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Products / Services   >   OVI walker


Academic project  

 2018 - 2019

An special academic project in collaboration with Maria Cano foundation and the National Learning Service, whose goal was to redesign a walker for children with cerebral palsy, specifically, those with Gross motor function classification system level III (GMFCS III); one of the most physically disabled groups with this medical condition. This was a 18-moths project with a 7-members team.

The project was initially dived into 3 stages: Research, design & prototyping and testing.


Stage 1

In this stage our aim was to understand problems and needs of GMFCS III children , from their perspective but also from physiotherapists, physiatrists, orthopedists and caregivers perspective. to gather this information in-depth interviews, secondary research, contextual interviews and participant observation were implemented. I designed and conducted two expert interviews, 4 in-depth user interviews with CP children and their parents, and in secondary research I was in charge of understanding the normal gate vs pathological gate in CP children and their pathological postures.

We synthesize all raw qualitative data from primary research initially through a clustering exercise and then put it into a (huge) research wall to clear up the analysis categories; on the other hand, the State of the art data was broken down into variables regarding the physical features of the then-available walkers (e.g. weight, dimensions, number of accessories). Finally, the variables on the charts were crisscrossed with the analysis categories found on step 1. An example of this is, we found that the category “walkers appearance and customization encourage incorporation and easy adaptation by children” was related to “number of accessories” and “number of frame colors” variables.

This gave us the main insights translated into walker features, with this information we built the Product design specifications chart as the foundation for stage 2. All the information from primary and secondary research was synthesized by our team on a illustrated 100-pages report


Photo. walkers analysis for the stage 1 report showing some of the variables analysed

The main insights pointed out that, in addition to the ideal physical features and measurements, the walker had to be customizable and stimulate an emotional connection with children. To enable this, we decided to create a videogame linked to the walker through sensors which could gather data about child´s performance when using the walker and this data will influence their performance on the videogame but also could be storage and analyzed for physiotherapy follow-up.

Stage 2

The team was split to design an prototype the features of the walker: frame, accessories, sensors, app (videogame). I was assigned all the accessories (handle, lumbopelvic and forearms support). 


Handle - design and prototyping

For the ergonomic handle I divided the design process into 5 steps: User needs review, State of the art review, Sizing, Shape and Assembly to frame.

On the first step I searched photos and videos of children with the typical forearms, fingers and thumb conditions of GMFS III which are:

  • Forearm pronation

  • Thumb condition type IV (flexed palm and finger joints + cortical thumb)

The main conclusion was: their most comfortable grip shape is spherical not cylindrical like the one in most walkers. 

For step II, searched videos on the internet and the ones from observation (Stage I) to evaluate the overall posture of the child with the then-available handles. Later, I reviewed 10 videos of different walkers noticing wrist ,elbow and shoulders posture during the gate. those videos confirmed my conclusion from step I.


Footage. children with cerebral palsy using their walkers

For sizing, I started using ergonomics charts, chose a 4.8 cm diameter grip for testing which was the average measure for 6-12 years old children (our main group). The testing was done with a 9-years-old boy with cerebral palsy. He ranked how he felt griping this 4.8 cm grip versus his walker grip (5 cm) ,the larger grip gave him most comfort.

With the previous information I designed the surface of the handle using as foundation a cylindrical shape with a spherical end, this shape became more fluid with strategic setoffs and anti-split surfaces.

I initially drew the overall shape then sculped it using Clay and finally scanned it with a 3D scan to create a digital model which I did on a CAD software (PTC Creo parametric)

For the assembly, a simple button and spring mechanism inside the walker´s frame was a chosen solution but

to reduce costs it was replaced by a screw assembly.


Final 3D prototype

Lumbopelvic support - design

The steps for this accessory were similar to the ones for the handle: User needs review, State of the art review,  Materials, Formal design.

For the first step, I considered 5 physical abnormal conditions during the gate: abnormal hip rotation, forward leaning,  off-center gate,  weak lower limbs and excessive leg abduction. This conditions were fully study in the context of pathological gate .Another aspect I reviewed during this step was the physical measurements which I obtained crisscrossing data from national ergonomics charts and Maria Cano Foundation´s patients database into an Excel file. The data I took into account was height, pelvis width and pelvis height.

For the state of the art review I crisscrossed physical conditions with the current state of the art on a chart to understand how these had been solved with accessories. I found that lumbar support and belts are used for less disabled children and the full-harness is the one used for children with all the previously mentioned gate conditions.


Photo. accesories analysis chart

The materials reviewed were from existing walker accessories and commercial back supports for chairs and sofas. With the previously gathered information, I decided to design a modular accessory which would allow me to add or remove parts according to children´s disability level. This design required 7 assembly mechanisms.  I sketched several proposals for each one of them which were then talked over with the Frame design team.

I brought ,together, chosen mechanisms into the final design which was 3D prototyped using a CAD software (CREO parametric). The lumbopelvic support had 5 pieces and 3 levels:

  • Level 1 : a C-shaped pad (adjustable in depth and width) to encourage a centered gate 

  • Level 2 :a hug-looking padded belt attaches to the pad to prevent forward leaning and hip rotation 

  • Level 3: the padded straps attach to the belt and pad to help with weak lower limbs.


With this piece aesthetic was essential ,to merge it with the frame design and to look and feel  friendly to stimulate an emotional connection with the child, that is why the belt looks like a hug given from behind as a symbol of love and safety.

Arm support - design

For the last accessory, the design steps were similar to the ones for the lumbopelvic support. On step 1, the physical conditions I considered were: inner rotation of the shoulder, forearms pronation, forward leaning, wrist flexion and swan-neck fingers.

After crisscrossing this with the state of art, I determinate the features the support had to have were: assembly to the frame, elbow height adjustment,  forearm length adjustment, trunk tilt adjustment, inner rotation of the arm adjustment and inner rotation of the wrist adjustment.

 The physical measurements considered were: height, weight, elbow-foot distance and forearm length and diameter. In this case de data used was only from Latin-American ergonomics charts because national data was unavailable. 

The design required 5 graduations linked to the physical conditions previously mentioned and child measurements, these were: wrist rotation, forearm length, elbow height, shoulders internal rotation and trunk forward tilting. For every mechanism required I sketched several proposals then analyzed them with the Frame design team.

The final design required a static analysis of the walker frame with the arms support to know the maximum force that could be applied on the arms support pad without tilting /rollover of the walker. Finally, I 3D modeled it on CREO Parametric using  middle-out design technique (special for designs with various pieces and mechanisms between them). The forearms support included 5 graduations, a  padded forearm support and ergonomic grip.

*Due to time and budget issues the project concluded after stage II with in-detail design of the frame, accesories ,videogame app and sensors testing.


Photo. forearm graduations

Conclusions and learnings

On Stage 1, qualitative data analysis was onerous at the beginning .After writing out all audios from interviews ,we highlighted relevant quotes from the transcripts which left us with a massive amount of information, we tried to categorize them in an excel chart but this way we couldn´t visualize all the information and we ended up with lots of categories that couldn´t be rewrite as meaningful insights, thus we had to start all over again using an old-fashioned On the wall method were we printed all the highlighted quotes and put similar ones into clusters, over and over again until the description of each cluster made sense and gave us insight about the problem.

Regarding our user, they were difficult to access because of their age and some communication issues caused by cerebral palsy. Looking backwards ,to include more didactic interviews where they could draw and user their imagination would have been a great way to gather deeper insights in less time.

During design we had little updated anthropometric measurements available for Latin-American children which is vital for right sizing of the product, to solve that we used anthropometric data from Maria Cano institution patients which was available for us thanks to one of the team allies.

Unfortunately, To know if the child had a better experience with this walker vs others was required a final testing on a gate lab with the physical prototype, but this phase did not occur as I previously mentioned. So I can´t ensure our solution was the right fit for the problem.

Finally some of the most important things I learnt were:

  • Team work when every member is completely compromised with the purpose of the project and fully immerse in all the information gathered gives the best results

  • In complex problems like this, doing in-depth primary and secondary research encompassing all the perspectives around the problem and then crisscrossing all that data is the key to have a global understanding of the context without getting lost on details

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