This measures the efficiency of the design in terms of generated workspace. It is defined as the ratio of the manipulator length sum to the cube root of the workspace volume. The objective is to minimize this value as a function of link lengths.
where L is the length sum and is defined as:
where 
is link length, and 
is the maximum offset for
prismatic joints.
As an example of using this measure, suppose that the given specification for the manipulator is three degrees of freedom with a certain workspace shape (sphere, cylinder, etc.), the maximum total length for its links is L, and the first two links are equal. The optimization problem will be:
where:
The last two equations constitute the constraints in the optimization problem. This problem is very easy to solve for the lengths. The problem here is to calculate the volume of the workspace, because sometimes it is too difficult to calculate when the workspace is irregular and if it has some gaps (nonreachable areas).