Reverse engineering and rapid prototyping for new orthotic devices
Y.E. Tosheva, L.C.Hieub, L.P. Stefanovaa, E.Y. Toshevaa,
N.B. Zlatovb, S. Dimovb,
aInstitute of Mechanics and Biomechanics, Bulgaria
bCardiff University, UK
Aims of the study
-
To propose new personalized 3D designed elbow orthoses and new ankle-foot orthoses using reverse engineering and rapid prototyping.
-
A general reverse engineering procedure was used including: data acquisition; preprocessing, contours and surface fitting; CAD model creation.
-
Mituyoto CMM machine and Hymarc Laser Scanning system were used for scanning data acquisition.
-
Wax print models of the upper limb and ankle-foot complex were obtained, laser scanned, CAD constructed and compared with the direct scanned CAD models.
-
Different versions of new devices were manufactured using rapid prototyping.
Reverse engineering
- In this study RE was used as an up-to-date methodology for constructing 3D CAD model of physical parts (human segments) by digitizing an existing part and then using that model to reproduce the part.
- The two basic tools needed for RE, are:
- different tools “digitizing” an existing part - Coordinate Measuring Machine (CMM) or Computed tomography (CT) or MRI (Magnetic Resonance Imaging);
- CAD software (modeller).
Data Acquisition
-
Mituyoto CMM machine and Hymarc Laser Scanning System were used for scanning data acquisition.
-
Different scanning angles were used to cover the surface points representing an arm or ankle-foot complex (see Fig. 1).
-
So called “original raw scanning data” was obtained (see Fig. 2, left).
-
Pre-processing was used in order to remove the redundant point data and noises and to reconstruct the point cloud data into “optimal” data for CAD modeling called “approximate point cloud” (see Fig. 2, right).
CAD model creation and
error analysis
-
Based on the contours representing the arm geometry, surface and solid models of an arm were constructed using CAD packages UniGraphics and ProEngineer.
-
Error analysis was accomplished between the CAD model and the “approximate point cloud” extracted from the “raw scanning data” (see Fig. 3).
-
Error analysis was also accomplished between the CAD model of an arm and the “original raw scanning data”.
Laser scanning of a human upper limb aimed to design a personalized elbow orthosis
Creation of a wax model of
a human upper limb
Laser scanning of a wax model of a human upper limb aimed to design
a personalized elbow orthosis
One of the prototypes of
a new elbow orthosis
CAD model of a new elbow orthosis
using ProEngineer
FEA of the elbow orthosis CAD model
using Mentat FEA Solver
Double purpose new elbow orthosis
-
The last prototype of the elbow orthosis was specially designed for double purpose:
-
(a) to immobilize totally the elbow joint in case of trauma or disease;
-
(b) to give possibility for elbow motion (Flexion/Extension) during rehabilitation.
Conclusion
- To achieve the main goal (design and manufacturing of new personalized orthoses) two initial approaches have been used:
- (a) a human upper limb and a human ankle-foot complex were scanned in vivo using Coordinate Measuring Machine “Mitutoyo Euro Apex” and Laser Scanner “Hymare CTD;
- (b) wax models of a human upper limb and a human ankle-foot complex were obtained and after that laser scanned.
- The wax modelling approach demonstrated sufficient surface accuracy and was more comfortable for the patient due to the shorter time for the procedure than in the case of “in vivo” scanning.
-
On the base of the scanned data 3D geometrical models of a human upper limb and ankle-foot joint were created and different prototypes were designed in two steps using reverse engineering:
-
(a) pre-processing and contours/surfaces fitting (Surfacer™, CopyCAD™ and GeomagicStudio™);
-
(b) CAD model reconstruction and evaluation (UniGraphics™ and ProEngineer™).
-
The CAD models of the orthoses were analyzed using Finite Element Analysis.
-
Layer Manufacturing (Rapid Prototyping) was used to manufacture different polymers prototypes of new Elbow Orthoses and Ankle-Foot Orthoses.
-
The results show good perspectives for implementation of the new orthoses in the industry.
