Design of a 3D-Printed Soft Robotic Hand With Integrated Distributed Tactile Sensing

Abstract

Humans rely on distributed tactile sensing in their hands to achieve robust and dexterous manipulation of delicate objects. Soft robotic hands have received increased attention in recent years due to their adaptability to unknown objects and safe interactions with the environment. However, the integration of distributed sensing in soft robotic hands is lacking. This is largely due to the complexity in the integration of soft sensing solutions with the hands. This paper proposes a novel soft robotic hand that incorporates an active palm and distributed pneumatic tactile sensing in both the fingers and the palm. Multi-material 3D printing allows the tactile sensors to be directly printed on the hand, whereas conventional tactile approaches require the sensors to be attached as part of multiple fabrication procedures. Active degrees of freedom are introduced in the palm to achieve increased dexterity. The proposed hand successfully performed 32 of the 33 Feix taxonomy grasps and all 11 Kapandji thumb opposition poses.

Anthropomorphic Twisted String-Actuated Soft Robotic Gripper with Tendon-Based Stiffening

“…For their combination of controllability and high force output, pneumatic actuators have been used in many grippers aiming to be both anthropomorphic and dexterous [4], [7], [36], [37], [55], [56]. Applications of non-pneumatic actuation methods, such as SMAs [57], SMTAs [42], or combined actuation methods [58] have been less developed in highperformance grippers, and existing grippers using these actuators have been limited in force output, dexterity, or both.…”

“…Comparing our gripper to all of these examples, the maximum grasp force resisted was higher than all but the gripper presented in [7], confirming that TSAs can provide high actuation forces to soft robotic grippers. Several of these grippers reported their mass excluding the weight of their full actuation systems [55], [56], which made a fair comparison of gripper masses difficult. However, among the papers that do report complete mass, our gripper was the lightest with the exception of [42], which does not claim the high degree of dexterity we achieved.…”

“…For this work, we chose to use the Kapandji Test [54] and the comprehensive Feix GRASP Taxonomy [41] to quantify the dexterity and grasping capabilities of our gripper. Application of the Kapandji Test varied between papers, with a minimum of 8 locations on the hand tested [4] and a maximum of 11 locations tested [37], [55]. We tested 10 points, of which 6 were achieved.…”

“…This is because, the data from the encoders is not directly used to control the posture of a particular finger [28]. Furthermore, sensors to measure the force outputs from the fingers and palm will also be required to perform efficient grasping [55]. The inclusion of sensors in the gripper design will be explored as a part of future work.…”

“…To maintain the compactness of the gripper, self-sensing TSAs, which use conductive supercoiled polymer (SCP) strings, can be used to measure the pose of a finger [63], [66]. In addition, tactile sensors [55] could be embedded into the design of the gripper for force sensing.…”