MoveJ / MoveL

关节运动与直线运动（MoveJ / MoveL）Common

The two most common arm-motion commands: move through joint space, or make the end-effector travel in a straight line.

MoveJ and MoveL are the two basic motion commands in industrial and collaborative arm programming — written as movej and movel in Universal Robots' URScript, with equivalents from other vendors. MoveJ interpolates in joint space: every joint rotates in sync from its current angle to its target angle, so the end-effector usually traces a curve, but the controller doesn't need to solve inverse kinematics along the way, which makes it fast and immune to singularities (poses where some directions can't move) encountered mid-path. MoveL interpolates in Cartesian space: it drives the tool center point along a straight line to the target pose, requiring the controller to solve inverse kinematics continuously, giving a predictable path suited to approaching an object, insertion, or dispensing glue. Both follow a trapezoidal velocity profile. A common pattern is MoveJ to a pre-grasp pose, then MoveL to approach the object in a straight line.

ExampleIn URScript, movej([0,1.57,-1.57,3.14,-1.57,1.57], a=1.4, v=1.05) drives all six joints to that set of angles at a lead-joint speed of 1.05 rad/s; movel(pose, a=1.2, v=0.25) moves the end-effector to pose along a straight line at 0.25 m/s.

Also called: Joint Move / Linear Move, movej / movel
Related: Joint Space · Task Space · Inverse Kinematics (IK) · Tool Center Point · Trapezoidal Velocity Profile · Pre-grasp Pose
Sources: The URScript Programming Language for e-Series, SW 5.11（movej / movel）
ur_rtde: rtde_control_interface.h（moveJ linear in joint-space / moveL linear in tool-space）