Michael Bartholomew
Bio-Robot Lecture 1 Wiki Page
Robot Lab
Traditional vs. Biologically Inspired Robots
Traditional Robots
Definitions
1) Traditional Definition: Robot as a machine designed to function in place of
human being.
2) Robot Society Definition: Programmable multi-functional manipulator designed
to move material parts, etc. (More industrial definition.)
For practical purposes, the general robotic function can be looked at categorically:
1) Static vs. Stationary
2) Autonomous vs. Remote Control
Stationary
Stationary robots are utilized in a variety of industrial settings, including inspecting,
moving, assembling, manufacturing, and medical devices.
Mobile
Mobile robots are different in that they are generally a moving platform, where the
primary function is locomotion. Mobile robots can be utilized as a transportation
platform, for surveillance, navigation, and other similar uses.
Biologically Inspired Robots
The main focus in biologically inspired robots is mobile robots. Generally, mobile
robotics has been concerned with automating/programming existing engineered devices.
1) Off-road trucks –> ATRV robots (Automated ATV)
2) Aircraft -> Predator UAV (Automated Aircraft)
3) Tanks -> Andros Wolverine (Automated Tank)
Design Motivation
An alternative source for robot inspiration is the entire animal kingdom. Biological
locomotion, biomechanics, biological structures, materials and geometry are involved in
the biological mechanics and are considered in the design process. Biological control,
sensors and processing are also key areas of interest from a functional standpoint.
Bio-inspired design concepts from nature can be implemented in imaginative ways, some
are illustrated in today’s pop culture. For instance, spider (Minority Report) and squid
robots (The Matrix.)
Traditional/Biological Locomotion Comparison
Land Based
Traditional – Wheels, tank treads
Biological - Legs, body undulation (snakes)
Water Based
Traditional - Propeller, Jets
Biological - Fins, Undulation
Air Based
Traditional - Rotating blades, Rocket propulsion
Biological - Flapping wings, Gliding
Traditional Advantages/Disadvantages
Advantages
Speed, strength, durability, reliability, repeatability
Disadvantages
Poor maneuverability, complex systems, many components, designed for single type of
locomotion, limited by terrain and obstacles, best suited for highly specific tasks
Why look to nature?
Variety of locomotion
On land: Walking, running jumping, variety of other tasks
In Water: Swimming, diving, leaping from water, neutral buoyancy
In Air: Flying, Gliding
Anywhere: Lifting, Carrying, Pulling, Pushing, Grasping
Natures Adaptability
Nature’s biology has adapted to tasks to meet all of its functional requirements.
Chase pray -> cheetah’s speed
Swim fast -> Shark’s skin, etc.
Climb slopes -> mountain goat’s mobility
Nature’s design is optimized
Running – Cheetah – 72 mph
Swimming – Sailfish, 68 mph
Flying - Dragonfly – 36 mph
Lifting – Elephants (1 ton)
Long jump – Kangaroos (30 ft)
High jump - Puma (18 feet)
Capabilities of nature
All of nature’s creatures exhibit one or more of the following qualities
1)
2)
3)
4)
5)
Stability
High Maneuverability
Ability to traverse highly irregular terrain
Ability to function in varied environments
One system capable of various types of motion
There are also many specializations: i.e., Gecko’s can walk upsides down, Hummingbirds
can hover.
Motivation for engineers
1)
2)
3)
4)
5)
6)
Nature offers engineers new design concepts
Nature uses unique forms of locomotion unseen in robotics
Bio-inspired robots can outperform traditional robots
No limitations of terrain
Nature’s creatures well adapted for nature world
Nature is capable of unique tasks
Traditional robot engineers typically have a set of design requirements, where they seek
designs that satisfy a set of functional requirements. Nature offers many alternatives to
same requirements. For example, consider an underwater mine reconnaissance problem:
Design task – Underwater mine reconnaissance
Functional requirement – Underwater locomotion
Approach: Look to nature of inspiration
There is a need to quantify and compare design parameters so that the appropriate
creature from nature can be decided upon for robotic inspirations.
Two types of engineering design parameters:
1) Design specifications
2) Operating specs
One must convert engineering design parameters into biological descriptors. To do this,
we examine creature characteristics:
1) Physical: include body height, clearance height, length, width, weight, degrees of
freedom, power, range, etc.
2) Locomotion performance: Velocity, acceleration, deceleration, cost of transport
(efficiency), maneuverability, etc.
Maneuverability
Definition: Ability to make controlled series of change in movement or direction toward
an objective.
For instance, the objectives may be to follow a target, negotiate obstacles, and navigate
through confined spaces. This can be characterized by agility, quickness, readiness to
move, and ease of movement.
Measuring maneuverability
There are various ways to quantify maneuverability:
1)
2)
3)
4)
Reaction time (seconds)
Turning rate
Turning radius
Linear maneuverability number (LMN) (Perpendicular force impulse proportional
to forward momentum)
5) Propulsor effectiveness number (Ratio of the angle of body rotational to the angle
of deflection)
Examples of Biologically-Inspired Robots
Land-based mobile robots
Functional requirements: propel forward, traverse terrain, overcome obstacles, avoid
obstacles, grasp objects, carry objects, etc.
Constraints: Obstacles spacing and height, slope of terrain, speed, force.
Some concepts from nature that fit the land-based requirements: Cockroach, scorpion,
stick-insect, lobster, dog, gorilla, human.
Cockroach Robot
Created by Mark R Cutkosky (Stanford University)
Design problem/application: Mine Clearing
Motivation: Time consuming, hazardous, costly errors (human life.)
Design requirements: Fast, stable, excel in natural environments (grass, dirt, rock,
pavement), can quickly traverse obstacles, maneuverability, inexpensive.
Why not use a conventional wheeled robot? The advantages are speed, durability, and a
high payload capacity. However, the disadvantages are that it has limited
maneuverability; it is limited by uneven terrain, no good manageable obstacle height vs
robot size, and only a single type of locomotion.
For biological concept selection there are certain goals. First we must match design
parameters: Speed, stability, maneuverability, ability to navigate rough terrain.
Nature has already solved these design specification with the cockroach. The DeathHead Cockroach was used for the inspiration for the robot:
Death-Head Cockroach
1) Static and dynamical stability
2) Can quickly and easily traverse obstacles 3x hip length
3) Fulfills all other design specifications.
Approach
Functional biomimesis of death-head cockroach: essentially, we mimic the functions of
nature, rather than the specific design.
Look at the following aspects of the cockroach: Structure, locomotion, and control
Design goals
Structurally simple design
Stable, cockroach-like running
Speed over 1.5 body-lengths per second
Traverse jip height obstacles
Mechanical Implementation
Self-stabilizing posture -> 6 legs sprawled in plane
Compliant hip joint
Embedded active components (integrated constructions)
2 degrees of freedom for each of 6 legs
Each set of 3 legs is alternatively activated (just like cockroach)
Thrusting/stabilizing legs
Cockroach legs motions
Feed-forward control, angle for each hip controlled
Passive dynamic self-stabilization (compliance of hips)
Size: 16 x 10 x 9cm
Leg length: 4.5cm
Speed: 80 cm/s
3.5 cm obstacles can be overcome
Met all functional requirements and design goals:
Fast and stable locomotion
Able to navigate rough terrain
Quickly traverse obstacles
Structurally simple design
Functional biomimesis of death head cockroach was successful.
Snake Robot
Design problem/application: Search and rescue, navigate urban environments, natural
environments. Planetary surface exploration, minimally invasive surgery, Bridge
inspection, disarming bombs, construction/repair in space, etc.
Search and rescue requirements
1)
2)
3)
4)
Exist in hazardous environments, further collapse, fire and toxic gases
Navigate narrow spaces
Need small body diameter
Small area required for locomotion, high maneuverability
Conventional robots have difficulty: they cannot navigate through narrow spaces, as well
as having limited maneuverability.
Natures choice is the snake: Same functional requirements, stability so we don’t fall
over, traction, make use of whole body length, sealing (body is one piece), flexibility,
many varied configurations, superior ability to maneuver, require little room to move,
capable of large reach. Both locomotor and manipulator with the ability to traverse
various terrains.
Snakes can traverse obstacles, climb steps, trees, steep slopes, reach in to narrow spaces,
span gaps, operate in sand, water, and in trees. The snakes is a vertebrate (100-400
vertebrate) and the skeletal form is a simple and repeated structure with only three types
of bones. Still, it is the most complex of all vertebrates (vertebral articulation
movement.)
The vertebra form ball and socket joints, so small individual articulations produce large
motions.
Snake Locomotion
Lateral Undulation
Changes body to s-Shape
Travels front to rear
No Static Contract
Efficient, but needs wide space
Concertina Progressions
Snake elbows out its body
Moves forward using static points of contact
Good for traversing tight spaces
Inefficient and slow
Rectilinear motion
Muscles shift the snake’s ribs linearly
Traction enabled by belly scales
Provides near constant speed
Effective and efficient
Side-Winding
Moves forward using two points of static contact with the ground
Efficient, but requires wide space
Works well on soft ground
Snake robots: Hyper redundant design
1)
2)
3)
4)
Composed of at least 2 “belly” modules linked together
Additional head or tail modules for visual sensors, power, etc.
Energy supply can self contained or from external source
Connected by series of joints of various types
Advantages
1) Can function with one or more failed segments
2) Can be segmented into many robots and then rejoin
3) More readily repairable due to redundant design
Disadvantages
1) Small payload capacity
2) Slow speed
3) Too many joints
Each module of the snake may contain: Actuator, Sensors, controllers, and “skin.” There
is the need for the motion control to provides snake-like motion - multiple actuated joints
create multiple DOF. There are too many joints to operate individually and the entire
process requires complex motion-planning algorithms.
Examples of Robot Snakes
GMD Snakes
ACM-R3
ModSnake
CONRO: Self-Reconfigurable Robot
Can reconfigure modules on its own.
No head or tail modules: any module can lead
Can separate into joints.
Ability navigate various terrain, narrow spaces, stairs, grass, rocks, water, gaps
Search and rescue, pipe-inspection
Water-based mobile robots
Tuna Robot Work Done at Draper Laboratory at Cambridge. Underwater robots can be
used for underwater reconnaissance with high maneuverability. For this particular robot,
the Yellow-Fin Tuna was used as inspiration. It can accelerate and decelerate quickly, it
is ultra maneuverable, and fast. Traditional solutions used unmanned undersea vehicles.
Requirements
1) High transit speed
2) Long range
3) Large operating depth station keeping ability
4) Maneuverability
The traditional solution of the unmanned underwater vehicle (UUV) has both limited
maneuverability and a reliance on a propulsion system. Yellow-Fin Tuna makes up for
some of these problems Essentially, a robot was created to mimic the kinetics of yellowfin tuna. The finished product was accomplished through bio-inspiration from the yellow
fin tuna, and met all design requirements It has shown advantages for variety of
underwater missions.
Why Bio-Inspired Robots?
Bio-inspired concepts can be successfully used to create mobile robot designs that offer
many advantages over traditional designs
1)
2)
3)
4)
Conventional mobile robots have limitations
Maneuverability is much improved in bio-inspired robots
Ability to traverse highly irregular terrain
Ability to function in varied environments
5) Nature’s creatures excel at certain tasks and use unique forms of locomotion
6) Engineers can look for bio-inspiration in bio structure, locomotion, and control
7) Source for bio-inspiration can be chosen by measuring “design parameters” in
nature
8) Can analyze animal characteristics, locomotion performance
All of these factors come together to allow the robots to be used for real-world
applications that would be otherwise difficult.