Positions and torque

This page shows how to read the position of a Yaskawa Motoman robot through the Ethernet Server: joint pulses, Cartesian position in the base, robot, user or tool frame, posture, torque and encoder temperatures. It covers the YRC1000 and YRC1000micro controllers.

Read the position

var robot = new YaskawaRobot();
robot.Connect(parameters);
// Joints, in encoder pulses
HostControlJointPositionData joints = robot.EServer.GetRobotJointPosition();
Console.WriteLine($"S={joints.S} L={joints.L} U={joints.U} R={joints.R} B={joints.B} T={joints.T}");

// Cartesian position in the base frame (default), mm and degrees
HostControlCartesianPositionData tcp = robot.EServer.GetRobotCartesianPosition();
Console.WriteLine($"X={tcp.X} Y={tcp.Y} Z={tcp.Z} Rx={tcp.Rx} Ry={tcp.Ry} Rz={tcp.Rz}");

// Posture of the arm and tool of the position
Console.WriteLine($"Front: {tcp.IsFront}, upper arm: {tcp.IsUpperArm}, flip: {tcp.IsFlip}, tool: {tcp.ToolNumber}");

// Same position in the robot frame, or in a user frame
var inRobot = robot.EServer.GetRobotCartesianPosition(HostControlCoordinateSystem.Robot);
var inUser1 = robot.EServer.GetRobotCartesianPosition(HostControlCoordinateSystem.User1);

// With the external axes (Re, Axis8...)
var withExternal = robot.EServer.GetRobotCartesianPosition(HostControlCoordinateSystem.Base, true);
robot.Disconnect();
}

Joint position

GetRobotJointPosition() reads the encoder pulses of each axis: S, L, U, R, B, T, then E and Axis8 to Axis12 for the external axes. Axes gives the same values in one array of 12 values.

The number of pulses per degree depends on the axis and on the robot model. To compute a position from joint angles, see Offline kinematics.

Cartesian position

GetRobotCartesianPosition(coordinateSystem, includeExternalAxes) reads the position of the tool center point, in mm and degrees.

ToolNumber gives the tool of the position. On a 7-axis robot, Re holds the elbow angle.

With includeExternalAxes set to true, Axis8 to Axis12 also hold the positions of the external axes. On a 6-axis robot, Re holds the 7th axis.

On a robot without base axis, the base frame and the robot frame give the same values.

Posture

The same Cartesian position can be reached with several postures of the arm. Type holds the posture, and these properties decode it:

Pass the Type to MoveJoint and MoveLinear to send the robot back to a position with the same posture. See Motion.

Torque and encoder temperatures

var robot = new YaskawaRobot();
robot.Connect(parameters);
// Torque of each axis, in percent of the rated torque
HostControlTorqueData torque = robot.EServer.GetTorque();
HostControlTorqueData maxTorque = robot.EServer.GetMaxTorque();

// Temperature of the encoder of each axis, in degrees Celsius
HostControlEncoderTemperatureData temperatures = robot.EServer.GetEncoderTemperature();

for (int axis = 0; axis < 6; axis++)
    Console.WriteLine($"Axis {axis + 1}: {torque.Values[axis]} % (max {maxTorque.Values[axis]} %), {temperatures.Values[axis]} C");
robot.Disconnect();
}

Each array has 12 values: the 6 axes of the robot, then the external axes. With the servo off, the torques are 0. A log of the encoder temperatures over a shift shows which axis heats up in a cycle.

Control group and task

GetControlGroup() reads the robot group, the station group and the task selected for the next commands. SetControlGroup(robotGroup, stationGroup) and SetTask(task) change them, on a controller with several robots, stations or tasks.

Reference

// Reads the current control group configuration. Returns robot group bits, station group bits, and current task number.
HostControlGroupData GetControlGroup();

// Reads the encoder temperature values of all robot axes.
HostControlEncoderTemperatureData GetEncoderTemperature();

// Reads the maximum torque values of all robot axes. Returns values as a percentage of the maximum rated torque.
HostControlTorqueData GetMaxTorque();

// Reads the current robot Cartesian position (TCP position and orientation). Coordinates are returned in millimeters for X, Y, Z and degrees for Rx, Ry, Rz.
HostControlCartesianPositionData GetRobotCartesianPosition(HostControlCoordinateSystem coordinateSystem = HostControlCoordinateSystem.Base, bool includeExternalAxes = false);

// Reads the current robot joint position in pulse (encoder) values. Returns raw pulse values for all robot axes (S, L, U, R, B, T, and external axes).
HostControlJointPositionData GetRobotJointPosition();

// Reads the current torque values of all robot axes. Returns values as a percentage of the maximum rated torque.
HostControlTorqueData GetTorque();

// Reads user coordinate frame data from the robot controller. Returns the three reference points (ORG, XX, XY) defining the user coordinate system.
HostControlUserFrameData GetUserFrame(int userCoordinateNumber);

// Changes the control group selection.
HostControlResponse SetControlGroup(int robotGroup, int stationGroup);

// Changes the current task selection.
HostControlResponse SetTask(int task);

// Writes user coordinate frame data to the robot controller. Defines a user coordinate system using three reference points (ORG, XX, XY).
HostControlResponse SetUserFrame(int userCoordinateNumber, HostControlUserFrameData frame);

What to read next

• Get the robot position: which protocol and which method to choose.
• Motion: send the robot to a position.