![]() ![]() Other robotic arms have singularities that are impossible to describe without the use of lengthy and complex formulas. Some robot arms have singularities that are extremely easy to identify. (Actually, the correct term is six-degree-of-freedom, but let’s stick to the popular, unscientific term six-axis). “A robot singularity is a configuration in which the robot end-effector becomes blocked in certain directions.”Īny six-axis robot arm (also known as a serial robot, or serial manipulator) has singularities. A robot singularity is a configuration in which the robot end-effector becomes blocked in certain directions. In contrast, try jogging the same robot in Cartesian space and the robot will frequently stop and refuse to go in certain directions, although it seems to be far from what you think is the workspace boundary. Try jogging a six-axis robot arm in joint space, and the only time the robot will stop is when a joint hits a limit or when there is a mechanical interference. Singularities arise when this calculation fails (for example, when you have division by zero) and must therefore be avoided. To find the necessary joint positions along the desired Cartesian path, the robot controller must calculate the inverse position and velocity kinematics of the robot. For Cartesian-space motion commands, you specify a desired pose (position and orientation) for the end-effector AND a desired Cartesian path (linear or circular). For joint-space motion commands (sometimes incorrectly called point-to-point commands), you simply specify - directly or indirectly - a desired set of joint positions, and the robot moves by translating or rotating each joint to the desired joint position, simultaneously and in a linear fashion. Hence, there are two sets of position-mode motion commands that make an industrial robot move. In general, it is impossible to cross a wrist singularity when controlling the robot in Cartesian spaceĪn industrial robot can be controlled in two spaces: joint space and Cartesian space. You must therefore know how to keep away from robot singularities by properly designing your robot cell. If this is the case, then you must learn about robot singularities, because these special configurations will often impede the Cartesian movements of your robot end-effector. You will likely also need the end-effector to follow prescribed paths as in gluing, or when inserting a pin. If you intend to use a six-axis robot arm, such as Mecademic’s Meca500, the example featured in this tutorial, you will probably need to do more than just position and orient the robot end-effector in various poses. ![]()
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