Move by Grid

Function

This Step is used to set multiple waypoints in the path according to the grid, specify the way to move to those waypoints, and guide the robot to move to the waypoints in sequence.

Parameter Description

Move-Type Step Common Parameters

Send Waypoint

Selected by default, i.e., send the current waypoint to the receiver, such as the robot. Once deselected, the current waypoint will not be sent. However, the waypoint will remain in the planned path.

Try Continuously Running through Succeeding Non-Moves

Unselected by default. When non-move Steps, such as Visual Recognition, Set DO, Check DI, etc., are connected between move-type Steps, the sending of the waypoints will be interrupted, and the real robot will take a short pause, reducing the smoothness of running.

When this parameter is selected, the project will continue to run without waiting for the current move-type Step to complete execution, and therefore the robot can move in a smooth way without pauses. However, selecting this parameter may cause the execution of the Step to end prematurely.

Why will this feature cause the execution of the Step to end prematurely?

Mech-Viz will send multiple waypoints simultaneously to the robot when the project is running. When the currently returned JPs of the robot correspond to the last waypoint sent by Mech-Viz, Mech-Viz will assume that the robot has moved to the last waypoint.

For example, there are 10 move-type Steps in a path, and the pose of the 5th move-type Step is the same as that of the last move-type Step. When the robot moves at a low speed, the current JPs will be sent to Mech-Viz after the robot moves to the 5th waypoint. Since the poses of the 5th move-type Step and the last move-type Step are the same, Mech-Viz may mistakenly determine that the robot has reached all waypoints and prematurely ends the command.

Do Not Check Collision with Placed Target Object

Once Detect collisions on target objects is enabled in the Collisions panel, selecting this parameter will disable the collision detection between the robot, robot tool, and placed target objects. Typically, this parameter is selected in the move-type Step following the Step whose Pick or place is set to Place to avoid false collision detections.

Application Example:

The TCP of a depalletizing vacuum gripper is usually set inside the model rather than on the surface of the vacuum gripper. As a result, when picking a box, the vacuum gripper model may overlap with the box model. However, the software does not detect collisions between the end tool and the picked target object, so no collision alarm will be triggered during picking. Once the robot places the box down, the picked box model becomes a scene model, and the software will start to detect the collision between the end tool and the box’s scene model, triggering a collision alarm and preventing the completion of the palletizing task.

Once this parameter is selected, no collision between the robot, end tool, and the model of the placed target object will be detected, and the above issue will be resolved.

Point Cloud Collision Detection Mode

Usually, Auto can be selected, i.e., directly apply the Point cloud collision detection settings in the Collisions panel. In the move-type Step after the robot picks the target object, Check collision can be selected.

Auto

Default setting. Once Detect collisions on target objects is enabled in the Collisions panel, only point cloud collisions of the “Vision Move” Step and the “Relative Move” Steps that depend on the “Vision Move” Step will be detected, while other move-type Steps will not be detected.

Do not check collision

Point cloud collisions of all move-type Steps will not be detected.

Check collision

Point cloud collisions of all move-type Steps will be detected.

Ignore Target Object Symmetry

This parameter is only visible when the Waypoint type of the move-type Step is set to Target object pose.

The target object symmetry here refers to the Rotational symmetry of held target object predefined in the target object editor during collision model setup.

None

Default setting, i.e., do not ignore symmetry on any axis.

Around target object frame Z axis

Only ignore symmetry around the Z-axis.

Around target object frame X&Y axes

Ignore symmetry around the X-axis and Y-axis.

Around all axes

Once the symmetry around all axes is ignored, the robot will place the object strictly according to the target object pose.

When the move-type Steps are used to place the target objects, the consistency of the placing poses of the target objects cannot be guaranteed once the rotational symmetry is applied. If you want all target objects to be placed strictly according to a specific rule, ignore the symmetry of the target object around all axes.
Plan Failure Out Port

Once this parameter is selected, a Plan failure exit port will be added to the Step.

If the path planning of the current Step succeeds, the workflow will continue along the Success exit port. If the path planning of the current Step fails, the workflow will proceed along the Plan failure exit port. If multiple move-type Steps with “Plan failure” exit ports display in the same plan history entry, the workflow will proceed along the “Plan failure” exit port of the first move-type Step.

Held Target Object Collision Detection Settings

Before configuring this parameter group, please go to the Collisions panel and enable Detect collisions on target objects.

Disabling collision detection will increase the collision risks. Please select the following parameters with caution.
Do Not Check Collision with Scene Objects

Once this parameter is selected, collisions between the held target object and the scene model will not be detected, reducing the computational load of collision detection in the software, speeding up path planning, and optimizing the overall cycle time.

Do Not Check Collision with Robot

Once this parameter is selected, collisions between the held target object and the robot will not be detected, reducing the computational load of collision detection in the software, speeding up path planning, and optimizing the overall cycle time.

Do Not Check Collision with Point Cloud

Once Point cloud collision detection is enabled in the Collisions panel, selecting this parameter will stop detecting collisions between the held target object and the point cloud, further reducing the software’s computational load, shortening path planning time, and enhancing the overall cycle time.

  • Do Not Check Collision with Robot is usually used in the first or second move-type Steps after the robot picks the object. It may increase the risk of collision. Please enable it with caution.

  • Enabling Do Not Check Collision with Scene Objects will not affect the collision detection between the held carton and the placed cartons. When there are scene objects under the pallet, this function can be used to avoid solution selection failure for palletizing.

Index

Starting Index

The index of the waypoint to be executed. Example: The index of the first waypoint is 0. If you want the robot to move from the third waypoint in the grid, please set the value to 2.

Current Index

The index of the waypoint currently being executed.

Grid

This parameter specifies the number and spacing of the current grid points in each direction.

X Count

The number of waypoints in the X direction of the grid.

X Space

The spacing between two waypoints in the X direction of the grid.

Y Count

The number of waypoints in the Y direction of the grid.

Y Space

The spacing between two waypoints in the Y direction of the grid.

Basic Move Settings

Basic move settings of move-type Steps are used to set the velocity and motion type for the robot when it moves to the waypoint.

Pick or place

Setting this parameter facilitates checking the logic of the Mech-Viz project. Please select a proper option according to the on-site situation and ensure that the Step used to pick is placed before the Step used to place.

Unspecified

Default value

Pick

Please select this option when the move-type Step is before “Vision Move”.

Place

Please select this option when the move-type Step is after “Vision Move”.

Motion type

Joint move

Joint motion, which guides the robot to move in a curved path. It is less likely to reach singularities in the path for joint motion.
This motion type is applicable to scenarios where the requirement of path accuracy is not strict and the robot moves in a large space.

Linear move

Linear motion, which guides the robot to move linearly.
This motion type is applicable to scenarios where there is a strict requirement for path accuracy, such as welding, gluing, and certain types of picking.

Singularity Avoidance

When the motion type is Linear move, enabling this function can simulate linear move by joint move with multiple segments, thus reducing singularity problems to a certain extent.

Parameters Setting

Limit to Motion Segments Specific Number No Limit

Feature

Simulate linear move using joint move with a user-specified number of segments.

The software calculates the number of segments needed to simulate linear move.

Advantages

  • The waypoints are more evenly distributed and the number is controlled.

  • Applicable to Standard Interface communication.

  • The success rate of path planning is higher.

  • Only move to the required number of waypoints.

Disadvantages

  • If the number of motion segments is set too much, the robot will jam and slow down.

  • Setting the number of segments manually may slightly increase the probability of avoidance failure.

  • The waypoints may be unevenly distributed.

  • Not available for Standard Interface communication.

Parameter Description

Number of Segments

The number of joint move segments specified by the user when the Limit to Motion Segments is set to Specific Number.

Max Position Deviation

The maximum allowable deviation of the new multi-segment joint motion path from the original linear motion path. The greater the max position deviation, the higher the success rate of singularity avoidance, and the lower the similarity between the actual trajectory and the straight line.

Max Angle Deviation

The maximum allowable angular deviation of the new multi-segment joint motion path from the original linear motion path. The greater the max angle deviation, the higher the success rate of singularity avoidance, and the lower the similarity between the actual trajectory and the straight line.

Velocity & Acceleration

Velocity and acceleration determine how fast the robot can move. Usually, the set acceleration should be lower than the velocity. When the set acceleration is higher than the velocity, the robot will move in a choppy way.

The velocities of Vision Move and its prior and subsequent Steps should be relatively low to ensure that the objects can be picked steadily.
Blend radius

Usually, the default setting can be used.

  • The blend radius refers to the distance between the target point and the point where the robot starts to turn. The larger the blend radius, the more smoother the robot motion transitions are. If the robot moves in a relatively small space, please set the blend radius to a smaller value.

  • If the robot moves in a relatively large space without obstacles and the distance between two consecutive path segments is long, please set the blend radius to a larger value.

Show Base

Once this parameter is selected, the grid waypoints and the corresponding index will be displayed in the 3D simulation area of Mech-Viz.

Show Target

Once this parameter is selected, the robot and object pose will be displayed in the 3D simulation area of Mech-Viz, while the grid will not be displayed.

Waypoint Type

Waypoint Type Description

Tool

The waypoint will be represented by the X, Y, Z values, Euler angles, quaternions or rotation vectors in the tool reference frame.
The tool pose describes the position of the tool reference frame relative to the robot base reference frame. It focuses on the positional relationship between the tool and the working space and describes the position and orientation of the tool, such as robotic claw, and welding torch, when the robot performs a task.

Joint positions (JPs)

The waypoint will be represented by the joint positions of the robot.
Joint positions represents the rotation angles of each joint of the robot relative to its initial position or reference position. This description can represent the state of each joint in line with the hardware structure of the robot.

Target object pose

The waypoint will be represented by the X, Y, Z values, Euler angles, quaternions or rotation vectors in the object reference frame. It focuses on describing the position and orientation of the actual target objects that need to be operated or handled when the robot is performing tasks.
Target object pose is the pose of a certain point on the target object relative to the robot reference frame.

The method to determine the waypoint type is shown in the figure below.

detailed parameter img
Parameter Description

Edit pose

Enter quaternions or Euler angles directly to adjust the pose. You can also copy and paste the pose.

Transform pose

Transform the current pose to a new one. It is suitable for fine-tuning.

Rectify pose

Set the coordinate of P1, P2, and P3 according to the instruction, and then rectify the object pose with the three-point method. It is suitable for scenarios where the objects are tilted and their poses cannot be easily determined. For instance, when a cuboid tilts, its pose is hard to determine. Rectify pose can be used here to calculate the pose of the cuboid and therefore the robot can move to the rectified pose.

Edit JPs

Similar to Edit Pose above; edit the JPs by copying and pasting or editing the JPs in either radians or degrees, which can be switched based on the actual requirement.

move_type_icon1

Get the pose of the simulated robot.

move_type_icon2

Move the simulated robot to the specified waypoint.

move_type_icon3

Show all the joint position solutions to the current waypoint.

JPs Constraint

Definition of Terms
Shoulder

The relative positional relationship between the center of the wrist and Axis1. Axis1 refers to the rotation center axis of the robot axis 1.

Elbow

Relative positional relationship between the wrist and lower arm, which refers to the line connecting the rotation centers of the robot axis 2 and axis 3.

Wrist

Wrist refers to axis 5 of the robot. The negative wrist JPs suggests that the robot’s wrist can rotate in the negative direction.

detailedparameter13 1
Value list
Auto

There is no constraints on the motion of this joint. The optimal solution is the one in which each axis rotates the least.

Keep

Constrain the next JPs solution according to the current JPs status. For example, if the current JP of the axis 3 is positive, only solutions in which the JP of axis 3 is positive will be considered for the next waypoint.

Ahead

The wrist center is ahead of axis 1.

Behind

The wrist center is behind axis 1.

After clicking move_type_icon3, a window showing all the JPs solutions to the current pose will pop up. After clicking one of the solutions, the corresponding pose of the solution will be displayed in the 3D simulation area. Therefore, you will know the possible solutions under different constraints, as shown below.

  1. JPs constraint settings only apply to 6-axis robots. It is considered that 4-axis robots do not have abnormal shoulder, elbow, or wrist positions.

  2. Relative Move, Custom Pallet Pattern, and Predefined Pallet Pattern do not support JPs constraint settings. There are default JPs constraint settings for these Steps, that is, the statuses of the shoulder, elbow, and wrist will not change, and the robot’s motion does not cross solution systems (does not go through singularities).

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