In this thesis, we propose a contribution to the design of medical robots, by offering a concurrent design or simultaneous approach. As opposed to a natural sequential view of the design process, the formalization of the creative process allows simultaneity, paving the way for innovative structures, dedicated: in the medical robotic field, low mass and low compactness of the mechanical structure are often sought. From a description of existing approaches, we design a tele-ultrasound robot and a minimally invasive surgery robot. For both applications, high physical integration is required. For tele-ultrasound robots, portability is highly sought, requiring low compactness. For minimally invasive surgery, geared motors of the in vivo robot must be sized correctly. Here, we formalized the improvement of compactness of an existing parallel structure for remote ultrasound application. The results show an improvement of compactness of around 5%. In the same way, we formalize the dimensional synthesis of two robots 2R-R-R for in vivo minimally invasive surgery. The results show the under-sizing of some actuators. We perform simultaneous optimization between the design of geared motors and lengths of the body of a robot 2R-RR, tendering towards full simultaneity of the creative process, allowing to improve minimal force and velocity at the end-effector of the robot. These experiments of design show limits to a strict simultaneity. We indicate the need to adapt the tools and methods of mechatronic design for simultaneous robotics design, taking into account the imperfect aspect of the creative process.