Emergence of Socially Assistive Robotics in Rehabilitation for Children with Cerebral Palsy: A Review

Abstract

Robotic assistive technology is today widely used in rehabilitation. Social assistive robotics (SAR) is one of the developing areas of research with potential advantages for areas involving elderly care, people with cognitive impairment, rehabilitation for people with physical disabilities and for educational purposes. Cerebral palsy (CP) is a common neurological disorder among children that impairs motor function and may involve cognitive function. The use of social assistive robotic technology serves as a potential approach for CP rehabilitation. The objective of this paper is to review published articles regarding SAR in rehabilitation for children with CP. Twelve published studies have been identified and will be discussed in this review paper.

Keywords

Human-robot Interaction Socially Assistive Robotic Cerebral Palsy Rehabilitation Robotic

1. Introduction

Cerebral palsy (CP) is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in children's development, primarily in the areas of body movement [1]. There are four types of CP: spastic, ataxic, dyskinetic and mixed [2]. The biggest challenge faced by children with CP are limitations in fundamental areas of humanity – mobility, communication, manipulation, orientation and cognition [2]. Since CP has no cure, treatments for CP focuses on how best to help individual maximize his or her potential to improve their quality of life [3].

1.1. Emerging technology

To date, many researchers have proposed using robotic technology for the treatment and diagnosis of various types of physical and mental disabilities [4]. As an example, a motorized wheelchair designed by Montesano [5] presents an intelligent wheelchair that is adapted for users with cognitive and physical impairments. The wheelchair has a tactile screen interface that allows the user to select arbitrary local destinations. An automatic navigation system has been incorporated in the wheelchair to drive the vehicle.

Assistive technology has been developed to replace impaired motor function; one example is orthotics devices. A previous study reported that the walking velocity of children with CP increased with the use of orthotic devices [6]. Papavasiliou [7] defined orthotics as devices that apply external force in an attempt to correct the abnormalities of body posture, both between body segments and with respect to gravity, caused primarily by spasticity.

As robotic therapy offers treatment options for CP and special devices can help children with brain injury to learn motor skills [8], human-computer interaction is now shifting to human-robot interaction (HRI). In the field of CP, three main branches of medical robotics are worth mentioning: rehabilitation robotics, assistive robotics and socially interactive robotics. Rehabilitation robotics pursue the recovery or regaining of impaired motor function, assistive robotics (AR) are intended to substitute or compensate for missing motor and sensing skills, while socially interactive robotics (SIR) are primarily involved with human behaviour through robotic companion, speech and gestures. Socially assistive robotics (SAR) is an interesting area that represents an intersection between SIR and AR [9].

1.2. Socially assistive robotics

Socially assistive robotics (SAR) is a field in HRI that focuses on assisting people through social interaction rather than physical interaction [9]. Service and assistive robotics include a broad spectrum of application areas such as office assistants, autonomous rehabilitation aids and educational robots.

SAR is a developing area of research with potential advantages. In this context, the robot acts as a social mediator that aims to assist the individual in health-related tasks such as physical exercise in both human-computer interaction (HCI) and human-robot interaction (HRI) communities. HRI is the dynamic collaboration between people and robots. Researchers and experts in HRI hail from a variety of areas including engineering and clinical and social science. Meanwhile, HCI is the study of the interaction between humans and computers [10].

2. Methods

A literature search was conducted using ISI Web of Knowledge, Google Scholar and IEEE Xplore. Keywords used in the search included humanoid, human-robot interaction, socially assistive robotic, cerebral palsy and rehabilitation robotic. All papers searched dated between November 2000 and up to 31 December 2015 were included in this literature search.

The inclusion criteria for selection were studies that used social robots, had implications for group identification or diagnosis and articles that had been peer-reviewed for journal or conference proceedings, and that were published in the English language.

3. Results

The search identified 12 journal articles that matched our inclusion criteria. The studies reviewed were summarized as presented in Table 1. For each study, the number of participants, diagnosis, age group, type of assistive social robot used, objective of the study, method of the study and main outcome measures used in the study were analysed.

Table 1.

Literature Review of Previous Related Socially Assistive Robotic Studies of Children with CP Discussion

Research works(Author, Year)	Participant			Robot	Objectives	Method	Findings
Research works(Author, Year)	No	Diagnosis	Age	Robot	Objectives	Method	Findings
VolodymyrKozyavkin, (2014)	6	CP	4–9 years old	The humanoid robot “KineTron”	• To increase the interest of a child in motor training. • The robot acts like a coach to encourage the patient in motor training.	• Two-week course of intensive neurophysiological rehabilitation. • Rehabilitation Robot was used during 5 to 7 treatment sessions of Computer Stepping Games with duration about 20 min.	The children were motivated and participate actively in the rehabilitation.
BranislavBorovac, (2014)	N/A	N/A	N/A	The humanoid robot Marko	• Robot design • Habilitation of gross motor & fine function • Motivate child	• Gross movement exercise • Fine motor by moving objects • Facial expression feedback • 2 way communication	Have not applied to clinical setting
Adriana Rios Rincon (2013)	1	CP	7 years old	Robot LEGO Mindstorm (TM) car-like.	Promoting mother-child communication during free play	• 2 sessions; first without robot (14min), 2^nd session (11min) with robot • Utterance of both mother and child measured • Child operated the robot through a switch on W/chair	• The children was being motivated and engaged in playing. • The children reacted positively towards the robot. • Direction of action was higher with robot, with mother being more responsive to child's play
M. Fridin (2011)	18	TD	4–8 years old	Humanoid robot NAO	• Development of learning algorithms for social interaction between a robot and children with CP, through interactive motor exercises • Verification and validation of clinical setup	• Single exposure (First meeting with TD child) • 3 scenario • Video measure of kinect	All but two children created positive interactions with the robot.
Luke Roberts(2012)	20	Normal human	18–23 years old	Humanoid robot “Manoi ATOI”	A system that uses a wireless arm glove input device to enable interaction to a robotic playmate during various play scenarios.	Four behaviors were programmed – • play back • dance suffle control • hand open and close • navigate robot	the system has potential, but certain aspects need to be improved before deployment with children with CP.
Suárez Mejías et al. (2013)	6	CP and brachial plexus	3 to 7 years old	Robot Toy named “URSUS”	To assist therapy in upper limb physical therapy	2 phase of program upper limb physical therapy Augmented reality training games	All children enjoyed the session
Peter Ljunglof (2011)	3	3 CP 3 TD	4–6 Years old	Toy robot “LEKBOT”	Communication board to control robot for communication and play therapy	Robot play within 20–30 minutes of free play with peerss	All enjoyed Improved play and interaction
Miyako Jones & Howard (2010)	N/A	N/A	N/A	Robotic arm Robot-piano playing playmate	To improve communication and play	Using boardmaker plus software to control robotic arm for piano play	• Have not applied to clinical setting • conceptual
PavanKanajar (2011)	N/A	N/A	N/A	Neptune	Design assistive device for CP	Direct interaction with remote control system to control Ass Devices	• Have not applied to clinical setting • Potential design system
Amy J. Brisben (2007)	6	CP	4–10 years old	CosmoBot	Upper limb physical therapy	Therapies with robot once a week for 16 weeks period.	• Used outcome measures for 3 types of matrix (ease of therapist use, child motivation, clinical outcome of technology efficacy) • All positive results
Andrew G. Brooks (2005)	N/A	N/A	N/A	Leonardo	Arm physical exercise	N/A	Have not applied to clinical setting (system development)
Catherine Plaisant (2000)	1	CP	5 years old	Toy “PETS”	• storytelling to act out emotions • Improve Motivation through play	Scenario creation through play	Improved motivation and engagement

Based on the literature review, six studies out of twelve had been clinically applied to children with CP. The remaining six were either works in progress, studies on the design or development of the robot, function of the robot and the methodology of the study, or application towards typically developing children or normal adults. The general result of the literature review indicated that social robots are potentially useful as therapeutic intervention tools for children with CP. The following discussion grouped the studies into four areas: (4.1) SAR focused on improving physical function; (4.2) SAR focused on improving social interaction via human-robot interaction and communication; (4.3) SAR focused on improving motivation; (4.4) studies on SAR usability.

3.1. SAR focused on improving physical function

All children with CP will have some degree of physical disability. As physical therapy is one of the mainstays of managing children with CP, we found that 10 of the reviewed studies used robots involving physical function, which included free play.

SAR can be used as a functional tool for aiding in the completion of physical tasks or as a therapeutic tool in the imitation of physical tasks. KineTron [11], Ursus [12] and Cosmobot [13] are robots that were used as tools in motor training activity. All three robots were used to act as a coach for encouraging participants in motor training and increasing the interest of children in therapy. The KineTron robot used in the study by Kozyavkin et al. [11] indicated that all six children with CP were motivated and participated actively in the physical exercises. Suarez and et al. [12] used a robot toy called 'Ursus' in their study to conduct upper limb physical therapy. Their results showed that all six children (a combination of children with CP and brachial plexus injury) enjoyed the session with the robotic platform when compared to conventional therapy. Most of the studies involving children with CP were of single exposure, with the exception of one study conducted by Brisben et al. [13], which repeatedly exposed the Cosmobot robot to six children with CP aged between four to six over a 16 week period. Their study employed a humanoid robot called 'Cosmobot' as a therapeutic tool in upper limb physical therapy and showed that all six children were motivated and maintained engagement during therapy.

Figure 1.

Cosmobot (left), KineTron (middle) and Pets (right)

Two studies used robots that were clinically applied to typically-developing children. Robotics Agent Coacher for CP Motor Function (RAC CP FUN) is a study that involves SAR and was designed to improve motor function and the activities of daily living for children with CP [14]. To prove the concept of the proposed system, the researchers performed an experiment wherein 18 typically-developing children met the robot for the first time and was given single exposure to the robot. This resulted in all but two children (from a total of 18 children) having positive interactions with the robot. It was also noted that three children advanced to dancing with the robot. This reflected a positive and encouraging response with regards to HRI.

Another study involving recruitments from non-CP subjects was conducted by Roberts et al. [15]. This study used a humanoid robot called 'Manoi ATOI'. The researchers coupled the concept of robot tele-operation with autonomous robot behaviour by developing a system that uses a wireless arm glove input device to enable interaction with a humanoid robot during various play scenarios. The study aimed to improve upper extremity function, similar to constraint-induced movement therapy for children with CP, by providing a motivating reason to use the affected limb. Results from testing the system with 20 human subjects, ages ranging from 18 to 32, showed that the system had potential, but that certain aspects needed to be improved prior to deployment for children with CP.

From the literature review, the criteria for a robot physical therapy system are described below:

Humanoid robot is used for repetitive physical exercise

The scenario is one-to-one and the robot and child faces one another during the interaction

The robot conducted the exercise system and provided real time feedback

The human-robot interaction was measured based on participant responses to the robot

All studies did not include physical contact between the child and the robot

Two further studies were identified that did not involve human subjects. The two papers were conceptual and considered system development and robot designs. Borovac et al. [16] designed a humanoid robot called the 'MARKO' robot to be used as a support tool for therapists with which to conduct specific therapeutic exercises that involves both gross and fine motor function. This paper was, however, still a work in progress in 2014. To date, Borovac has not translated their design to a clinical setting. In 2005, Andrew G. Brooks [17] also proposed the use of SAR for repetitive physical tasks by using a robot toy called 'Leonardo'. Again, system development has not yet proceeded to clinical settings and to date, no further advancement was found in literature search.

This raises the question of why certain conceptual and system development studies that look at the physical function of children with CP never progressed to translation studies involving physical therapy. A few hypotheses were raised as to why this was the case. These included:

The research team did not involve medical experts and therapists partnering to translate the research

The concepts or designs proved to be difficult and not clinically translatable

The SAR scenarios/modules and outcome measures were not studied carefully to produce clinical relevance

The system was not feasible for large studies

Most of the studies were of single exposure with the exception of Brisben et al.

3.2. SAR to improve social interaction (HRI and communication)

Two studies were reviewed that used robots for communication skills development and that were applied to children with CP. Robot LEGO Mindstorms (TM), a car-like robot, was used in a study by Rincon et al. [18] to promote mother-child communication during free play. The aim was to compare the reaction of the child and his/her mother during free play with and without the robot. The result showed that the child was more motivated and engaged in playing and communication with the mother in the presence of the robot. A study conducted by Ljunglof et al. [19] = used a toy robot called 'Lekbot' and involved children using a communication board for talking and playing activities. The use of Lekbot resulted in all of the three children reacting positively toward the robot and their peers using improved play and interaction skills. Some children showed an increased attention span and kept good activity engagement while using the robots.

Based on the review, both of the above-noted robots were successfully used to elicit positive social behaviours. As communication is an important factor for developing good social skills, both studies used robots with a communication component in their method and for achieving their objectives. Consequently, the robots were shown to have encouraged a change in social behaviour by developing and strengthening the children's communication skills through the creation of good joint attention. Joint attention is created here by the robots as the object of a shared focus between the children and their peers or caregiver. By solidifying this triadic interaction, the children benefitted in terms of improved communication and social skills. In addition, the robot not only generated social behaviour and participation in social interaction, but also functioned to provoke human-human interaction. The potential for extending this to augmentation therapy for children with CP shows good promise, based on these two small studies.

Two further studies were identified that explored HRI and engagement. These two studies involved no human subjects and were based on concept and design. Miyako Jones et al. [20] explored the possibility of using the “Board maker R Plus” special needs educational software to develop an interface for providing alternative access to toys. As such, a piano-playing robotic playmate was used as a device that may potentially engage children with CP into learning and communicating their emotions. A mobile robot called 'Neptune' was proposed by PavanKanajar et al. [21] in 2011, to be used for acting as a social mediator for learning activity. This robot's design and interface also provided the potential use of assistive devices via remote control, which aimed to promote social inclusion.

In summary, numerous published studies have focused on the impact of HRI between children and a robot. However, most of these studies did not exhibit any significant impact via validated outcome measures following execution of the application. As such, these studies need to be expanded in order to validate the hypothesis.

3.3. SAR to improve motivation (engagement)

Motivation and engagement is synonymous with learning. The more an individual is motivated and engaged in the learning activity, the better the learning outcome. As rehabilitation of children with CP requires extensive learning of motor, cognitive and social skills, motivating children during therapy sessions is important. A study done by Plaisant et al. [22] used a storytelling method to help children with CP in therapeutic exercises by using a robot toy called 'PETS'. The children execute physical movements to remotely control the robot and these movements are saved and demonstrated during storytelling. This pilot study involved one five-year-old child with CP and the study results showed that the child was engaged and motivated to do the physical therapy.

Most of the studies mentioned above also found motivation and engagement in their findings to be an important component. The studies that looked specifically at outcomes involving children were observed in six of the studies [11 –13, 15 –17]. Two further studies that did not involve children as subjects [19, 21] also hypothesize the use of engagement and motivation as a driving component to their robotic and system designs. However, as all but one study involved single exposure to the robots, the question of novelty arises. Will engagement be reduced after repetitive exposure? Brisben et al. [13] was the only reviewed study that featured repetitive exposure over 16 weeks. The researchers overcame this issue by creating variability and added novelty to every session.

In summary, creating the correct SAR that will promote motivation and engagement involved the following:

The robot had to be attractive to the child

The robot promoted active participation and free play

The system had a goal that pertained to therapeutic benefits

The robot must have activity variability to promote continuous engagement after repetitive sessions

The robot had to be easy to use

The robot had to have predictive behaviour

3.4. Ease of SAR use in therapy

From the review, for the device to be operational, certain requirement had to be met. These included:

Have no risk to children

Robustness

Easy to set up

Low maintenance

Low risk of technology failure

Easy trouble shooting

Wireless and long-lasting battery to last through the therapy session

Only Brisben et al. analysed ease of use of SAR during therapy. Their 16-week study reflected positive responses from the therapist using the CosmoBot.

Figure 2.

Humanoid robot NAO (left) and Manoi AT01 (right)

Figure 3.

Marko (left), piano robotic playmate (middle) and Leonardo (right)

4. Conclusion

There is evidence of the positive effects of SAR on children with CP. The reviewed studies that employed SAR to investigate the potential application of SAR for children with CP are few in number and have not been fully explored. The majority of these studies have a small sample size, were of single exposure or had only been conceptually developed.

With the aid of SAR, it is recommended that play, social interaction skills and repetitive physical therapy be combined in one study. To take full advantage of this potential, engineers and clinicians should actively engage in transferring knowledge and development from the technical arena to clinical scenarios. The noted studies that did include children subjects lacked structured, validated clinical measures; hence, to generalize outcomes may be unethical. In order to conduct clinical assessment, the designed system's architecture must meet the therapeutic objectives. Researchers need to define the number of subjects and assess the spectrum of disability amongst the sample of children with CP.

However, most of the noted studies have the potential for being used in clinical settings. Improvement and larger studies, however, must be conducted to enhance its potential in clinical practice for children with CP.

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