Transcript Obstacle Avoidance

PowerBot
Group #2:
Tarik Ait El Fkih
Luke Cremerius
Marcel Michael
Jerald Slatko
Sponsored By: Aeronix, Inc.
Project Description
 Autonomous robot purposed to provide
supplemental power to mobile devices
(laptops, mobile phones, etc.).
 Uses onboard navigation algorithms to
navigate to user’s location.
 Incorporates an iOS application to provide
robot statistics and manual control.
Project Motivation
 Battery life longevity in mobile devices is a constant
issue.
 Wanted to create a charging solution that could charge
the device without inconveniencing the user.
 The device would be simple to use, allowing for easy
adoption into a users everyday routine.
Objectives
 PowerBot should be able to navigate autonomously to
a user’s location.
 PowerBot should be able to be remotely controlled by
the user through the use of an onboard camera and the
provided iOS application.
 PowerBot will contain a battery used to charge external
devices through the use of inductive and USB
interfaces.
Specifications
 Will be at most 36” long
 Max speed of 5 mph
 Battery life of minimum 24 hours
 Ability to provide charge to mobile devices 100% of the
time.
Switching Voltage Regulators
 Needed to regulate power to the different
systems in PowerBot.
 Highly efficient
when compared to
linear voltage
regulators; 1440% vs. 85-90%.
Inductive Charging
 9 V switching regulator:
LT1424-9
 Used to step down voltage
for charging mat.
 SO-8 package.
 Charging mat offers a degree
of flexibility due to lack of
wires.
 Inductive cases are needed
unless implemented (Qi) by
manufacturer.
USB Charging
 5 V switching regulator: DESW050
 Used to step down voltage
for USB charging.
 Pin-compatible with 78XX
family (TO-220 package) of
linear voltage regulators.
 USB, although wired, is, well,
universal.
Microcontroller Supply
 3 V switching regulator: DESW033
 Used to step down voltage
for the microcontrollers.
 Pin-compatible with 78XX
family (TO-220 package) of
linear voltage regulators.
Motors
 Stepper Motor:
 To be used to rotate (Θ-axis) the solar panel.
 Brushed DC Motor:
 To be used to drive the rear wheels.
Motor Specifications
Part Number
SST58D3830
RS-540
Manufacturer
Shinano Kenshi
Tamiya
Stepper
DC Brushed
Step Angle (°)
1.8
N/A
No Load RPM
N/A
16,800
Voltage (V)
2.1
4.5-12
Current (A/Phase)
3.0
1 (no load)
Resistance (Ω/Phase)
0.7
N/A
Inductance (mH/Phase)
1.3
N/A
Holding/Stall Torque (kg-cm)
7.3
2.84
Rotor Inertia (g-cm3)
290
N/A
Weight (kg)
0.71
0.153
54 mm
50 mm
Type
Dimension (L)
Motor Controllers
 MSP430F123 will be
used to control the
solar panel [stepper]
motor.
 Contains hardware
UART for serial
communications.
Motor Controllers
 MSP430F2616 will be used
to control the DC brushed
motor.
 Its features:
 Interfaces with UART.
 16 MHz with 4 kB of RAM
and 92 kB of flash memory.
 48 GPIOs.
 ADC resolution of 12 bits
with 8 channels.
R/C Car Chassis
 Somewhat standard overthe-counter licensed R/C car.
 Large wheels allow for
maneuverability.
Chassis Modifications
 Swap out the drive motor to (DC Brushed).
 Remove the [red] plastic body frame and create a
foundation for PowerBot.
Obstacle Avoidance
 Obstacles will be detected using ultrasonic ranging sensors
 As PowerBot moves, the ultrasonic sensors rapidly take readings
to gather range data in real time.
 The obstacle avoidance algorithm will maneuver PowerBot in
response to the presence of obstacles.
 Three modes of operation:
 Active Adjustment (AA)
 Reverse-Reset (RR)
 Off
 Obstacle avoidance is OFF by default. It must be enabled by the
iPhone user
Modes of Operation
Active Adjustment (AA)
 Primary mode of operation
 Front two ultrasonic sensors are active
 A range reading within the AA minimum
distance causes PowerBot to steer either
left or right to avoid it.
 PowerBot will attempt to re-align
Ultrasonic Sensors
LV-MaxSonar® – EZ0™

Operates at 2.5 V – 5.5 V

Avg. current draw: 2 mA

Min. Distance: 6 in.
 Obstacles closer than 6 in. give reading
of 6 in.

Max. Distance: 254 in. (21 ft.)

1 inch Resolution

Range readings can be taken at about 20
Hz, every 50 ms.

Output modes include:
 Analog
 Pulse Width
 UART (not quite RS-232)
Image Credit: www.maxbotix.com
PIC32 Microcontroller
 PIC32 family of microcontrollers was chosen to drive
PowerBots navigation and Wi-Fi communication
functions.
 The PIC32 features an 80 MHz clock with onboard 512
kB of flash and 128 kB of RAM.
 Model Number: PIC32MX695F512H
Wi-Fi Communication
• Used as the primary mode of communication between PowerBot and the iOS
application.
• 802.11 Wi-Fi used as a physical layer with TCP sockets used for higher level
communication.
Embedded Software
iOS Software
Application
Layer
Application
Layer
MCU – Serial
iOS – Serial
802.11 – Socket
802.11 – Socket
Wi-Fi Module: MRF24WB0MA
• The MRF24WB0MA microchip provides a complete Wi-Fi solution for
onboard communication with PowerBot.
• The Microchip TCP/IP stack works with the MRF24WB0MA and allows
for easier implementation of sockets and the passing of data via TCP.
PIC32 Wi-Fi Circuit Board
 Microchip Wi-Fi Comm Development
Board was used for prototyping.
 Custom circuit board was based off
of this design.
 Combines PIC32 MCU with the
MRF24WB0MA Wi-Fi module.
 Additionally gives access to 4 UART
ports, as well as 6 GPIO pins used
for ultrasonic sensor data acquisition
and motor commands
PIC32 Wi-Fi Circuit Board
PTR 1 PA D1- 13
PTR1 PA D1- 13
PTR1 PAD 1- 13
.1uF
C4
TP4
PTR1 PAD 1- 13
TP5
SV4
TP3
.1uF
C5
8
LED1
TP1
S1
R8
10K
470
R7
SV3
1
LED2
PIC32MX695F512H
8
C6
.1uf
8
2
SV2
1
R6
4.7K
100K
R5
1
LED3
.1uF
10uF
C2
C1
1
X1
C3
.1uF
10K
R9
SV1
6
R1
R2
1K
R3
1K
1K
100K
R4
.1uF
C8
10uF
C7
1
11/11/2012 4:55:28 PM f=3.00 C:\Users\Luke Cremerius\Desktop\Senior Design Wifi Board Eagle Files\wireless board mods.b
PIC32 Wi-Fi Board Layout
Software Layout
iOS
Application
PowerBot
Obstacle
Avoidance
Algorithm
Motor Control
Power
Management
Sonar
Sensors
Stepper
Motor
Solar Panel
Charging
Ports
iOS Application
 Written in Objective-C using
Xcode 4.4.
 Provides users access to:
 Manual mode
 Obstacle Avoidance
 Ultrasonic sensor status
Manual Control
 Gives the user manual
controls to drive PowerBot.
 Sensor icons blink when
currently taking distance
readings.
 Status of Wi-Fi connection
shown above robot controls.
System Status
 Shows the user the current
sensor status of PowerBot.
 Displays the onboard sensor
distance readings
 Shows the number of
readings received from each
sensor
 I/O Data button allows viewing
all incoming TCP data
System Settings
 Allows the user to open a
socket connection to
PowerBot once the user has
joined the ad-hoc network
PowerBot broadcasts.
 Toggle button for turning
obstacle avoidance on or off.
Power
Battery Requirements
 24 V battery
 At least 2 Ah
 Deep cycle for increased usage time
 Low internal resistance
 Flat discharge rate
 Lightweight
Battery Choice
SPECIFICATIONS
Ni-Cd
Ni-MH
Li-ion
Li-Po
Energy Density (W·hr/kg)
40–60
70-90
100-160
130-200
Capacity (Amp-hr)
1
2.4
2.8
2.6
Internal Resistance (mΩ)
100-200
200-300
100-200
200-300
Nominal Voltage (V)
1.2
1.2
3.6
3.7
Discharge Rate
Flat
Flat
Flat
Flat
Recharge Life
500-700 cycles
600-1000
>600
>1000
Disposal
Must be recycled
Recyclable
Recyclable
Recyclable
Charge/Discharge
Efficiency
70-90 %
66 %
80-90 %
99.80 %
Cost ($/Whr)
2
2.75
2.5
2.8-5
Lithium Polymer Battery
 Polymer Li-Ion Battery





18650 cell type
14.8 V (working)
16.8 V (peak)
2.2 Ah
32.56 Wh
 Reasons for choosing:
• High energy density (Wh/kg)
• High energy/dollar (Wh/$)
Alternative Power Source
 Power outlet:
 “Unlimited” power
 Quick charging of the battery
 Solar panel:
 Environmental Impact
 Financial Benefits
 Energy Independence
Solar Panels Specifications
Monocrystalline
Polycrystalline
Thin film
Power
10 W
10 W
10 W
Open Circuit voltage
21.5
21.4
24.2
Short Circuit Current
0.64
0.68
0.84
Maximum Power Voltage
17.5
16.8
17.3
Maximum Power Current
0.57
0.6
0.64
Efficiency
15 %
12.5 %
6.3 %
Cost/W
10-11
8.5-9.5
10
Solar Power Selection Details
Solar Panel Type
Monocrystalline
Manufacturer
INSTAPARK
Efficiency
15 %
Power
10 W
Maximum Voltage Power
17.5
Maximum Current Power
0.57 A
Open Circuit Voltage
21.95 V
Cost
$39.95
Output Efficiency
 Increasing the output efficiency of the panel:
 Increase panel size
 Implement tracking system
 Single axis
 Dual axis
Single Axis Control System
Ambient Light
Photoresistor
MSP430
Longitude
Orientation
Dual Axis Control System
Latitude
Orientation
Ambient
Light
Photoresistor
MSP430
Longitude
Orientation
Compare and Contrast
 Dual axis control system would require more
maintenance.
 There’s an extra cost involved in utilizing an extra
motor or actuator.
 Increased complexity.
 6% extra efficiency compared to a single axis control
system; not worth it.
Solar Panel Implementation
 Free rotation of theta
(𝜃) angle.
 Phi (𝛷) is fixed in
single axis system.
 Optimal angle of phi
(𝛷) is 15°.
Budget
Part
Cost
Quantity
Total Cost
RC Car
Chassis
$50
1
$50
Solar Panel
$40
1
$40
Inductive
Charger
$40
1
$40
Battery
$105
2
$210
Dev Board
$50
1
$50
PICKit 3
$50
1
$50
Sonar
Sensors
$30
10
$300
Motors
Circuit
Components
Total
~$550
Distribution of Labor
Tarik
Luke
Marcel
Jerald
Solar Panel
80%
5%
10%
5%
MCU Software
25%
25%
25%
25%
Robot Construction
10%
5%
80%
5%
Wireless Design
5%
70%
5%
20%
Navigation/AI
5%
20%
5%
70%
Concerns
 Ability to accurately depict a global map and link it to
PowerBot’s local map.
 Ability to correctly implement EERUF.
 Ability for PowerBot to become unstuck in a trap
situation.
Questions?