Industrial Automation and Robotics Muhajir Ab. Rahim School of Mechatronics UniMAP

Robot Classification Based on Control Systems Point-to-point (PTP) control robot Continuous-path (CP) control robot Intelligent Control robot

Point to Point Control Robot (PTP) The PTP robot is capable of moving from one point to another point. The locations are recorded in the control memory. PTP robots do not control the path to get from one point to the next point Common applications include: - component insertion - spot welding - hole drilling - machine loading and unloading - assembly operations

Continuous-Path Control Robot (CP) The CP robot is capable of performing movements along the controlled path. With CP from one control, the robot can stop at any specified point along the controlled path All the points along the path must be stored explicitly in the robot's control memory. Applications Straight-line motion is the simplest example for this type of robot. Some continuous-path controlled robots also have the capability to follow a smooth curve path that has been defined by the programmer. In such cases the programmer manually moves the robot arm through the desired path and the controller unit stores a large number of individual point locations along the path in memory (teach-in).

Continuous-Path Control Robot (CP) Typical applications include: - spray painting - finishing - gluing - arc welding operations

Intelligent Control Robot Intelligent control robot, posses the capability for both PTP and CP control. This type of control requires high level of computer control and advanced programming language. Some characteristics that make robot appear intelligent include the capacity to; - interact with its environment - make decisions when things go wrong during the work cycle. - communicate with humans - make computations during motion cycle

Robot Reach Robot reach, also known as the work envelope or work volume, is the space of all points in the surrounding space that can be reached by the robot arm. Reach is one of the most important characteristics to be considered in selecting a suitable robot because the application space should not fall out of the selected robot's reach

Robot Reach For a Cartesian configuration the reach is a rectangular-type space. For a cylindrical configuration the reach is a hollow cylindrical space. For a polar configuration the reach is part of a hollow spherical shape.

Robot Reach Robot reach for a jointed-arm configuration does not have a specific shape.

Envelope Envelope: A three-dimensional shape that defines the boundaries that the robot manipulator can reach; also known as reach envelope. a) Maximum envelope: the envelope that encompasses the maximum designed movements of all robot parts, including the end effector, workpiece and attachments. b) Restricted envelope is that portion of the maximum envelope which a robot is restricted by limiting devices. c) Operating envelope: the restricted envelope that is used by the robot while performing its programmed motions.

Other Terminologies Maximum Speed: A robot moving at full extension with all joints moving simultaneously in complimentary directions at full speed. The maximum speed is the theoretical values which does not consider under loading condition.. Payload: The maximum payload is the amount of weight carried by the robot manipulator at reduced speed while maintaining rated precision. Nominal payload is measured at maximum speed while maintaining rated preci-sion. These ratings are highly dependent on the size and shape of the payload due to variation in inertia

Robot Motion Analysis In robot motion analysis we study the geometry of the robot arm with respect to a reference coordinate system, while the end-effector moves along the prescribed path This kinematic analysis involves two different kinds of problems: 1. Determining the coordinates of the end- effector or end of arm for a given set of joints coordinates. 2. Determining the joints coordinates for a given location of the end-effector or end of arm.

Location of End-effector Generally, for robots the location of the end-effector can be defined in two systems: a. joint space b. world space (also known as global space)

Exercise In the image below the end effector of the robot arm is moving from the blue point to the red point. In the top example, the end effector travels a straight line. This is the only possible motion this arm can perform to travel a straight line. In the bottom example, the arm is told to get to the red point as fast as possible. Given many different trajectories, the arm goes the method that allows the joints to rotate the fastest. Which method is better?

Joint Space In joint space, the joint parameters such as rotating or twisting joint angles and variable link lengths are used to represent the position of the end-effector Vj = (θ, α) for RR robot Vj = (L1, , L2) for LL robot Vj = (α, L2) for TL robot where Vj refers to the position of the end-effector in joint space

World Space In world space, rectilinear coordinates with reference to the basic Cartesian system are used to define the position of the end-effector Usually the origin of the Cartesian axes is located in the robot's base VW = (x, y) where VW refers to the position of the end-effector in world space

Coordinate Transformation The transformation of coordinates of the end-effector point from the joint space to the world space is known as forward kinematic transformation Similarly, the transformation of coordinates from world space to joint space is known as backward or inverse kinematic transformation

Forward Kinematics- LL Robot

Forward Kinematics- LL Robot should be –L3

Forward Kinematics- RR Robot cos(A+B)= cosA.cosB – sinA.sinB

Forward Kinematics- TL Robot Let α be the rotation at twisting joint J1 and L2 be the variable link length at linear joint J2.

Forward Kinematics- TL Robot

Inverse Kinematics- LL Robot In inverse kinematic transformation, the objective is to derive the variable link lengths of the known position of the end effector in world space. By combing above equations, one can get;

Inverse Kinematics- RR Robot the known position of end-effector *cos(A+B)= cosA.cosB – sinA.sinB

Inverse Kinematics- TL Robot the known position of end-effector