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
A robot is a machine—especially one programmable by a computer—capable of carrying out a complex series of actions automatically. A robot can be guided by an external control device, or the control may be embedded within. Robots may be ...
. The links of such a manipulator are connected by joints allowing either rotational motion (such as in an
articulated robot) or translational (linear) displacement. The links of the manipulator can be considered to form a
kinematic chain
In mechanical engineering, a kinematic chain is an assembly of rigid bodies connected by joints to provide constrained (or desired) motion that is the mathematical model for a mechanical system. Reuleaux, F., 187''The Kinematics of Machine ...
. 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
proscribe
Proscription ( la, proscriptio) is, in current usage, a 'decree of condemnation to death or banishment' (''Oxford English Dictionary'') and can be used in a political context to refer to state-approved murder or banishment. The term originated ...
d.
Types
*
Cartesian robot / Gantry robot: Used for
pick and place work, application of sealant, assembly operations, handling machine tools and arc welding. It is a robot whose arm has three prismatic joints, whose axes are coincident with a Cartesian coordinator.
*
collaborative robot / Cobot: Cobot applications contrast with traditional industrial robot applications in which robots are isolated from human contact. Cobot has a large variety o
applicationssuch as: Commercial Application, Robotic Research, Dispensing, Material Handling, Assembly, Finishing, Quality Inspection. Cobot safety may rely on lightweight construction materials, rounded edges, and the inherent limitation of speed and force, or on sensors and software that ensures safe behavior.
* Cylindrical robot: Used for assembly operations, handling at machine tools, spot welding, and handling at die casting machines. It is a robot whose axes form a cylindrical coordinate system.
* Spherical robot / Polar robot: Used for handling machine tools, spot welding, die casting, fettling machines, gas welding and arc welding. It is a robot whose axes form a polar coordinate system.
*
SCARA robot
The SCARA is a type of industrial robot. The acronym stands for Selective Compliance Assembly Robot Arm or Selective Compliance Articulated Robot Arm.
By virtue of the SCARA's parallel-axis joint layout, the arm is slightly compliant in the ...
: Used for pick and place work, application of sealant, assembly operations and handling machine tools. This robot features two parallel rotary joints to provide compliance in a plane.
*
Articulated robot: Used for assembly operations, diecasting, fettling machines, gas welding, arc welding and spray-painting. It is a robot whose arm has at least three rotary joints.
*
Parallel robot: One use is a mobile platform handling cockpit flight simulators. It is a robot whose arms have concurrent prismatic or rotary joints.
*
Anthropomorphic
Anthropomorphism is the attribution of human traits, emotions, or intentions to non-human entities. It is considered to be an innate tendency of human psychology.
Personification is the related attribution of human form and characteristics t ...
robot: It is shaped in a way that resembles a human hand, i.e. with independent fingers and thumbs.
..
Notable robotic arms
In
space
Space is the boundless three-dimensional extent in which objects and events have relative position and direction. In classical physics, physical space is often conceived in three linear dimensions, although modern physicists usually con ...
, the
Canadarm and its successor
Canadarm2
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, su ...
are examples of multi
degree of freedom robotic arms. These robotic arms have been used to perform a variety of tasks such as inspection of the Space Shuttle using a specially deployed boom with cameras and
sensors attached at the end effector, and also
satellite
A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...
deployment and retrieval manoeuvres from the
cargo bay of the
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program na ...
.
[IEEE Xplore:The Canadarm grasps this boom and can position it in the necessary positions to permit a complete inspection ](_blank)
/ref>
The ''Curiosity'' and ''Perseverance'' rovers on the planet Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin atmos ...
also use robotic arms. Additionally, ''Perseverance'' has a smaller sample caching arm hidden inside its body below the rover in its caching assembly.
TAGSAM is a robotic arm for collecting a sample from a small asteroid in space on the spacecraft OSIRIS-REx.
The 2018 Mars lander InSight
Insight is the understanding of a specific cause and effect within a particular context. The term insight can have several related meanings:
*a piece of information
*the act or result of understanding the inner nature of things or of seeing intu ...
has a robotic arm called the IDA, it has camera, grappler, is used to move special instruments.
Low-cost robotic arms
In the decade of 2010 the availability of low-cost robotic arms increased substantially. Although such robotic arms are mostly marketed as hobby or educational devices, applications in laboratory automation have been proposed, like their use as autosamplers.
Classification
A serial robot arm can be described as a chain of links that are moved by joints which are actuated by motors. An end-effector, also called a robot hand, can be attached to the end of the chain. As other robotic mechanisms, robot arms are typically classified in terms of the number of degrees of freedom
Degrees of freedom (often abbreviated df or DOF) refers to the number of independent variables or parameters of a thermodynamic system. In various scientific fields, the word "freedom" is used to describe the limits to which physical movement or ...
. Usually, the number of degrees of freedom is equal to the number of joints that move the links of the robot arm. At least six degrees of freedom are required to enable the robot hand to reach an arbitrary pose (position and orientation) in three dimensional space. Additional degrees of freedom allow to change the configuration of some link on the arm (e.g., elbow up/down), while keeping the robot hand in the same pose. Inverse kinematics is the mathematical process to calculate the configuration of an arm, typically in terms of joint angles, given a desired pose of the robot hand in three dimensional space.
Robotic hands
The end effector, or robotic hand, can be designed to perform any desired task such as welding, gripping, spinning etc., depending on the application. For example, robot arms in automotive assembly line
An assembly line is a manufacturing process (often called a ''progressive assembly'') in which parts (usually interchangeable parts) are added as the semi-finished assembly moves from workstation to workstation where the parts are added in sequ ...
s perform a variety of tasks such as welding
Welding is a fabrication process that joins materials, usually metals or thermoplastics, by using high heat to melt the parts together and allowing them to cool, causing fusion. Welding is distinct from lower temperature techniques such as br ...
and parts rotation and placement during assembly. In some circumstances, close emulation of the human hand is desired, as in robots designed to conduct bomb disarmament and disposal.
See also
* 3D printing
* Articulated robot
* Offline programming
* Robot simulator
* European Robotic Arm
* Mars ''Curiosity'' Rover - Robotic Arm
* Open-hardware robotics
Open-source robotics (OSR) is where the physical artifacts of the subject are offered by the open design movement. This branch of robotics makes use of open-source hardware and free and open-source software providing blueprints, schematics, and s ...
* Prosthetics
* Robotics suite
* Working envelope
References
External links
Robot Arm Types
{{Robotics
Arm