Analysis of the inertia tensor of autonomous mobile robot

Abstract

The object of research is the inertia tensor of an autonomous mobile robot (AMR) with a manipulator with different configurations of their mutual position. As an example of the AMR design of a changing configuration, an all-wheel drive four-wheeled platform with a manipulator is considered, consisting of a docking disk rotating around a vertical axis and rod links of the arm connected by rotational kinematic pairs of the fifth class. The mass of moving structural elements, i. e., a manipulator with a load, is 10–20 % of the mass of the robot platform. Let’s consider that the links of the manipulator and the platform are absolutely rigid and homogeneous bodies with a constant density; let’s neglect the mass of kinematic pairs. The next step in the analysis of the AMR inertia tensor of a changing configuration can be a study taking into account the elastic properties of the manipulator links, the uneven distribution of the masses of the platform, and the characteristics of the kinematic pairs. The dependence of the values of the elements of the AMR inertia tensor of a changing configuration on the values of the generalized coordinates of the moving elements of the structure and the ratio of the mass of the platform and the mass of the moving elements of the structure has been studied. The analysis of the inertia tensor of the AMR with a manipulator at different configurations of their mutual position showed that the values of the centrifugal moments of inertia of the system during the relative motion of the manipulator are commensurate with the value of the axial moments of inertia of the system, even if the mass of the moving structural elements is less than 10% of the mass of the platform. In most existing AMRs, the mass of moving structural elements is up to 20% of the platform mass, therefore, in the general case, the inertia tensor of such a system should be taken as off-diagonal and non-stationary. In the future, this will make it possible to refine the equation of dynamics, take into account the relationship of control channels, simulate the movement of AMR of a changing configuration, and optimize energy costs. Since AMR with the manipulator is an example of the «changing AMR» object class, the results obtained can be applied to all objects of this class.