This document describes a wireless snake robot prototype called WASP. It has 8 linked segments that provide multiple degrees of freedom for flexible motion. The robot is intended to demonstrate horizontal and basic vertical movement as a proof of concept. Key components include a microcontroller for motion control, sensors for environmental analysis, and wireless communication between the robot and a PC interface. Algorithms are used to generate servo motor angles from user instructions to achieve the snake-like locomotion. The prototype aims to establish wireless control, sensor data reception and basic on-field movement capabilities. Future work may include improving gaits, mechanism design, power efficiency and adding autonomous capabilities.

1. WIRELESSLY ACTUATED SNAKE
PROTOTYPE (WASP)
Presented By,
George Rahul Paul
Meenu Saji
Titto Thomas
Tony Mohan Varghese
Vidya Sekhar

2. Snake Robots: What & Why ?
• Snake Robot -Multiple actuated joints implying multiple degrees of
freedom.
• superior ability to flex, reach, and approach a huge volume in its
workspace with infinite number of configurations.
• Hyper redundant robots.
• Advantages of Serpentine Motion:
• Stability, Terrainability, Traction
• Redundancy, Modular structure.
• Applications
• Rescue and Military Operation
• Exploration, Inspection
• Medical
• Hazardous Environment

3. In Scope
•To create a control • Generate angles for •Parameter Sensing •Proof of Concept /
signal format for all servos using Design
•Signal Processing of
communication algorithms environmental data •To Demonstrate
•Generate signals as •To Pass them in Horizontal
•Video of the scene
per user’s instructions proper format to Movement
•ZigBee motors • Basic vertical
Communication movement
WIRELESS ON FIELD ENVIRONMENTAL PROTOTYPE I
CONTROL MOVEMENT ANALYSIS

4. Functional Description
• Control of Robot
• Reception and Display of sensor parameters & Video
PC • Provide a user interface for controlling the motion
• Link between Modules on PC and Robot side
Wireless
• Highly secure one-to-one communication
• Sensors for environmental sensing
• Motion execution using motors.
Snake
Robot • Onboard microcontroller for master control.

5. Block Diagram
SENSORS
WIRELESS WIRELESS
CAMERA CAMERA
RECEIVER
SERVO MAIN TRANSMITTER RECEIVER
MOTOR CONTROLLER
PC
GUI IN
BATTERY
VB
SNAKE ROBOT ON FIELD PC SIDE

6. Block Diagram of Mechanical Subsystem
Mechanical Subsystem

7. Development Process
Link Structure in
WASP
Orthogonal Joint –
WASP Mechanical
by DOWLING
Structure

8. Mechanical specification
SPECIFICATIONS DETAILS
Material Used Light weight, Low cost Aluminum alloy
Number of links 8
Size of link(mm) 130x62x77
Weight of link(Kg) 0.28
Motion Range of joint(deg) [-90,+90]
Actuators Servo motor, (Vigor – 6Kg cm Stall Torque)
Sensors Temperature Sensor ( LM35 ) Light sensor (LDR)

9. MOTION CONTROL
MOTION
CONTROL UNIT PWM SERVO MOTOR
(MCU)
Block Diagram – Motion Subsystem
Motion Subsystem

10. PWM SIGNAL SERVO ANGLE
Positions of
Servo with
respect to
PWM width

11. Motion Subsystem
• Head is controlled to trace a desired path
• Head performs a new set of actions at a time,
previous set of actions is propagated to next
link
• Speed at which one link performs the previously
executed actions of head must be modulated.

12. OBSERVER BASED CONTROL SCHEME
Mappings for Control :
=C(*-)=(1/s)K(s)(*-)
(s)=C(s)( *-)
*= sin(+(i-1))+ 

13. CIRCUIT SUBSYSTEM
Circuit subsystem includes following selection processes:
•Microcontroller Selection
•Wireless interface Selection
•Sensor Selection

14. MICROCONTROLLER SELECTION
Various Alternatives
• Separate Servo Controllers
• PIC with PWM Modules
DSPIC33FJ256GP710 was chosen owing to the following specialties:
•Multiple PWM modules to control 16 servo motors with single chip
•High speed data processing
•ADC module for sensor data
•Simpler Circuit and Less cost of production

15. DSPIC33FJ256GP710
Operating voltage : 3.3V
Digital I/O Pins : 85 programmable pins
Core Size : 16bit
Clock Speed : 10MHz
PWM channels : 8
16 bit timer : 9
Operating Temperature : -40˚C to 85˚C
External interrupts : 5
On-chip 2.5v voltage regulator
Low power consumption

17. SERVO MOTOR SELECTION
VIGOR VTS- 08A was selected owing to following reasons
•Fairly high stall torque of 6kg-cm
•Compatible Operating voltage range: 4.8V-6V
16 servo motors are used to implement serpentine motion
•8 for vertical motion
•8 for horizontal motion

18. 7414 IC
Output from PWM port is incompatible for input to servo motor.
7414 IC is hence used
•Converts output from a PWM port voltage level to 5v
•Operating Voltage: 5V
•Three 7414IC used for 16 servo motors

19. WIRELESS INTERFACE SELECTION
Various alternatives :
•IR Transmitters and Receivers
•xBee
•Bluetooth
•Wi-Fi
•Cell Phone
xBee was chosen owing to following reasons
•Very Low Power requirement
•Wider Range
• Ease of use
• High baud rate
•Fast response

20. SENSOR SELECTION
Temperature Sensor Selected- LM35
•Calibrated directly in ° Celsius (Centigrade)
• Rated for full −55° to +150°C range
• Operates from 4 to 30 volts

21. Light Sensor Selected- LDR
•Resistance variation with incident light intensity
•Compact and low cost
• LDR used in voltage divider configuration
•If R1 is the photoresistor, V increases with
light intensity.
•If R2 is the
photoresistor, V decreases with light
intensity.

22. • (Vm)3.3 • (Vs)4.8-
V/ 6V/ 1.0A –
(Im)250 1.2A(Is)
mA dsPIC Servo
Zigbee Sensors
• LM35 : 4V-
• (Vz)2.8V 20V/10mA(It)
– 3.4V/ • LDR :
45mA(Iz) (Vl)5V/150m
A(I L)
POWER SUBSYSTEM

23. Total current requirement of power subsystem : ( Im+Iz+IL+It+Is )=
4560mA
Maximum voltage of power subsystem : 5V
Maximum input to 7805 ( to get 5V) : 7.4V
Total Power Consumption = 7.4V * 4560mAH=33750mW
Average lifetime of the battery ( Full charge) = 30 minutes
Total Power required = 33750 * 0.5h = 16.872 Wh
--If battery of 7.4V taken ,
Then its current rating should be = 16.872Wh / 7.4V = 2- 2.25 Ah
POWER MODEL OF SNAKE ROBOT

24. Li-Po
Lead Acid NiMH
Li-ion Ni-Cd Alkaline
BATTERY SELECTION
LiPo Battery – 7.4V/2200mAh selected

25. BATTERY
MONITORING
SYSTEM

26. ON-BOARD POWER SUPPLY CIRCUITRY

27. SOFTWARE SUBSYSTEM
• UI software with coded commands that tells the
robot what tasks to perform and control its
actions.
• low level control realization.
• Visual Basic platform.
• Identifies the COM Port to which xBee is
connected and it does the low level controlling
needed for snake motion.
• Then by clicking the connect button connect to
the particular communication port selected.
• Individual control buttons : STOP, FORWARD,
RIGHT and LEFT, PAUSE

28. Flow chart of communication

29. VB FLOWCHART

30. - Using VB platform
FRONT END GUI – A screen shot

31. Final Specifications:
Weight : 2.5Kg
Length : 1m
Speed : 0.25m/s
On battery lifetime : 15min
Battery charging time : 3Hr
Range : Indoor - 20m, Outdoor – 70m
Result and Conclusion

32. • Various Gaits : Additional work in steering and gait transitions is necessary for more
general locomotion.
• Mechanism : an easier-to-disassemble joint structure with a rapid mechanical and
electric connection, light weight materials such as polymers etc.
• Power: Power efficient working system with long term battery life.
• Sensing: use of sensors in achieving an autonomous locomotion and terrain
adaptability.
• Electronics: SMT miniaturization of circuits
• Learning: Learning the environment , introducing a memory and adaptability.
FUTURE SCOPES

33. Lateral Undulation – A video

34. Thank You