Confutation of the “Counterexample to Passivity Preservation for Variable Impedance Control of Compliant Robots”

This letter reveals the incorrect argumentation, erroneous mathematical calculations, and misleading observations reported in the article titled “Counterexample to Passivity Preservation for Variable Impedance Control of Compliant Robots” published in volume 28, issue 1 of this journal, in February 2023. All the calculations in the said article are either incorrect or redundant, and this letter apodictically reveals that the peculiar simulation results therein contained were produced from a failure to follow the implementation guidelines delineated in the original publication. This letter further generates a set of examples to confute the so-called “counterexamples,” thereby proving the erroneousness of the article's argumentation. Furthermore, numerous of the incorrect claims contained in the said article stand in stark opposition to results and theories reported in the robotics literature over the last three decades. This letter provides point-to-point refutations of the erroneous comments and calculations contained in all five pages of the article titled “Counterexample to Passivity Preservation for Variable Impedance Control of Compliant Robots” (Medrano-Cerda, 2023), thereby invalidating all its arguments and exposing its want of substantiality to the reader.