Joint Types
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Manipulator Joint and Arm Structure
Link: Individual rigid sections that make up a mechanism are called links.
Joint: The connection between two links is called a joint. There are a few different robot joints that can be used. The table below outlines the most common joints found in robotic arms today:
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These can be summarized under two types of joints: linear and revolute. In the table above, the first two joints are linear joints and the last three are revolute.
Degrees
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of Freedom and Manipulator Workspace
The degrees of freedom (DOF) of a robot manipulator or mechanism is the total number of independent variables that can completely identify the configuration of the manipulator mechanism in the space. The following robotic arm has 2 DOF:
While this manipulator has 6 DOF:
The workspace of a manipulator is defined as the set of all end-effector locations (positions and orientations of the end-effector) that can be reached using a combination of joint variables within their permissible ranges, which include physical limitations such as joint limits and link lengths.
When designing a robotic arm, it is important to consider what workspace you want the robot to have and design the joints accordingly.