Snake Motion inspired Robots
Outline
• Robot Motion Models • Sn Snak ake e Lo Loco como moti tion on • Sn Snak ake e Ro Robo bott Mo Mode dell • Pr Prop opos osed ed Mo Mode dell • Des Design ign and Tec Technic hnical al Con Concer cerns ns • Implications and Future Work
Motivation •
Occupy a wide variety of ecological niches
•
Movement without limbs
•
Small cross section to length ratio
Ability to change the shape of their body
•
"To "T o walk is i s human, to slither divine" divi ne"
Other Models
Applied AI Systems, Inc., Canada
Ijspeertt et al Ijspeer Science 315, 1416 2007
Advantages Advan tages of Serpentine Ser pentine Locomotion
STABILITY oten enti tial al Ener Energ gy lo low w in mo most st si situ tuat atio ions ns • Pot
• Les Lesss proba probabl ble e failur failure e points points
TERRAINABILTY Can n cli clim mb he heiights ghts ma man ny ti tim mes it’s own girt girth h • Ca possi sibi bili lity ty of get getti ting ng st stuc uck k • No pos
Advantages Advan tages of Serpentine Ser pentine Locomotion
TRACTION ing g Sn Sna ake ca can n exer ertt a for forc ce upt upto o a 3r 3rd of of • Movin it’s own wei eigh ghtt Large contac contactt ar area ea resul results ts in greate greaterr tr tracti action on • Large
EFFICIENCY Reduce ced d co cost sts s due due to lo low w CO COG G, el elim imin inat atio ion n of • Redu accele accelerration ation and deccel decceler erati ation on of limbs limbs
Advantages Advan tages of Serpentine Ser pentine Locomotion
SIZE & SHAPE • Small frontal area • Sl Slend ender er design design impli implies es bet better ter ma maneu neuv ver erabi abilty lty
REDUNDANCY Employs ys simple simple moti motion on actuat actuators ors in sequen sequence ce • Emplo ailu lurre/De e/Defec fectt co coul uld d be ea easi silly repla eplace ced d • Fai
Snake Locomotion
Scales & Weight distribution.
Scales have similar design as Wheels and Ice skates.
•Lateral undulation S-shaped wave travelling from head to tail, it is the most common and efficient mode, and used by almost all snakes. Snake’s body moves back and forth causing lateral waves that force longitudinal motion. Used mostly in areas with uneven uneven or variable variable terrain terrain . e.g swimmi swimming ng snakes,, anguill snakes anguilliform iform swimmi swimming ng lamprey lampreys s eels.
•Rectilinear locomotion ( "inchworm" )employed by the heavyweights snake like boas & pythons. By cyclically “fixing” parts parts of the skin to the ground ground using scales, and then moving the backbone bac kbone forward with respect to the skin, and finally releasing the scales allowing the skin s kin to move forward. Stabbing and pushing mechanism of the scales. Very slow motion used while stalking its prey.
•Concertina mode: can be thought of as snake taking steps. Part of the snake’s body is pushed against a surface forming a small number of waves: by moving these waves, and the corresponding contact points, the snake progresses. The only place where concertina progression is primarily used is by arboreal snakes on tree limbs as one part is always attached to the tree ,here LU and RP are difficult.
•Sidewinding is used by desert snakes that need to move on sand; Fastest mode of locomotion can be thought of as equivalent to horse galloping. In this mode, the snake lifts a part of the body to maintain only a few contact points with the ground, using them to move the rest of the body. body.
Other types of locomotion: Climbing Climbing:The :The
two most common ways of ascent are LU and RP. Hard to believe a snake lashing itself up a tree, but it does work and ascent ascen t is fluid. When on branches the much safer concertina mode is used in place of the other two
Swimming:The :The horizontal Swimming
undulatory progression lends itself well well to moving through water and is employed by most aquatic serpents. Even large snakes like Python reticulatus and Eun Eunect ectes es mu murin rinus us are known to use HUP in the water (something large boids generally avoid avoid doing on land).
Flying Flying:Flying :Flying
snakes have longitudinal hinges on their ventral scales which allows them to create a concavity which creates more surface area for air to pass through which creates drag, which slows descent and voila, we have flight.
Simulation of Motion
Miller et. Al.
Simulation
Implementation
Which Gait should we choose?? Factors influencing Selection • Speed • Terrain • Ability to maneuver • Energetic efficiency
Lateral Undulation
Configuration Parameters •Design •Morphology •Control System
Design • Segments – “v “ver ertteb ebra rae” e” • Actuators – “Musc scle les” s” Actuator is a mechanical device for controlling a mechanism. Takes Energy and converts into motion
Morphological Segments connected by universal joints Mechanism was proposed by Dr. Dr. Hirose and is called
Active Cord
Design Optimization • Number of Scales and Angle of rotation
For Speed
Number Of Segments
But , Number Of Segments
Design Complexion
Snakes usually have 100-400 segments
Earlier Models – Dr.. Hirose Dr Hiro se et. Al. 10 Segments – 20 actuators
S5 – Miller et. Al. Closest to natural snake locomotion 32 Segment – 64 actuators
Morphology Low friction force -in the direction of forward movement High frictio friction n force - in lateral lateral directio directions ns Achieved By Directionality of scales Fiber Skins with various surface treatments
Dowling et. al.
Control System “Follow the Head” Travelling Wave propagated from head to tail Generated from predefined gait patterns, usually computed as sine waves
Works pretty well for uniform terrains
Velocity changes with friction coefficients
Jae-Kw Jae -Kwan an Ryu et all.
What will happen when the terrain changes?? phase difference between the head and tail joints will not remain constant – Snake will wriggle in place
Central Pattern Generators (CPG) can be defined as neural networks that can endogenously produce rhythmic patterned outputs
Work On Feedback Mechanis m Jae-Kwan Jae-Kw an Ryu Ryu et al.
Matsuoka’s neural oscillators oscillators on each joints – take velocity as input and modulate frequency
Existing Models 1. Robots bots that that mov move us using ing powered powered wheels
Existing Models 2. Robots that move by applying torques on the joints between the segments. Can have passive wheels.
Technical Concerns • For search and rescue missions, and possible medical applications. Waterproofing. Completely autonomous. Distributed control Different type of movement for different
terrains.
Remote control Remote controlled led - GSM GSM against against radioradiowaves Degree of freedom Falling over The movement patterns obtained with the robot have to be compared to biological data.
Proposed Design
Multiple identical elements – same algorithm,
easy to replace , redundancy Distributed actuation, power and control
Each individual element is made waterproof
The center of gravity is placed below the
geometrical center. Large lateral surfaces for good swimming
efficiency. Asymmetric friction for the lateral undulatory
locomotion
Controlled Controlled by a CPG mechanism Remotely controlled in terms of speed and
direction commands, commands, but otherwise have an onboard locomotion controller for coordinating coordinating its it s multiple degrees degrees of freedom.
For better control – servo motors in head and
tail with paddles. Sensing – points of contact with the ground. Miniaturization – use of bionic arm like
mechanism. mechanism. 70 % weigh weightt is due to to motor motors. s.
Proposed Model
Linker Design and mechanism
Expected outcome • Based on the work plan we will get a fully functional robotic snake which should be capable of autonomous motion in a 3d environment by mimicking the snake movement of lateral undulation. b e easy to control and will be able to traverse traverse • The robot will be through rough terrain, rubble, sand, fluids or over obstacles with ease.
• Making the robot design simple(bionic arm method) , we should be successfully be able to miniaturize it thus giving us a lot more interesting applications like medical applications. appl ications.
Amphibious ACM R5 robot snake – Hirose Fukushima Robotics Lab
Snake Bot – Sac Sacros ros des designs igns,, Utah
Applications • Can be used to detect leaks in oil pipes • Can be used in search and exploration missions during earthquakes and floods.
• Essentially can be used to reach or explore places which are not easily accessible.
• If scaled down significantly, it could even be used for a very specific drug delivery system.
Anna Konda – a fir fire e fig fight htin ing g ro robot bot,, SINTEF Norway
Robot motion in a fluid
Future work technology, we should be able to • With advancement in technology,
make make smaller motors which will enable us to make make smaller robot snakes with good control. • By studying all the methods of movement, we can design a robot snake to change its motion motio n from serpentine to concertina to side-winding, simply by providing different different inputs to each segment. • The material used to make the robot must be improved upon to better mimic the scales and stretchable skin of the snake.
Take home message… • Motivation/Background •Motion of the snake •Models and Work plan •Applications and challenges
