An Extension of Spatial and Tactile Perception based on Haptics

Alejandro Rafael Garcia Ramirez

Depto. Engenharia de Computação

Universidade do Vale de Itajaí

Santa Catarina, Brazil

ramirez@univali.br

Renato F. Livramento da Silva

Depto. de Arquitetura e Urbanismo

Universidade Federal

Santa Catarina, Brazil.

fonsilva2@hotmail.com

Milton José Cinelli

Depto. de Design,

Universidade do Estado

Santa Catarina. Brazil.

dfi2mjc@joinville.udesc.br

Abstract—This paper describes the assistive technology device called ELC (Electronic Long Cane), which was developed as a mobility aid for blind or visual impaired people. This approach comprises an ergonomic design along with an embedded electronics inside the grip of a traditional long cane which, by mean of haptics, spreads human spatial and tactile perception, so improving human locomotion. Qualitative results are presented and discussed.

Keywords— Assistive technology, design, haptics, embedded electronics, visual impaired.

I. INTRODUCTION

Blind and visual impaired people face several accessibility and mobility problems in everyday life. Some tasks and situations can have physical constrains sometimes impossible to overcome for them [1]. Those difficulties are related to the lack of autonomy and information that could help them to avoid obstacles and identify alternative ways to reach the desired destination. They can be overcome by adapting the surrounding environment or improving the ability to sense and recognizes it [2].

In general, urban accidents are influenced by a lack of a right signalization or by a chance and some related causes are: public phones, mailboxes, poles, dump-carts and twigs of trees [3].

In an earlier work [4], it was observed that traditional long cane, widely used by blind and visual impaired people, did not detect all the physical barriers above the waistline. The authors developed a solution to enhance the primary mobility for the vision impaired, using a multi-element ultrasonic sensor for collecting spatial data, which have been processed in order to estimate surrounding features and provide an assessment of potential hazards, based on multiple stimulus tactile user-interface.

In our paper, to prevent a possible hazardous collision, a simpler electronic complement was added to the traditional long cane based on haptics [5]. The electronics, embedded on the grip, can detect obstacles above the waistline in order to give a tactile feedback, through a vibration inside the cane. This tactile reply becomes more frequent meanwhile the user reaches the obstacle. The integrated hardware-ergonomic

solution, in spite of simplicity, gives a new esthetical concept to improve mobility, by signalizing the relevant surrounding features above the user waist, so, contributing to a safer locomotion.

This work comprises six different sections. Section 2 addressed the theory that supports this study. Section 3 describes the developed ergonomic and electronic design process and also, the new cane is presented. In section 4 are discussed the experimental results obtained through several tests performed in Florianopolis down town using the device. Section 5 presents the conclusions and the future research. At the last section, 6, bibliographic references are listed.

II. HAPTICS

Haptics - a word derived from the Greek verb meaning "touch" - is a science that states the incorporation of the cybernetic sense of touch through computer interfaces [5].

Haptics technology is becoming an important tool in today's world, providing digital information about shapes and textures of a surface designed in a virtual environment, allowing people to have the exact feeling of a direct contact and becoming an increasingly important component of the so called immersive systems [6]. According to [7] this interaction becomes more real and can even let to feel the object in three dimensions, being this object a tool, a work of art or any other object.

The term “haptics” also refers to the modality of touch and the associated sensory feedback [5], like electrical impulses, sounds, temperature, among others.

The importance of haptic feedback is present in our lives all the time. But for blind people, a tactile feedback is even more important.

A. Haptics components

Most haptic systems rely on a combined visual/haptic interface. Basically, to develop a system in order to perform a ‘touch’ in a virtual environment, it should have the blocks showed in Fig. 1. Haptics interface gives a tactile feedback to the user, and the computer can return sounds and virtual information [8].

Figure 1. Components of a PC virtual system based on haptics

An example of haptic application is the three DOF robot

built by SensAble Technologies [9] which produces an interaction between the user and several objects inside a dynamic virtual environment.

The presented approach minimizes the computer block, by just using a microcontroller, and it is concerned with a real environment, instead of a virtual one.

B. Tactile feedback

From the decade of 90, researchers and companies have been invested in new technologies for human-machine interfaces approaching, in certain way, human tact sense, mainly in virtual reality environments [10]. The devices created, for touch sense emulating, were called like “touch feedback” or “tactile feedback” [8] by the literature.

Tactile feedback technologies are based on pneumatic, vibration, thermal, neural and electric stimulation, and it can be found in touch screens, video games and skin senses, for example.

According to literature, vibratory devices, like the piezoelectric actuators used in mobile phones, are common devices to produce touch sensation, because they are small, slight and cheap [11].

III. NOVEL DESIGN

This study considers that the traditional long cane detects ground irregularities and obstacles but fails to detect potential collisions above the user waistline, Fig. 2.

Figure 2. Traditional long cane limitations

To avoid that limitation a concept was developed to achieve

a better spatial perception by using an ultrasonic sensor, which detects obstacles above the waistline, and a micro-motor

actuator for the tactile feedback human interface. So the user can identify or “visualize” obstacles and reorganize the course, avoiding the collision, Fig. 3.

Figure 3. Spatial perception improvement

This sensory-actuation information alerts the presence of physical barriers above of the waist, meanwhile preserves the original functions of the traditional cane, contributing to a better perception of the surrounding space.

It should be noted that whole spatial information will be complemented through the user preserved senses. According to [1], “The cane, as the dog guides, only serves to alert the presence of some physical barriers. The space is perceived by them through its other senses like the ear, the sense of smell, and the haptics”.

A. Preliminary studies

In an earlier work, a small box embedding an electronic circuit controller was used as a complement to the traditional long cane functionality (called Electronic Cane). The system was designed to detect physical barriers, giving a tactile feedback through a vibration inside the cane, advising a potential collision. Fig. 4 illustrates a blind student of the ACIC (Santa Catarina Association for the Vision Impaired Citizen Integration) using the first device, which was built in 2003.

The device was attached to a waist belt, then, it was wired to a traditional cane, which supports the tactile feedback controller. The user should set the device position by pointing the controller just in front direction, which make this setting be user dependent.

The controller box dimensions were 8.5 x 10 x 4.5 cm and it weights 0.320 Kg.

Figure 4. First developed prototype

Meanwhile the developed device showed good results advising potential aerial collisions through the tests performed, it was clearly ergonomically uncomfortable. So, subsequent work was focused in a new layout.

B. New prototype

Fig. 5 illustrates the cane model detailed components. In this proposal, both blocks (haptic interface and controller) were embedded inside the cane.

The haptic interface comprises an ultrasonic sensor (12) (www.maxbotix.com) and a micro-motor (1), commonly found in cell phones. The controller is an Atmel AVR microcontroller (11) (www.atmel.com). A 9V battery (9) supplies the power to the embedded hardware.

Figure 5. Embedded long cane components diagram

As well as the ultrasonic sensor detects an aerial obstacle, a vibration inside the cane, advices a potential collision. The tactile feedback becomes more frequent meanwhile the user approaches to the obstacle.

It is important to remark that ultrasound wave range was chosen accordingly to cane dimensions, because it is not relevant (and could be confused) to ‘feel’ the obstacles outside the cane reach. Also, the tactile feedback was selected to preserve hearing sense, which is necessary for perception and recognition processes. So, haptic feedback acts as an extension of human senses.

ELC was evaluated together with Mobility Techniques Department experts at ACIC. The needs of blind people users were analyzed and an alternative evaluation study was carried out. So, the most suitable solution for the grip was chosen, as well as its features (dimension, texture, weights, etc).

The physical volume design as well as electronic components selection was also optimized by an engineers team. After that, the proposal was digitally modeled. A new prototype was finished in 2006, Fig. 6.

The grip large is 22 cm, with a 3 cm diameter and it weights 0.170 Kg improving the preliminary design.

ELC ergonomic design also guaranties the usual long cane functionalities in case of battery discharge.

Figure 6. New prototype

IV. EXPERIMENTS AND DISCUSSION

A set of experiments in the city of Florianópolis, Brazil, were carried out in order to analyze ELC effectiveness. It was emphasized the contribution to the availability of surrounding information in open urban spaces; in particular, it was observed the capacity of detecting hazardous obstacles above the waistline.

The study developed in [3], according to [12], assumed a descriptive character. So to perform a qualitative evaluation four methods and their associated techniques were adopted. Those were based on the data treatment focusing on users behaviors using the ELC.

At first, documentary analysis method was applied by the study of the related bibliography. Then, the exploratory visit and the tour followed methods were adopted and, finally, several structured interviews were performed by a quiz.

The exploratory visit recorded the relevant spatial features where the experiments should be later performed. Barriers were classified into three categories: physical barriers, cultural barriers and information barriers.

Qualitative measurement was made, as proposed by Ying in [12], which exposes how well the users have accomplished some objectives, previously defined for each task, without relaying on time wasted or troubles found during task execution.

Figure 7 illustrates an example of main spatial features where one of the experiments was performed. Letters A and C represents plastics garbage boxes attached in light posts, meanwhile B, D and E are public phone boxes.

Then, interviews were performed after each tour, mapping the description details and the opinion of visual impaired volunteers and the professors whom participated in all the experiment stages.

The whole process was registered by using three common techniques (e.g. annotations, audio-video recordings and photography).

Figure 7. Route: departure point, barriers and goals

Next section describes the applied tour followed methodology.

A. Tour followed

Some routes in the center of Florianopolis city were characterized and selected considering their physical characteristics and occupation commonly founded by blind people in their habitual situations. Tour followed; previously defined in [1], consist of several visits to the selected place, accompanied by blind voluntaries.

According to [13], an optimal number of users is needed to carry out experiments with functional prototypes. The authors claimed that it is a matter of logistics and depends mostly on schedule, budget, participants and available resources. They also stated that from five to twelve people is enough for to obtain a successful outcome. Then, eight volunteers were employed to carry out the tour followed experiment. The volunteers were blind man who has preserved their remaining senses, being adults aged 21 to 52 years, members of the ACIC teaching program in Orientation and Mobility, so, knowing the art of touch.

Proper use of the cane by voluntary people was observed. The tactile technique, on real time events as well as facing situations imposed by the selected spaces, especially in relation to the located physical barriers, was also observed.

As mentioned above, routes had a departure point and diverse goals to reach, Fig. 7. The volunteers must be followed during the planned activities without leading or helping by the observer. Thus, it was settled down that voluntaries had to complete several tasks based on the touch technique by using the ELC such as correctly to switch on-off the device; to correctly set the cane position; to stop the route when a tactile signal (vibration) into the grip alerts the presence of an obstacle; to identify, through exploratory touch, the shape characteristics of the physical barrier that has been

identified and to bypass the obstacle after its recognition, following the original route.

As a result of tour followed experiments some expected and occasional barriers were found, as depicted in Figure 8.

Figure 8. Examples of collisions sources: urban barriers

Table I summarizes quiz output data starting from volunteers and professors information. It concerns about the spatial information quality provided by ELC. Score scale values were: Yes-No, Positive-Negative-Undefined. From the table can be concluded that barrier detection and secure mobility was properly evaluated in all cases.

TABLE I QUIZ DATA SUMMARY

No. Question Qualitative Score

1 Accuracy, related to detecting obstacles above the waistline

Positive

2 Satisfaction related to the use of the device and their functions

Positive

3 Satisfaction related to the ergonomics design

Positive

4 Is it of ease learning?

Yes

5 Is it customisable?

Yes

6 Could the cane be used for Mobility and Orientation programs?

Yes

The experiments results, showed the effectiveness of ELC

prototype as an extension of the human spatial perception, and as a complement for the traditional touch technique.

Touch technique improvement also allowed a better accessing of the surrounding environment information, aiding the mobility process in urban spaces.

It should be remarked that interviews and quiz responses proved a good human satisfaction which emphasizes the importance and good quality of ELC project for a safer and efficient displacement in urban spaces.

V. CONCLUSIONS

Secure and autonomous locomotion represents a serious challenge for blind and visual impaired people. In this work, a

novel electronic cane, called ELC, was presented and evaluated. This approach comprises an ergonomic design along with an embedded electronics inside the grip of a traditional long cane which spreads human spatial and tactile perception.

In order to evaluate ELC functionalities the methods of documentary analysis, exploratory visit, tour followed and structured interviews, were performed.

The importance of maintaining the features and the use of the traditional long cane was verified. This result ensures transference of all prior cane knowledge, which significantly simplified its acceptance by potential users.

The evaluation of ELC prototype showed its effectiveness for detecting any kind of physical barriers located above of the imaginary waistline, so, contributing to a more effective perception of the surrounding space by blind people.

Its use, in combination with other architectonic and urban solutions, could provide an interesting complement for the mobility process of blind and visual impaired people, improving their locomotion.

Future works will consider the technological adaptations required to carry out a pilot production.

ACKNOWLEDGMENT

The authors want to thank to FINEP – Brazil Projects and Studies Financial, ACIC - Santa Catarina Association for the Vision Impaired Citizen Integration, and ITSBrasil – Brazil Institute for Assistive Technologies, for the support. Our special gratitude to Alejandro Durán Carrillo de Albornoz.

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