First validation of the Haptic Sandwich: a shape changing handheld haptic navigation aid

This paper presents the Haptic Sandwich, a handheld robotic device that designed to provide pedestrian navigation instructions through a novel shape changing modality. The device resembles a cube with an articulated upper half that is able to rotate and translate (extend) relative to the bottom half, which is grounded in the user’s hand when the device is held. The poses assumed by the device simultaneously correspond to heading and proximity to a navigational target. The Haptic Sandwich provides an alternative to screen and/or audio based pedestrian navigation technologies for both visually impaired and sighted users. Unlike other robotic or haptic navigational solutions, the haptic sandwich is discrete in terms of form and sensory stimulus. Due to the novel and unexplored nature of shape changing interfaces, two user studies were undertaken to validate the concept and device. In the first experiment, stationary participants attempted to identify poses assumed by the device, which was hidden from view. In the second experiment, participants attempted to locate a sequence of invisible navigational targets while walking with the device. Of 1080 pose presentations to 10 individuals in experiment one, 80% were correctly identified and 17.5% had the minimal possible error. Multi-DOF errors accounted for only 1.1% of all answers. The role of simultaneous or independent actuator motion on final shape perception was tested with no significant performance difference. The rotation and extension DOF had significantly different perception accuracy. In the second experiment, participants demonstrated good navigational ability with the device after minimal training and were able to locate all presented targets. Mean motion efficiency of the participants was between 32%-56%. Participants made use of both DOF

Tacsac: a wearable haptic device with capacitive touch-sensing capability for tactile display

This paper presents a dual-function wearable device (Tacsac) with capacitive tactile sensing and integrated tactile feedback capability to enable communication among deafblind people. Tacsac has a skin contactor which enhances localized vibrotactile stimulation of the skin as a means of feedback to the user. It comprises two main modules—the touch-sensing module and the vibrotactile module; both stacked and integrated as a single device. The vibrotactile module is an electromagnetic actuator that employs a flexible coil and a permanent magnet assembled in soft poly (dimethylsiloxane) (PDMS), while the touch-sensing module is a planar capacitive metal-insulator-metal (MIM) structure. The flexible coil was fabricated on a 50 µm polyimide (PI) sheet using Lithographie Galvanoformung Abformung (LIGA) micromoulding technique. The Tacsac device has been tested for independent sensing and actuation as well as dual sensing-actuation mode. The measured vibration profiles of the actuator showed a synchronous response to external stimulus for a wide range of frequencies (10 Hz to 200 Hz) within the perceivable tactile frequency thresholds of the human hand. The resonance vibration frequency of the actuator is in the range of 60–70 Hz with an observed maximum off-plane displacement of 0.377 mm at coil current of 180 mA. The capacitive touch-sensitive layer was able to respond to touch with minimal noise both when actuator vibration is ON and OFF. A mobile application was also developed to demonstrate the application of Tacsac for communication between deafblind person wearing the device and a mobile phone user who is not deafblind. This advances existing tactile displays by providing efficient two-way communication through the use of a single device for both localized haptic feedback and touch-sensing

IV.3. Bioreactors in tissue engineering.

IV.3. Bioreactors in tissue engineering

Development of flexible, durable and ionic materials based on poly(acrylamide) hydrogels for soft conducting and sensing applications

Soft ionic hydrogels have garnered significant interest for their applications in soft electronics and tissue engineering. However, further demands are still on the rise for developing these materials to possess flexibility, durability, low cost, non-toxic and reliable conductivity. In this work, a poly(acrylamide) (PAAm) hydrogel containing salt was utilised for its significant features such as high flexibility and excellent conductivity. Therefore, several hydrogels were prepared from the polymerisation reaction of the mononer acrylamide (AAm) to produce different polymers networks of PAAm hydrogels by the use of different crosslinking materials and methods aiming to optimise their mechanical and electrical characteristics, with the aim of applying these hydrogels in different applications such as soft sensing and conducting devices. Ionic-covalent entanglement hydrogels were prepared by mixing cross-linked gellan gum (GG) and CaCl2 ionically with PAAm and methylenbis(acrylamide) (MBAAm) covalently. The mechanical behaviour was modified by altering the ionic and the covalent polymers ratio. The electrical properties were investigated with varying hydrogel ratios which displayed optimised mechanical properties for use in conducting and sensing applications. It was observed that gels prepared with 0.1 M CaCl2 and 1.11 % (w/v) GG with PAAm consisting of 4.44 % (w/v) and AAm with 3 % (w/v) MBAAm exhibited optimum mechanical characteristics reporting 216±12 kPa (compressive stress to failure) for the compression test analysis and 264±5kPa (shear modulus) for the oscillatory rheology demonstration. The electrical conductivity and the water content for the optimised ICE gel displayed a noticeable increase from 3.3±0.5 mS.cm-1 to 127±15 mS.cm-1 and from 78 % to 85 %, respectively, after it was immersed in 2.7 M NaCl solution

Investigations into the design of a wheelchair-mounted rehabilitation robotic manipulator

This research describes the steps towards the development of a low-cost wheelchair-mounted manipulator for use by the physically disabled and elderly. A detailed review of world rehabilitation robotics research has been conducted, covering fifty-six projects. This identified the main areas of research, their scope and results. From this review, a critical investigation of past and present wheelchair-mounted robotic arm projects was undertaken. This led to the formulation of the key design parameters in a final design specification. The results of a questionnaire survey of fifty electric wheelchair users is presented, which has for the first time established the needs and abilities of this disability group. An analysis of muscle type actuators, which mimic human muscle, is presented and their application to robotics, orthotics and prosthetics is given. A new type of rotary pneumatic muscle actuator, the flexator, is introduced and through extensive testing its performance characteristics elucidated. A review of direct-drive rotary pneumatic, hydraulic and electrical actuators has highlighted their relative performance characteristics and has rated their efficiency in terms of their peak torque to motor mass ratio, Tp/MM. From this, the flexator actuator has been shown to have a higher Tp/MM ratio than most conventional actuators. A novel kinematic arrangement is presented which combines the best features of the SCARA and vertically articulated industrial robot geometries, to form the 'Scariculated' arm design. The most appropriate actuator for each joint of this hybrid manipulator was selected, based on the criteria of high Tp/MM ratio, low cost, safety and compatibility. The final design incorporates conventional pneumatic linear double-acting cylinders, a vane type rotary actuator, two dual flexator actuators, and stepping motors for the fme control of the wrist/end effector. An ACSL simulation program has been developed which uses mass flow rate equations, based on one-dimensional compressible flow theory and suppressed critical pressure ratios, to simulate the dual flexator actuator. Theoretical and empirical data is compared and shows a high degree of correlation between results. Finally, the design and development work on two prototypes is discussed. The latest prototype consists of a five-axis manipulator whose pneumatic joints are driven by pulse width modulated solenoid valves. An 8051 microprocessor with proportional error feedback modilles the mark to space ratio of the PWM signal in proportion to the angular error of the joints. This enables control over individual joint speeds, reprogrammable memory locations and position monitoring of each joint. The integration of rehabilitation robotic manipulators into the daily lives of the physically disabled and elderly will significantly influence the role of personal rehabilitation in the next century

The Fifth NASA/DOD Controls-Structures Interaction Technology Conference, part 2

This publication is a compilation of the papers presented at the Fifth NASA/DoD Controls-Structures Interaction (CSI) Technology Conference held in Lake Tahoe, Nevada, March 3-5, 1992. The conference, which was jointly sponsored by the NASA Office of Aeronautics and Space Technology and the Department of Defense, was organized by the NASA Langley Research Center. The purpose of this conference was to report to industry, academia, and government agencies on the current status of controls-structures interaction technology. The agenda covered ground testing, integrated design, analysis, flight experiments and concepts