How do you calculate the reachable workspace of a manipulator?
Robotic arms or manipulators have finite workspaces or regions that the
end effector can reach. This workspace size mostly depends on the length of the adjacent links between each joint – for example, a robot with a 2m link can reach 2m, but this isn’t the whole picture. The amount of space that the manipulator can reach within its range of maximum extension is dependent on the following:
- The number of joints
- Each joint – rotate or translate
- The number of joints
- The range of motion of each joint
- The lift capacity of each joint
Take the 5- and 7-function versions of the
Reach Bravo – the Bravo 7 can maintain the orientation of the end effector while the other joints move, but the Bravo 5 is unable to do this due to the lower number of joints. Similarly, a Bravo 7 can hold a tool/marker/welder and draw circles on a plane, whereas a Bravo 5 can trace a circle, but the end effector must tilt as the lower joints move.
Both the Bravo 5 and 7 have continuous rotation on the inline rotary joints, meaning that the Bravo can reach just as much behind it as in front of it, giving it a bigger workspace than a human arm.
The last factor affecting the manipulator’s workspace is more related to the weight of the object the manipulator is holding. Suppose it’s near or exceeding the maximum capacity of the manipulator. In that case, there will be some areas of the workspace where the manipulator can operate and others where it will not be able to apply enough force.