Trans RINA, Vol 153, Part C1, Intl J Marine Design, Jul - Dec 2011


interacted with that the object can be fully appreciated with respect to comfort and ease of use.


The Digital Human Model (DHM) provides a stepping- stone to optimising the humans' interaction with an object before it leaves the computer screen. Unfortunately the muscular control that humans have over their bodies is highly complex and difficult to model with a CAD representation, particularly one that is accessible to the Small & Medium Sized Enterprises that make up the majority of the marine industry. Even with the limitations of a DHM there are still many aspects of the HMI that can be enhanced, particularly field of view and limb range of motions to operate a systems controls.


3.1 EVALUATION USING RAMSIS The example evaluation


described is for a Rigid


Inflatable Boat (RIB) using a jockey/straddle type seat. As with the majority of DHM software the DHM may be scaled to represent the required anthropometric range of the boats


evaluating whether both short and tall humans can effectively interact with the craft in question.


3.1 (a) Advantages


One of the issues with a number of DHMs is the ability pose the figure in the correct position and have the ability for them to interact with the CAD model of the vehicle. As RAMSIS is designed specifically for use in an automobile the posture control allows the DHM to co- locate its points-of-contact (i.e. hands, feet, etc) with the required cockpit components (i.e. steering wheel, gear lever, seat etc.). RAMSIS also provides the ability to locate the seat in the optimum position for the control of the vehicle and identify the range


adjustment to ensure the vehicle fits the anthropometry of the


user population. From the seating identified the output RAMSIS system allows 3.1 (b) Limitations


Although there are similarities between the driver and coxswain positions in cars and boats there are also many differences. Some of these limitations are relatively small and account may be easily taken of them in the design process. But, some of them are significantly different include:


and need further consideration; examples


 The RAMSIS DHM does not easily sit correctly on a jockey/straddle style seat


 The standard RAMSIS DHM does not wear bulky protective clothing,


which is a requirement maritime operations, particularly in open craft. for for


deficiencies to be identified in vision and reach envelopes that may subsequently be modified.


of seat/control position


users, e.g. 5th to 95th percentile, thus


 The RAMSIS DHM doesn't wear equipment that is typically worn by the operators of utility craft.


3.2 MARINE DHM REQUIREMENTS


For marine applications, it is essential that the DHM is, or can be appropriate clothed in protective clothing (e.g. waterproof and


wearing the equipment required for the tasks being undertaken (e.g. lifejacket, communications system). This equipment results in two issues:


providing thermal insulation) and safety


bulky clothing and


 Reduced mobility that restricts limb range of motion and alters the ability to sit normally on seats.


 Increases the overall size envelope of the individual thus increasing the space requirement for ingress and egress.


Both of these issues have an impact on safety and performance. The restricted range of motion means that system controls located for use by an individual dressed in 'casual' clothes are potentially out of reach, or are difficult to reach.


Similarly, it may be easy of the


casually dressed individual to move around the craft but when wearing protective clothing and equipment their movement


around the craft can become impaired.


Therefore the location of system controls and space allocation must be designed with account being taken of the occupants restricted range of motion/mobility and their greater size.


4. CONCLUSIONS


The use of DHMs within the marine CAD design process provides a great advantage in optimising the ergonomic aspects of the craft. The transfer of technology from the automotive sector, e.g. RAMSIS software, provides an effective introduction of how ergonomic tools may be used within the design process. The evaluation of RAMSIS demonstrated that for circumstances similar to those experienced in automotive transport the software could be successfully used. Where the operation of a marine craft seating and


required the use of non-automotive style the wearing of specific clothing and


equipment then the evaluated version of RAMIS was found to have limitations that need to be overcome.


It should also be noted that industry are Small Enterprises, and may often


the majority of the boat be


described as cottage industries. Such organisations are unlikely to be able to afford the cost of software programs such as RAMSIS, and therefore the proliferation of its use within the sector is unlikely. Imbedded in this cost is the time required to learn how to use the software and maintain the required skill/competence to use it when required. Again for a small organisation this will be difficult to achieve.


equipment,


C-36


©2011: The Royal Institution of Naval Architects


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