Fast-moving industrial robots exert large varying reaction forces and moments on their base frame, inducing vibrations, wear and accuracy degeneration. These shaking forces and moments can be eliminated by a specific design of the mass distribution of the robot links, resulting in a dynamically balanced mechanism. Obtaining the conditions for dynamic balance proves to be a hurdle even for simple planar parallel mechanisms due to the required inclusion and inspection of the kinematic relations. In this paper, a screw theory based methodology is presented, which gives and solves the necessary instantaneous dynamic balance conditions for planar and spatial mechanisms in an uniform and geometrical manner. Instantaneous dynamic balance yields a pose in which robot accelerations induce no shaking forces and moments. This is interpreted as an intersection point of multiple reactionless paths. This method is applied to a 2-DOF planar mechanism, named the Fuga I, for which it resulted in two perpendicularly intersecting reactionless paths, intersecting in the middle of the workspace. Experiments on this demonstrator validated the instantaneous dynamic balance by showing a reduction of approximately 95% of the peak-to-peak shaking forces and moments over the intersecting reactionless paths.

Background: Clinical studies investigating medicinal products need to comply with laws concerning good clinical practice (GCP) and good manufacturing practice (GMP) to guarantee the quality and safety of the product, to protect the health of the participating individual and to assure proper performance of the study. However, there are no specific regulations or guidelines for non-Medicinal Investigational Products (non-MIPs) such as allergens, enriched food supplements, and air pollution components. As a consequence, investigators will avoid clinical research and prefer preclinical models or in vitro testing for e.g. toxicology studies. The aim of this article is to: 1) briefly review the current guidelines and regulations for Investigational Medicinal Products; 2) present a standardised approach to ensure the quality and safety of non-MIPs in human in vivo research; and 3) discuss some lessons we have learned. Methods and results: We propose a practical line of approach to compose a clarifying product dossier (PD), comprising the description of the production process, the analysis of the raw and final product, toxicological studies, and a thorough risk-benefit-analysis. This is illustrated by an example from a human in vivo research model to study exposure to air pollutants, by challenging volunteers with a suspension of carbon nanoparticles (the component of ink cartridges for laser printers). Conclusion: With this novel risk-based approach, the members of competent authorities are provided with standardised information on the quality of the product in relation to the safety of the participants, and the scientific goal of the study.