Transcript Robotics Chapter 1 - Introduction Dr. Amit Goradia

Robotics
Chapter 1 - Introduction
Dr. Amit Goradia
Topics
•
•
•
•
•
•
•
•
•
Introduction –
Coordinate transformations –
Forward Kinematics Inverse Kinematics Velocity Kinematics Trajectory Planning Robot Dynamics (Introduction) Force Control (Introduction) Task Planning -
2 hrs
6 hrs
6 hrs
6 hrs
2 hrs
6 hrs
2 hrs
1 hrs
6 hrs
Introduction
• Definition (Robot Institute
of America):
– A robot is a programmable
multifunction manipulator
designed to move material,
parts, tools, or specialized
devices through variable
programmed motions for
the performance of a
variety of tasks.
Puma 560 Robot used for inspection
Types of Robots
• Stationary
• Mobile – Ground
– Wheeled
– Tracks
– Legs
• Mobile – Underwater
• Mobile – Aerial
• Microgravity (Space)
Honda ASIMO
Robot Types - Stationary
Puma
560 Arm
ABB
Arm
MSU Microbot
Mobile
Sony’s
QRIO
MSU
Mobile
Manipulator
Research
Platform
(R2-D2)
MSU
Micro
Crawler
Stanford’s Stanley
(First winner of DARPA Grand Challenge)
Space
Sojourner
-First Mars
Rover
(1998)
Canada Arm
On International
Space Station
JPL’s
Pioneer
Space Probe
ISRO’s
Chandrayaan -1
Robot – Mechanical Structure
Brief History
• 1921 – Word robot derived from a Czech play
• 1940s – Teleoperator developed at Oak Ridge national
Labs
• 1954 – George Devol, Programmed articular transfer
device
• 1956 – Joe Engelberg, Unimation (first robotics
company)
• 1961 – First robot installed on assembly line in GM
• 1968 – Japan, Kawasaki makes robots
• 1969 – GE makes first walking robot
• 1974 – First Hydraulic drive robot, Cinciniti Milacron
• 1978 – First Puma Robot (Programmable Universal
Machine for Assembly)
Accuracy, Repeatability and
Resolution
• Accuracy:
– A measure of how close a
manipulator can come to a
given point within its
workspace
• Repeatability:
– A measure of how close a
manipulator can return to a
previously taught point
• Resolution (Precision):
– The smallest increment of
motion that can be sensed
(executed). It is a function
of distance traveled and
the number of bits of
encoder accuracy.
Accuracy
Actual Desired
Position
A
B
Resolution
Robot Specifications
• Joint Variable (joint):
– Relative displacement between adjacent links. Can be revolute or
prismatic.
• End effector:
– Gripper or tool used to perform the robots tasks.
• Degree of freedom (DOF)
– Number of joints (DOF > 6 implies redundant robot)
• Configuration:
– Determines the location of every point on the manipulator (not just the
end effector).
• Configuration Space
– The set of all possible configurations
• Workspace (work envelope):
– Total volume spread out by the end effector as the manipulator executes
all possible motions
• Accuracy, Repeatability and Resolution
• Speed and Acceleration (min and max)
• Payload Capacity
Typical Robot Specifications
• Hydraulic or Electric
• Payload capacity
– 50 – 100 Kgs (Hydraulic)
– 1 – 25 Kgs (Electric)
• Degrees of freedom: 4 to 7 based on application
• Repeatablity
– ± 1 mm – 1.5mm (Hydraulic)
– ± 0.05mm – 0.01mm (Electric)
• Cost
– $80,000 - $200,000 (Hydraulic)
– $40,000 – $100,000 (Electric)
Robotic System Architecture
• Components
– Mechanical structure
– Drives
• Electric
• Hydraulic
• Pneumatic
Environment
Sensors
World space
Output
Planner
– Computing and Control
– Sensors
•
•
•
•
Encoders
Force
Vision
many more
– Communication
• CAN, ethernet, Wireless,
Serial link (RS232), USB,
analog link, PROFIBus,
GPIB, and many more
Controller
Drives
Mechanical
Structure
Computer
Configuration
Sensor
Common Robot
Configurations
• Joint types
– Revolute
– Prismatic
• Revolute joints (R)
– Compact
– Increased dexterity – easier to
maneuver around obstacles
– Large kinematic and dynamic
coupling between links
– Larger error accumulation
– Difficult control problem
• Prismatic joints (P)
–
–
–
–
Increased accuracy
Higher payload
Difficult to integrate
Require more volume
Cartesian Configuration
• PPP
– First three joints are
prismatic
• Features
–
–
–
–
High resolution
High accuracy
High payload capacity
More volume needed for
motion
– Difficult to integrate with
other machines
– Uniform resolution
Epson Cartesian Arm
Reachable Workspace
Cylindrical Configuration
• RPP
– One revolute joint
– Two linear joints
• Joint coordinates map to
cylindrical coordinates
Denso
Cylindrical
arm
– r, θ, z
• Non-uniform precision
– Horizontal precision highest
along inside edge of work
envelope
Reachable Workspace
Spherical Configuration
• RRP
– Two revolute joints
– One prismatic joint
• Joint variables
directly correspond
to spherical
coordinates
–φ
–θ
–r
Reachable Workspace
Articulated Configuration
• RRR
– Three revolute joints
• Features
– Light payload capacity
– Lower accuracy
– Easy to integrate with
other manipulators
SCARA Configuration
• Selective Compliant
Articulated Robot for
Assembly (SCARA)
• RRP
– Two revolute
– One prismatic
• Introduced in 1979
• Revolutionized
manufacturing of
small electronics
Reachable Workspace
Basic Research Issues
• Effectors and Mobility
–
–
–
–
–
Autonomous Flight
Fish Robots
Legged Motion
Artificial Muscles
Drives
• Sensors
–
–
–
–
Vision
Force / Haptic
Communication
Encoder
• Control Systems
–
–
–
–
Behaviour control
Networked control
Active vibration control
Hyper redundant
robotic systems
• Task Planning
– Understanding the real
world
– Failsafe planning to
work in the real world
Robot Programming
• Motion based
– RCCL
– RAPID
– VAL++
• Task / Goal based
– Behavior Language
– PRS (Procedural Reasoning
System)
• Intermediate level
– Combines aspects of low level
motion based and high level
task based
– FRP (Functional Reactive
Programming)
– FROB (Functional Robotics)