1. ACQUISITION & ANALYSIS OF CUSTOMISED POSTURAL SUPPORT SYSTEMS Posture & Mobility Group National Training Event 16 th April 2009 Lorna Tasker MEng MSc Pre-registrant Clinical Scientist, Rehabilitation Engineering Unit, Medical Physics & Clinical Engineering, Morriston Hospital, Swansea

2. Customised Postural Support Systems  Approximately 20% of wheelchair systems  Shape is taken directly from the client  To accommodate  To correct

3. Problem  Insufficient knowledge and scientific evaluation of these postural support shapes  Shape information is not retained  No comparable measurement or outcome data  Customised seating systems are:  Expensive  Labour-intensive  Require highly skilled professionals  Not reproducible

4. Digital Seating Service  Microscan 3D laser scanner  CAD/CAM software  CNC machine  More affordable  Research opportunities

5. Aims  Develop a technique for 3D shape data collection and analysis of custom seating systems  Understanding of human shape of individuals with complex disabilities  To influence fabrication techniques  Investigate two laser scanners  Research question: Can 50% of customised support systems be represented (and manufactured) using standardised geometric shapes that are within ±10mm from the actual shape?

6. Methodology: Equipment  Equipment:  Faro Scan Arm- high-cost £100,000 Accuracy: ±61µm  Microscan-low-cost £15,000 Accuracy: ±100µm

7. Methodology: Shapes (25 total) Swansea (SW)North Wales (NW)Chailey Heritage Services (CH) FARO laser scans Microscan laser scans

8. Methodology: Scanner comparison  10 shapes compared:  Faro scans=Gold standard/reference  Microscan =test  Using Geomagic Qualify software-  3D shape information was overlaid and compared to produce 3D comparison/deviation results  Results validated the use of the Microscan for research purposes and clinical work in special seating

9. Results: Scanner comparison

10. Results: Bounding Box Sizes  Simple analysis- use global feature e.g. area or volume  Bounding box sizes  Minimum and maximum point in each direction  Depth X= 296-559mm  Height Y=133-321mm  Width Z= 305-609mm  Inform manufacturing techniques Y X Z X

11. Methodology: Shape analysis- Geometric representation  Represent the shape volume using columns rods- reduced the variables for analysis to take place  Shape function- describes the frequency of column heights

12. Results: Column representation

13. Results: Proposed manufacturing technique  Geometric representation of contours provides an alternative, low-cost manufacturing method  Valuable information which can specify the shape of the seat  Shape histograms provides the number of components (columns) required

14. Demonstration

15. Results: Proposed manufacturing technique

16.  Data confirms that > 50% of customised support systems can be represented (and manufactured) using standardised geometric shapes  Areas which exceed ±10mm tolerance  Statistical measures used to highlight these areas

17. DATABASE? -MATCH SHAPES LOW-COST GEOGRAPHICALLY CENTRAL ON-SITE -FASTER TURN AROUND TIME FOR CLIENT THE BIG PICTURE...

18. Summary  Developed shape acquisition and analysis processes to advance the knowledge of individuals’ shapes with complex disabilities  Results confirmed the use of the lower cost laser scanner  Routine shape capturing method of clinical work-eliminate plaster casting  Potential manufacturing technique explored by the definition and use of geometric shapes

19. Thank you Acknowledgements Acknowledgements:  Posture & Mobility Group (PMG) for funding  Nigel Shapcott, Head of Rehabilitation Engineering, Swansea  Staff at Rehab Engineering, Swansea  National Leadership and Innovation Agency For Healthcare (NLIAH) and Welsh Assembly Government for funding my postgraduate degree  Digital Design Partnership for 3D scanning/comparison services  Paul Marl (North Wales Rehabilitation Engineering Unit) and Dr Donna Cowan (Chailey Clinical Services, East Sussex) for supplying plaster casts.  ALAS (Artificial Limb and Appliance Service), Cardiff

20. Methodology: Column representation  Using raw point data  Java program designed to provide heights of columns Z X

21. Results: Shape Analysis 10 x10mm

22. Results: Shape Analysis 50 x 50mm

23. Scanner comparison SpecificationFaro ScanArmMicroscan Company details FARO Technologies Inc., Florida, USA Immersion Corp., San Jose, CA, USA Degrees of Freedom76 Resolution ±61µm±100µm Accuracy ±61µm±100µm Weight9.5kg7kg Speed19,200 points per second Up to 28,000 points per second Size200mm square150mm square Workspace2.8m spherical volume 1. 675m spherical volume Laser type Laser type 660nm, CDRH Class II/IEC Class 2M Laser type 660nm, 1mW Cost£100,000 (including £20,000 for software) £15,000

24. Results: Use of statistical measures Average column height Standard deviation

25. Results: Scanner comparison  Chailey Shape ( ±0.5mm)

26. Results: Scanner comparison  Chailey shape ( ±1.0mm)

27. Results: Testing ±10mm tolerance  41.2% > ±10mm @ 20x20 resolution  31.3% > ±10mm @ 10 x10 resolution

28. Results: Generic Shape Analysis  Exploratory data analysis  Pattern-recognition  Gaussian kernel was used to ‘smooth’ the histograms  Tested potential groupings  Demonstrated potential use of cluster analysis Height (mm) Probability Density