“…This takes place regardless of the large variations in payload mases, link masses, coefficients of friction and disturbances. In our case, the validity of expression (19) stems from the fact that the matrix C(q, (1) of (2) is a linear function of q and so is Co(q, (1). Thus it follows that the term C(q, (1)X 2 appearing in (17) is quadratically dependent on the error e via (3) and (14).…”