Positions

This page shows how to read the position of a Yaskawa Motoman robot with the SDK: the Cartesian position of the tool, the joint positions, the position error and the torque, for the robot, a station or base axes. All these methods only read: they work in any mode.

Cartesian position

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

var robot = new YaskawaRobot();
robot.Connect("192.168.0.1");
RobotPositionCartesianData position = robot.HighSpeedEServer.GetRobotCartesianPosition();

// Tool center point in mm, orientation in degrees
Console.WriteLine($"X={position.X} Y={position.Y} Z={position.Z}");
Console.WriteLine($"Rx={position.Rx} Ry={position.Ry} Rz={position.Rz}");

// Frame, tool and posture of the position
Console.WriteLine($"{position.DataType}, tool {position.ToolNumber}, user frame {position.UserCoordinateNumber}");
Console.WriteLine(position.Form);
robot.Disconnect();
}

Keep the Form of a position when you send the robot back to it: the same Cartesian position can be reached with several postures.

Joint positions

GetRobotJointPosition() reads the position of each axis of the first robot, in encoder pulses.

var robot = new YaskawaRobot();
robot.Connect("192.168.0.1");
RobotPositionIntData joints = robot.HighSpeedEServer.GetRobotJointPosition();

// One value per axis, in encoder pulses. Index 0 is the S axis
int[] pulses = joints.Axes;
Console.WriteLine(string.Join(", ", pulses));

// The same values, axis by axis
Console.WriteLine($"S={joints.Axis1} L={joints.Axis2} U={joints.Axis3} R={joints.Axis4} B={joints.Axis5} T={joints.Axis6}");
robot.Disconnect();
}

Axes has 8 values. On a 6 axis robot, the indexes 0 to 5 are the axes S, L, U, R, B and T, and the indexes 6 and 7 are 0. Axis1 to Axis8 give the same values. Axis names gives the axes of your robot.

The pulses are the unit of the controller for the joints. The number of pulses per degree depends on the axis and on the robot model: it is a parameter of the controller. Send the pulses back to MoveJoints as they are, without conversion.

Position error and torque

GetPositionError() reads the difference between the command and the feedback of each axis, in pulses. GetTorque() reads the torque of each axis, in percent of the rated torque.

var robot = new YaskawaRobot();
robot.Connect("192.168.0.1");
// Difference between the command and the feedback of each axis, in pulses
RobotAxisIntData error = robot.HighSpeedEServer.GetPositionError();
Console.WriteLine(string.Join(", ", error.Axes));

// Torque of each axis, in percent of the rated torque
RobotAxisIntData torque = robot.HighSpeedEServer.GetTorque();
Console.WriteLine(string.Join(", ", torque.Axes));
robot.Disconnect();
}

Read them in a loop during a move to see the load of each axis, or to detect a collision or a wear in your application.

In Python 2.2.0, these two methods take the control group, as in the code above.

Other control groups

A controller can drive several robots, base axes (travel tracks) and stations (positioners). GetRobotPosition(group), GetPositionError(group) and GetTorque(group) read the axes of one control group.

var robot = new YaskawaRobot();
robot.Connect("192.168.0.1");
// Second robot of the controller, in pulses
var r2 = new RobotControlGroup(ControlGroup.RobotPulseValue, 2);
RobotPositionIntData r2Joints = robot.HighSpeedEServer.GetRobotPosition(r2);

// First base axis group (travel track), in pulses
var b1 = new RobotControlGroup(ControlGroup.BasePulseValue, 1);
RobotPositionIntData b1Axes = robot.HighSpeedEServer.GetRobotPosition(b1);

// Torque of the base axes
RobotAxisIntData b1Torque = robot.HighSpeedEServer.GetTorque(b1);
robot.Disconnect();
}

GetRobotPosition returns the raw values of the controller. With a Cartesian group, Axes holds X, Y, Z in micrometers and Rx, Ry, Rz in 1/10000 degree. GetRobotCartesianPosition() does this conversion for the first robot.

RobotControlGroup.DefaultRobotCartesian and RobotControlGroup.DefaultRobotPulse are the groups of the first robot, in .NET.

Try it in the demo application

Everything on this page can be tried without writing code, in the Current position page of the demo application.

The demo application is open source. The C# source of this page is PositionControl.cs.

Reference

// Reads the position error (difference between commanded and actual position) for the default robot. Values indicate servo tracking error in pulse units.
RobotAxisIntData GetPositionError();

// Reads the position error for a specified control group. Position error indicates the difference between commanded and actual position.
RobotAxisIntData GetPositionError(RobotControlGroup type);

// 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.
RobotPositionCartesianData GetRobotCartesianPosition();

// Reads the current robot joint position in pulse (encoder) values. Returns raw pulse values for all robot axes.
RobotPositionIntData GetRobotJointPosition();

// Reads position data for a specified control group. Can read robot, base, or station position data depending on the control group specified.
RobotPositionIntData GetRobotPosition(RobotControlGroup type);

// Reads the current torque values for the default robot's servo motors. Torque values indicate motor load as a percentage of rated torque.
RobotAxisIntData GetTorque();

// Reads the current torque values for a specified control group's servo motors. Torque values indicate motor load as a percentage of rated torque.
RobotAxisIntData GetTorque(RobotControlGroup type);