**1. Introduction**

Recently, many researchers focus on studies of remote robot operation with force feedback in which a user operates a remote robot having force sensors by using a haptic interface device while monitoring the remote operations by a video camera [1–3]. By using force feedback, since users can touch remote objects and feel the shape, weight, and softness of each object, the efficiency and accuracy of operation can be largely improved [4]. Therefore, the remote robot operation with force feedback is expected to be used in many areas such as remote surgery, disaster rescue, and outer space. However, when the information about force and/or position is transmitted over a QoS (Quality of Service) [5] non-guaranteed network like the Internet, QoE (Quality of Experience) [6] may seriously deteriorate [3, 4] owing to the network delay, delay jitter, and packet loss. Furthermore, as the network delay increases, the reaction force becomes larger, and unstable phenomena such vibrations of the robot and device may occur more often [7–9]. To solve the problems, we need to carry out QoS control and stabilization control together [4]. In this chapter, we mainly focus on QoS control at the application layer. The QoS control alleviates the influences of network delay, delay jitter, and packet loss on QoE.

We also introduce our remote robot system with force feedback which we constructed to study the QoS control and stabilization control by experiment. In the system, a user operates a remote industrial robot with a force sensor by using a local haptic interface device while monitoring the robot operation. We handle two types of operation; operation with a single remote robot system and that between two remote robot systems. We explain several types of QoS control which we have proposed so far for remote robot operation with force feedback.

In this chapter, first, we explain the remote robot system with force feedback in Section 2. Next, we introduce expected applications of the remote robot system with force feedback in Section 3. Then, we outline the problems to be solved for the applications in Section 4 and describe the QoS control which is used to solve the deterioration problems owing to the network delay, delay jitter, and packet loss in Section 5. Finally, we discuss the challenges and future directions of QoS control in Section 6 and conclude the chapter in Section 7.
