Motion planner overview

The Motion module creates smooth robot trajectories that respect velocity, acceleration and jerk limits. It works offline, without robot connection, and its trajectories can be sent with Stream Motion, used in a simulation, or checked before use.

Motions are described as in a TP program: joint (J), linear (L) and circular (C) motions, with a speed and a FINE, CNT or CR termination. The module also creates splines through points, geometric shapes, and trajectories from your own positions.

The planner is in the UnderAutomation.Robotics.Motion namespace. This namespace is the same in all UnderAutomation robot SDKs, so the same code can plan trajectories for other robot brands. The FanucMotion class of UnderAutomation.Fanuc.Motion converts FANUC positions, FINE, CNT and CR terminations and I/O to the types of the planner.

Quick start

    new double[] { 1125, 1125, 1687, 2530, 1265, 2530 });
var cartesianLimits = new CartesianLimits(500, 2000, 10000, 90, 360, 1800);
var planner = new MotionPlanner(jointLimits, cartesianLimits);

// Joint motions, as J instructions of a TP program
var home = new JointValues(0, 0, 0, 0, -90, 0);
var pick = new JointValues(30, 20, -10, 0, -70, 30);
Trajectory trajectory = planner.CreateJointPath(home)
    .MoveJoint(pick, 50, FanucMotion.Cnt(100))   // 50% speed, CNT100
    .MoveJoint(home, 50, FanucMotion.Fine())
    .Build();

Console.WriteLine($"Duration: {trajectory.Duration:0.000} s");

// Position at any time, or one position per communication cycle
JointValues middle = trajectory.GetJoints(trajectory.Duration / 2);
JointValues[] samples = trajectory.SampleJoints(0.008);

// FANUC joint position, when needed
JointsPosition fanucMiddle = FanucMotion.ToJointsPosition(middle);

// Velocity, acceleration and jerk of each axis, computed as the robot does
TrajectoryReport report = trajectory.Check(jointLimits, 0.008, false);
Console.WriteLine(report.IsValid);
}
}

Try it in the demo application

The demo application (Windows) has a Stream Motion page with two buttons that build trajectories with the motion planner and send them to the robot with Stream Motion.

• Joint demo uses a JointPathBuilder: J1 moves to +amplitude, then to -amplitude with a Cnt termination between the two moves, then back to the start with Fine.
• Cartesian demo uses a CartesianPathBuilder: a horizontal circle of the given radius, starting and ending at the current position.

Change the amplitude, the radius or the speed and send the demo again: the duration of the resulting trajectory is shown in the log, and the joint and Cartesian positions update in real time while the robot moves.

The C# source of this page is in the StreamMotionControl.cs file of the Fanuc.NET repository.

Main concepts

All motions use jerk limited profiles: the acceleration changes progressively, which gives smooth motions and avoids the jerk alarms of the robot. 100% speed means the velocity limits, and the acceleration percentage (ACC) scales the acceleration and the jerk.

What do you want to do?

Units and conventions

• Joint positions in degrees (mm for linear axes), Cartesian positions in mm, angles in degrees.
• Velocities per second, accelerations per second squared, jerks per second cubed.
• The W, P, R angles of FANUC use the fixed XYZ convention: CartesianPose.FromEuler(x, y, z, w, p, r, EulerConvention.FixedXYZ) gives the same pose as FanucMotion.ToCartesianPose(new XYZWPRPosition(x, y, z, w, p, r)).
• FanucMotion.SampleCartesian() gives FANUC positions whose W, P, R angles stay continuous: an angle can go beyond 180 degrees instead of jumping to -180.

API reference