Transcript confocal based fea of cockroach trochanter

THREE DIMENSIONAL RECONSTRUCTION OF EXOSKELETON
BY CONFOCAL MICROSCOPY
TROCHANTER OF FRONT LEG
Confocal microscopy:
DAVID NEFF
LAURA QUIMBY
FAITH FRAZIER
CONVERTING CONFOCAL MODELS OF EXOSKELETON
TO MODELS FOR FINITE ELEMENT ANALYSIS
TROCHANTER OF HINDLEG
CLAY FLANNIGAN,
CASE WESTERN
PEGLEG EXPERIMENTS: PHYSIOLOGY AND
FINITE ELEMENT ANALYSIS STUDIES
PEG LEG TESTS ON HINDLEG
Clay Flannigan, Case Western
FORCE FLEX
FORCE EXTEND
RESULTS
- RECEPTORS SIGNAL FORCES
AS AN ARRAY
- SOME GROUPS ARE EXCITED BY
EXTERNAL LOAD AND MUSCLE
CONTRACTIONS AND CAN
PROVIDE POSITIVE FEEDBACK
TROCHANTERAL GROUP 3 SENSILLA ENCODE
FORCED FLEXIONS: PHYSIOLOGY ABLATION EXPERIMENTS
STRAINS PRODUCED BY EXTENSOR MUSCLE
CONTRACTIONS: SOME GROUPS CAN
MEDIATE POSITIVE FEEDBACK
POSITIVE FEEDBACK DECLINES AS LEG IS EXTENDED
STRAINS DURING STANCE PHASE:
S. Ramasubramanian, G. Nelson, Case Western
Fy
Fz
Fx
Femur and Tibia Attached to Trochanter - FT Joint Angle from Kinematic
Studies, Forces applied at Levels (Fx, Fy, Fz) for early, middle and late
stance.(Kinematic Data from J. Watson, R. Ritzmann; Force Data from R. Full)
STRAINS DURING MIDSTANCE PHASE:
S. Ramasubramanian, Case Western
LEG LOADING
RESULTS
-ARRAY ENCODES FORCE DIRECTION
(FORCE POSTERIOR, FLEXION)
-ARRAY ENCODES FORCE MAGNITUDE
TROCHANTERAL FORCE SENSORS AS LOAD CELL: Fx, Fy
and Fz INDEPENDENTLY VARIED
ARRAY CAN DETECT INCREASES IN FORCE VECTORS
Summary:
ENCODING PROPERTIES OF CAMPANIFORM SENSILLA- signal level
of load rate of change of force, provide active signal for sudden
decreases
MODELING THROUGH FINITE ELEMENT ANALYSIS - trochanteral
campaniform sensilla encode forces as a array; some groups
provide positive feedback in limited ranges of joint angles
LEG DESIGN/ANATOMY DETERMINES SPECIFICITY OF AFFERENT
INPUTS
FEA Modeling Studies:Strain in
Exoskeleton
1- Exoskeleton is a tubular structure
that is rigid (modulus =3160 N/mm^2);
fixed beam analysis is useful
2- Receptors located on proximal ends
of segments and are subject to large
bending forces when end of leg is
pushed against substrate
TIBIAL EXTENSOR
MUSCLE
TIBIAL
SENSILLA
TROCHANTERAL
EXTENSOR
MUSCLE
TROCHANTERAL
SENSILLA
3- Strains also result from muscle
contractions:
• Muscles with insertions near receptors
produce strains; locally distribution depends
upon shape
• Muscles located close to body can
produce bending along length of leg
Three Dimensional Reconstruction of Exoskeleton by
Confocal Microscopy Converted to FEA Model
CLAY FLANNIGAN, ROGER QUINN
CASE WESTERN RESERVE
FEA MODEL
Confocal microscopy:
DAVID NEFF
LAURA QUIMBY
FAITH FRAZIER
FORCE RECEPTORS ON
TROCHANTER
The trochanteral segment
contains the largest number
of strain sensing
campaniform sensilla in the
leg.
These receptors have been
characterized physiologically
and their responses have
been modeled by Finite
Element Analysis.
The trochanteral receptors can
provide precise information
about the magnitude,
direction and rate of forces
applied to the femur.
Insect-Like Hexapods
•Robot II - “stick insect”
•6 symmetric 3 DOF Legs
- 18DOF
•Locomotion controller
Robot II
uses network of inter-leg
•Robot III - cockroach
influences
•Pneumatic actuation
•Able to walk over rough
and unstable terrain •24 DOF: 5 front, 4
middle, 3 rear
Robot III
•Currently shows high
Cockroach Anatomy
•5 leg segments:
coxa, trochanter,
femur, tibia, tarsus
•CT, FT are 1 DOF,
hinge-like and
articulate about 2
condyles
•Large muscles of
the coxa insert on
the trochanter
Coxa
Tibia
Tarsus
Femur
Trochanter
Cockroach Leg
Muscle Definition
Trochanter
•Approximately 2.5 mm in length for the adult
P. americana
•Outer surface is smooth; inner surface has
variable topology
Dorsal
Coxal
Condyles
•Coxa attaches
via
2
condyles
on
the
anterior
Femur
and
Distalposterior sides
Proximal
y
•Femur attachesFemoral
viaCondyles
2 condyles on the distal
Trochanter
x
anterior surface
Anterior view trochanter
Ventral
Campaniform Sensilla
•Campaniform
Sensilla (CS) are
cuticular caps in the
exoskeleton
innervated by a
single nerve
•Ellipsoidal with longaxis length from 6 to
24 mm
Cuticle
Cap
Dendrite
Sensory Neuron
Axon
Campaniform sensilla structure
Trochanteral
Campaniform Sensilla
•CS found in 6
groups on the
leg (10-15 in a
group)
•Within groups
the CS are
similarly
oriented
•4 groups on
the trochanter
Group 3
Group 4
Group 2
Anterior campaniform sensilla groups
Group 1
Posterior campaniform sensilla group
Confocal Modeling
(Zill Lab)
•Confocal microscope used to optically
section the trochanter
•Irradiation of the specimen with UV Light
causes the cuticle to fluoresce
•Microscope indexes its focal plane
through the trochanter
•Result: A series of bitmap images, when
combined using specialized software,
creates 3-D model of the trochanter
Confocal Sections
Meshed Trochanter
Thickness Scale:
red 6mm
blue 265mm
Anterior
Posterior
Trochanter-Femur Model
Forced Flexion
Anterior
•Von Mises strain:
2
Posterior
 VM  1/ 2(( x   y )  ( y   z ) 2  ( z   x ) 2 )  3(  2xy   2yz   2zx )
STRUCTURE AND LOCATION OF
CAMPANIFORM SENSILLA
FUNCTION
LIKE STRAIN
GAUGES
DETECT STRAIN
IN EXOSKELETON COMPRESSIONS
PERPENDICULAR
TO CAP LONG AXIS
EXCITE RECEPTOR
TROCHANTERAL CAMPANIFORM
SENSILLA:
IMAGING BY CONFOCAL
MICROSCOPY
1) OCCUR AS FOUR GROUPS (Gp1-4)
2) EACH GROUP HAS CONSISTENT
ORIENTATION
3) GROUPS ARE ASSOCIATED WITH INTERNAL
BUTTRESSES OR THICKENINGS OF
EXOSKELETON
OUTER SURFACE
INNER SURFACE
CONFOCAL IMAGES OF CUTICLE
diI OUTFILL
THREE DIMENSIONAL RECONSTRUCTION OF
EXOSKELETON BY CONFOCAL MICROSCOPY
Confocal microscopy:
DAVID NEFF
LAURA QUIMBY
FAITH FRAZIER
TROCHANTER OF FRONT LEG
ACCURACY CONFIRMED BY
SECTIONING MODEL/ORIGINAL
TROCHANTER
3D RECONSTRUCTION
SEM
CONFOCAL and FEA models
Confocal model
FEA model
Overlay comparison
ACTIVITIES OF CAMPANIFORM SENSILLA
ARE EVALUATED BY STRAINS AT
LOCATION OF CUTICULAR CAPS
- nodes corresponding to CS are
located on the finite element model
- Compressions (negative strain
values) excite receptors
Group 1, posterior trochanter
Groups 2,3,4, anterior trochanter
FEA PEGLEG EXPERIMENT
BEHAVIORAL PARADIGM
ATTACH
PEG LEG
PHYSIOLOGY PARADIGM
BEND FEMUR
SENSORY
RECORDING
FEA PEGLEG
APPLY FORCES
TO ATTACHED
FEMUR, POINTS
OF MUSCLE
INSERTIONS
PEG LEG TEST ON Blaberus Discoidalis
FRONT LEG
FORCE FLEX
Group 3 short axis strain
FORCE EXTEND
Group 4 short axis strain
RESULTS:
Campaniform Sensilla
- Function as a strain gauge array
signals forces in all directions of load
- Can provide positive feedback
FINITE ELEMENT MODELLING OF
STRAINS DURING WALKING
Fz
Fy
Fx
High speed video:
Adam Noah
Angela Ridgel
Mid-stance
Late stance
SENSORY ACTIVATION PATTERNS DUE TO
GROUND REACTION FORCES DURING
STANCE
Mid Stance
1.00E-03
8.00E-04
Short Axis Strain
6.00E-04
4.00E-04
2.00E-04
0.00E+00
-2.00E-04 0
1
2
3
4
5
-4.00E-04
-6.00E-04
-8.00E-04
-1.00E-03
Group
•Groups 1 and 4 show excitation
due to ground reaction forces
throughout stance.
•These sensilla groups could be
responsible for signaling that leg is
on substrate and bearing load.