BS EN 894-4:2010 pdf free download

BS EN 894-4:2010 pdf free download.Safety of machinery – Ergonomics requirements for design of displays and control actuators Part 4: Location and arrangement of displays and control actuators.
5.1.1 Step 1.1 — Define tasks and functions
Typical operator tasks are e.g. monitoring, error detection, diagnosis of faults and performing control actions:
the following operating situations should be considered: start up, normal operation, troubleshooting, shutdown, emergency stop, etc., see EN 894-1, -2 and -3.
Task sequence and relevant information flows shall be recorded for each relevant operating situation. If two or more operators may work at the same workplace the interactions between their tasks, control actions
and information flows shall be specified to help avoid possible conflicts and improve overall safety.
5.1.2 Step 1.2— Determine the operators’ relevant physical and cognitive characteristics
The general principle as defined in EN 614-1, e.g. strength, body size, visual acuity, skills, experience and disabilities, shall be considered. Specific information on relevant physical characteristics for displays and control actuators is given in EN 894-2 and -3.
5.2 Phase 2 — Evaluation of task requirements and constraints
5.2.1 Step 2.1 — List of displays and control actuators
Types of displays and control actuators which comply with the reievant requirements of EN ö4-2 anu EN 894-3 should be compiled in a list.
Technological features and/or constraints such as for multifunctional elements, e.g. touch screens, scroll balls, remote or handheld controllers need to be assessed.
5.2.2 Step 2.2 — Determine general priorities
The task requirements for each operational situation shall be specified and prioritized taking into account safety, performance and usability goals. Task requirements include accuracy, speed, force, frequency, importance, duration of use, sensitivity to error and sequence of use, etc.
Tasks should be assigned a level of priority, i.e. primary or secondary elements as defined in 3.3 and 3.4.
These priorities are used in Phase 3 to help locate displays and control actuators, and to exclude unnecessary elements.
The activities that make up the tasks should be identified, this helps to choose the most appropriate physical arrangements, e.g. which parts of the task can be done seated, which parts of the task require communication with other operators, which parts of the task require problem solving activities. There also needs to be consideration of the operator’s action strategy in each operating situation.
The following constraints on activities shall be considered where appropriate:
a) need for direct vision over the top of a console e.g. when monitoring supplementary information;
b) need for continuous direct vision while contolling e.g. during a driving task, using a mobile machine;
c) need for indirect vision (by e.g. camera systems) while contolling;
d) need for direct vision and interaction with other people, e.g. crane operation;
e) need to use horizontal surfaces e.g. for writing, placing written material, work material, etc.
5.2.3 Step 2.3 — Define operators work postures
5.2.3.1 General
The postures that have to be adopted when using displays and control actuators need to be specified as they strongly influence where the elements can be placed. Natural (not awkward) body postures should be selected which allow a balance between avoiding excessive movement and encouraging sufficient movement to allow a range of muscles to be used. Arrangements which allow changing of posture and do not continuously stress one part of the body should be selected. EN ISO 14738 provides additional information on how to select the main working postures.
5.2.3.2 Activities in seated position
The sitting position shall be selected particularly if the following demands are made:
— a high degree of body stability:
— high accuracy requirements.
For prolonged work periods it is important to allow for changes of posture and rest periods.
5.2.3.3 ActivIties in standing position
The standing position shall be selected for carrying out activities if:
— high mobility is required:
extensive control movements are to be carried out;
— body weight is used in application of the force; and
— a large workplace is to be serviced.BS EN 894-4 pdf download.