I NTRODUCTION TO R OBOTICS CPSC - 460

T EXTBOOK Robot Modeling and Control, Mark W. Spong, Seth Hutchinson and M. Vidyasagar, Wiley ISBN-10: ISBN-13:

T OPICS C OVERED Transformations Kinematics Inverse kinematics Jacobians Trajectory generation Robot control

Karel Čapek was one of the most influential Czech writers of the 20 th century. At one time the Gestapo had ranked him as "public enemy number 2" in Czechoslovakia! R OBOT The term ‘Robot’ was first used by the Czech playwright Karel Čapek in 1920 in his satirical play called RUR (Rossum's Universal Robots) The term robot originates from the Czech word, ‘Robota’, (pronounced "chop'ek"), meaning compulsory labor or slave The plot was simple: A man makes a robot, then the robot kills the man! Cover page of the first edition

R OBOTICS The word ‘Robotics' also comes from science fiction. Robotics was coined and was first used in “Runaround”, a short story published in 1942, by Isaac Asimov. But it was not until 1956 that a real robot came into existence. Russian-born American scientist and writer Isaac Asimov wrote prodigiously on a wide variety of subjects. He was best known for his many works of science fiction. The most famous include: I Robot (1950), The Foundation Trilogy ( ), Foundation's Edge (1982), and The Gods Themselves (1972), which won both the Hugo and Nebula awards.

D EFINITIONS Robotics – The science dealing with the design, construction and operation of robots Robot – According to The Robot Institute of America (1979) a robot is “a reprogrammable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through various programmed motions for the performance of a variety of tasks." Virtually anything that operates with some degree of autonomy, usually under computer control, has been called a robot. Roboticist – A person who design, builds, or programs robots

R OBOTS FOR 3D J OBS Dull Dirty Dangerous

A DVANTAGES OF R OBOTICS The major advantages of robots are: Decreased labor costs Increased precision and productivity Increased flexibility compared with specialized machines Robots can perform dull, repetitive jobs Robots can operate in hazardous environments

R OBOTICS E NGINEERING Robotics is a relatively new field of modern technology that crosses traditional engineering boundaries Understanding the complexity of robots and their applications requires knowledge of electrical engineering mechanical engineering industrial engineering computer science

W HAT IT T AKES TO M AKE A R OBOT Robotics is a multi-disciplinary field. Mechanical Engineering – concerned primarily with manipulator/mobile robot design, kinematics, dynamics, compliance and actuation. Electrical Engineering – concerned primarily with robot actuation, electronic interfacing to computers and sensors, and control algorithms. Computer Science – concerned primarily with robot programming, planning, perception and intelligent behavior.

S ERIAL M ANIPULATORS / R OBOTS A connection of mechanical linkages A serial manipulator is a open kinematic chain of two or more links Joint is the connection between 2 links Joints constraint the motion of the connected links Joints can be electrically, hydraulically, or pneumatically actuated.

S ERIAL M ANIPULATOR R OBOTS Physically anchored to their workplace Manipulator motion usually involves an entire chain of controllable joints, enabling such robots to place their effectors in any position within the workplace Manipulators are by far the most common type of industrial robots - a 2 billion dollar industry!

U NIMATE – F IRST S ERIAL M ANIPULATOR

M ANIPULATOR J OINTS Joints are either Revolute (R) or Prismatic (P) Revolute joint allows relative angular motion between the links, like a hinge Prismatic joint allows relative linear motion between the two links

S YMBOLIC R EPRESENTATION OF J OINTS

R EVOLUTE J OINTS Rotational joints can have more than one degree of freedom (DoF) One DoF revolute joint

2 D O F R EVOLUTE J OINT Universal Joint (U)

3 D O F R EVOLUTE J OINT Spherical Joint (S) Example: Ball and Socket Joint

W RIST AND E ND E FFECTOR Wrist: the joints between the arm and the end effector / gripper. Typically, the arm controls the position of the end effector, and the wrist controls the orientation.

3 D O F WRIST A typical wrist would have 3 DOF described as roll, pitch and yaw. Roll - rotation around the arm axis Pitch - up and down movement (assuming the roll is in its centre position) Yaw - right to left rotation (assuming the roll is in its centre position)

E ND E FFECTOR The device on the end of the arm, attached via the wrist, that performs the task, such as: Grippers - Use to hold and move objects Tools - Used to perform work on a part, not just to pick it up. A tool could be held by a gripper, making the system more flexible.

D EGREES OF F REEDOM An object is said to have a n degrees of freedom (DOF), if its configuration can be minimally specified by n parameters. For a robot manipulator, the number of joints determine the number of DOF.

D EGREES OF F REEDOM To reach any point in the space with an arbitrary orientation: 6 DOF (3 DOF for positioning and 3 DOF for orientation ) Less than 6 DOF: the arm cant reach any point in the space with an arbitrary orientation. More than 6 DOF: Kinematically redundant manipulator. Certain applications may require more than 6 DOF, for example: Obstacle Avoidance.

C LASSIFICATION OF S ERIAL R OBOTS Power Source – AC / DC Application – Assembly / Non-Assembly Control – Servo / Non-Servo Geometry (Manipulator Configuration)

M ANIPULATORS C ONFIGURATIONS Cartesian: PPPCylindrical: RPPSpherical: RRP RRP (Selective Compliance Assembly Robot Arm) Articulated: RRR Hand coordinate: n: normal vector; s: sliding vector; a: approach vector, normal to the tool mounting plate

W ORKSPACE The Workspace of the manipulator is the total volume swept out by the end effector as the manipulator executes all possible motion. Workspace is constrained by: Geometry of the manipulator. Mechanical constraint of the joints (a revolute joint may be limited to less than 360 degrees)

W ORKSPACE Reachable Workspace: the entire set of points reachable by the manipulator. Dexterous Workspace: consists of those points that the manipulator can reach with an arbitrary orientation of the end effectors. Dexterous Workspace is a subset of Reachable Workspace

W ORKSPACE

W ORKSPACE OF A C ARTESIAN (PPP) M ANIPULATOR

W ORKSPACE OF A C YLINDRICAL (RRP) M ANIPULATOR

W ORKSPACE OF A S PHERICAL (RRP) M ANIPULATOR

W ORKSPACE OF A SCARA (RRP) M ANIPULATOR

P ERFORMANCE M EASURES Accuracy is a measure of how close the manipulator can come to a given point within its workspace. Repeatability is a measure of how close the manipulator can return to a previously taught point.

O THER C RITERIA Payload Capacity Dexterity Size of Workspace Operating Volume Speed Easy of Use Cost

C OMPONENTS OF A R OBOTIC S YSTEM

P ARALLEL M ANIPULATORS More than one serial manipulator arms working together Closed Kinematic Chain

A REAS OF R OBOTICS Surveillance – UAVs, Drones, Medical Robotics – Surgical Robots, Prosthetics Mobile Robotics – Telepresence, Navigation SWARM Robotics Service Robotics – Refueling, Assisting Security Space Explortion