Move Command in UR Robot

Move Command

The Move command is used to control a robot's motion based on the waypoint. Move command defines the robot's speed and acceleration between these waypoints.

Three moving commands included: MoveJ, MoveL, MoveP and Circle move.

MoveJ the movement based on the calculated robotics joint spaces. The robot reaches the desired end position by controlling each joint state. This MoveJ movement is usually used in the following application, which is target positions are critical, but the trajectory is not essential. Applications:

• Pick and place

• Injection Molding

• CNC & Machine tending

• Packaging and palletizing

Example 1.1 MoveJ example

Move the TCP of the robot from Home Position to position A with the position and orientation following:

$$A= \begin{bmatrix} x\\ y \\ z \\ r \\ p \\ y \\ \end{bmatrix} = \begin{bmatrix} 0.0 mm\\ -400.0 mm \\ 400.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix}$$

Demonstration UR Robot with MoveJ command

Now, we remove the Waypoint 1 (Home position) and create the new waypoint B with addition x position with 600mm and z with 800mm.

$$B= \begin{bmatrix} x\\ y \\ z \\ r \\ p \\ y \\ \end{bmatrix} = \begin{bmatrix} 400 mm\\ -400.0 mm \\ 600.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix}$$

Demonstration UR Robot with MoveJ command

MoveL

MoveL can be called linear movement in UR Robot, this movement follows desired tool speed (mm/s) and tool acceleration (mm/s2). Application for linear movement included:

• Polishing

• Welding gluing, and dispensing

• Assembly

Example 1.2 Robot move from waypoint A to waypoint B following the line with MoveL command.

Demonstration UR Robot with MoveL command

MoveP

The robot moves the TCP at a constant speed and circular blends. The size of the blend radius can be set. Application of this command is usually found in gluing and dispensing.

Exercise 1. Programming UR Robot Moving with the following points C-->D-->E-->F in PolyScope with MoveJ, MoveL and MoveP (radius=50mm) commands and speed = 80 m/s and acceleration= 600m/s2.

$$C=\begin{bmatrix} 400 mm\\ -400.0 mm \\ 400.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix} D=\begin{bmatrix} 400 mm\\ 0.0 mm \\ 400.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix} E=\begin{bmatrix} 400 mm\\ 0.0 mm \\ 800.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix} F=\begin{bmatrix} 400 mm\\ -400.0 mm \\ 800.00 mm \\ 180.0^{o} \\ 0.0^{o} \\ 0.0^{o} \\ \end{bmatrix}$$

MoveJ following the square shape

MoveL following the square shape

MoveP following the square shape with blend radius =50mm

Exercise 2. Using the MoveP command and adding the Circle Move, robot will make a circular movement with config a position D(Via Point) and E (End Point). The mode of Circle Move:

• Fixed: the tool orientation is based only on the start point and keeps that orientation relative to the circle.

• Unconstrained: the tool orientation is based on the Start point transforming to the End Point.

Let's see how the robot moves following the video below.

MoveP with Circle Move Fixed Mode

MoveP with Circle Move with Unconstrained Mode

Variable Waypoint

A waypoint can describe by a variable. Go to the Advanced Tab--> Assignment to create a variable. A variable has to be a pose. For example, we can create the pose

$$var_1= \begin{bmatrix} x\\ y \\ z \\ r \\ p \\ y \\ \end{bmatrix} = \begin{bmatrix} 400 mm\\ -200.0 mm \\ 600.00 mm \\ 3.14 rad \\ 0.0 rad \\ 0.0 rad \\ \end{bmatrix}$$

var=p[0.4,-0.2,0.6,3.14,0,0]

Exercise 3. Adding a variable var_1 below the C waypoint means the robot will move following steps waypoint C-->var_1-->D-->E-->F. And running the robot program. Check your result with the video below.

Variable Waypoint

Direction

The robot moves in along X, Y, and Z paths in positive and negative directions and only stops when it meets the Until condition. Some Until conditions:

• Distance: the robot will move a certain distance.

• Tool Contact: the robot will stop the movement when the robot tool detects a contact (Note: set the lower speed of motion to less than 100m/s to get the Tool Contact effect to avoid Protective Stop)

• Expression and I/O input

Exercise 4. Program the UR robot by adding a Direction after Waypoint C by following the -Z direction and only stops when it reaches 100mm. See a video for more detail.

Exercise 5. Program the UR robot Direction with Until Tool Contact and observe the robot's behavior.