# On the Improvement of ROS-Based Control for Teleoperated Yaskawa Robots
## 1 Introduction  
Robotic teleoperation is used in a wide variety of areas such as medicine [1], underwater exploration [2], space activities [3], and nuclear operation [4] to perform tasks in environments that are hazardous [5] or inaccessible to humans. Teleoperation systems involve manipulators enabling man to act mechanically and remotely via sensory feedback, mostly vision and effort. It typically requires a high level of operator expertise and may imposes a considerable cognitive load [6]. Probably the most important issue for tele-robotics is the time-delay issue [7] as it includes human in the loop. Teleoperation latency is the subject of paper [8], as it has a substantial impact on the surgical robots performance. The authors of this work present an improved teleoperation system that includes supervisory control, haptic feedback and motion scaling with augmented reality. This improvement results in signal latency reduction and superior performance compared to the conventional telesurgery system. A survey on bilateral teleoperation is presented in [9]. A bilateral teleoperation system consists of operating a machine at a distance while exchanging the action and reaction information between the master and the slave bidirectionally in real time via a communication channel. A bilateral teleoperation system with time-varying time-delay was studied in [10]. An observer-based control was proposed while considering the different time-delay in the forward and backward paths. By applying this control law, synchronization of the teleoperation system at both sides are achieved. However, teleoperation systems frequently experience significant time delays in communication between the local and remote sites, which necessarily limit the user performance as shown in [11, 12]. Furthermore, the combination of system control with even small time delays creates stability problems [13], which has led to alternative control approaches. Robotic teleoperation is proposed in [14] for imitation learning data collection. Such method represents stochastic artificial intelligence approaches and is used for complex manipulation tasks. Alternative deterministic artificial intelligence approaches are proposed in [15] to assert deterministic self-awareness statements based on either the physics of the underlying problem or systemidentification to establish governing differential equations. Significant time delay between the command specification and its execution may occur in some teleoperated robotic systems because of the distance separating the robot and control site [16], which is the case in [17]. Researchers of the latter work used CAD-based models and computer graphics overlays of the camera views to check if the robot path is collision-free. It was shown that such technique is not practical for guaranteeing collision-free motion for the entire body of the robot arm manipulator because of time delays. The research work in [18] concludes that latencies between 400 ms and 500 ms may be acceptable for precise teleoperation tasks, such as telesurgery. Beyond 600 ms, latencies are difficult to deal with and are acceptable only for low risk and simple procedures. It is confirmed in [19; 20] that the inspection of robot real-time response is necessary for teleoperated robotic applications. In fact, as we are interested in robotic teleoperation, one contribution of this paper is the identification of real-time performance degradation sources in order to identify and apply the required developments and improvements of robot control. Workspace limitations make the robot control and remote piloting difficult. Simulation tools are useful to predict robot behavior in teleoperation to verify the interactions absence between the robot links and its environment. ROS-based robot simulation has developed relative maturity over the past two decades thanks to ROS benefits.