Teach pendant programming
Teaching Linear vs Joint Motion
For a technician choosing between joint (J) and linear (L) motion when teaching a move instruction, matched to the path shape the application needs. Covers the motion format, feed rate units, FINE and CNT positioning, and how singularities force a choice. Uses the standard motion menu, the [CHOICE] key, and the singular point check.
- Step 1.
Understand joint motion (J)
Joint motion is the basic move: the robot accelerates all axes, runs at the feed rate, then decelerates and stops on every axis at the same time. The path of the tool center point is usually non-linear, and the tool attitude is not controlled during the move. Feed rate is a percentage from 1 to 100 percent of maximum, and it can also be given in seconds or milliseconds of travel time.
- Step 2.
Understand linear motion (L)
Linear motion controls the tool center point so it travels in a straight line from the start point to the end point. The tool attitude is controlled by blending the attitude at the start with the attitude at the target. Feed rate is a real-world unit chosen from mm/sec, cm/min, inch/min, or a travel time in sec or msec.
- Step 3.
Know the rotation case of linear motion
When the tool rotates about the tool center point from one orientation to another, that reorientation is a form of linear motion with the feed rate given in deg/sec. The TCP position is held while the orientation blends from start to end. Reach for this when a pure reorientation at a fixed point matters more than travel distance.
- Step 4.
Match the motion type to the path the application needs
Pick joint motion for general point-to-point moves in open clearance, where cycle time matters and the exact path shape does not. Pick linear motion when the tool tip must follow a straight line, such as a straight weld seam, a dispensing bead, or an approach through a tight, guarded clearance. Remember that a joint move can swing the arm through space the tool tip never visits, so verify clearance for the whole body.
- Step 5.
Select the move instruction to edit
On the program edit screen, move the cursor to the motion type field of the line you want to change (the leading J or L). The instruction items you can change are motion type, position variable, feed rate, positioning type, and any additional motion instruction.
- Step 6.
Change the motion type with [CHOICE]
Press F4 [CHOICE] to open the Motion Modify menu, then select 1 Joint, 2 Linear, 3 Circular, or 4 Circle Arc. When you change the motion type, the feed rate unit changes automatically to a unit valid for that type, so review the feed rate value after the switch.
- Step 7.
Set the feed rate in the correct unit
For joint motion enter 1 to 100 percent, or a time from 0.1 to 3200 sec or 1 to 32000 msec. For linear motion enter 1 to 2000 mm/sec, 1 to 12000 cm/min, 0.1 to 4724.4 inch/min, or a travel time; a rotation move uses 1 to 272 deg/sec. The maximum allowed depends on the robot model, and the running speed is further scaled by the feed rate override of 1 to 100 percent.
- Step 8.
Choose the positioning path: FINE or CNT
FINE makes the robot stop exactly at the target before moving on, which suits a taught process point. CNT with a value from 0 to 100 lets the robot round the corner without stopping: CNT0 takes the path nearest the point without stopping, and CNT100 passes widest because it does not decelerate near the point. Note that a following instruction such as a WAIT still forces a stop at the point even under CNT.
- Step 9.
Teach a new move with the standard motion menu
To add a move rather than edit one, jog the robot to the target, put the cursor on [End], and press F1 POINT to list the standard motion statements. Selecting one records the current position into the instruction. Hold SHIFT and press F1 to program the same standard statement repeatedly.
- Step 10.
Edit the default motion statements if you teach many of one type
Press F1 POINT, then F1 ED_DEF to open the Default Motion list (for example J P[] 100% FINE and L P[] 100mm/sec FINE). Cursor to a field, press F4 [CHOICE] or enter a value to change motion type, feed rate, or positioning type, then press F5 DONE. This sets what each new taught line starts as, which saves changing every line by hand later.
- Step 11.
Turn on the singular point check before teaching near a singularity
Set system variable $MNSING_CHK to TRUE so the controller checks a taught Cartesian point against the robot's singular points. When enabled, teaching or touching up a point at a singularity prompts you to record the position on joint coordinates instead. Recording on joint keeps the taught attitude reliable where a Cartesian record would drift.
- Step 12.
Test the path in low-speed manual mode
With the cell clear and the controller in low-speed manual mode, step the instruction and watch the actual path the tool tip takes between points. Confirm a linear line looks straight and a joint move clears surrounding fixtures. Raise speed only after the path proves correct at low speed.
- Step 13.
Handle a wrist singularity on a linear move with Wjnt
A linear, circular, or circle arc move cannot pass through a singular point because the joint placement cannot change mid-path. To carry the TCP through a wrist-axis singular point, add the Wrist joint motion option (Wjnt) from the F4 [CHOICE] additional-instruction menu. Under Wjnt the wrist attitude is allowed to change during the move so the tip stays on the programmed line without the wrist axis inverting.
- Step 14.
What can go wrong: a linear move reports a configuration or position change
If a Cartesian move stops with a warning about a configuration or position change, the joint placement or turn number needed at the target differs from the start, which a straight-line move cannot resolve. Replace that segment with a joint move, or add an intermediate point so the arm reconfigures in open space. If servo power dropped from an e-stop and the axes slipped slightly, abort the program, jog back to the correct attitude, then resume.
- Step 15.
What can go wrong: the point you teach lands on a singularity
With the singular point check on, teaching a Cartesian point at a singularity warns that the point cannot be recorded on Cartesian coordinates and offers to record it on joint. Answer YES to store it as an axial (joint) position, which preserves the taught attitude. If you answer NO, the point is not recorded and you should jog off the singularity before teaching again.
- Step 16.
What can go wrong: the programmed speed exceeds the robot range
If you enter a feed rate above the robot's allowable range, the controller issues a warning alarm rather than running that value. Re-enter a feed rate within the model's limit, and remember the true speed is the programmed value scaled by the override. If a register supplies the feed rate, check the register value carefully at teach and run time, because a bad value can drive the robot at an unexpected speed.
- Step 17.
What can go wrong: a CNT corner rounds more or less than expected
Rounding depends on the CNT value and on how much room the robot has to decelerate, so short, fast back-to-back CNT moves can still slow at the corner even at CNT100. Lower the CNT value or add distance if the tip cuts a corner too tightly, and raise it toward 100 if you need a wider, faster blend. Use FINE where the process truly requires a full stop on the point.
Common questions
- How long does Teaching Linear vs Joint Motion take?
- Teaching Linear vs Joint Motion is rated Basic and takes about 20 minutes across 17 steps.
- What tools do I need?
- You will need Teach pendant, Robot with a taught destination position in the program.
- What should I do before starting?
- A TP program open on the edit screen with the teach pendant enabled. A position already taught at the destination point. A tool frame active if the path shape is judged at the tool center point.
- What is the first step?
- Understand joint motion (J). Joint motion is the basic move: the robot accelerates all axes, runs at the feed rate, then decelerates and stops on every axis at the same time. The path of the tool center point is usually non-linear, and the tool attitude is not controlled during the move. Feed rate is a percentage from 1 to 100 percent of maximum, and it can also be given in seconds or milliseconds of travel time.