## 2 System Description
### 3D Printed Anthropomorphic Hybrid Robotic Gripper  
In the bimanual teleoperation system, two 3D printed anthropomorphic hybrid robotic grippers are developed for the manipulation tasks. Generally, the two grippers share similar structures. They are cable-driven and five-fingered. As depicted in Figure 2, the hybrid robotic gripper is composed of a rigid structure (rigid gripper) and the soft augmented layer (soft layer). Each rigid gripper has a palm and five fingers. It has 7 DoFs in total, where the thumb has two, while the palm and the other four fingers have one each. Correspondingly, seven servo motors of Dynamixel MX-64R (Robotis, Seoul, Korea) are used as the actuators. Based on the bio-inspired design philosophy, the rigid structure can be seen as the bone of human hand while the soft layer acts as the skin. The rigid structure is used to compensate the gravity of the object and the soft layer is adopted to increase the friction between the gripper and the grasped object. Therefore, the hybrid rigid-soft gripper not only takes advantage of the rigid structure in manipulating rigid objects but also makes use of the soft layer in potential contact and slippery augmentation. In addition, the rigid gripper is a modular product. As shown in Figure 2, each finger module has a dovetail anchor and a dovetail anchor slot. A dovetail joint is gener  
Figure 1: Diagram of the bimanual robotic teleoperation system. Figure 2: Illustration of the anthropomorphic hybrid robotic gripper. finger modules. Thus, the length of the finger can be quickly adjusted by installing or removing the finger modules. With modular and reconfigurable joints on each finger, the workspace of the gripper is flexible and can be easily changed according to specific tasks, which enables the gripper to adapt to various manipulation tasks with objects in different sizes and shapes. Besides the rigid modular structure, three fingers (the thumb, index, and middle) are mounted with additional soft augmented layers, which are made of a stretchable material named as EcoFlexTM 00-30 (Smooth-On, Macungie, PA, USA). Generally, the soft layer is composed of suction and inflation modules, which are staggered arranged. As illustrated in Figure 3, the suction module consists of four layers, namely the base layer, spacer layer, suction layer, and top layer. The dimension of the whole suction module is around 20 mm \(\times\) 20 mm \(\times\) 6 mm, with a thickness of 1.5 mm for each layer. An air pump with one positive-pressure channel and one negative-pressure channel is connected to the suction module via a soft tube. A negative air pressure ranging from \(-\)73 kPa to 0 is provided to actuate the suction capability. Then the suction module would be firmly attached to the object with the effect of the negative pressure. By contrast, the inflation module has two layers. The size of the whole module is approximately 20 mm \(\times\) 30 mm \(\times\) 4 mm, with a thickness of 2 mm for each layer. A soft tube is inserted and a positive air pressure ranged from 0 to 73 kPa is input to activate the inflation functionality. The cavity between the two layers would be inflated with the effect of the positive pressure, which is used to increase the contact area between the gripper and the object. Furthermore, the whole rigid gripper including the five fingers and the palm can be equipped with the soft augmented layer. Specifically, the suction modules are placed on the finger belly of the rigid gripper, which is supposed to provide suction force. The inflation modules are placed on the hinges of the rigid gripper to engage the contact with the object. Thus, the soft layer may not only enhance the grab strength by increasing the contact area but also provide a buffer between the rigid gripper and the grasped object to prevent the object from damage by the hard surface. The 3D printed anthropomorphic rigid-soft gripper takes both the advantages of the rigid and soft grippers, as well as the gripper and the suction cup.