# Design Methodology for Soft Wearable Devices--The MOSAR Case
## 2 Design Methodology
### Phase 3: Control and Manufacturing  
If a control law must be synthesized (Step 19), the control strategy design goes hand in hand with the mathematical model in order to reduce the error between the reference and output of the system. With a defined closed-loop control law or in open-loop contexts, numerical simulations (Step 20) are performed to analyze the aforementioned theoretical behavior.  
The control interface of SWD will define the communication between patient, SWD and environment. This procedure ensures safe operation but depends on the actuation type and required precision.  
Prior to the manufacturing of a SWD, theoretical (from the mathematical model) and virtual (from the CAD model) behaviors must be assessed (Step 21). The CAD model can use the data obtained from numerical simulations to compare the virtual behavior with the theoretical one.  
Once the behavior of the SWD is validated, geometric dimensioning and tolerancing (GDT) are specified together with materials, surface finishing, tools and manufacturing processes, among other aspects, during the detail engineering design (Step 22).  
Phase 3 continues with a review of the aforementioned criteria in order to guarantee their fulfillment (Step 23). If all the requirements are met, an experimental physical model is approved and can be manufactured (Step 24). Otherwise, the design concept must be analyzed (see step 15). This cycle continues until the EPM satisfies mobility, usability and control requirements. It is highlighted that the EPM corresponds to the SWD that will be tested.  
SWD manufacturing focuses, mainly, on actuators. The SWD actuation could be done by fluid pressurization or cables. Conventionally for fluid pressurization, pneumatic actuation has been used for inflatable structures, pneumatic artificial muscles (PAM) and fluid elastomer actuators (FEA) which also used hydraulic energy [30]. Regarding cable actuation, the designs have been diversified with dielectric elastomer actuators (DEA), electro active polymers (EAP), shape memory alloys (SMA) or tendon and muscle wires [38].  
Materials selection is crucial to obtain the desired actuators trajectories since actuators represent the core component for driving the SWD. For both types of actuation (fluids or cables), the materials selection include polymers, fabrics, composites, shape memory polymers (SMP), silicone, neoprene, elastomers and thermoplastic polyurethane (TPU) [39].  
Additive manufacturing as 3D printing, SLT techniques such as continuous liquid interface production (CLIP) or digital projection lithography (DPL) are mainly used in SWD fabrication [23]. Other processes include shape deposition modeling (SDM) [40], fused deposition modeling (FDM) [41], laser sintering, direct ink writing, inkjet printing, inverse flow injection, bonding, thin film, inclusions or reinforcement. Detailed information concerning SWD manufacturing techniques can be consulted in Reference [42].  
For example, in the pneumatic actuators' fabrication, FEA includes 3D printing molds and a casting process using elastomer materials followed by air extraction under vacuum conditions and the use of ovens to accelerate the curing process [43]. Reported FEA designs include elastomer winding for fiber reinforcements to enhance support [10]. PAM actuators are commercially available and soft inflatable TPU bladders are cut with laser, sealed with heat and then sewn [44].