For a fast and prescriptive ergonomics simulation, various CAD 3d simulation software and their modules have been developed. It is suggested that the right choice for the simulation software is dependent on the human factors requirements and complexity of the simulation that will be performed.
It is also important for the simulation software to meet proper requirements for especially HMI analysis as:
• Simulation software should have a basic library of anthropometric models or allow the user to create and customize models according to required anthropometric dimensions.
• It should obey physiological limitations for human body part movements or allow the user customize models according to these limitations.
• It should allow user to model 3D work environment, add the designed systems or products with their physical means and limitations.
• It should support maximum amount of limb and joint to move in a degree of freedom according to physiological limitations.
• It should create view of the model according to its location, posture and body part movement.
• It should create and highlight reach envelope of the model according to its location, posture and body part movement, allow the user to perform reach action within defined status, illustrate the movement for reach action if needed and support feedback for geometric output of distances, angles…etc. in the action required.
• It should allow the user to apply sitting in various positions, standing in various postures, holding, grabbing, turning, pulling, pushing…etc. actions by using the anthropometric model and the work environment and support feedback to the user about their acceptability.
• It may also be capable of simulating or animating more dynamic actions like walking, running, jumping, crouching, crawling and so on.
Most common simulation software that can perform advanced versions of most of these tasks are Ramsis, Jack, HumanCAD, AnyBody and Human Builder.
Basic standards and guidelines for human factors and ergonomics are mostly military based standards because of the needs that developed ergonomics in military based industries which are:
1. MIL-STD-1472G; this standard defines human factor requirements for anthropometry, display and console designs, maintenance and repair, facility design, hardware and equipment, elements of input and output systems.
2. MSIS NASA STD 3000; this standard mostly is interested in ergonomics requirements of work environment without the gravity.
3. MIL-HDBK-1908; this guideline explains ergonomic terms.
4. MIL-HDBK-743; is about basics of anthropometry.
5. MIL-HDBK-46855; this guideline explains ergonomic design and application methods, ergonomic tests and test evaluation methods.
6. COE-UIS; is about hardware and equipment, elements of input and output systems, direct control, menu designs, text and graphical themes.
7. WS HCI Style Guide; design concerns for head up displays and human-machine(computer) interface in weapon systems.
To apply the principles of ergonomics, one should be aware of the systemic breakdown of the design or the product; requirements of the user and tasks that will be performed by the user with the design or the product which means that there are principles in a widespread range to be applied and human factor analyst should be capable of optimizing them to the required and applicable levels. If these principles are summarized shortly:
- Designed system should allow the user to work and focus on the system in a least effected state from the outer environment.
- Quantity of displays, screens, indicators…etc. should be optimized.
- Number of steps to perform an action with the system should be optimized.
- Calibrating, relocating and rearranging of system elements should be minimized.
- System should not force the user to remember the task or performance order and should inform the user and support feedback about the next and current process.
- Default arrangements of the system should prevent the user from customizing the interface repeatedly.
- Visual or text information based feed should not prevent the user from monitoring the vital feeds by creating clutter.
- Related controls and displays should be located close to each other.
- Relation between controls and displays should be maintained according to their functional groups, forms, labels and frames in design stage.
- Unnecessary sensitivity of the controls should be avoided, cognitive and physical limits of the user should be considered.
- System should support suitable feedback for the user. Delay time due to the action and the feedback should be avoided.
- Sequential used controls should be located from left to right or bottom to top due to their order.
- Emergency controls or displays must be located at the best location for the reach and view area.
- Movement direction of the controls should be determined according to user expectations and habits. Vehicle control movements must be consistent and related to the vehicle movement.
- Control and display ratio (C/D) should not prevent the user from achieving his task.
- Displays should be located at right angle with the user normal view if possible, and must be limited to 45˚ angle minimum.