The aspiration to replicate the capabilities of the human hand has driven innovations in the design of soft robotic hands. Despite these advancements, many existing designs of soft hands still lack effective in-hand vision and the ability for each finger to achieve active multi-degree-of-freedom motion. This paper proposes a cable-driven soft robotic hand that can achieve dexterous grasping and manipulation, vision-guided grasping, vision-based slip detection and compensation, as well as visually servoed in-hand manipulation. The hand has five soft fingers, each capable of independent flexion/extension motion and bidirectional ad/abduction motion. A red-green-blue-depth (RGB-D) camera is integrated into the palm of the soft hand to enable in-hand vision capability. Modeling of the soft hand is established to analyze its kinematics, statics, and manipulability. A series of experiments are conducted to demonstrate its dexterous grasping and manipulation capabilities on a variety of objects. Using 3D point cloud data from the in-palm camera, an effective vision-guided grasping strategy is developed to grasp objects on a table. The in-hand vision also enables slip detection and compensation during grasping to maintain the grasp stability. Furthermore, a hierarchical, visually servoed controller is developed to perform closed-loop in-hand object manipulation. With its high dexterity and visual feedback capabilities, the soft hand will find important applications such as household object manipulation and food picking/sorting, and may also be used as a prosthetic hand or an auxiliary hand for humans.

Soft robotic systems are inherently compliant, giving them unique capabilities not possessed by traditional rigid-bodied robot systems. Many soft systems rely on soft pneumatic actuators. One of the biggest downsides of such actuators is the need for bulky pressure-regulating devices and individual pneumatic supply lines. In this work, a miniaturized pressure-regulating system is developed and embedded into the unused space inside of a soft pneumatic McKibben actuator, enabling the simultaneous pressure control of multiple actuators connected to a single pneumatic supply line. This "valve-embedded" actuator is capable of regulating its internal pressure within 0.05 psi of a desired set point, even under external load. Compared to a conventional McKibben actuator driven by external valves, the valve-embedded actuator is experimentally shown to consistently achieve faster settling times. To showcase the practical application of the valve-embedded actuator on a robotic system, a 0.9m serial-linked robot driven by five independently controlled valve-embedded actuators was assembled, and was shown to achieve an average root mean square error of less than 1.5cm in a waypoint tracking experiment. The miniaturized pressure control system developed in this work is open source and could be embedded in any fluid-driven actuator, enabling more capable and densely actuated pneumatic soft robots.

Soft robotic grippers possess high structural compliance and adaptability, allowing them to grasp objects with unknown and irregular shapes and sizes. To enable more dexterous manipulation, soft sensors that are similar in mechanical properties to common elastomer materials are desired to be integrated into soft grippers. In this paper, we develop ionic hydrogel-based strain and tactile sensors and integrate these sensors into a three-finger soft gripper for learning-based object recognition and force-controlled grasping. Such hydrogel-based sensors have excellent conductivity, high stretchability and toughness, good ambient stability, and unique antifreezing property; they can be readily attached to a soft gripper at desired locations for strain and tactile sensing. By using a deep-learning model, the sensory soft gripper is demonstrated to be capable of grasping and recognizing objects at both room and freezing temperatures, and achieving close to 100% recognition accuracy for ten typical objects. Moreover, the capacitive tactile feedback of the gripper is utilized to develop a closed-loop force controller and realize force-controlled grasping of fragile or highly deformable objects. A new slip detection and compensation strategy is also proposed and validated for the sensory gripper for adjusting the grasping force in real time upon detecting slippage. Note to Practitioners—The multimodal sensation of a soft robotic gripper could enrich its grasping functionalities and improve its manipulation performance. This research integrates novel antifreezing ionic hydrogel-based strain and tactile sensors into a three-finger soft robotic gripper for learning-based object recognition and force-controlled grasping. Constructed from a highly stretchable, ambient-stable, and antifreezing ionic hydrogel, the strain and tactile sensors can be readily integrated at the desired locations on the soft gripper, and can reliably operate at both ambient and freezing temperatures with excellent mechanical and electrical properties. Based on the feedback of the strain and tactile sensors, a deep learning model is employed to enable high-accuracy object recognition while grasping, which can be useful for manipulation in vision-free environments. Closed-loop force control and slip compensation strategies are also demonstrated for reliably grasping fragile/deformable objects and handling slip events during the manipulation of heavy objects. The sensory soft gripper and the associated object recognition and force control methods could find practical applications in a variety of robotic manipulation tasks.

Soft robotic grippers possess high structural compliance and adaptability for grasping objects with unknown and irregular shapes and sizes. To enable more dexterous manipulation, soft sensors with similar mechanical properties to common elastomer materials are desired to be integrated into soft grippers. In this paper, we develop ionic hydrogel-based strain and tactile sensors and integrate these sensors into a three-finger soft gripper for learning-based object recognition. Such hydrogel-based sensors have excellent conductivity, high stretchability and toughness, good ambient stability, and unique anti-freezing property, and can be readily attached to a soft gripper at desired locations for strain and tactile sensing. Based on a deep-learning model, we demonstrate the capability of the sensory soft gripper for object grasping and recognition at both room and freezing temperatures, and achieve high recognition accuracy close to 100% for 10 typical objects. With these abilities, our gripper can find interesting applications such as sorting food or chemicals in low temperature storage and cold chain transportation, or manipulating equipment in polar area.