Transcript DD Presentation Slides

ITT Mirror Steering System
Team P11565
Andrew Bishop
Katie Hall
Matt Manelis
Ben Geiger
Nurkanat Suttibayev
Agenda
Meeting Timeline
Start Time
12:30
12:35
12:40
1:00
1:20
1:40
2:00
2:10
2:20
Topic of discussion
Review Project Goals
Review Customer needs
Over all System Design
Voice Coil Design
Mechanical Mounting Design
Control System Design
Sensor and Feedback Design
Power Regulator Design
Wrap up Discussion
Project Goals
 The mission of this project is to design and build a
mirror steering system that can outperform
commercially available systems in terms of Power
Consumption.
 This project will provide appropriate documentation
that can be utilized by future senior design teams for
further refinement.
Project Description
 The mirror steering system is a device that controls
the angle of a mirror in two dimensions.
 This device is used in directing optical devices at the
mirror and aiming the mirror at an object located a far
distance away.
 The tilting of the mirror is achieved by the use of
actuators, which push and pull the mirror into
different locations.
Project Appeal
 High Interaction between Mechanical and
Electrical Designs which creates more design
challenges
 The goal is to compete with and do better than
commercially available designs
 The chance to work hands on with a design outside
of our previous experiences.
Customer Needs
Importance Ranking:
9 – These needs have the highest importance and will be the main focus of the project
3 – These needs are somewhat important and will be the secondary focus of the project if time allows
1 – These needs are not as important as the rest of the needs and will only be focused on if the main and secondary needs have been satisfied
Target Specs
Importance Ranking:
9 – These needs have the highest importance and will be the main focus of the project
3 – These needs are somewhat important and will be the secondary focus of the project if time allows
1 – These needs are not as important as the rest of the needs and will only be focused on if the main and secondary needs have been satisfied
System Design
 2 Voice coils and 1 sensor
Per Axis
 Flexure Spring Mounting
 PID Controller with VCCS
Stage
 Underhung Voice Coil
System Design (Section View)
Mechanical System Model

c1
Jӫ
ө
k
c2
k
F1
X(t)
F1
L1
L2
L2
L1
Model for Axis 1 (ө-direction)
y
x
Complete System Model
 PID controller to ensure system stability and settling
time.
 The Trans-conductance (voltage converted to current)
stage can be modeled as an attenuation.
 The voice coil is also modeled as a gain stage.
 PID controller is being tuned
Voice Coil
 The basics of the voice coil is a
device that uses current flow
through a loop of wire and opposes
a magnetic field to produce a force
in single direction (positive or
negative).
 It is the heart of the system and
everything was based off of the
force and dimensions of the Vc for
a given input current.
Voice Coil Continued
 The final design included 2 different voice coils, both
with a 20mm outer diameter, one being 32mm tall,
the other being about 22mm tall
 The 22mm tall VC has a higher magnetic field of .33T
field in the gap area, the taller one having .38T field.
 Height not being too much of an issue for these gave
us the choice to use the stronger field, and so giving
more force for a given current.
Mechanical Design
 Main assembly:
- Waffle mirror (provided by ITT)
attached to mirror mount by RTV
adhesive
- Flexure spring that allows
system range of motion
- Stem that connects the flexure
to the top face of electronics box
- Four actuators connected to
mirror mount that will push and
pull on mirror mount with
generated force
Relating Design to Needs/Specs
 Mirror Mount
- CN8 (Size): The surface area of the
mount is large enough to fit the
flexure, voice coil contact point, and
sensors, while not exceeding the
diameter of the mirror
- CN13 (Feasibility): The thickness is a
standard value that can easily be
purchased in stock (0.16’’)
- ES3 (Modulus of Elasticity): Material
must be stiff enough to withstand the
forces and stresses imposed on part
(6061 Aluminum)
Finite Element Analysis
 To determine the displacement and stresses of the
model, Finite Element Analysis is required
 SolidWorks/COSMOS software used for FEA
 Two types of analyses performed
- Mirror and Flexure Structure
- Electronics Box
Mirror and Flexure FEA Setup
 To perform this analysis, the model is
first constrained on the bottom face
 To simulate actuators acting in one
axis, an upward force of 0.105 lbf is
applied at one actuator, and a
downward force of 0.105 lbf is
applied at the other actuator
 To simulate actuators in two axes,
two additional forces are added to
the model at the other actuators
Mirror and Flexure FEA Results
 One axis simulation
- Displacement: 0.0587 in
- Angle: 2.24º
- Max Stress: 8350 psi
- FOS: 4.78
von Mises Stress
Displacement
Factor of Safety
Mirror and Flexure FEA Results
 Two axes simulation
- Displacement: 0.0825 in
- Angle: 3.15º
- Max Stress: 10296 psi
- FOS: 3.87
von Mises Stress
Displacement
Factor of Safety
Electrical Box FEA Setup
 To perform this analysis, the
model is first constrained on the
bottom face
 The total weight of the
components is summed, and
applied on the top surface of the
box
 Extra weight is added to simulate
a worst case scenario
(total force = 5lbs)
Electrical Box FEA Results
 Results:
- Displacement: 1.37e-5 in
- Max Stress: 64.4 psi
- FOS: 619
von Mises Stress
Displacement
Factor of Safety
Determining Spring Constant
 To determine the spring
constant of the flexure, varying
forces were applied to the
mount, and displacement was
measured for each data set
 A graph was generated to show
the Force and Displacement
relationship
 The slope of the line is equal to
the spring constant
 Simulated spring constant equal
to 626.8 N/m, or 3.58 lbf/in
Flexure Spring Design
 Modeled as seen on
McMaster’s website
 Specific dimensions not
given, so spring constant is
not known
 Plan on purchasing part,
and testing to determine kvalue, otherwise, machine
our own part
PID Controller
3
R7
C1
U2
2
1n
1k
- V+
R10
5
1 +
1k
4
V-
OP1177
C2
.1n
U3
- V+
1 +
V-
R11
5
1
110K
OP1177
4
3
2
1k
2
5
4
V1
V+ +
V-
R5
R3
0
OP1177
U5
3
15Vdc
R13
1k
R9
.9k
R4
2
- V+
5
V-
V_CMD
0
5
1 +
1k
V-
4
4
R2
1k
V_FB
10Vdc
1k
R12
- V+
1k
V
OP1177
0Vdc
U4
2
1 +
R1
10k
3
3
V
U1
V2
15Vdc
OP1177
R17
1k
Voltage Controlled Current Source
R21
R22
4k
2k
0
R23
100
R15
3
R14
10k
R8
2
2
U6
1k
- V+
0
V-
+ 5
6
8
OPA547/BB
V+
4
10k
Vo
1
(10.000,9.578)
U87 4 3
E/S
V- ILim
-
5
1 +
12
OP177
4
V4
(10.000,145.345m)
R_Iset
25
15Vdc
0
0
V5
15Vdc
U7
3
-4
(10.000,-10.000)
2
5
V+ +
V-
-8
1
Theta X +
4
R18
10k
OP177
-12
R19
I
25
0V
V(U1:34)
Theta X -
1
L1
420uH
2
1V
V(U5:34)
2V
-I(R19)
3V
4V
5V
V_V_CMD
6V
7V
8V
9V
10V
Sensor Design
 The sensor is based on the idea of a
varying capacitance by using 2 metal
plates close to each other
 One is stationary while the other
moves with the mirror moves.
 As the plate moves the capacitance
changes and changed the
impedance of the circuit.
 An Impedance converter creates an
equivalent resistance.
 A Wheatstone bridge circuit is used
to find the variation of the
impedance in terms of a voltage.
 The voltage VG Is then supplied back
to the control circuitry to use as
feedback.
Sensor Design (cont.)
Power Regulator
2
IN
V1
OUT
3
V
1
DC = 24
AC = 6
TRAN =
ADJ
U3
LM317K
C1
.1u
R3
500
C2
100u
150mV
R4
5.36k
(362.611,141.542m)
100mV
0
U2
1 IN
OUT
3
50mV
V
ADJ
DC = -24
AC = 6
TRAN =
2
V2
LM337K
C3
.1u
R1
500
(1.6033K,6.0046m)
C4
150u
0V
10mHz
V(U3:OUT)
R2
5.63k
100mHz
V(U2:19)
1.0Hz
10Hz
100Hz
Frequency
1.0KHz
10KHz
100KHz
1.0MHz
Test Plan
 Pre-assembly and construction test plan:
 Makes sure that customer needs and engineering specs are met in pre-assembly
stage
 Serves as a quality control procedure, in order to eliminate defects at early stage
 Mistake proofing
 Example: testing PCB, voice coil functionality, measuring important part
dimensions.
 Final product test plan
 Shows if all the customer needs and specs met by final product
 Displays if there are functionality issues that needs to be eliminated prior delivery
 Examples: testing slew rate, settling time, power consumption, tilt range.
Test Plan cont.
Final Product Testing Tasks
Engr. Spec. #
Task (description)
Unit of Measure
Marginal Value
ES4, ES5
Testing mirror settling time
ms
60 ±5
ES6
Testing mirror speed (slew rate)
rad/sec
>50
ES8
Tilt range (max range of angle tilt can move)
degrees
4.5 ±.5
N/A (QC
purpose)
Movement in X-axis
NA
NA
N/A (QC
purpose)
Movement in Y-axis
NA
NA
N/A (QC
purpose)
Movement in X and Y axis
NA
Na
N/A (QC
purpose)
Movement flexibility (ability to draw geometrical shape)
NA
NA
CN5, CN6
Testing steering accuracy/precision
TBD
TBD
ES15
Testing Signal to noise ratio
dB
96 ±25
ES1
Testing total power consumption of the system
W
<10
Comments/Status
MSD II Project Plan
Bill of Materials
Note: Additional items will be added as necessary