Ergonomics Product Development of a Mobile Workstation for Health Care
Risto Toivonen, Dong-Shik Choi, and Nina Nevala
Journal of Usability Studies, Volume 7, Issue 1, November 2011, pp. 40 - 50
Article Contents
Results
The following sections discuss the results of the expert evaluation and the user study, and the list of criteria for optimal mobile workstation design.
Expert Evaluation
According to the group of experts, the functioning of the wheels, the height of the screen, the mobility of the workstation, and the adjustability of the workstation height were the best features of the prototype. The keyboard tray, the mouse tray, and the difficulty of installing the laptop computer onto the workstation were reported as needing further development. The evaluation showed that the design needed to be simplified (i.e., the height needed to be easier to adjust, and the case for the computer needed to be redesigned). Table 2 lists the usability requirements for any mobile workstation according to the experts.
Table 2. Expert Evaluators’ Usability Requirements for Mobile Workstations
Before the user study, the mechanism to adjust the height of the workstation and the locking mechanism of the laptop were redesigned.
User Study
This section reports the quantitative and subjective responses of the eight test participants after using the workstation for rounds. The usability of the mobile workstation according to the mean SUS index was 73 (SD 11.0). The SUS scores of the eight participants were the following: 90, 82.5 (n=2), 75, 72.5, 65, 62.5, and 52.5. There was no difference between the scores for the nurses and physicians.
The results of the VAS ratings are presented in Figure 4. Movability, the functioning of the wheels, the adjustability of the height, and the stability of the mobile workstation were the highest rated factors. On the other hand, the combined keyboard and mouse tray feature (see Figure 1) received the lowest scores. Some of the VAS ratings were heavily influenced by the work practices that individual nurses and physicians had adopted in their ward and, therefore, the ratings showed large variations. For example, some participants preferred the disinfection bottle holder on the mobile workstation as was the case in their ward, while others thought a bottle located by the patient's bed was enough.
Figure 4. Perceived usability (VAS: 0=Very Poor, 100=Very Good) of the mobile workstation according to the doctors and nurses (n=8; means, standard deviations)
In response to questions, the participants pointed out that the mobile workstation must be an easy-to-use and sought-after tool for work, so that everyone would be able to make use of it easily and effectively. The doctors and nurses stated that they would like to use the mobile workstation because
"The use of the COW [computer on wheels; mobile workstation] seems very convenient."
"It is nice to make the round alone—I talk more with the patient."
"I send the instructions for the nurses and physiotherapists directly to their electronic work list."
"I have my own schedule."
All the participants were eager to comment on the usability of the new mobile workstation model because previous mobile workstation models had shortcomings. Large variations in specific VAS features clearly indicated that the basic workstation should have as simple a construction as possible, but be equipped according to users' varying needs.
Criteria for the Ergonomics and Usability of the Mobile Workstation
Based on the findings of both the expert evaluation and the user study, we formulated the following criteria for a usable and ergonomically designed mobile workstation. These same criteria were taken as essential design points by the developers of the mobile workstation prototype.
- Small as possible
- Usable for a mobile computer, separate keyboard, and mouse
- Computer easily installed and removed
- Lockable computer or laptop
- Equipped with handles
- Computer, keyboard, and mouse stay immobile during workstation movement
- Easily moved and equipped with wheels that turn and lock
- Cleanable—no sharp corners
- Extra equipment available if needed
- Can be used when standing or sitting
- Easy to get near the computer and stand with a straight back
- Easy to adjust the height with one hand
- Height adjustability between 80-120 cm
- Angle of the screen adjustable
- Mouse usable with both hands near the keyboard
- Arms supportable during computer use
- Easy to walk with the mobile workstation, i.e., the construction of the mobile workstation does not interfere with movements of legs
- Easy to learn how to use
- Manual includes ergonomic instructions
In addition to data gathered from the expert evaluation and user study, the ErgoSHAPE method (Launis & Lehtelä, 1992) was used to define the minimum range of adjustability for the height to make it possible to work with the mobile workstation while either sitting or standing. (ErgoSHAPE is a collection of human anthropometric models and ergonomic recommendations for work place designers to be used with AutoCAD.) The recommended and minimum ranges for the height adjustment for the mobile workstation are presented in Figure 5. A range of 80–120 cm enabled even the shortest and the tallest workers (P5 or 5% of the population is shorter than 80 cm / P95 or 5% of the population is taller than 120 cm) to work comfortably with the mobile workstation, either while sitting on, for example, a saddle chair or while standing.
Figure 5. The recommended and minimum ranges for the height adjustability of the mobile workstation