Chih-Hung King

Tactile Feedback Induces Reduced Grasping Force in Robot-Assisted Surgery

Robot-assisted minimally invasive surgery has gained widespread use over the past decade, but the technique is currently operated in the absence of haptic feedback during tissue manipulation. We have developed a complete tactile feedback system, consisting of a piezoresistive force sensor, control system, and pneumatic balloon tactile display, and mounted directly onto a da Vinci surgical robotic system. To evaluate the effect of tactile feedback on robotic manipulation, a group of novices (n = 16) and experts ( n = 4) were asked to perform three blocks of peg transfer tasks with the tactile feedback system in place. Force generated at the end-effectors was measured in all three blocks, but tactile feedback was active only during the middle block. All subjects used higher force when the feedback system was inactive. When active, subjects immediately used substantially less force and still maintained appropriate grip during the task. After the system was again turned off, grip force increased significantly to prefeedback levels. These results demonstrate that robotic manipulations without tactile feedback are done with more force than needed to grasp objects. Therefore, the addition of tactile feedback allows the surgeon to grasp with less force, and may improve control of the robotic system and handling of tissues and other objects.

A Haptic Feedback System for Lower-Limb Prostheses

A haptic feedback system has been developed to provide sensory information to patients with lower-limb prostheses or peripheral neuropathy. Piezoresistive force sensors were mounted against four critical contact points of the foot to collect and relay force information to a system controller, which in turn drives four corresponding pneumatically controlled balloon actuators. The silicone-based balloon actuators were mounted on a cuff worn on the middle thigh, with skin contacts on the posterior, anterior, medial, and lateral surfaces of the thigh. Actuator characterization and human perceptual testing were performed to determine the effectiveness of the system in providing tactile stimuli. The actuators were determined to have a monotonic input pressure-vertical deflection response. Six normal subjects wearing the actuator cuff were able to differentiate inflation patterns, directional stimuli and discriminate between three force levels with 99.0%, 94.8%, and 94.4% accuracy, respectively. With force sensors attached to a shoe insole worn by an operator, subjects were able to correctly indicate the movements of the operator with 95.8% accuracy. These results suggest that the pneumatic haptic feedback system design is a viable method to provide sensory feedback for the lower limbs.

A Multielement Tactile Feedback System for Robot-Assisted Minimally Invasive Surgery

A multi-element tactile feedback (MTF) system has been developed to translate the force distribution, in magnitude and position, from 3times2 sensor arrays on surgical robotic end-effectors to the fingers via 3times2 balloon tactile displays. High detection accuracies from perceptual tests (> 96%) suggest that MTF may be an effective means to improve robotic control.

Optimization of a Pneumatic Balloon Tactile Display for Robot-Assisted Surgery Based on Human Perception

Robot-assisted surgery is characterized by a total loss of haptic feedback, requiring surgeons to rely solely on visual cues. A compact, flexible, and lightweight pneumatic balloon tactile display has been developed suitable for mounting on robotic surgical master controls. The tactile display consists of a molded polydimethylsiloxane substrate with cylindrical channels and a spin-coated silicone film that forms the array of balloons. Human perceptual studies were conducted to determine the optimal diameter, spatial resolution, and temporal resolution of the balloon actuator design. A balloon diameter of 3.0 mm provided the highest average accuracy (ges 95%) while offering five detectable inflation levels. Spatial accuracy in a two-actuator discrimination task reached 100% with 1.5 mm edge-to-edge spacing, and the accuracy of determining the order of two successive stimuli was greater than 90% when the time separation was 100 ms. Design optimization based on the results from this study enables the described tactile display to provide the effective tactile feedback that is otherwise unavailable during robotic surgery.

Pneumatic balloon actuators for tactile feedback in robotic surgery

Purpose – Robotic surgery is limited by the lack of haptic feedback to the surgeon. The addition of tactile information may enable surgeons to feel tissue characteristics, appropriately tension sutures, and identify pathologic conditions. Tactile feedback may also enable expansion of minimally invasive surgery to other surgical procedures and decrease the learning curve associated with robotic surgery. This paper aims to explore a system to provide tactile feedback.Design/methodology/approach – A pneumatic balloon‐based system has been developed to provide tactile feedback to the fingers of the surgeon during robotic surgery. The system features a polydimethyl siloxane actuator with a thin‐film silicone balloon membrane and a compact pneumatic control system. The 1.0 × 1.8 × 0.4 cm actuators designed for the da Vinci system feature a 3 × 2 array of 3 mm inflatable balloons.Findings – The low‐profile pneumatic system and actuator have been mounted directly onto the da Vinci surgical system. Human perceptua...

Fabrication and Characterization of a Balloon Actuator Array for Haptic Feedback in Robotic Surgery

Robot-assisted surgery is characterized by a total loss of haptic feedback, requiring surgeons to rely solely on visual cues. A pneumatically-driven balloon actuator array, suitable for mounting on robotic surgical master controls, has been developed to provide haptic feedback to surgeons. The actuator arrays consist of a molded polydimethylsiloxane substrate with cylindrical channels and a spin-coated silicone film that forms the array of balloons. Preliminary human perceptual studies have demonstrated that balloon diameters greater than 1.0mm may provide effective haptic feedback to the index finger. Before conducting further human perceptual tests, refinements of the fabrication process and performance data of the actuator are required. Balloons with diameters ranging between 1.5mm and 4.0mm were fabricated with film thicknesses of 200μm and 300μm. Inflation pressure versus balloon deflection tests and cyclic actuation tests were performed to characterize each balloon type. The results demonstrated a high linearity between inflation pressure and balloon deflection (R2>0.93) and negligible hysteresis effects between inflation and deflation over 100,000cycles. The studies indicated that 300μm films are optimal for 3.0mm and 4.0mm diameter balloons, and 200μm films are optimal for 1.5mm, 2.0mm, and 2.5mm diameter balloons. Due to its compact size and high performance, the described pneumatic actuator can provide sensory input that is otherwise unavailable during robotic surgery.

A tactile feedback system for robotic surgery

A tactile feedback system was developed and mounted on the da Vinci robotic surgical system. The system features silicone-based tactile balloon actuators mounted on the robotic master controls, modified commercial piezoresistive sensors mounted on the robotic end effectors, and a pneumatic control system. The system has a frequency response of up to 20 Hz, a linear input force-output pressure relationship, and provides five discrete levels of actuation over a force input range of 0 to 25 N. A demonstration of the system with four subjects grasping a phantom with an embedded pressure-sensitive film suggested that less force was applied with tactile feedback. This paper describes the design, fabrication, characterization, and demonstration of the mounted tactile feedback system and its components. Ongoing studies using the system will assess the benefit of tactile stimuli to learning and control in robotic surgery.

An integrated pneumatic tactile feedback actuator array for robotic surgery.

A pneumatically controlled balloon actuator array has been developed to provide tactile feedback to the fingers during robotic surgery.

Tactile Feedback in Surgical Robotics

While commercial surgical robotic systems have provided improvements to minimally invasive surgery, such as 3D stereoscopic visualization, improved range of motion, and increased precision, they have been designed with only limited haptic feedback. A number of robotic surgery systems are currently under development with integrated kinesthetic feedback systems, providing a sense of resistance to the hands or arms of the user. However, the application of tactile feedback systems has been limited to date. The challenges and potential benefits associated with the development of tactile feedback systems to surgical robotics are discussed. A tactile feedback system, featuring piezoresistive force sensors and pneumatic silicone-based balloon actuators, is presented. Initial tests with the system mounted on a commercial robotic surgical system have indicated that tactile feedback may potentially reduce grip forces applied to tissues and sutures during robotic surgery, while also providing high spatial and tactile resolution.