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In the article$^a$, the authors introduced a time-varying Lyapunov functionfor the stability analysis of nonlinear systems whose motion is governed bystandard Newton-Euler equations. The authors established asymptotic stabilitywith the choice of two symmetric positive definite matrices restricted bycertain eigenvalue bounds in the control law. Exponential stability in thesense of Lyapunov using integrator backstepping and Lyapunov redesign isestablished in this note using just one matrix in the derived controller. We donot impose minimum eigenvalue bound requirements on the symmetric positivedefinite matrix introduced in our analysis to guarantee stability. Reducing theparameters needed in the control law, our analysis improves the stability andconvergence rates of tracking errors reported in the article$^a$.  $^a$Ren, W., Zhang, B, Li, H, and Yan L. IEEE Access. vol. 8. pp.51510-51517. 2020.

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