This project is a continuation of the projects TEC2006-12376-C02 y TEC2009-14446-C02 in the field of design and application of advanced tactile sensors. These previous projects have had as general objetive the research into tactile sensors based on electroactive polymers, made with screen´printing technologies and also as layers of active materials on flexible printed circuits, and also the research into electronics to do the signal conditioning and acquisition based on ASICs, microcontrollers, FPGAs or PSoCs.
This project focuses on the solution of problems and the answering of questions related to the aplicability and usability of these sensors. Specifically, the project is built around two main goals: an electric wheel-chair or trolley with a driving assiting device based on a tactile sensor, and a tactile sensor suite for an artificial hand.
The first system has been developed as a prototype in the current project(TEC2009-14446-C02) and there is a patent pending on it. This project is intended to go further and get
a mature design. This means working on a tactile sensor specific for this application, with the proper
shape and size of the tactels and with a low cost technology that performs well enough, and also
developing an electronics that is compact, consumes low power and has good dynamic response, and
finally to improve and debug the control algorithms and calibration procedures to make them robust
against changes of the user and in the environment.
Regarding the second system, there are many
similar suites developed by other research groups and also commercially available. Our goal is to
develope a sensor suite (palm, mid-digits and fingertips) to be mounted on the Barret robotic hand. The
value added in our porposal lies on a patented technology for the raw sensor plus a strategy of direct
tactile sensor-FPGA proposed by our team. The aim is to take advantage of this strategy that has been
proved on a single sensor, and implement a whole architecture with communications based on serial
buses and/or wireless links. A complete suite of raw sensors has to be developed for this specific
application, and it is necessary to implement on the FPGAs the algoritms for calibration (please note that
they are arrays with high mismatching observed between tactels), feature extraction, event detection, and
communication, all with short response times due to the objetive of being used in manipulative tasks in
real time.
A more fundamental work runs in parallel to the activities on the above mentioned applied
objetives that looks for scientific results that can be useful in other fields, and also improvements for the
proposed systems in the medium term. Finally, it is worth mentioning that this work is strongly oriented to
find resources to increase the autonomy of elderly or disabled people, which is a priority in occidental
societies.
This proposal is aimed to continue the work of the project TEC2006-12376-C02 with regard to the design and application of advanced tactile sensors.
During the last years approximately, tactile sensors based on electroactive polymers have been proposed, designed and tested. Printed circuit board and screen-printing technologies have been used. Work has been done also on signal conditioning circuitry with ASICs and FPGAs, on the implementation of algorithms to obtain the main features of a tactile image, and on equipping a robot with tactile sensors. This proposal has the following main goals: advance in tactile sensors, advance in signal conditioning, advance in analysis of tactile information, and extension to other sensors and applications.
With respect to the work on tactile sensors, it is proposed the design of a sensor able to detect normal as well as tangential forces to the contact area. It will be based on electroactive polymers and fabricated with techniques of screen-printing. The design will be inspired on the proposals made by other authors to be implemented on silicon. Specifically, we will focus on finite element analysis and multi-physics tools to carry out the task. Other important aspects that are going to be faced are: the advance in the design of non flat sensors, sensors able to cover large areas, and the incorporation of electronics on the same substrate.
With respect to the advance in signal conditioning circuitry, research into a direct connection tactile sensor-to-FPGA is proposed (without an analog-to-digital converter). The direct connection of other sensors to a microcontroller has been implemented with success. The main reasons to use a FPGA are: parallel computation is possible (high dynamic performance), they have a high number of I/O pins (large sensors can be interfaced), and flexibility (they are programmable).
From the point of view of the analysis of the information provided by tactile sensors, we propose the use of tools from artificial intelligence to know more about the information from these sensors that is relevant in manipulative tasks. This is interesting to know the tasks to do by the electronics of the smart sensor.
Finally, with respect to the extension to other sensors and applications, two main tasks are planned. First, we will build a demonstrator with human-machine interface based on tactile sensors. Second, we will evaluate the use of bending sensors to monitor the human spine posture.