Ultrasonic Tracking System

1
Ultrasonic Tracking System

• Group 4
• Bill Harris
• Sabie Pettengill
• Enrico Telemaque
• Eric Zweighaft

2
Introduction

• What is our project?
• Pan and tilt implemented system tracking an
  ultrasonic beacon which sends a signal to 3
  ultrasonic receivers, is carried around the room
  by a team member
• How does it work?
• The signal coming from an ultrasonic transmitters
  is measured at three different locations
• The difference in the time the signal is received
  at each sensor is used to calculate a distance
  relationship
• Why is this project practical?
• Mitsubishi Motor company uses a similar design in
  their automobiles for a collision avoidence
  system
• Various pest and animal repellent systems use
  ultrasonic waves for tracking and repelling.

3
Objective

• Simulation of pan tilt system used as a cost
  efficient method to determine
• Motor required to drive system
• Gear, belt and pulley combination needed
• Response of system to motor, gear, belt and
  pulley
• Maximum performance variables for system
• Rough estimate of system response to sample
  payload
• Chance to show that we were paying attention in
  all those math classes

4
Specifications

• The system will track objects between 2 and 10
  meters from the array
• The system will track objects between 0 and 2
  meters off the ground
• The system will track items within .5 degree of
  accuracy (within 10 cms of the object with
  beacon)
• The system must be able to track the beacon at
  the speed of a human walking (.64 rad/sec)

5
Major Change in Design

• With our previous sensor structure, there was not
  a large enough motor that could handle the torque
• We decided make a more compact sensor structure
  which allowed us to go with a much smaller motor
  in the Pittman 8000 series.
• The sensor structure was made L shaped instead of
  T shaped to allow for a simpler timer circuit

6
Motor

• Pittman GM8724S017
• 19.51 internal gearing ratio
• Encoder mounted directly to rotor increases
  accuracy of encoder (encoder is not geared down)
• External transmission gives additional reduction
  ratio of 31

7
Motor

• Pittman GM8724S017
• Larger gearing ratio does not allow us to meet
  our speed requirements
• Smaller gearing ratio does not allow us to meet
  our torque requirements
• Gains must be chosen carefully to remain inside
  the feasible range for both speed and torque

8
Motor

• Simulation
• Sinusoidal input
• Frequency of 0.63 rad/s

9
Motor

• Speed vs. Torque plot
• Shows that motor is well within limits, as long
  as gains are kept at reasonable levels

10
Controller

• By intuitive adjustment of gains, a reasonable
  response was obtained
• But guessing is not a valid design approach

11
Controller

• SISO Design tool was used
• Linearized model was obtained using the
  linearlization routines provided
• Alternatively, the linmod command could be
  called to create a linear State Space model from
  the Simulink Diagram
• This allows the designer to view pole/zero
  locations, bode plots, AND response plots all at
  the same time, and adjust poles, zeros, and gains
  in any of these formats

12
Controller

• SISO Window Step Response
• Overshoot is very undesirable

13
Controller

• SISO Window Step Response
• PM 98.2 GM Inf. Zero overshoot, 1
  ess

14
Notes on Controller

• Because of assumptions made in order to linearize
  the system, this controller does not perform
  perfectly on the non-linearized model, so some
  adjustments will have to be made during assembly
  and testing
• We may wish to add an Integral term later to
  cancel the 1 overshoot
• Does not seem necessary now- it would only hurt
  our transient response, and require more torque
  and speed from the motor

15
Justification for Sensor Parts

• Given the cost of larger motors, needed to have a
  design with a small moment of inertia
• The higher the clock frequency of timer circuit,
  the smaller our sensor structure has to be
• The cheapest TTL components had a maximum
  functional frequency of 5 MHz
• Chose an oscillator accordingly

16
Cost

• Pan and Tilt Parts
• Total 478.64

Part Part Quanity Price Total
Motor GM8724S017 2 192.86 385.72
Gear (large) A 6A 6-75NF01812 2 15.15 30.30
Gear (small) A 6A 6-25DF01806 2 7.76 15.52
Carbon Fiber T155-5 1 43.40 43.40
Timing Belt A6Z16-C018 2 1.86 3.70
17
Additional Costs

• Total Amount for Timing Circuit and Sensors
  46.52
• Total Cost for project 533.84

18
February
Week 2
Week 3
Week 4
Placing parts and payload on CAD drawings to
calculate P,I,M values for Matlab simulation
(Bill, Sabie)
Hardware - CAD designed payload added to Bens
CAD drawings system and edited P,I,M values are
calculated (Eric, Sabie)
Final design specifications are met (All
members) Parts are ordered (Eric, Sabie)
Hardware
Simulation of pan and tilt system to obtain
feasibility and performance of test motor with a
test payload (Bill)
Final Motor feasibility simulation with payload
on pan and tilt system (Bill, Enrico)
Testing of control systems ability to track a
signal using amplitude, or distance and time
measurements (All members)
Software
Reports
Presentation writeup (Enrico Eric)
Proposal writeup (Sabie, Enrico)
TBD
19
March
Weeks 1-2
Week 3
Week 4
Sensor development with focus on time\distance
relationship (Eric, Sabie) Encoder and amplifier
properties researched (Bill, Enrico)
Design model assembled (Enrico, Sabie) Sensor
assembly (Bill, Eric)
Further tolerance testing of physical equipment
Hardware
Current Feedback control analyzing and testing to
find proper gains for accurate tracking (Bill,
Enrico) Encoder and amplifier properties
simulated (Eric, Sabie)
Testing and fine tuning of control feedback
system (Bill, Sabie) Sensor testing with
system (Enrico, Eric)
Test mechanics of system in terms of
motion (Bill, Enrico) Test mechanics of system
in terms of tracking (Eric, Sabie)
Software
Reports
Progress Report (All members)
TBD
TBD