This paper introduces a dual-user training system whose design is based on an energetic approach. This kind of system is useful for supervised hands-on training where a trainer interacts with a trainee through two haptic devices, in order to practice on a manual task performed on a virtual or teleoperated robot (e.g., for an Minimally Invasive Surgery (MIS) task in a surgical context). This paper details the proof of stability of an Energy Shared Control (ESC) architecture we previously introduced for one degree of freedom (d.o.f.) devices. An extension to multiple degrees of freedom is proposed, along with an enhanced version of the Adaptive Authority Adjustment function. Experiments are carried out with 3 d.o.f. haptic devices in free motion as well as in contact contexts in order to show the relevance of this architecture.

In this paper, a control methodology is proposed for dual-user teleoperation system in the presence of unknown constant communication time delay. To satisfy dual-user system-desired objectives, three impedance characteristics are defined as the desired closed-loop system. In order to satisfy the desired impedance characteristics, a sliding-mode-based impedance controller is applied. The proposed controller affords unknown communication delay, an issue that is disregarded in the previous studies performed on dual-user systems. The nonlinear gain of the controller is achieved independent of time delay caused by communication channels. Therefore, the necessity of measurement or estimation of the time delay is relaxed. In addition, the stability analysis is presented for the closed-loop system using the passivity theory. The validity of the proposed controller scheme is demonstrated via experimental results performed on a dual-user system in the presence of unknown communication delay. In addition, due to lack of availability of forces corresponding to the operators’ hand that are required in the proposed controller, a Kalman Filter-based Force Observer (KFFO) is proposed.