Articulated robot

Last updated
A six-axis articulated welding robot reaching into a fixture to weld FANUC welding robot reaching.jpg
A six-axis articulated welding robot reaching into a fixture to weld

An articulated robot is a robot with rotary joints [ citation needed ] (e.g. a legged robot or an industrial robot). Articulated robots can range from simple two-jointed structures to systems with 10 or more interacting joints and materials. They are powered by a variety of means, including electric motors.

Contents

Some types of robots, such as robotic arms, can be articulated or non-articulated. [1] [2]

Articulated robots in action

Definitions

Articulated Robot: See Figure. An articulated robot uses all the three revolute joints to access its work space. Usually the joints are arranged in a “chain”, so that one joint supports another further in the chain.

Continuous Path: A control scheme whereby the inputs or commands specify every point along a desired path of motion. The path is controlled by the coordinated motion of the manipulator joints.

Degrees Of Freedom (DOF): The number of independent motions in which the end effector can move, defined by the number of axes of motion of the manipulator.

Gripper: A device for grasping or holding, attached to the free end of the last manipulator link; also called the robot’s hand or end-effector.

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 precision. These ratings are highly dependent on the size and shape of the payload.

Pick And Place Cycle: See Figure. Pick and place Cycle is the time, in seconds, to execute the following motion sequence: Move down one inch, grasp a rated payload; move up one inch; move across twelve inches; move down one inch; ungrasp; move up one inch; and return to start location.

Reach: The maximum horizontal distance from the center of the robot base to the end of its wrist.

Accuracy: See Figure. The difference between the point that a robot is trying to achieve and the actual resultant position. Absolute accuracy is the difference between a point instructed by the robot control system and the point actually achieved by the manipulator arm, while repeatability is the cycle-to-cycle variation of the manipulator arm when aimed at the same point.

Repeatability: See Figure. The ability of a system or mechanism to repeat the same motion or achieve the same points when presented with the same control signals. The cycle-to-cycle error of a system when trying to perform a specific task. Repeatability of this robot lies between 0.1 to 0.5mm with the payload between 5kg to 100kg.

Resolution: See Figure. The smallest increment of motion or distance that can be detected or controlled by the control system of a mechanism. The resolution of any joint is a function of encoder pulses per revolution and drive ratio, and dependent on the distance between the tool center point and the joint axis.

Robot Program: A robot communication program for IBM and compatible personal computers. Provides terminal emulation and utility functions. This program can record all of the user memory, and some of the system memory to disk files.

Maximum Speed: The compounded maximum speed of the tip of a robot moving at full extension with all joints moving simultaneously in complementary directions. This speed is the theoretical maximum and should under no circumstances be used to estimate cycle time for a particular application. A better measure of real world speed is the standard twelve inch pick and place cycle time. For critical applications, the best indicator of achievable cycle time is a physical simulation.

Servo Controlled: Controlled by a driving signal which is determined by the error between the mechanism's present position and the desired output position.

Via Point: A point through which the robot's tool should pass without stopping; via points are programmed in order to move beyond obstacles or to bring the arm into a lower inertia posture for part of the motion.

Work Envelope: A three-dimensional shape that defines the boundaries that the robot manipulator can reach; also known as reach envelope.

See also

Related Research Articles

<span class="mw-page-title-main">Industrial robot</span> Robot used in manufacturing

An industrial robot is a robot system used for manufacturing. Industrial robots are automated, programmable and capable of movement on three or more axes.

<span class="mw-page-title-main">Mobile Servicing System</span> Robotic system on board the International Space Station

The Mobile Servicing System (MSS), is a robotic system on board the International Space Station (ISS). Launched to the ISS in 2001, it plays a key role in station assembly and maintenance; it moves equipment and supplies around the station, supports astronauts working in space, and services instruments and other payloads attached to the ISS and is used for external maintenance. Astronauts receive specialized training to enable them to perform these functions with the various systems of the MSS.

<span class="mw-page-title-main">Inverse kinematics</span> Computing joint values of a kinematic chain from a known end position

In computer animation and robotics, inverse kinematics is the mathematical process of calculating the variable joint parameters needed to place the end of a kinematic chain, such as a robot manipulator or animation character's skeleton, in a given position and orientation relative to the start of the chain. Given joint parameters, the position and orientation of the chain's end, e.g. the hand of the character or robot, can typically be calculated directly using multiple applications of trigonometric formulas, a process known as forward kinematics. However, the reverse operation is, in general, much more challenging.

<span class="mw-page-title-main">Feed forward (control)</span> Control paradigm in which errors are measured before they can affect a system

A feed forward is an element or pathway within a control system that passes a controlling signal from a source in its external environment to a load elsewhere in its external environment. This is often a command signal from an external operator.

<span class="mw-page-title-main">Canadarm</span> Robotic arm used to manoeuvre and capture mission payloads on the Space Shuttle

Canadarm or Canadarm1 is a series of robotic arms that were used on the Space Shuttle orbiters to deploy, manoeuvre, and capture payloads. After the Space Shuttle Columbia disaster, the Canadarm was always paired with the Orbiter Boom Sensor System (OBSS), which was used to inspect the exterior of the shuttle for damage to the thermal protection system.

<span class="mw-page-title-main">Dextre</span> Robotic arm on ISS

Dextre, also known as the Special Purpose Dexterous Manipulator (SPDM), is a two-armed robot, or telemanipulator, which is part of the Mobile Servicing System on the International Space Station (ISS), and does repairs that would otherwise require astronauts to do spacewalks. It was launched on March 11, 2008, on the mission STS-123.

<span class="mw-page-title-main">European Robotic Arm</span> Robotic arm installed on the ISS Russian Segment

The European Robotic Arm (ERA) is a robotic arm that is attached to the Russian Orbital Segment (ROS) of the International Space Station. Launched to the ISS in July 2021; it is the first robotic arm that is able to work on the Russian Segment of the station. The arm supplements the two Russian Strela cargo cranes that were originally installed on the Pirs module, but were later moved to the docking compartment Poisk and Zarya module.

<span class="mw-page-title-main">Manipulator (device)</span> Device used to manipulate materials without direct contact by the operator

In robotics, a manipulator is a device used to manipulate materials without direct physical contact by the operator. The applications were originally for dealing with radioactive or biohazardous materials, using robotic arms, or they were used in inaccessible places. In more recent developments they have been used in diverse range of applications including welding automation, robotic surgery and in space. It is an arm-like mechanism that consists of a series of segments, usually sliding or jointed called cross-slides, which grasp and move objects with a number of degrees of freedom.

In physics, the degrees of freedom (DOF) of a mechanical system is the number of independent parameters that define its configuration or state. It is important in the analysis of systems of bodies in mechanical engineering, structural engineering, aerospace engineering, robotics, and other fields.

Motion planning, also path planning is a computational problem to find a sequence of valid configurations that moves the object from the source to destination. The term is used in computational geometry, computer animation, robotics and computer games.

<span class="mw-page-title-main">Common Berthing Mechanism</span> Berthing mechanism used to connect ISS modules

The Common Berthing Mechanism (CBM) connects habitable elements in the US Orbital Segment (USOS) of the International Space Station (ISS). The CBM has two distinct sides that, once mated, form a cylindrical vestibule between modules. The vestibule is about 16 inches (0.4 m) long and 6 feet (1.8 m) across. At least one end of the vestibule is often limited in diameter by a smaller bulkhead penetration.

<span class="mw-page-title-main">Parallel manipulator</span>

A parallel manipulator is a mechanical system that uses several computer-controlled serial chains to support a single platform, or end-effector. Perhaps, the best known parallel manipulator is formed from six linear actuators that support a movable base for devices such as flight simulators. This device is called a Stewart platform or the Gough-Stewart platform in recognition of the engineers who first designed and used them.

<span class="mw-page-title-main">Robotic arm</span> Type of mechanical arm with similar functions to a human arm.

A robotic arm is a type of mechanical arm, usually programmable, with similar functions to a human arm; the arm may be the sum total of the mechanism or may be part of a more complex robot. The links of such a manipulator are connected by joints allowing either rotational motion or translational (linear) displacement. The links of the manipulator can be considered to form a kinematic chain. The terminus of the kinematic chain of the manipulator is called the end effector and it is analogous to the human hand. However, the term "robotic hand" as a synonym of the robotic arm is often proscribed.

<span class="mw-page-title-main">Grapple fixture</span>

Grapple fixtures are used on spacecraft or other objects to provide a secure connection for a robotic arm.

<span class="mw-page-title-main">Glossary of robotics</span> List of definitions of terms and concepts commonly used in the study of robotics

Robotics is the branch of technology that deals with the design, construction, operation, structural disposition, manufacture and application of robots. Robotics is related to the sciences of electronics, engineering, mechanics, and software.

The following outline is provided as an overview of and topical guide to robotics:

<span class="mw-page-title-main">Docking and berthing of spacecraft</span> Joining of two or more space vehicles

Docking and berthing of spacecraft is the joining of two space vehicles. This connection can be temporary, or partially permanent such as for space station modules.

<span class="mw-page-title-main">Orbital replacement unit</span>

Orbital replacement units (ORUs) are key elements of the International Space Station that can be readily replaced when the unit either passes its design life or fails. ORUs are parts of the main systems and subsystems of the external elements of the ISS, none are intended to be installed inside the pressurised modules. Examples of ORUs are: pumps, storage tanks, controller boxes, antennas, and battery units. Such units are replaced either by astronauts during EVA or by the Dextre (SPDM) robotic arm. All are stored on the three external stowage platforms (ESPs) or the four ExPRESS Logistics Carriers (ELCs) mounted on the Integrated Truss Structure (ITS).

<span class="mw-page-title-main">High performance positioning system</span> Industrial Engineering method

A high performance positioning system (HPPS) is a type of positioning system consisting of a piece of electromechanics equipment (e.g. an assembly of linear stages and rotary stages) that is capable of moving an object in a three-dimensional space within a work envelope. Positioning could be done point to point or along a desired path of motion. Position is typically defined in six degrees of freedom, including linear, in an x,y,z cartesian coordinate system, and angular orientation of yaw, pitch, roll. HPPS are used in many manufacturing processes to move an object (tool or part) smoothly and accurately in six degrees of freedom, along a desired path, at a desired orientation, with high acceleration, high deceleration, high velocity and low settling time. It is designed to quickly stop its motion and accurately place the moving object at its desired final position and orientation with minimal jittering.

This glossary of industrial automation is a list of definitions of terms and illustrations related specifically to the field of industrial automation. For a more general view on electric engineering, see Glossary of electrical and electronics engineering. For terms related to engineering in general, see Glossary of engineering.

References