Sensorization of Robotic Hand Using Optical Three-Axis Tactile Sensor: Evaluation with Grasping and Twisting Motions

Abstract

Problem statement: Sensitization of robot hand is still remaining as crucial issue since most of robot hand systems nowadays are only capable to grasp a predefined specific object. It is still difficult for robot hand system to realize human-like tactile sensation. Some common problems in robot hand system are low accuracy sensing device, sensors are not robust enough for long time work and heavy duties, inconsistence tactile sensing detection and difficulties in control of sensing fusion with robot trajectory. These problems are apparently drawback the progress to commercializing robot hands as real consumer products. Approach: This study presented the application of optical three-axis tactile sensor to robot hand to improve sensitization quality in robotic hand system. The proposed tactile sensor system was designed with compliance modules to communicate with robot hand control system. The sensing principle used in this tactile sensor comparatively provides better sensing accuracy to detect contact phenomena from acquisition of three axial directions of forces. Methodology of force and slippage detection in the tactile sensor system was presented. Accordingly, the optimization of robot hand control algorithm to comply with the tactile sensor system was presented and verified in experiment of grasping and twisting. Results: The tactile sensor presented in this study is capable of detecting normal and shear force simultaneously. The proposed methodology was verified in experiment with paper cup and water, in which the result shows the robot control system managed to respond to the proposed object stiffness distinction parameters and effectively respond to sudden change of object weight during grasping. An experiment of grasping and twisting motions was conducted using a bottle cap. In order to perform simultaneous grasping and twisting tasks, optimization of the control algorithm was conducted with additional parameters to satisfy the desired tasks. Conclusion: Experimental result shows that the robot hand managed to perform grasping and twisting of bottle cap smoothly. The overall results revealed good performance of the proposed optical three-axis tactile sensor system and robot hand control algorithm for future application in a real artificial robot hand. In addition, slippage sensation measured in a robot control system could contribute a better maneuvering of the robot arm-finger system.

Neuromorphic Event-Based Slip Detection and Suppression in Robotic Grasping and Manipulation

“…3measuring and analysing the vibration of the shearing force caused by relative motions by sensors such as acoustic resonant sensors [40], thick-film piezoelectric sensors [41], piezoresistive sensors [42], and optoelectric tactile sensors [43], etc. (4) physically observing the slip displacement of the object from robotic hands using various sensors such as optical sensors [44], accelerometers [45], array tactile sensors [46]. Tactile sensing hardware and technologies are still underdeveloped when compared to other perception modalities such as vision.…”

“…Recently, Kazuhiro in [51] reviewed the earlier works and recent developments in vision-based tactile sensors. He classified such sensors into three categories based on the sensing principles that is light conductive plate based [46], marker displacement based [50], [52], [53] and reflective membrane based [54]. In most of the works, vision sensors are placed underneath the skin surface to detect the motion of markers which somehow limits the ability of the vision sensor in distinguishing whether the change of contacts are from grasped object or external disturbances.…”

Algorithm for Controlling Manipulator with Combined Array of Pressure and Proximity Sensors in Gripper

“…The current course of research in the domain of force-torque sensing of manipulators [1,2] and pedipulators [3,4] in robots is a vibrant topic. Many papers are published regarding this domain, which detail, particularly, development of new pressure sensor designs [5,6], as well of combined sensors, intended for measurement of various quantities-such as external applied pressure and object proximity [7,8]. Development of algorithms for object gripping, which relies on signaling from such sensors, is a relevant problem.…”

Pressure Sensor: State of the Art, Design, and Application for Robotic Hand

“…It is used to improve sensitization quality in robotic hand system [64]. The arm actuators use the tactile information as feedback to execute and request the orders as needed.…”