Physically assistive technology and robotics

Assistive robots give support to people with disabilities by physically interacting with them. Researchers have typically examined how such robots could help people in areas such as physical therapy rehabilitation and assisting those with disabilities to perform simple tasks. Because they are rarely designed to interact with people in social contexts, the robots are seen as helpful tools by their users.

Robotic wheelchairs

Frustrated by the lack of mobility options available to disabled people, Miller and Slack described two different low-cost robotic wheelchair systems that they built with off-the-shelf components and could be used to help disabled people to avoid ob- stacles, autonomously navigate from one location to another, and maneuver through confined areas. The first wheelchair, Tin Man I, features three modes of semi- automatic operation and was positively received by potential users despite the au- thors’ reports of slow travel speeds. The second wheelchair, Tin Man II, featured similar modes of semi-automatic operation, traveled faster than its predecessor, and received positive qualitative reviews from non-disabled people [Miller and Slack, 1995]. Bourhis and Pino developed another kind of robotic wheelchair for the AVHM project based on a Robuter mobile base and gave it three operating modes: auto- matic for entering a global trajectory and a user-defined destination, assisted-manual for using wall-following and obstacle-avoiding behaviours, and manual for joystick- based control. In an evaluation which tested how well able-bodied individuals could navigate through an apartment, it was found that assisted-manual mode was easier

to use than manual mode and that a fully automatic mode of operation would be very useful for certain users who could not use joysticks very well [Bourhis and Pino, 1996].

Yanco and Gips compared two different methods of controlling a powered wheelchair, which were single-switch scanning (manual control by pressing a switch at specific times) and robotic operation with emergency stop/selection. After having able-bodied participants practice each control method, followed by the participants running a short test course using each control method, the researchers determined that the number of switch presses and the time spent scanning through movement options were both significantly lower during the robotic control runs. Participants also took less time to navigate the course in robotic control, but not significantly less. Furthermore, all participants rated robotic control as significantly better than single-switch scanning in questionnaires [Yanco and Gips, 1998]. Levine, Bell, Jaros et al described the NavChair assistive wheelchair navigation system, a prototype robotic wheelchair based on the Lancer powered wheelchair that could operate in three modes: obstacle avoidance using the minimum vector field histogram and vector force field techniques, manuevering through doorways as narrow as 32 inches 70% of the time, and wall-following [Levine et al., 1999].

Full-contact robots used in physical rehabilitation

Researchers have also designed robotic systems meant to help individuals undergoing upper-limb physical therapy after suffering from strokes. Because stroke rehabilita- tion is labour-intensive and requires one-on-one interaction between therapists and patients, robotic systems for post-stroke rehabilitation have the potential to allow each physical therapist to treat more patients and to also help patients recover from strokes more quickly. Because this is a new field of research, there are few large-scale, long-term studies of the effectiveness or feasibility of various systems. However, comprehensive literature reviews which compared different kinds of sys-

tems found that in general, robot-assisted post-stroke rehabilitative therapy can help to improve short-term and long-term control and strength of upper limbs, can help both chronic and acute stroke patients to recover motor control, and leads to greater restoration of upper-limb motor control than conventional therapy. However, the literature reviews did not find evidence that robot-assisted physical therapy leads to improvements in activities of daily living and could not determine which factors of robot-assisted therapy (e.g. type of system, number of repititions per session, frequency of therapy) most affected motor control recovery [Prange et al., 2006] [Mehrholz et al., 2008].

Burgar, Lum, Shor et al conducted a series of studies on using robot arms to assist in post-stroke physical rehabilitation. After determining that a proof- of-concept elbow-forearm manipulator could help participants in patient-controlled mirror-image therapeutic exercises, another study was conducted in which a robot manipulator-assisted pair of planar mobile arm supports known as MIME (mirror- image motion enabler) were used to help participants carry out therapeutic exercises while gathering position, force, and torque data on the patients’ movements. Be- cause this robot-aided therapy setup helped the participants to perform their exer- cises and gave objective data on the participants’ progress, a set of clinical trials were carried out over the course of two months which showed that while robot-assisted therapy using the MIME robot did not result in significantly greater improvement in upper-limb movement than conventional therapy, it did result in significantly greater improvements in shoulder and elbow mobility, which are the two areas that the robot targeted [Burgar et al., 2000]. This robot system was later updated to a design called ARCMIME which did not limit patients movements as much as MIME, in addition to being evaluated as safer, simpler, and easier to use [Mahoney et al., 2003].

Dubowsky, Genot, Godding et al developed various PAMM (Personal Aids for Mobility and Monitoring) robots based on traditional walkers and canes to help

elderly individuals in assisted living facilities. The robots were meant to help the elderly to walk and keep their balance, to monitor their health and vital signs, to guide them through their care facility as well as keep them from stumbling into obstacles if they became disoriented, and to remind them to take various medications at the appropriate times. In a series of field tests, the elderly seemed to accept using the device fairly quickly and appreciated its use as a mobility aid [Dubowsky et al., 2000]. Later, Kahn, Zygman, Rymer et al compared the effectiveness of two kinds of post-stroke physical therapy: active-assist rehabilitative training using the ARM (Assisted Rehabilitation and Measurement) Guide and unassisted, unconstrained “free reaching” training. However, with nine stroke patients in the “free reaching” group and the ten patients in the robotic active-assist group all participating in three exercise sessions per week for eight weeks, a set of single-blind evaluators could not find any significant differences in improvement between the robotic and unassisted groups; instead, the patients in both groups made great improvements in their upper-limb mobility after attending physical therapy for eight weeks [Kahn et al., 2006].