Get the robot position

This article shows how to read the position of a Yaskawa Motoman robot from a PC, in C# or Python. It gives a complete program that reads the Cartesian position and the joint pulses, then polls the position 10 times per second.

Prerequisites

• The SDK is connected to the controller: see Connect to your robot.
• Nothing else: reading the position works in teach mode and in play mode, without the remote mode.

Which method to choose

Example

using UnderAutomation.Yaskawa;
using UnderAutomation.Yaskawa.HighSpeedEServer;

public class HowToGetPosition
{
    static void Main()
    {
        
        var robot = new YaskawaRobot();
        robot.Connect("192.168.0.1");

        // Tool center point in the robot frame: mm and degrees
        RobotPositionCartesianData tcp = robot.HighSpeedEServer.GetRobotCartesianPosition();
        Console.WriteLine($"X={tcp.X:F3} Y={tcp.Y:F3} Z={tcp.Z:F3} Rx={tcp.Rx:F4} Ry={tcp.Ry:F4} Rz={tcp.Rz:F4}");
        Console.WriteLine($"Tool {tcp.ToolNumber}, posture {tcp.Form}");

        // Joints: encoder pulses, one value per axis
        RobotPositionIntData joints = robot.HighSpeedEServer.GetRobotJointPosition();
        Console.WriteLine("Pulses: " + string.Join(", ", joints.Axes));

        // Poll the position 10 times per second for 5 seconds
        for (int i = 0; i < 50; i++)
        {
            tcp = robot.HighSpeedEServer.GetRobotCartesianPosition();
            Console.WriteLine($"{DateTime.Now:HH:mm:ss.fff} X={tcp.X:F1} Y={tcp.Y:F1} Z={tcp.Z:F1}");
            Thread.Sleep(100);
        }

        robot.Disconnect();
        
    }
}

The program:

1. reads the Cartesian position of the tool, with its tool number and its posture;
2. reads the pulses of each axis;
3. reads the Cartesian position every 100 ms for 5 seconds.

Polling period

Each read is one request and one answer over the network. On a local network, a request takes a few milliseconds: measure it on your cell before you choose the period. Read only what you need in a loop: the Cartesian position alone is one request, the position and the joints are two.

Troubleshooting

• The values are all 0: check the control group and the number of axes with GetConfigurationInformation.
• The Cartesian position differs from the pendant: compare the frame and the tool. DataType and ToolNumber give the ones of the answer.
• The first call fails after a pause: a SocketException means that the controller did not answer before DataTimeoutMilliseconds. Check the network, then call again.

What to read next

• Positions: the reference of the position methods.
• Move the robot from a PC.