Asimov proposed three “Laws of Robotics”
- • Law 1: A robot may not injure a human being or through inaction, allow a human being to come to harm.
- • Law 2: A robot must obey orders given to it by human beings, except where such orders would conflict with the first law.
- • Law 3: A robot must protect its own existence as long as such protection does not conflict with the first law.
Kinematics and dynamics
• Degrees of freedom—number of independent motions
• Translation --3 independent directions
• Rotation -- 3 independent axes
• 2D motion = 3 degrees of freedom: 2 translation, 1 rotation
• 3D motion = 6 degrees of freedom: 3 translation, 3 rotation
Robots Configurations• Cartesian/Rectangular Gantry (3P) : These Robots are made of 3 Linear joints that orient the end effector, which are usually followed by additional revolute joints.
• Cylindrical (R2P): Cylindrical coordinate Robots have 2 prismatic joints and one revolute joint.
• Spherical joint (2RP): They follow a spherical coordinate system.
• Articulated/anthropomorphic(3R) :An articulated robot’s joints are all revolute, similar to a human’s arm.
• Selective Compliance Assembly Robot Arm (SCARA) (2R1P): They have two revolute joints that are parallel and allow the Robot to move in a horizontal plane, plus an additional prismatic joint that moves vertically.
• Typically has 3 degrees of freedom
• Roll involves rotating the wrist about the arm axis
• Pitch up-down rotation of the wrist
• Yaw left-right rotation of the wrist
• End effector is mounted on the wrist
• Non Servo Control
• implemented by setting limits or mechanical stops for each joint and sequencing the actuation of each joint to accomplish the cycle
• end point robot, limited sequence robot, bang-bang robot
• No control over the motion at the intermediate points, only end points are known
• Servo Control
• Point to point Control
• Continuous Path Control
• Closed Loop control used to monitor position, velocity (other variables) of each joint
• Only the end points are programmed, the path used to connect the end points are computed by the controller
• user can control velocity, and may permit linear or piece wise linear motion
• Feedback control is used during motion to ascertain that individual joints have achieved desired location
• need to interface robot control system to external sensors, to provide “real time” changes based on sensory equipment
• computing based on geometry of environment
• ability to interface with CAD/CAM systems
• meaningful task descriptions
• off-line programming capability
• Large number of robot languages available
• AML, VAL, AL, RAIL, RobotStudio, etc. (200+)
• Each robot manufacturer has their own robot programming language
• No standards exist
• Portability of programs virtually non-existent