Personal Adaptive Mobility Aid (PAM-AID) for the Infirm and Elderly Blind

Gerard Lacey and Kenneth M. Dawson-Howe

ComputerScience Dept., School of Engineering, Trinity College Dublin, Dublin 2, Ireland. Gerard.Lacey @cs.tcd.ie, [email protected]

independently. This often results in their becoming bed-ridden "for their own safety". Abstract There is therefore a real and present need for a device to improve the independent mobility of People with both visual and mobility the frail visually impaired. The elderly and impairments have great difficulty using infirm blind are excluded, by virtue of their conventional mobility aids for the blind. frailty, from using the conventional mobility As a consequence they have little aids such as long canes and guide dogs. opportunity to take exercise without Consequently the elderly visual impaired are assistance from a cater. The combination heavily dependent on carets for personal of visual and mobility impairments occurs mobility. This level of carer involvementis often most often amongthe elderly. In this paper beyond the resources of a family or residential we examine the issues related to mobility care facility and the person is forced into a for the blind and pay particular attention to the needs of the elderly or frail. We sedentary lifestyle. A sedentary lifestyle overview current mobility aids and detail accelerates the degeneration of the cardio- some of the research in this area. Wethen pulmonarysystem and in addition the increased describe a robot mobility aid "PAM-AID" isolation and dependence can lead to severe that aims to provide both physical support psychological problems. In Europe over 65%of during walking and obstacle avoidance. all blind people are over 70 years of age We examine the factors relevant to the therefore this represents a serious issue. operation of PAM-AID and give an overview of its design. Finally we describe The PAM-A/Dproject aims to build a mobility the current status of the project and indicate aid for the infirm blind which will provide both its future direction. a physical support for walking and navigational intelligence. The objective is to allow users to retain their personal autonomy and take 1 Introduction independent exercise. In this research we have attempted to examine the needs of potential users and we have been aided in this by the staff The opportunity for independent mobility is a of the National Council for the Blind of Ireland major factor affecting the quality of life of all (NCBI). Initially we examine the issues people. Frailty when combined with a visual involved in mobility for the visually impaired impairment has a devastating effect on the and look at the state of the art in mobility aids ability of the elderly to move around for the blind. We then examine the unique

53 mobility and navigational needs of the elderly space in front of next stride. The length of the and infirm and identify how these affect the cane is the distance from the base of the sternum technical issues associated with constructing a to the ground, thus the blind person is given mobility aid. Wethen detail the design of the approximately one stride preview of the terrain PAM-AIDrobot and report on the progress in directly ahead. If an obstacle is detected the cane developing the prototype system. user must be able to react quickly to avoid a collision.

The limitations of the long cane are that the 2 Mobility and Navigation for the entire space through which the body moves is Visually Impaired not scanned. Of particular importance is the fact that overhanging obstacles such as the rear of parked trucks and holes in the ground cannot be Blind and visually impaired people experience detected reliably. Sophisticated use of the long difficulties in moving around dynamic cane is possible by using the sound of echoes environments. Twogeneral classes of problems from the tapping of the cane or by following occur, mobility problems and navigational walls, kerbs and other environmental features. problems. Mobility is the ability to avoid Howeverit can be very difficult for users to obstacles and movethrough a knownspace with detect slowly curving paths and thus orientation confidence while navigation is knowing where can be lost. Noises and smells from the you are, where you are going and how to get environment also play a part in helping the there. There is a certain degree of overlap visually impaired cane user move around an between these two functions, however they environment. There can however be a high represent two different ways of thinking about degree of stress associated with cane use due to the space through which the person is moving. the limited previewof the terrain and the limited In mobility it is not strictly necessary to amountof information it provides. recognize the various objects which are being avoided, their size and position is all that is required. To navigate on the other hand it is 2.2 Guide Dogs necessary to identify a sequence of landmarksto allow the person to recognize their route. The other most commonmobility aid is the Mobility aids, advance route planning using guide dog. Dogs have been used as a guide for tactile maps and occasional assistance from the blind since at least Romantimes. However sighted people afford the able-bodied blind systematic training of guide dogs did not begin person a great deal of personal freedom. Wewill until the 18th century. Guide dogs becamewide examine the currently available mobility aids spread after the first world war when the and identify howthey work in general. Wewill German army began training German Shepherd also try to identify their limitations particularly dogs to guide war veterans (Welsh & Blasch in the case of the elderly and infirm. 1987). The typical guide dog begins training at 2 years of age and has a workinglife of roughly nine years. Guide dogs cost approximately $16,000 to train and about $30 per month to maintain. Guide dogs are not suitable as a 2.1 The Long Cane mobility aid for all blind people.

By far the most commonmobility aid for the The blind person’s visual impairment must be visually impaired is the long cane. Techniques severe so as to prevent the anticipation of stops for the use of the long cane were developed by or turns before receiving this information from the Veteran’s Administration in the US during the dog. If the guide dog user could anticipate the 1960’s (Welsh & Blasch 1987). At its most such events the dog would not have the simplistic the cane is swept from left to right opportunity to put its training into practice and synchronized to the stride of the user. The without sufficient reinforcement the guide dog synchronization is such that the cane sweeps the mayno longer function effectively.

54 The training process is physically strenuous and the users must have good coordination and 2.4 Electronic Mobility Aids balance. A typical guide dog walking speed is 5 to 6 kilometers per hour therefore the user must have an active lifestyle to provide the dog with Even though the long cane is a very cheap and sufficient exercise and reinforcement. The dog reliable mobility aid it does have the drawback must be given constant correction if it disobeys a that all the space through which the body travels commandor does not perform correctly except is not scanned. This leaves the upper body in the case of intelligent disobedience. This is particularly vulnerable to collisions with where the dog disobeys the commandif it would overhangingobstacles or with other people. This cause danger to the person and is particularly deficit of the long cane has prompted much important for crossing roads. research into electronic mobility aids. Several reviews have been done such as (Nye & Bliss 1970), (Boyce 1991) which contains a good 2.3 Walking Aids overview and (Welsh & Blasch 1987) which reviews mobility devices in depth.

There are a variety of mobility aids for those Personal electronic mobility aids are not used by with a balance or weight bearing problem. the majority of blind users, primarily due to the Although there are many different models of excessive cost, poor user interfaces and poor walking frames they fall into three distinct cosmetic design. If a mobility aid is to be categories, conventional walking frames, successful the device must provide the user with reciprocal walking frames and rollators. a great deal more information about the Conventional walking frames, often called environment than the long cane. It must also "Zimmer" frames, are designed to provide a present this information in a manner that does larger base of support to a person with lower not occlude the remaining senses. For example limb weakness. Most are adjustable in height requiring the user to wear a pair of headphones and some models can be folded away. The would exclude noises from the environment. The frame is used by lifting, placing it forwards, device must be affordable, robust and not draw bearing weight through the grips and taking two undueattention to the user’s blindness. This is a strides to the center of the frame. Particular difficult specification to achieve as emphasized attention must be paid to the height of the frame by the continued preference for long canes and to ensure good posture during walking. guide dogs by the majority of blind people. Reciprocal Frames are similar to the standard Manyinterfaces to mobility devices have been "Zimmer" frames except that the frame is proposed including stereo headphones, vibrating hinged on either side allowing the sides of the pads on the forehead, chest or back, however frame to be moved alternately. They are none have been very popular. A mobility device designed to accommodate a normal walking currently under development in the European pattern with opposite arm and leg moving Project "Autonomous System for Mobility, together. They are also used in domestic homes Orientation, Navigation and Communication where space is confined. (ASMONC)"proposes to use an instrumented Rollators are walking frames with wheels handle to give the user directional information. attached, there are manydifferent configurations The ASMONCsystem is primarily designed for of the base available. Rollators are used where use in outdoor urban environments. balance is the major problem rather than weight bearing. They are also used where upper limb strength is not sufficient to lift the walking 3 Related Work in Assistive frame on a regular basis. Rollators are often Technology attached with brakes to prevent "run away", baskets for carrying shopping and seats in case of tiredness. A great deal of attention is paid to There are a wide range of projects aimed at the cosmetic design of Rollators as they are often improving the mobility of persons using used out of doors. wheelchairs. European projects such as OMNI

55 (Hoyer et al. 1995), SCENARIO(Katevas et Signal processing techniques have been 1995.) and MANIAS(Kwee et a1.1988) focus developed to use cheap sensors for mobile robot improvingthe operation of conventional electric navigation. Leonard in (Leonard & Durrant- wheelchairs or extending their functionality. Whyte 1993) showed that sonar, despite having OMNIis building a very high maneuverability somelimitations, can be used to reliably detect wheelchair for confined domestic and office features such a corners and walls etc. using a- environments. SCENARIOis improving on priori feature maps. This allows the robot to conventional wheelchairs by the introduction of successfully navigate around a complex navigational intelligence, the user is able to environment. choose manual control or fully autonomous navigation. MANUSis a wheelchair fitted with The control of mobile robots has undergone the a robot arm to the wheelchair to facilitate most radical change in the recent past. Systems manipulation of objects by persons with with multiple competing behaviors have proven quadriplegia. US projects such as NavChair and to be successful in dynamic environments DeVARhave also investigated the integration of (Brooks 1986). The inter-relationship of these navigational intelligence onto wheelchairs. behaviors can perform tasks such as hall Other projects are attempting to replace following etc. However in some cases several functionality lost to people whoare bed ridden. contradictory behaviors may be invoked The MOVAID-URMADproject (Guglielmelli et simultaneously and arbitration is required. The a1.1994) and WALKY(Neveryd & Blomsjo arbitration can be a fixed hierarchy as in 1995) are projects that aim to assist the (Brooks 1986) or by inter-behavioral bidding bedridden person be as independent as possible in (Sahota 1994) or by a variety of other by performing commondaily tasks remotely schemes. A fixed hierarchy can be quite brittle from their bed by meansof a mobile robot fitted especially when the robot is tested in an with an arm. environmentdifferent to the one in which it was developed.

Of particular relevance to our work are 4 Related Work in Robotics techniques for shared control between robot and user. This research is commonin tele-operated Mobile robotics and signal processing research robots which are used for bombdisposal or other is undergoing a period of rapid advancement hazardous environments. Borenstein in due to a numberof factors, not least due to the (Borenstein & Koren 1990) describes a system availability of cheap, portable and powerful of tele-autonomous guidance which allows for computing. This has brought the possibility of the gradual sharing of control between the user viable applications for mobile robot technology and the robot for obstacle avoidance. ever closer. In (Horswill 1993) it was shown that a reliable robot guide could be constructed using only visually sensed data. This robot 5 The Visually Impaired Elderly guided people around the floor of a building giving a running commentary on the Vision loss in later life can be crippling surroundings. He also noted that when movedto particularly for those in long term care. a new environment the robot detected false Psychological problems associated with lack of obstacles due to shadowsand color changes. In motivation and lessened expectations make (Garibotto, Ilic & Masciangelo 1994) a robot mobility training difficult (Welsh & Blasch guide for public spaces such as theaters and 1987). This difficulty is compoundedby memory museumsis described. The authors reported that loss, the need for a support during walking and the robot guide required human intervention an increased fear of falling. If the long cane is approximately every 10 minutes. While these used both for support and mobility it can be applications have experienced some minor quite heavy and lead to rapid fatigue. Using a difficulties they show the potential for long cane and a walking aid in tandem would harnessing this technology. result in both hands being occupied and thus an increased fear of falling. In long term care

56 facilities practical concerns discourage 5.2 Quality of Life of the Elderly independent mobility for the aged visually impaired as long canes pose a risk of tripping the other residents. In (Roweet al. 1991) Chonand Sugar conducted a survey of the perceptions of residents and The difficulties involved in providing the carers as to the determinants of quality of life. elderly visually impaired with independent The residents chose morale and social-emotional locomotion results in their being confined to environment as the key determinants of quality their beds or to chairs for their ownsafety. In of life. The carers generally chose the quality of this sedentary state a rapid deterioration in the care and the morale as the key determinants of cardio-pulmonary systems occurs. The link quality of life. The conclusion drawn was that a between inactivity and the deterioration of tension existed between the needs of the health in older persons has been noted in various residents and the limitations of the institution studies (Bonner 1969),(Brunner 1970). and an expansion of resident choice in as many psychological effect of increased dependence areas as practicable was recommended.Quality also has an adverse effect on the persons quality of life is a very difficult thing to measure. of life. Even limited independent mobility can Measures that are currently used often only greatly increase the quality of life of the elderly relate to the medical condition of the person. person. 5.1 User Profile The target user group Quality of life can be seen to be a complex for PAM-AIDis the visually impaired whoalso relationship of physical activity and social require physical support while walking. A contacts as well as a purely medicaldefinition. British survey (Richards 1993) of blind library users showedthat 63%of blind persons are aged over 70. The ratio of females to males among 5.3 Technology and the Elderly the blind was 2:1 and the ratio of blind to partially sighted was also 2:1. Also notable from Firnie (Rowe et al. 1991) reviews assistive the survey was a preference for spoken rather devices for the elderly and their affect on their than Braille material particularly in the 70+ age quality of life. He focuses attention on the need group. to retain the ability of the individual to make choices and on the need to pursue the real A 1986 survey of the 1.5 million residents of problems as he describes them of falls, US residential care facilities (Ficke 1991) incontinence and cognitive dysfunction. In the showedthat 70.7% of persons over 65 years had design of technology for the elderly Nicolle et. a mobility impairment and 22.7% had a visual al. (Poulson, Nicolle & Richardson 1995) advise impairment. Amongthose aged 85 and older a broadly based approach to the specification of the proportion of visually impaired increased to new technology involving carers, observation of 30%. potential users as well as user interviews.

According to the European Blind Union there Wellford in (Birren, J. 1959) reports that the are 4 million people in the EU who can be speed and accuracy of elderly people for simple described as being visually impaired (persons motor tasks is quite good but this deteriorates with residual vision below 6/18). Many rapidly as the complexity increases. This is population projections say that, if current particularly true if there is a extended time population trends continue, as manyas 25%of between the stimulus and the taking of the Europeans will be aged 65+ by the year 2020, respondingaction. This result is attributed to a the biggest increase will be in those aged 75+. poor short term memory. In general where This increase will be most notable in the possible the elderly shift concentration from Netherlands, Germanyand Denmarkwhere it is speed to accuracy in an attempt to maximizethe projected that by 2040, the numberof over 65’s use of limited physical resources. This can often will be approaching 45%of the number of 15-64 result in lower error rates than younger people year olds in society. for simple motor tasks.

Kay in (Birren, J. 1959) examines learning and the effects of aging. Short term memoryis very

57 dependent on the speed of perception and thus be fitted with a moduleto allow it navigate from deterioration in perception skills will produce a point to point in the building, in a nursing home consequent deterioration in short term memory. it could lead the person from their bedroomto Learning in older people consists of the the dining room. Other enhancements proposed modification of earlier experiences as opposedto include a wide variety of user interface learning from new stimuli. This consists of a configurations tailored to suit the individual process of adapting the previous routine to the needs and preferences of the user. In particular new task and features the continuous repetition adaptations to cope with hearing impairment of small errors. and arthritic complaints will be considered.

The major factor in learning is motivation. In The safety of the device is of major concern to the elderly motivation for learning is much both the carers and the users themselves. The reduced as the acquisition of a newskill maynot most important factor in the design is the seen to be worththe effort given the limited life detection of descending stairs. In the words of expectancy. Karlsson in (Karlsson 1995) notes one mobility expert "If the device fails to detect that usability or "perceived ease of use" is not descending stairs it will be useless". PAM-AID the limiting factor in the adoption of new must be extremely responsive to user input i.e. technology by elderly people. She shows that not drag the users after it or exert any force on "perceived usefulness" is the prime factor in the them which might upset their balance. adoption of a new technology as it is directly related to the users motivation. Perceived usefulness is influenced by information and is 6.1 PAM-AIDRapid Prototype sustained by the evaluation of "service quality" parameters. Perceived ease of use on the other Our work to date has been concerned with the hand influences the adoption of new sub-systems construction of the mobile robot base which is technology and is in turn influenced by currently being used as the prototype for PAM- hardware and software design, user experiences AID. Three types of sensor are used to provide and by training and support. Introducing new information on the environment : sonar, infra- technology into the domestic area affects that red proximity sensors and bumpers switches. environment and this must be considered when The data gathered is sufficient for obstacle assessing the design of the system. avoidance and is simple enough to allow rapid processing. This fast reaction time ensures reliable obstacle avoidance. 6 Personal Adaptive Mobility Aid Sensor data is processed to provide reactive (PAM-AID) obstacle avoidance. The reactive control system is based on a subsumption architecture (Brooks Weaim to develop an robot mobility aid which 1986). The robot base controller is connected to will be a primary mobility aid to the aged or the master P.C. via a serial link. The PC infirm visually impaired for use in the homeor contains a text-to-speech card and performs the in a residential care facility. The robot guide at sensor processing and control. its most simplistic will provide obstacle avoidance to a visually impaired person. This will be achieved by a combination of warning 6.2 Current Status messages and direction control provided by PAM-AID. The control strategy aims to As a primary mobility aid PAM-AIDmust combinethe control input of the user with the address the needs of the users by providing both sensor information to provide a safe path. a support for walking and a mobility aid. To ensure user confidence in what is effectively "a Weaim to keep the technologies as simple and rollator with a mind of its own" a fail safe modular as possible to maintain a low overall strategy is incorporated into the operation of the cost and to allow for tailoring the systemto meet base unit. If the robot gets "confused" by the individuals needs. For example PAM-AIDcould sensor input or the user attempts to enter a

58 region deemeddangerous by the robot the robot also has the added advantage of safety as it stops. makes possible the detection of the user stumbling by attending to sudden increases in 6.2.1 User Interface the downward force. The aim of the control systems research is a shared control in the The feedback to the user comes in the form of manner of guide dog users where the user will proprioceptive feedback through the frame and be unaware of the scene complexity or of the speech feedback from the on-board computer. subtle maneuvering of the robot. A guide dog The joystick interface is limited in several user communicateswith the dog via a series of respects due to the fact that it only indicates simple spoken commandssuch as "forward", position, ideally the user could indicate both "right", "left" ,"stop", "steady" to slow the dog direction and speed via a force controlled input and "hup-hup" to speed up. Whenboth dog and device. This type of user input device is owner are used to an area more complex currently under development. instructions can also be used such as heading to particular locations. Currently we are extracting these commandsfrom a joystick input, soon this 6.2.2 Control System will be replaced by the force sensing interface and ultimately we hope to compliment this with The control system determines a great deal a simple speech based interface. about the users experience of the robot and several options are under development. One option involves complete directional control by the user with the robot only providing direction 7 Future work assistance via speech feedback and stopping before dangerous situations occur. Control can be swapped between the user and the robot by To date the robot has been tested by graduate allowing the robot to control the direction for students as it is not sufficiently well developed fixed lengths of time. This "bang-bang" control for field trials. The descending stairs detection is signaled by the user placing and holding the system is currently being developed and remains joystick in "reverse" during a dialogue with the to be integrated, a force sensing handrail system robot. is also under development. All of these subsystems will be integrated into the overall The main issue in control is that unlike a control strategy before the first field trials which conventional mobile robot or a robot wheel chair are scheduled for early 1997. the user is a separate entity. This presents its own individual set of problems in that users actions must be sensed accurately. Currently this 8 Conclusions requires the users to indicate via the joystick their intended direction. The motion of the robot, particularly when moving from rest or This workis seen as part of a long term effort to initiating a turn affects user hand position apply Artificial Intelligence and Robot relative to the robot. Thus an element of Technology to the needs of the wider "debouncing’is required on the joystick input. community. We have chosen a well focused The robot also must be prevented from reversing project such as PAM-AIDas it represents both a over the user or performingvery tight turns. concrete need and a significant challenge. The needs of the infirm blind and visually impaired In (Borenstein & Koren 1990) a system for are quite different from those of the able-bodied shared control between user and robot in tele- blind. This manifests itself in the need to operated robots is described. The user indicated combine both a walking support and a mobility direction via a joystick and speed via a foot device. Weare in the early stages of this work pedal. Currently we are developing a force and are concentrating on developing the user sensing handrail for the PAM-AIDdevice which interface and control systems required to provide will allow us to sense both the direction and a reliable mobility aid in a dynamic intensity of the forces applied by the users. It environment. We aim to develop a modular

59 robot design in which complex tasks and user interfaces can be customized to meet the needs of individual users.

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