Vibration suppression control of robot arms using a homogeneous-type electrorheological fluid

A variable viscous damper using electrorheological fluid is developed to su ppress vibrations of industrial robots, An integrated system consisting of drive motor, harmonic drive, arm linkage, and electrorheological (ER) dampe r is experimentally measured, and it is found that resonant/antiresonant ph enomenon is effectively reduced by increasing the viscosity of the ER dampe r. A position control system based on the conventional semiclosed-loop cont rol with this new type of ER damper is analyzed, and the relationship betwe en the properties of the control system and the ER damping coefficient is d iscussed by means of pole-assignment technique. It is shown from analysis a nd experiment that the ER damper contributes both vibration suppression and disturbance rejection.