ناهمسان گردی سرعت یک ربات صنعتی

Industrial robots are part of production systems and it is important to place them into the system according to their properties and behaviour. The information, obtained from the technical sheets of robots, about workspace (its dimensions and shape) is insufficient for designing the production system. The information about mobility is missing. To represent the behaviour of the robot in the workspace, velocity anisotropy of the robot is introduced and defined as the length of the shortest velocity ellipsoid axes, which can be constructed for any position of robot in its tool centre point. The position of a tool centre point is equivalent to the point in the workspace. A graphical representation of the 3D workspace with included velocity anisotropy is then performed and an example for a design of a robotised welding production system is given. In this example the benefits of the graphical representation of the workspace with included velocity anisotropy are presented and discussed.

When we design robotised production systems, we recognise some difficulties, which result from the data sheets of industrial robots. Technical manuals offer insufficient information about the robot’s workspace. The given data are restricted to two layouts, which give us just rough information about the dimension and the shape of the workspace. From this data we cannot comprehend the manipulability and the real velocity levels of the tool centre point (TCP) of the robot in an arbitrary point in the workspace. So it can happen that some difficulties appear after designing of the robotised production system within the first testing run. In the testing phase we can recognise some, for the robot, inaccessible points on the work piece or there are some parts on the produced work piece where the robot cannot perform the prescribed technological requirements.

In the present paper a procedure for analyzing and 3D representation of robot’s workspace is given. Additionally a parameter for velocity anisotropy determination in each point of the workspace is introduced. The velocity anisotropy is defined with the normalized length of the shortest axis of the velocity ellipsoid for each point of the workspace. To show the benefits of the presented procedure an analysis of a realized robotised production system for MAG welding is presented, Fig. 8. In the presented figure it is clearly shown that the upper edge of the welded part (point d, Fig. 8) is close to the singular position of the robot. In this region of the workspace the welding on a straight line was impossible. The robot’s TCP could reach just the starting and the ending point of the trajectory, but it was impossible to follow the whole trajectory.