I was reading the paper "Full-Speed Range Self-Balancing Electric Motorcycles Without the Handlebar" released in March 2016 by Professor Yang and Murakami in Keio University.

I couldn't figure out what the meaning of the following block is :

Unkown Block

from the following control system diagram on page 1915 of IEEE Transactions on Industrial Electronics, Vol. 63, No. 3, March 2016.

Control System Diagram

I would greatly appreciate if someone could explain the meaning of the mentioned block symbol.

  • 1
    $\begingroup$ Is there an index or explanation of the various symbols in the book? $\endgroup$
    – Solar Mike
    Commented Jun 27, 2021 at 6:53

1 Answer 1


If $\alpha$ has units of angle and $\tau$ has units of torque, then $I$ has units of moment of inertia. It is likely to be the moment of inertia about the axis which is being controlled.

The block is very likely a plain gain block which multiplies the angular acceleration signal with the value of the moment of inertia.

Published papers usually have a nomenclature section. Even otherwise, they will describe all symbols used. Check if the paper describes the symbol.


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