Fig. 4: Robotic arm with multiple modules.

a Schematic design of a three-module robotic arm and a module. The three-module robotic arm consists of three modules and a gripper (vacuum-actuated). b Diagram of the three-module robotic arm’s motion modes and experimental results of the three-module robotic arm cap-grasping and pouring water from the top view and front view. c Diagram of the robotic arm failing to reach the cap when the cap is moved off the working boundary of the three-module robotic arm. d Process of a three-module robotic arm changing to a four-module robotic arm. e The partial working boundary of a three-module/four-module robotic arm. f Diagram of the four-module robotic arm’s motion modes and experimental results of the four-module robotic arm cap-grasping and pouring water from the top view and front view. The shaded region in b and f indicates the grasping process of the soft gripper. C and E in C/E represent contraction and elongation, respectively.