Design and Grasping Control of Rib-Reinforced Bending Soft Actuators by Vacuum Driven

This paper is concerned with developing a soft robot hand consisting of three Rib-Reinforced Vacuum-Driven Actuators that perform tasks requiring flexibility in the same workspace as humans. Most of the conventional soft actuators are powered by compressed air, which is easy to obtain the output, however, there is a risk of rupture. In consideration of workers' and products' safety, vacuum-driven soft actuators were developed to avoid rupture. In order to prevent undesirable buckling due to atmospheric pressure, resin ribs are appropriately placed inside to enable bending motion by vacuum drive. This soft actuator generated a maximum force of about 2.9 N at its tip. Furthermore, the tip force is controlled by the force feedback PID control, which was established by using the pressure-force characteristic of the soft actuators and could be controlled for a mixture of step, linear, and sinusoidal waves as the reference force inputs. In the experiments of grasping, the soft robot hand was able to grasp workpieces of various materials and shapes, including a plastic bottle with water (0.535 kg). In addition, by introducing the pressure feedback control, the soft robot hand achieved to gently grasp the paper balloon without changing its shape.