Transcript autoresonant excitation and control of non

1st Space Glasgow Research Conference,
Glasgow, UK, 28 October, 2014
Modelling and Experimental Validation
of a Novel Ultrasonic Planetary Core
Drill (UPCD) Tool Design
X.Li, A.Bolhovitins, R.Timoney,
P.Harkness, M.Lucas
University of Glasgow, UK
Outline
Background
UPCD Assembly
Numerical Model
Simulation Results
Conclusions
Background
NASA – Jet Propulsion Laboratory (JPL)
SELEX GALILEO – ExoMars Mission
Conventional Driller/Corer
Ultrasonic/Sonic Driller/Corer (USDC)
operated from the Sojourner platform
Background
Compared with conventional drilling/coring,
USDC has the following advantages:
 Light-weighted, compact, low pre-load, low
power
 Operate with a minimum axial load and
holding torque which is suitable for low
gravity environments
 Operate at extreme temperatures
 Avoid drill bit jamming, breaking, dulling etc
 Capable of drilling a wide range of rocks
UoG/MP Drill in Tenerife 2011
UPCD Assembly
UPCD Assembly
UPCD Mechanism
• Due to piezoelectric effect, piezoceramic rings convert
high frequency voltage into ultrasonic vibration at the
transducer base, and the level is adjustable depending
on the power consumption.
• A tapered horn is used to amplify the vibration and
ensure a considerable level of vibration at the horn tip
• The ultrasonic transducer assembly drives a free
flying mass which bounces between the horn tip and
the base of drill stems at sonic frequencies.
• The chaotic motion of the free mass create stress
which propagates through the drill stems to the rock
surface, rock fractures once stress exceeds the
compressive limit
• Three drill stems will be used with each length 10cm.
UPCD assembly target mass is 7kg, target power
consumption 40W.
Numerical Model
UPCD assembly dynamic equations:
Simulation Results
Simulation Results
Conclusions
 A novel driller/corer device has been developed with the USDC mechanism
however employs two compression springs for different purposes
 Dynamics of the UPCD process has been modelled and analysed,
compression spring rates are optimized which delivers the maximum effective
impulse from the drill to the rock
 Experiments with dual springs are currently being performed which allows to
validate the simulation results
 A 1/2 wavelength ultrasonic transducer has been designed to decrease the
weight and length of the UPCD assembly
Thank you !