Inmechanical engineering, akinematic diagram orkinematic scheme (also called ajoint map orskeleton diagram) illustrates the connectivity oflinks andjoints of amechanism ormachine rather than the dimensions or shape of the parts. Often links are presented as geometric objects, such as lines, triangles or squares, that support schematic versions of the joints of the mechanism or machine.[1]
For example, the figures show the kinematic diagrams (i) of theslider-crank that forms a piston and crank-shaft in an engine, and (ii) of the first three joints for aPUMA manipulator.
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| PUMA robot | and its kinematic diagram |
Akinematic diagram can be formulated as agraph by representing the joints of the mechanism as vertices and the links as edges of the graph. This version of the kinematic diagram has proven effective in enumerating kinematic structures in the process of machine design.[2]
An important consideration in this design process is thedegree of freedom of the system of links and joints, which is determined using theChebychev–Grübler–Kutzbach criterion.
Elements ofkinematics diagrams include the frame, which is the frame of reference for all the moving components, as well as links (kinematic pairs), and joints.Primary Joints include pins, sliders and other elements that allow pure rotation or pure linear motion.Higher order joints also exist that allow a combination of rotation or linear motion. Kinematic diagrams also include points of interest, and other important components.