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R U S S I A N S T A T E S C I N T I F I C C E N T R ER U S S I A N S T A T E S C I N T I F I C C E N T R EC E N T R A L R E S E A R C H A N D D E S I G N I N S T I T U T E O F C E N T R A L R E S E A R C H A N D D E S I G N I N S T I T U T E O F
R O B O T I C S A N D T E C H N I C A L C Y B E R N E T I C SR O B O T I C S A N D T E C H N I C A L C Y B E R N E T I C S
5th APRIL 2006
Oleg Shmakov
CRDI RTC DEPARTMENT OF SPbSPU
Joint Advanced Student School 2006Saint Petersburg
Course 5: Mechatronics – Foundations and Applications
Introduction
• Why snakelike robots?• Biomechanics of snakes• Review• Mechanic model of snakelike robots• Mathematical model of snakelike robots• Hardware realization control• Snakelike robot CRDI RTC• Conclusion
Oleg A. Shmakov Snakelike robots locomotions control
Why snakelike robots?Advantages
• Stability
• Terrainability is the ability of a vehicle to traverse rough terrain • Traction is the force that can be applied to propel a vehicle
• Redundant
• Simple anatomy
Oleg A. Shmakov Snakelike robots locomotions control
Why snakelike robots? Applications
• Search and Rescue• Examination blockages after earthquake• Planet’s exploration • Medical applications • Examination hard-to-reach areas • Tube inspection• Bio Terrorist• Remote sampling• Military inspection• …
Biomechanics of snakesVertebrate
Oleg A. Shmakov Snakelike robots locomotions control
Real snakes have 100-400 vertebrae
Snake vertebral articulation is one of the most complex of all vertebrates.
Biomechanics of snakes Locomotion modes
• Lateral undulation• Sidewinding• Propulsion (with creeping)• Concertina• Rectilinear movement
Oleg A. Shmakov Snakelike robots locomotions control
ReviewDesign snakelike robots
Oleg A. Shmakov Snakelike robots locomotions control
Non-modular Modular
WITH WHEELS WITHOUT WHEELS
ReviewHirose & Umetami - SERPENOID
Oleg A. Shmakov Snakelike robots locomotions control
• the waveform that the snake assumes during creeping movement is a curve which changes sinusoidally along the curvature of the body, and a formula for this, called a serpenoid curve.
ReviewHirose & Umetami – ACM III
• Active Cord Mechanisms – ACM
• Wheeled robots
• Robots that could perform lateral undulation
Oleg A. Shmakov Snakelike robots locomotions control
• Hirose’s development of modeling and control first derived expressions of force and power as functions of distance and torque along the curve described by the snake.
• Comparisons with natural snakes across constant friction surfaces showed close agreement between the serpenoid curve and the empirical data.
• Snakes quickly adapt locally to variations in terrain and environment.
• The control took the form of angle commands at each joint
ReviewCarnegie Mellon University – Kevin Dowling
Oleg A. Shmakov Snakelike robots locomotions control
ReviewCarnegie Mellon University – Biorobotics Lab
Oleg A. Shmakov Snakelike robots locomotions control
Mechanic model of snakelike robotsDobroluybov A.I.
Oleg A. Shmakov Snakelike robots locomotions control
1970 - Dobroluybov A.I.
«genetic relationship» wheels and waves and
Snakes are using rolling motion ”
Some points of a moving body or set of bodies during movement should vary periodically roles: mobile points become motionless and on the contrary. On character of this procedure of locomotion can be divided into two big classes: pacing when reference points of a body only during some moments of time pass from motionless in a mobile condition and back, and rolling when these transitions are carried out continuously. Snakes can move by pacing and rolling. Carry of points of a support of the essences, moving in the way rolling, can be various.
Mechanic model of snakelike robotsIvanov A.A.
Oleg A. Shmakov Snakelike robots locomotions control
Lateral bendingRectilinear movement
curving (without creeping)
Side winding
Concertina
Shank movement
Propulsion (with creeping)
Mathematical model of snakelike robotsHow to control?
• Random Search• Hill climbing• Simulated• Annealing• Neural Nets• Response Surface Methods• Genetic Algorithms• Trigonometric forms• Fourier• Parametric curves• Bayesian optimization
algorithms
Oleg A. Shmakov Snakelike robots locomotions control
DOWLINGCONROTANEV
CMU – Biorobotics Lab
Genetic algorithms for locomotions control
Oleg A. Shmakov Snakelike robots locomotions control
Category Value
Function set {sin, cos, +, -, *, /}
Terminal set {time, segment_ID, Pi, random constant, ADF}
Population size 200 individuals
Selection Binary tournament, ratio 0.1
Elitism Best 4 individuals
Mutation Random subtree mutation, ratio 0.01
Fitness Velocity of simulated Snakebot during the trial
Trial interval180 time steps, each time step account for
50ms of “real” time
Termination criterion
(Fitness >100) or (Generations>30)or (no improvement of fitness for 16
generations)
Fitness convergence characteristics of 10 independent runs of GP for cases where fitness is measured as velocity in any direction (a) and snapshots of sample evolved best-ofrun sidewinding locomotion gaits of simulated Snakebot (b, c), viewed from above. The dark trailing circles depict the trajectory of the center of the mass of Snakebot. Timestamp interval between each of these circles is fixed and it is the same (10 time steps) for both snapshots.
Trajectory of the central segment (cs) around the center of mass (cm) of Snakebot for a sample evolved best-of-run sidewinding locomotion (a) and traces of ground contacts (b).
Hardware realization control
Oleg A. Shmakov Snakelike robots locomotions control
С0 С1 С2
18 1916 1714 1512 1310 118 96 74 52 30 1
RS232
Microcontrollers
Hardware realization control
Oleg A. Shmakov Snakelike robots locomotions control
microcontroller DC motorsFeedback from sensing
Control & power
SensorsPower supply
MAINMicrocontroller
For all joints(CMU)
Snakelike robot CRDI RTC
Oleg A. Shmakov Snakelike robots locomotions control
Total mass 3 kg
Length 1120 mm
Width 65 mm
Maximal course torque 0,3 Nm
Maximal pitch torque 1,2 Nm
Number of the links 16
Number of the joints 15
Number of the servos 30
Voltage 4,8 – 6 V
System of snakelike robot control
“SnakeWheel -1”
Coding - MAX 232
Power supply servo
PC
Camera
Power supplyMicrocontrollers
6 volt
4.8 - 6 volt
USB 1.1RS232
Oleg A. Shmakov Snakelike robots locomotions control
Structural control scheme
AA F1 1 CS59 60
63 byte
63 byte*
Oleg A. Shmakov Snakelike robots locomotions control
Low level control
1 channel 2 channel 1 channel
t, мс
10 мс
20 мс
0,9 1,5 2,1
fsend ≤ 50 Гц
t
φ
T
20 – 40 main points
fsend = 30 – 60 Гц
fbase = 1,5 Гц
T ≥ 2/3
fsend ≤ 50 Гц
60°/0,11 с
Oleg A. Shmakov Snakelike robots locomotions control
Software scheme
Entering parameters
Send
VisualizationBlocOf
Protection
BlokChangingmovement
BlocCamera control
Forming
RS-232
Oleg A. Shmakov Snakelike robots locomotions control
EXPERIMENTLateral bending
Amplitude corner by course
35
Amplitude corner by pitch 18
Quantity link which are using in course wave
8
Quantity link which are using in course wave
4
Phase 0
SPEED (max) (cm/sec) 2.5
SPEED (min) (cm/sec) 1
Oleg A. Shmakov Snakelike robots locomotions control
EXPERIMENTSide winding
Amplitude corner by course
35
Amplitude corner by pitch 20
Quantity link which are using in course wave
8
Quantity link which are using in course wave
8
Phase π/2
SPEED (max) (cm/sec) 4,3
SPEED (min) (cm/sec) 3
Oleg A. Shmakov Snakelike robots locomotions control