Tactile Sensor-Based Steering as a Substitute of the Attendant Joystick in Powered Wheelchairs

Analysis of Light Grip Influence on Standing Posture

Upright posture control and gait are essential for achieving autonomous daily living activities. Postural control of upright posture relies, among others, on the integration of various sensory information. In this context, light touch (LT) and light grip (LG) of a stationary object provide an additional haptic sensory input that helps to reduce postural sway. When LG was studied through the grasp of a cane, the sensory role of this assistive tool was often limited to a mediation interface. Its role was restricted to transmit the interaction forces between its tip and the ground to the hand. While most studies involve participants standing in an unstable way, such as the tandem stance, in this paper we study LG from a different perspective. We attached a handle of a cane firmly to a stationary support. Thus, we can focus on the role of the hand receptors in the LG mechanism. LG condition was ensured through the tactile information gathered by FSR sensors placed on the handle surface. Moreover, participants involved in our study stood in a usual way. The study involved twelve participants in an experiment composed of two conditions: standing relaxed while lightly gripping an equipped handle attached to the ground, and standing in the same way without gripping the handle. Spatial and frequency analyses confirmed the results reported in the literature with other approaches.

Use of technology to sustain mobility in older people with cognitive impairment and dementia: a scoping review

PURPOSE

This paper provides a review of studies that evaluated technology devices to sustain various forms of mobility in older people with cognitive impairment or dementia and mobility problems (e.g., inability to ambulate or difficulties to orient with consequent failures to reach relevant destinations).

METHODS

A literature search was performed for English language articles indexed in PubMed, PsycINFO, and Web of Science. This search was then supplemented with an ancestral and forward search. The search covered the period ranging between January 2010 and October 2020.

RESULTS

Twenty-seven articles were included in the review. They were divided into four groups according to whether they aimed to promote (a) supported ambulation, (b) use of safe power wheelchair, (c) ambulation guided by orientation cues, and (d) ambulation with GPS-based assistance. The studies were coded in terms of the objective pursued, technology used, participants involved, strategies applied to assess the technology, and outcome reported.

CONCLUSION

A variety of technology devices are available to address the mobility problems of older people with cognitive impairment or dementia. The devices' accessibility and usability differ widely. Data on their impact are still largely preliminary and new systematic research is needed.IMPLICATIONS FOR REHABILITATIONA variety of mobility problems may afflict older people with cognitive impairment or dementia and curtail their opportunities to freely move indoor or outdoor.Technology devices have been developed to (a) promote forms of supported ambulation, (b) facilitate safe use of power wheelchairs, (c) deliver orientation/navigation cues, and (d) ensure tracking and possible assistance.The technology devices differ in terms of accessibility and affordability, with some of them readily available and others at a developmental stage.Data on the effectiveness of the various technology devices in reducing the impact of the mobility problems are still largely preliminary and new systematic research is needed.

Using 3D Convolutional Neural Networks for Tactile Object Recognition with Robotic Palpation

In this paper, a novel method of active tactile perception based on 3D neural networks and a high-resolution tactile sensor installed on a robot gripper is presented. A haptic exploratory procedure based on robotic palpation is performed to get pressure images at different grasping forces that provide information not only about the external shape of the object, but also about its internal features. The gripper consists of two underactuated fingers with a tactile sensor array in the thumb. A new representation of tactile information as 3D tactile tensors is described. During a squeeze-and-release process, the pressure images read from the tactile sensor are concatenated forming a tensor that contains information about the variation of pressure matrices along with the grasping forces. These tensors are used to feed a 3D Convolutional Neural Network (3D CNN) called 3D TactNet, which is able to classify the grasped object through active interaction. Results show that 3D CNN performs better, and provide better recognition rates with a lower number of training data.

Assistive Handlebar Based on Tactile Sensors: Control Inputs and Human Factors

Tactile sensors can be used to build human-machine interfaces, for instance in isometric joysticks or handlebars. When used as input sensor device for control, questions arise related to the contact with the human, which involve ergonomic aspects. This paper focuses on the example application of driving a powered wheelchair as attendant. Since other proposals use force and torque sensors as control input variables, this paper explores the relationship between these variables and others obtained from the tactile sensor. For this purpose, a handlebar is instrumented with tactile sensors and a 6-axis force torque sensor. Several experiments are carried out with this handlebar mounted on a wheelchair and also fixed to a table. It is seen that it is possible to obtain variables well correlated with those provided by force and torque sensors. However, it is necessary to contemplate the influence of issues such as the gripping force of the human hand on the sensor or the different kinds of grasps due to different physical constitutions of humans and to the inherent random nature of the grasp. Moreover, it is seen that a first step is necessary where the contact with the hands has to stabilize, and its characteristics and settle time are obtained.