1 Project submitted by Sagar Warghade Virendra Parab Saurav Singh Under the guidance of Prof K T Talele Electronics Engineering Department Sardar Patel Institute of Technology ID: 560907
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Slide1
Spherical Mobile Robot
1
Project submitted by:
Sagar
Warghade
Virendra
Parab
Saurav
Singh
Under the guidance of:
Prof. K. T.
Talele
Electronics Engineering Department
Sardar
Patel Institute of Technology
Andheri
(W), Mumbai 400 058
2011-12Slide2
Table of Contents
2Slide3
Introduction
3
Nature of mobility attracts many researchers.
Challenges: Complex dynamics and Non linear control
Very few successful in practice.Slide4
System Design
4
Microcontroller
RF
Transceiver
Servo Motor
Servo Motor
Battery & Additional Weight
H-Bridge
Geared
DC
MotorSlide5
The Magical Sphere
5
Only one point of contact
Protective outer shell
Effectively zero turning radius
Inherently non-invertible
Greater rolling efficiencySlide6
Internal Propulsion Mechanism
6
Primary means of locomotion: Shifting the centre of massSlide7
Driving Mechanism
7
The centre of mass : directly above
contact point
Offsetting the centre of
mass
TORQUE
Continuous displacement Continuous torque. Slide8
Driving Mechanism Implementation
8
Geared DC Motor
Driving RodSlide9
H-Bridge:
Enables you to control the motor in both forward and reverse with a microcontroller.Slide10
H-Bridge
10
Interface between DC Motor and Microcontroller
Provides speed control
4 control signals:
-EN : Control pin
-DIR1 and DIR2 : Motor direction
-PWM pinSlide11
Steering Mechanism
11
Servo motors : NRS-995
Torque: 18
Kgs
/Cm
To steer in one direction, one motor
rotates clockwise and the other
anticlockwise
To steer in opposite direction, both
the motors rotate the opposite way.Slide12
Servo Motor
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
0
1
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
0
1
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms
0
1
1.50 ms: Neutral
1
.0
ms: 0 degrees
2.00
ms: 180 degrees
Requires constant pulsing
(
=
50 times / second)Slide13
Servo Motor Step Control
13
Interrupt Service Routine Method used
4MHz clock speed-20 degrees
8MHz clock speed-10 degrees
16MHz clock speed-5 degrees
32MHz clock speed-2.5 degrees
Clock speed used in the final design-8 MHzSlide14
Wireless Interface
14
Wireless PS2 console
2.4 GHz RF Transceiver
SPI mode of communication
Communication speed : 64 Kbps to 512 KbpsFinal data rate used-128KbpsSlide15
15
Remote ControlSlide16
16
RF TransceiverSlide17
17
RF Transceiver WorkingSlide18
What is SPI?
Shorthand for “Serial Peripheral Interface”Defined by
Motorola
Generally
faster,
capable of several MbpsApplications:Used in EEPROM, Flash, and real time clocks
Better suited for “data streams”, i.e. ADC converters
Full duplex
capabilitySlide19
SPI Bus Configuration
Synchronous serial data link operating at full duplex
Master/slave relationship
2 data signals:
MOSI – master data output, slave data input
MISO – master data input, slave data output2 control signals:SCLK – clock
/SS – slave select (no addressing)Slide20
SPI Protocol
Clock
Polarity (CPOL) and Clock Phase (CPHA
),
determine
the active edge of the clockMaster and
slave: Common data rate
CPOL
CPHA
Active edge
0
0
Rising
0
1
Falling
1
0
Falling
1
1
RisingSlide21
SPI Protocol (cont.)
Hardware realization is usually done with a simple shift register
SPI defines communication
lines
and clock
edge
No acknowledgementSlide22
Power Supply
22
Servo Motor
DC Motor
Servo MotorSlide23
23
Batteries Position
Additional Weights
BatteriesSlide24
Central Control Board
24
Micro-controller used- PIC18F4520
9V battery operated and 7805 IC regulated power supply
Directly pluggable into a 5V adapter
Built with future expansion in contextICSP programmableSlide25
PIC18F4520 – MPU and Memory
25Slide26
PIC18F4520 Special Features
Sleep modeWatchdog timer (WDT)
Code protection
In-circuit serial programming
In-circuit debugger
330_02
26Slide27
The Final Pictures
27
Internal & External Bodies
External Shell
Internal AssemblySlide28
28
Electronic Module Positions
H-Bridge
RF Transceiver
Central Control BoardSlide29
29
Motor Positions
Servo Motors
Geared DC MotorSlide30
30
In Sync Communication
Wireless Connection EstablishedSlide31
Microcontroller Programmer
31
A JDM-based programmer
In Circuit Serial Programming
Ease of program burning and testingSlide32
Softwares
Used32
MPLAB IDE - Code Development
Eagle – Schematics and PCB Layout
Proteus VSM –Microcontroller Simulation
Solidworks
– Mechanical CAD Design
PICPgm
– Code BurnerSlide33
References
33
Schroll, G. “Design of a Spherical Vehicle with Flywheel Momentum Storage for High Torque Capabilities.” B.S. Thesis, Massachusetts Institute of Technology, 2008
Chemel, B.;
Mutschler
, E. &
Schempf
, H. “Cyclops: miniature robotic reconnaissance system,” IEEE Int. Conf. on Robotics and Automation (ICRA’99),May, 1999, pp. 2298-2302
Mukherjee
, R; Minor, M. &
Pukrushpn
, J. “Simple motion planning strategies for
Spherobot
: a spherical mobile robot,” Proc. Of The 38
th
Conference on Decision & Control, Phoenix, AZ, December, 1999.
A.
Bicchi
, A.
Balluchi, D. Prattichizzo, A Gorelli: “Introducing the Sphericle: an experimental
testbed for research and teaching in nonholonomy,” IEEE Int. Conf. on Robotics and Automation, 1997Slide34
34