# Analysis of the Leap Motion Controller Workspace for HRI Gesture Applications
## 2 Related Work  
In this section, we refer in detail to some key HRI applications to show how the LMC is currently used in robotics research. [PERSON] et al. designed an HRI interface which incorporated marker-less tracking and a wearable-based approach to interact with a human operator via continuous movements of their hand. Marker-less tracking was completed using the LMC; wearable-based tracking was completed using a wireless wristwatch. Two Kalman filters were used to suppress the noise of the measurements [1]. [PERSON] et al. presented an intuitive grasping control of their proprietary 13-DOF humanoid soft robotic hand, BCL-13. They used the LMC to obtain information about hand joint angles; these are then mapped onto the robotic hand through a dedicated filter. This way, the 13 degrees of freedom can be controlled by the hand of the operator [6]. [PERSON] et al. presented a remote manipulation method for a mobile manipulator via the gestures of the operator. A small mobile robot was equipped with a 4-DOF robot arm to grasp objects. The operator used one hand to control both the motion of the mobile robot and the posture of the robotic arm. The LMC was used to gather information on the operator's hands. Two filters were employed to estimate the position and posture of the human hand to reduce the inherent noise of the sensor. A Kalman filter was used to estimate the position, and a particle filter was used to estimate the orientation of the operator's hand. The effectiveness of the proposed human-robot interface was experimentally verified in a laboratory. The authors claimed they have proven the system can be used for robot teleoperation by a non-professional operator [7]. Figure 1: HRI workplace including the Leap Motion Controller. [PERSON] et al. proposed a robot-human handover with a \"hand/arm\" robotic manipulator with the Universal Robot Hand II as its end effector. The authors stated that in the robot-human handover, the robot must avoid not only hurting a human receiver but also can not disturb the operator's activity. Therefore, in the developed HRI method, the \"hand/arm\" robot measured the position and posture of the human hand for a smooth handover using the LMC. The handover motion was executed according to the position and posture of the operator's hand [14]. [PERSON] et al. proposed a gesture-based telemanipulation scheme to control the NAO humanoid robot. Using the LMC, the NAO robot was telemanipulated to accomplish locomotion, dexterous manipulation, and composite tasks [18]. [PERSON] et al. presented their implementation of drone control via simple human gestures. They used the LMC sensor and the Parrot AR DRONE 2.0, which is an off-the-shelf quad rotor having an on-board Wi-Fi system. The AR DRONE was connected to the ground station via Wi-Fi, and the LMC was connected to the ground station via USB port. The LMC was used to detect the hand gestures and send them to the ground station. The ground station used ROS (Robot Operating System) on Linux [22]. [PERSON] et al. presented experiments that explored the possibility of using an optical tracking device input to remotely control dual-arm robots. They proposed using the Leap Motion Controller as an alternative to using joysticks, which should allow for more intuitive 6-DOF control where only one hand is needed to control each robot arm. They affixed two end effectors to the [PERSON] research robot: a standard electric gripper, and an AR10 robotic hand. The standard electric gripper was controlled via pinch gestures, and all five fingers and the thumb were controlled on the AR10 robotic hand using finger movement detected by the LMC. Authors performed only simple tests; the results indicated that in lifting standard objects the standard electric gripper had a higher success rate. The main issue was the lack of any touch or force feedback for the operator. However, as the user became more comfortable with the system, their performance became better [24]. [PERSON] et al.