A haptic display for robotic rehabilitation of stroke

The effects of stroke are debilitating on the American population. Past studies of robot-aided motor training for survivors have proven to be effective in upper limb motor recovery. However, survivors also suffer from loss or impairment of sensation. Sensory impairment is an important predictor for motor recovery of stroke survivors. Studies have suggested that sensory inputs during robot-aided motor training might be critical for the creation and promotion of cortical reconstruction due to brain plasticity during post-stroke recovery. This paper presents a new haptic display for the handle of the InMotion2 robot in order to enhance cutaneous sensory inputs for stroke survivors during hand motion. The sensory enhancement is realized through pins attached to servomotors mounted inside the robot handle that vibrate and contact the middle and index fingers, the palm, and the thumb during motor training. Each servomotor is independently controlled using a computer via parallel port with a Field-Programmable Gate Array (FPGA) board as the hardware interface.This project is partially supported by research grants from NIH (NS043331) and NSF (BES-0302466)

Design, Modeling, Fabrication and Testing of a Piezoresistive-Based Tactile Sensor for Minimally Invasive Surgery Applications

Minimally invasive surgery (MIS) has become a preferred method for surgeons for the last two decades, thanks to its crucial advantages over classical open surgeries. Although MIS has some advantages, it has a few drawbacks. Since MIS technology includes performing surgery through small incisions using long slender tools, one of the main drawbacks of MIS becomes the loss of direct contact with the patient’s body in the site of operation. Therefore, the surgeon loses the sense of touch during the operation which is one of the important tools for safe manipulation of tissue and also to determine the hardness of contact tissue in order to investigate its health condition. This Thesis presents a novel piezoresistive-based multifunctional tactile sensor that is able to measure the contact force and the relative hardness of the contact object or tissue at the same time. A prototype of the designed sensor has been simulated, analyzed, fabricated, and tested both numerically and experimentally. The experiments have been performed on hyperelastic materials, which are silicone rubber samples with different hardness values that resemble different biological tissues. The ability of the sensor to measure the contact force and relative hardness of the contact objects is tested with several experiments. A finite element (FE) model has been built in COMSOL Multiphysics (v3.4) environment to simulate both the mechanical behavior of the silicone rubber samples, and the interaction between the sensor and the silicone rubbers. Both numerical and experimental analysis proved the capability of the sensor to measure the applied force and distinguish among different silicone-rubber samples. The sensor has the potential for integration with commercially available endoscopic grasper

Development of Piezoresistive Tactile Sensors and a Graphical Display System for Minimally Invasive Surgery and Robotics

Development of Piezoresistive Tactile Sensors and a Graphical Display System for Minimally Invasive Surgery and Robotics Masoud Kalantari, PhD Concordia University, 2013 This PhD work presents a new tactile and feedback systems for minimally invasive surgery (MIS)and robotics. The thesis is divided into two major sections: the tactile sensing system, and the graphical display system. In the tactile sensing system, piezoresistive materials are used as measuring elements. The first part of the thesis is focused on the theoretical modeling of piezoresistive sensing elements, which are semiconductive polymer composites. The model predicts the piezoresistive behavior in semiconductive polymer composites, including their creep effect and contact resistance. A single force sensing resistor (FSR) is, then, developed by using the semiconductive polymer composite materials. The developed FSR is used in the structure of a novel tactile sensor as the transduction element. The developed tactile sensor is designed to measure the difference in the hardness degree of soft tissues. This capability of the sensor helps surgeons to distinguish different types of tissues involved in the surgery. The tactile sensor is integrated on the extremity of a surgical tool to provide tactile feedback from the interaction between surgical instruments and the tissue during MIS. Mitral valve annuloplasty repair by MIS is of our particular interest to be considered as a potential target for the use of the developed tactile sensor. In the next step, the contact interaction of the tactile sensor with soft tissues is modelled, parametrically. Viscoelastic interaction is considered between the tactile sensor and atrial tissue in annuloplasty mitral valve repair; and a parametric solution for the viscoelastic contact is achieved. In addition to the developed sensor, a novel idea regarding measuring the indentation rate, in addition to measuring force and displacement is implemented in a new design of an array tactile sensor. It is shown that the indentation-rate measurement is an important factor in distinguishing the hardness degree of tissues with viscoelastic behaviour. The second part of the thesis is focused on the development of a three-dimensional graphical display that provides visual palpation display to any surgeon performing robotic assisted MIS. Two matrices of the developed piezoresistive force sensor are used to palpate the tissue and collect the tactile information. The collected data are processed with a new algorithm and graphically rendered in three dimensions. Consequently, the surgeon can determine the presence, location, and the size of any hidden superficial tumor/artery by grasping the target tissue in a quasi-dynamic way