Common normal (robotics)

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A model of a robotic arm with joints. Robot arm model 1.png
A model of a robotic arm with joints.

In robotics the common normal of two non-intersecting joint axes is a line perpendicular to both axes. [1]

Robotics design, construction, operation, and application of robots

Robotics is an interdisciplinary branch of engineering and science that includes mechanical engineering, electronic engineering, information engineering, computer science, and others. Robotics deals with the design, construction, operation, and use of robots, as well as computer systems for their control, sensory feedback, and information processing.

The common normal can be used to characterize robot arm links, by using the "common normal distance" and the angle between the link axes in a plane perpendicular to the common normal. [2] When two consecutive joint axes are parallel, the common normal is not unique and an arbitrary common normal may be used, usually one that passes through the center of a coordinate system. [3]

The common normal is widely used in the representation of the frames of reference for robot joints and links, and the selection of minimal representations with the Denavit–Hartenberg parameters.

Denavit–Hartenberg parameters

In mechanical engineering, the Denavit–Hartenberg parameters are the four parameters associated with a particular convention for attaching reference frames to the links of a spatial kinematic chain, or robot manipulator.

See also

Forward kinematics

Forward kinematics refers to the use of the kinematic equations of a robot to compute the position of the end-effector from specified values for the joint parameters.

Robotic arm 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.

Related Research Articles

Machine tool using energy to perform an intended action

A machine is a mechanical structure that uses power to apply forces and control movement to perform an intended action. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors that monitor performance and plan movement, often called mechanical systems.

Industrial robot automated, programmable robot used in manufacturing, and capable of movement on two or more axes

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

Inverse kinematics

Inverse kinematics is the mathematical process of recovering the movements of an object in the world from some other data, such as a film of those movements, or a film of the world as seen by a camera which is itself making those movements. This is useful in robotics and in film animation.

Robot kinematics

Robot kinematics applies geometry to the study of the movement of multi-degree of freedom kinematic chains that form the structure of robotic systems. The emphasis on geometry means that the links of the robot are modeled as rigid bodies and its joints are assumed to provide pure rotation or translation.

Four-bar linkage

A four-bar linkage, also called a four-bar, is the simplest movable closed chain linkage. It consists of four bodies, called bars or links, connected in a loop by four joints. Generally, the joints are configured so the links move in parallel planes, and the assembly is called a planar four-bar linkage. Spherical and spatial four-bar linkages also exist and are used in practice.

Linkage (mechanical) assembly of bodies connected to manage forces and movement

A mechanical linkage is an assembly of bodies connected to manage forces and movement. The movement of a body, or link, is studied using geometry so the link is considered to be rigid. The connections between links are modeled as providing ideal movement, pure rotation or sliding for example, and are called joints. A linkage modeled as a network of rigid links and ideal joints is called a kinematic chain.

In physics, the degree of freedom (DOF) of a mechanical system is the number of independent parameters that define its configuration. It is the number of parameters that determine the state of a physical system and is important to the analysis of systems of bodies in mechanical engineering, aeronautical engineering, robotics, and structural engineering.

Overconstrained mechanism

An overconstrained mechanism is a linkage that has more degrees of freedom than is predicted by the mobility formula. The mobility formula evaluates the degree of freedom of a system of rigid bodies that results when constraints are imposed in the form of joints connecting the links.

Serial manipulator

Serial manipulators are the most common industrial robots and they are designed as a series of links connected by motor-actuated joints that extend from a base to an end-effector. Often they have an anthropomorphic arm structure described as having a "shoulder", an "elbow", and a "wrist".

A kinematic pair is a connection between two bodies that imposes constraints on their relative movement. Franz Reuleaux introduced the kinematic pair as a new approach to the study of machines that provided an advance over the motion of elements consisting of simple machines.

Kinematic chain assembly of rigid bodies connected by joints to provide constrained motion that is the mathematical model for a mechanical system

In mechanical engineering, a kinematic chain is an assembly of rigid bodies connected by joints to provide constrained motion that is the mathematical model for a mechanical system. As in the familiar use of the word chain, the rigid bodies, or links, are constrained by their connections to other links. An example is the simple open chain formed by links connected in series, like the usual chain, which is the kinematic model for a typical robot manipulator.

There are many conventions used in the robotics research field. This article summarises these conventions.

Mechanism (engineering) device designed to transform input forces and movement into a desired set of output forces and movement

In engineering, a mechanism is a device that transforms input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components that can include:

Kinematics equations are the constraint equations of a mechanical system such as a robot manipulator that define how input movement at one or more joints specifies the configuration of the device, in order to achieve a task position or end-effector location. Kinematics equations are used to analyze and design articulated systems ranging from four-bar linkages to serial and parallel robots.

The Robotics Toolbox is MATLAB Toolbox software that supports research and teaching into arm-type and mobile robotics. This is free software but requires the proprietary MATLAB environment in order to execute. A subset of functions have been ported to GNU Octave and Python. The Toolbox forms the basis of the exercises in several textbooks

Actin is a software toolkit for designing, simulating, and controlling robots, created by the American firm Energid Technologies of Cambridge, Massachusetts. In addition to their headquarters in the United States, the firm opened an office in India to sell Actin in Asia.

The product of exponentials (POE) method is a robotics convention for mapping the links of a spatial kinematic chain. It is an alternative to Denavit–Hartenberg parameterization. While the latter method uses the minimal number of parameters to represent joint motions, the former method has a number of advantages: uniform treatment of prismatic and revolute joints, definition of only two reference frames, and an easy geometric interpretation from the use of screw axes for each joint.

References

  1. Introduction to Robotics by Saeed Niku ISBN   0-470-60446-8 page 75
  2. Robot manipulators: mathematics, programming, and control by Richard P. Paul 1981 ISBN   0-262-16082-X page 51
  3. Foundations of Robotics: Analysis and Control by Tsuneo Yoshikawa 1990 ISBN   0-262-24028-9 page 33