Cognitive Assistance to Support Maintenance and Assembly Tasks: Results on Technology Acceptance of a Head-Mounted Device

Industrial workplaces are increasingly digitised. In line with this, new technologies are being introduced to support employees in their work tasks. These technologies can support employees cognitively (e.g., by providing information about products or by supporting complex analyses) or physically (e.g., using robots or exoskeletons that support carrying heavy loads). For cognitive assistance, head-mounted devices have been developed, which are widely used to provide information to employees. This technology originated in 1950 and 1960 when Morton Heilig telesphere mask was patented [11]. A current innovation is the RealWear HMT-1 published in March of 2017, which has previously been introduced.

Previous research on user acceptance of HMDs has revealed differences in acceptance between usage scenarios [13] and differences in technology properties [8]. For instance, [13] analysed augmented reality smart glasses and their role in work assistance in electronics manufacturing in two use cases (order picking in warehouse logistics and assembly machine setup). They conducted a survey investigating the users’ expectations in terms of usability, usefulness, and user acceptance. The findings demonstrated that the overall user expectations were more positive in the second use case than in the first case among all aspects of usability and acceptance. The authors explained these results with a task-technology fit approach (see also [4, 5, 7]). The results of this study highlight the necessity to consider potential properties of use cases in which new assistive technologies should and should not be used.

Technology acceptance is usually assessed based on the widely acknowledged technology acceptance model (TAM; [3, 14, 15]). The model proposes two relevant variables predicting the intention to use technologies: i) perceived ease of use and ii) perceived usefulness. Perceived ease of use is described as the degree to which a user thinks that using the technology is free of physical and mental effort. Perceived usefulness describes that the user thinks that using the technology increases his/her task performance. Perceived ease of use and perceived usefulness are fundamental determinants of actual system use. The fulfilment of both is [3].

In the following sections, we present the findings separately for the perceived ease of use and perceived usefulness. In terms of perceived ease of use we describe mentioned advantages and disadvantages of the technology; for perceived usefulness we describe despite statements about the general perceived usefulness also suitable use cases that have been mentioned by the study participants.

Perceived Ease of Use. Participants mention initial advantages and disadvantages of the technology which we have categorised into three categories: i) user experience, ii) ergonomics, iii) device characteristics. The following two tables (Table 1 and Table 2) summarise the advantages and disadvantages for these three dimensions. The numbers in parentheses indicate the frequency of the respective statement.

In general, the most frequently mentioned advantage of HMT-1 was that it is perceived as suitable in terms of the display (location) and the related adjustability. Participants for instance mentioned the advantage that the arm can be located directly in front of the workers’ eyes (14 times). In connection to that, they reported that their field of view is unrestricted (5 times). They further highlighted the adaptivity and controllability (that the boom arm can be folded back and forth with one hand (10 times) and the possibility to move freely (10 times) as advantages.

Disadvantages primarily concern the hardware and quality of experience with respect to (media) the display abilities of the technology. For instance, 26 participants mentioned that the display is very small. Similarly, participants also mentioned disadvantages related to health at work, for example, that working with the small display may be strenuous for the eyes (12 times) or that the weight of the technology may lead to headache (8 times). Further, regarding the quality of the visualisation, participants mentioned that the image is blurred, fuzzy, and pixelated (11 times) or that the voice control is not precise enough (once). We want to mention here that participants did not evaluate the finished system with a visualisation that has been properly developed and tested; therefore, some of these statements are expected.

Perceived Usefulness. In terms of perceived usefulness, 15 participants reported that the device is useful. One participant stated, “that it would enrich the workflow" and that ‘it gives the impression of efficiency’ (Participant ID 2). However, others did not assess the device as useful. For example, it was stated that ‘in any case, it would hinder me more’ (Participant ID 42). We further asked participants about suitable use cases for HMT-1. A total of 34 suggestions were made. According to the interviewees, HMT-1 is appropriate for non-routine tasks and for tasks of medium-to-high complexity. Furthermore, it is considered practical ‘when you have to manufacture something big and complex and have to move around a lot’ (Participant ID 10). In addition to the implementation of the technology in manufacturing (e.g. for quality control; participants with IDs 17, 29, and 30), it could also be used in logistics, for instance as a ‘navigation device for truck drivers or for crane or forklift drivers in larger warehouses’ (Participant ID 23).

In our interview study we investigated user acceptance of a head-mounted device called HMT-1, which is designed to support users by presenting information (e.g. visualizations) in the visual field. The information is shown on a foldable display. We had two main results that are relevant for both the assembly and the maintenance context. Firstly, we found that besides the possibility to move freely, the participants mentioned that it is of central advantage to have the display in their field of view, combined with the autonomy to decide where and when the visualization is given. In particular, the users reported that the position of the display and the adaptability and control of the extension arm to which the display belongs were mentioned as advantages. The ability to fold away the information distinguishes the HMT-1 from other HMDs. Thus, this technology allows to support the workflow while avoiding possible distractions or interruptions. The individual control of the employee is thus maintained, which has proven to be limited when using other HMDs (see e.g. [2]). Secondly, the results showed that HMT-1 contains functionalities that both support and hinder the workflow. These results are consistent with the results of the study reported by [8]. Therefore, as with any technology, when introducing the technology into an organization, it is necessary to invest time in considering appropriate work tasks in order to benefit from the technology. For example, the participants in this sample mentioned that HMT-1 is particularly suitable for non-routine tasks and tasks of medium to high complexity.

Finally, as regards the implementation of head-mounted devices in general, we recommend that the positive aspect of control over the technology should be maintained. For example, if organizations require employees to pretend to have their arm in front of their head at all times, these positive effects will disappear. As some ergonomic aspects have also been mentioned, we also recommend that the occupational physician be involved in the implementation. It is important to decide how and for how long the technology can and should be used. For example, maximum usage times can then be defined in cooperation (for further recommendations on how to implement assistive technologies see [6]). Such rules of use, appropriate for the specific workplace and workers, can minimise the potential negative effects on health and well-being and support comfort.