Achieving Excellence in Rehabilitation Engineering Design Process

1. Rehabilitation Engineering Design Lecture # 5 Institute of Bio-Medical Technology, LUMHS.

2. Rehabilitation Engineering Design • deliberate purposeful planning, • applied to assistive technology, • design skills of R.E engineer makes him different from other members of rehabilitation team, • Heuristics, one of the oldest design methods applied to assistive technology, • Using heuristics one can imagines that the device is completed and that the consumer is using it, • Helps to solve complex problems. Institute of Bio-Medical Technology, LUMHS.

3. Basic step in design process is to define when the problem is solved • Once it is completed R.E engineer will sit with the consumer and discuss the problem which consumer has identified to improve to working conditions. • To over come these type of problems one has huge past experience or can do brain storming. • There are two rules of brain stroming; 1) ideas should meet the need, 2) criticism of any sort is forbidden. Institute of Bio-Medical Technology, LUMHS.

4. Best idea selected after brain storming and added to the final design. Institute of Bio-Medical Technology, LUMHS.

5. Principles of Rehabilitation Engineering • R.E is multidisplinary field, • Knowledge and techniques from different disciplines must be utilized to design technological solutions, • most relevant principles depend on the particular problem being examined • For example, • principles from the fields of electronic and communication engineering are paramount when designing an environmental control system that is to be integrated with the user’s battery-powered wheelchair. • When the goal is to develop an implanted functional electrical stimulation orthosis for an upper limb impaired by spinal cord injury, • principles from neuromuscular physiology, biomechanics, biomaterials, and control systems would be the most applicable. Institute of Bio-Medical Technology, LUMHS.

6. Rehabilitation engineering is inherently design oriented. • Creative process of identifying needs and then devising an assistive device to fill those needs. • A systematic approach is essential to successfully complete a rehabilitation project. • Key elements of the design process involve the following sequential steps: analysis, synthesis, evaluation, decision, and implementation. Institute of Bio-Medical Technology, LUMHS.

7. Analysis • thinking about possible solutions, • careful analysis of the problem or need, • Rehabilitation engineers first must determine where, when, and how often the problem arises • What is the environment or the task situation? • How have others performed the task? • What are the environmental constraints (size, speed, weight, location, physical interface, etc.)? • What are the psychosocial constraints (user preferences, support of others, gadget tolerance, cognitive abilities, and limitations)? • What are the financial considerations (purchase price, rental fees, trial periods, maintenance and repair arrangements)? Institute of Bio-Medical Technology, LUMHS.

8. Answers to these questions will require diligent investigation and quantitative data such as the weight and size to be lifted, the shape and texture of the object to be manipulated, and the operational features of the desired device. An excellent endpoint of problem analysis would be a list of operational features or performance specifications that the ‘‘ideal’’ solution should possess. Institute of Bio-Medical Technology, LUMHS.

9. Problem • Develop a set of performance specifications for an electromechanical device to raise and lower the lower leg of a wheelchair user (to prevent edema). • Solution • A sample set of performance specifications about the ideal mechanism might be written as follows: • Be able to raise or lower leg in 5 s • Independently operable by the wheelchair occupant • Have an emergency stop switch • Compatible with existing wheelchair and its leg rests • Quiet operation • Entire adaptation weighs no more than five pounds Institute of Bio-Medical Technology, LUMHS.

10. Synthesis • ideas for solving the problem, • synthesis of possible solutions usually follows the analysis of the problem, • creative activity that is guided by previously learned engineering principles and supported by handbooks, design magazines, product catalogs, and consultation with other professionals, • a deeper understanding of the problem • design process includes sketches and technical descriptions of each trial solution. Institute of Bio-Medical Technology, LUMHS.

11. Evaluation • two or three most promising solutions should undergo further evaluation, • via field trials with mockups, computer simulations, and/or detailed mechanical drawings, • the end user and other stakeholders in the problem and solution should be consulted, • Experimental results from field trials should be carefully recorded, possibly on videotape, for later review. • use a quantitative comparison chart to rate how well each solution meets or exceeds the performance specifications and operational characteristics based on the analysis of the problem. Institute of Bio-Medical Technology, LUMHS.

12. Decision • After comparing the various promising solutions, more than one may appear equally satisfactory. • the final decision may be made • may involve consulting with someone else who may have encountered a similar problem. Institute of Bio-Medical Technology, LUMHS.

13. Implementation • To fabricate, fit, and install the final (or best) solution requires additional project planning that, depending on the size of the project, may range from a simple list of tasks to a complex set of scheduled activities involving many people with different skills. Institute of Bio-Medical Technology, LUMHS.

14. example • Design a power wheelchair for use by people with quadriplegia which can be used indoor and outdoor. • Gel Cell batteries for cost and durability • Servo amplifer in full H-bridge (moves chair forward and backward) • 12 V Permant magnet d.c motor provides high torque • 2 batteries in series • Oil filled sealed gear box to keep noise and maintainance down • Chromium molybdenum steel alloy for frame (high strngth) • Pneumatic tires (shock absorbtion) • Joystick (limited upper-limb function) Institute of Bio-Medical Technology, LUMHS.

15. Thanks Institute of Bio-Medical Technology, LUMHS.