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We present the design, analysis and construction of a biologicallyinspired tactile sensor. The sensor can measure normal and lateralforces, conform to the surfaces with which it comes in contact andincrease the friction of the surface for a good grasp.The sensor is built using a simple process and the applied forcesare read using standard electronics. These features make thesensors ideal for mass production.We are motivated to build tactile sensors that are useful forrobotic manipulation given that the current ones do not have thefeatures that we consider necessary. The sensors presented in thispaper have been designed to deal with these issues. They have beendesigned and implemented in the fingers of the humanoid robotObrero.

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An instrument is being developed at the Department of Biomedical Engineering; Research and Development (MT-FoU), at the University Hospital of Umeå with the aim to detect prostate cancer ex vivo. Using a combination of tactile resonance technology and Raman spectroscopy the instrument is intended to be used in the operating room during radical prostatectomy to identify positive surgical margins. The hypothesis was that the length of the piezoelectric element used in the tactile resonance sensor affects the sensor's sensitivity and reproducibility when measuring the stiffness of soft tissue, and that there might be an optimal impression depth to measure at. The specific aim of this study was to evaluate two piezoelectric elements, of different lengths, by the sensitivity and reproducibility of the measurements they performed. Measurements were performed on five silicone samples of different stiffness, during a 2 mm impression. The standard deviation of the stiffness parameters, the R2 of the linear regression used to determine the stiffness parameter, and the depth at the which the most linear relationship between impression force and frequency shift was found were studied using linear mixed-effects models to identify any significant differences between the elements. The long element had a significantly higher R2 of 0.98 compared to 0.93 for the short element, and a higher measurement depth of 0.47 mm compared to 0.37 mm for the short element. No difference between the elements were found on accuracy as measured by standard deviation of the stiffness parameter. It was concluded that this was not enough to claim that one element was better than the other. / Ett instrument utvecklas på avdelningen för Medicinsk teknik, forskning och utveckling, vid Norrlands universitetssjukhus med målet att detektera prostatacancer ex vivo. Instrumentet kombinerar taktil resonansteknologi med Ramanspektroskopi och är tänkt att användas i operationssalen under radikal prostatektomi för att identifiera positiv kirurgisk marginal. Hypotesen var att längden av det piezoleketriska element som används i den taktila resonanssensorn påverkar sensorns känslighet och reproducerbarhet vid mätning av styvhet av mjukvävnad, och att det kan finnas ett optimalt intryckningsdjup att mäta på. Målet med denna studie var att utvärdera två piezoelektriska element, av olika längd, utifrån känsligheten och reproducerbarheten av mätningarna de utförde. Mätningarna gjordes på fem silikonsprover av olika styvhet, under 2 mm intryckning. Standardavvikelsen av styvhetsparametern, R2 av den linjära regression som användes för att bestämma styvhetsparametern, samt det intryckningsdjup på vilket det mest linjära förhållandet mellan intryckningskraft och frekvensskift hittades, studerade med så kallade linear mixed-effects modeller för att identifiera signifikanta skillnader mellan elementen. Det långa elementet hade ett signifikant högre R2 på 0.98 jämfört med det korta elementets 0.93, och ett högre mätdjup på 0.47 mm jämfört med det korta elementets 0.37 mm. Ingen skillnad mellan elementens standardavvikelser av styvhetsparametern hittades. Slutsatsen drogs att resultatet inte var nog för att påstå att det ena elementet är bättre än det andra.

"This thesis presents an extension of sensitive manipulation which transforms tactile sensors away from end effectors and closer to whole body sensory feedback. Sensitive manipulation is a robotics concept which more closely replicates nature by employing tactile sensing to interact with the world. While traditional robotic arms are specifically designed to avoid contact, biological systems actually embrace and intentionally contact the environment. This arm is inspired by these biological systems and therefore has compliant joints and a tactile shell surrounding the two primary links of the arm. The manipulator has also been designed to be capable of both industrial and humanoid style manipulation. There are an untold number of applications for an arm with increased tactile feedback primarily in dynamic environments such as in industrial, humanoid, and prosthetic applications. The arm developed for this thesis is intended to be a desktop research platform, however, one of the most influential applications for increased tactile feedback is in prosthetics which are operate in ever changing and contact ridden environments while continuously interacting with humans. This thesis details the simulation, design, analysis, and evaluation of a the first four degrees of freedom of a robotic arm with particular attention given to the design of modular series elastic actuators in each joint as well as the incorporation of a shell of tactile sensors. "

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