A Comparative Study of Force Observers For Accurate Force Control of Multisensor-Based Force Controlled Motion Systems

This paper presents a comprehensive comparative study of the multisensor-based force observers for accurate force control. A force controlled system which contains a force sensor for measuring force transmitted to the load by the motor and an encoder for measuring motor position is considered as the general multisensor-based motion system in this study. Even though these multisensor-based motion systems are emerging as potential motion systems as the demands for collaborative robots increase, there has been few studies that investigate their advantages and limitations. to address this issue, three types of observer-based force controllers that utilize the multisensors are designed and implemented. These controllers exploit the availability of force sensor, motor encoder, and motor torque information from the multisensor-based motion system to estimate accurate force which is later utilized to close the feedback loop. Mathematical and quantitative analyses are conducted to compare performances of the proposed observer-based force control and through this, their advantages and limitations are pointed out. Finally, simulation and an experimental case study with an actual robot are conducted to validate the force tracking performance of the designed force control systems.