## 1 Introduction  
Recent literature reports an increasing number of new connected and unconnected medical device proposals for ambulatory monitoring or simply for wellness monitoring. The technical aspects to be resolved often lead to rigorously tested solutions. However, many of these devices do not go beyond the prototype stage, particularly because the search for solutions does not include the human factor in these considerations [1]. It seems essential to take users' opinions into account in the very first stages, either to participate in the development of the system or to ensure good appropriation and, thus, satisfy a favorable acceptance judgment. The objective of this article is, therefore, to propose some recommendations, in the design phase of a medical device co-constructed between engineers and users. This relationship is made possible by recourse to the human sciences. It enables the needs of potential users to be taken into account in order to develop a technology that can suit its market. However, predicting and explaining the behavior of users of an ambulatory monitoring system is not an easy task. The challenge is to try to predict the intention to use a technological device that is not yet on the market and still under development. The approach used in this article is based on models of social cognition that consider acceptability as the study of social constructs towards a technology. The study of these social constructs make it possible to measure if the use of the technology is acceptable from the point of view of a potential user. These models of acceptability refer to a temporal dynamic. Indeed, after a user test design to adjust the functioning of the device, the relationship between the person and the technology is inscribed along a continuum that is based on three moments: preindustrial development (before the object is available), implementation in a practice, and post-industrial development. Acceptability involves three distinct measures related to these three moments: acceptability, appropriation at the time of implementation, and adoption by users to include it among the object used in their daily lives [2; 3; 4]. In this article, a case study was conducted to assess the relevance of studying acceptability during the industrial pre-development phase of the SHERPAM platform, which was developed for activity quantification and recognition. The models available in the literature for making this prediction refer to two theoretical fields: (1) the judgment towards the target behavior (i.e., the performance of a particular act, in a given time and space, towards a specific object) and (2) the judgment towards the technology whose use is to be predicted. Only this second field has been considered, which focuses on the practical and exclusive relationship between a user and a technology. Acceptability then depends on the user's intention to use the technology, the benefits he/she thinks he/she can get from its use, and his/her motivation to use it compared to the cost involved. In these models, acceptability is operationalized by behavioral intention, which is itself dependent on two perceptual determinants: perception of performance and perception of expected ease of use (Technology Acceptance Model, TAM) [5]. Expected performance is defined as \"the degree to which a person believes that using the system will improve his or her performance\" [6] (p. 982). Expected ease of use is \"the degree to which a person believes that using a system will require no effort\" [5] (p. 383). Both dimensions are dependent on external factors such as the characteristics of the system, the development of the process or the training that accompanies the deployment. Although TAM has demonstrated its robustness, it has, nevertheless, been criticized for the absence of a social dimension influencing behavioral intention [7]. A second version of TAM (TAM 2), [8] particularly develops extrinsic motivation through the study of social influence.