Design parameters of torque spring

Torsion Spring is the ultimate variant of spring, which can be shaped according to design, from a single torsion spring to a double torsion spring, and even the deformation of various torsion bars.
Torsion Spring is one of the most complex design principles among all spring categories, and its variations in form are also quite lively. Therefore, the theory involved in design is also the most cumbersome. Therefore, it is also difficult to master during design
Necessary information for torsion springs:
(1) Free length.
(2) Control diameter: (a) outer diameter, (b) inner diameter, (c) inner diameter of the casing, or (d) outer diameter of the circular rod traversed.
(3) Wire size "wire diameter".
(4) Material (type and grade).
(5) Torsion force: The number of pounds deflected to a certain angle.
(6) Maximum deflection (angle from free position).
(7) The form of the end.
Please specify: material diameter (d), outer diameter (D), torsion arm length (L), free height (Lo), and other geometric dimensions, such as guide moment (T 1 T 2... T j) and corresponding and corresponding torsion angles（ Ψ ）