. The measurement offsets and air gap definitions are described in "Mesure entre-fer et cotes aimants GRIPIT OHWABOO" or "Airgaps and magnet dimensions GRIPIT OHWABOO DeepL en-US"

The analog data in data1.csv contains the two triaxial load sensor data as well as POWHARO steam pressure and rail distance laser gate sensor output (pulse every 3m), (2kHz sampling rate, sensor data in Volt, in sync with data0.csv). The description of the channels (column) and calibration of the sensors is in the "GRIPIT OHWABOO_Sensors_Control_Datalogger_v7b" document. The force channel offset need to be determined from the value just before launch (zero force at rest).

For both data0 & data1.csv, the acquisition is trigger several seconds before launch and thus the t0 of the launch need to be determined based on data.

The digital IMU data (5 sensors) are in log_ttyACMxx.txt and contain triax acceleration and gyro data sampled at 250Hz for 8s. The acquisition is trigger (t=0) by the vehicle acceleration (t=0 at first move). Headers in the txt files give details on the data order; the sensor ID  vs positions on vehicle are in "GRIPIT OHWABOO_Sensors_Control_Datalogger_v7b".

For more information, contact Joël Cugnoni ; joel.cugnoni@heig-vd