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Update example documentation for ur_driver example
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‎doc/examples/ur_driver.rst‎

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Original file line numberDiff line numberDiff line change
@@ -2,13 +2,72 @@
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.. _example-driver:
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5-
Example driver TODO
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Example driver
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==============
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In the ``examples`` subfolder you will find a minimal example of a running driver. It starts an
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instance of the ``UrDriver`` class and prints the RTDE values read from the controller. To run it make
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sure to
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* have an instance of a robot controller / URSim running at the configured IP address (or adapt the
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address to your needs)
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* run it from the package's main folder (the one where this README.md file is stored), as for
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* run it from the package's main folder (the one where the README.md file is stored), as for
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simplicity reasons it doesn't use any sophisticated method to locate the required files.
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This page will walk you through the `full_driver.cpp
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<https://github.com/UniversalRobots/Universal_Robots_Client_Library/blob/master/examples/full_driver.cpp>`_
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example.
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Initialization
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--------------
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At first, we create a ``UrDriver`` object giving it the robot's IP address, script file and RTDE
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recipes.
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.. literalinclude:: ../../examples/full_driver.cpp
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:language: c++
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:caption: examples/full_driver.cpp
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:linenos:
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:lineno-match:
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:start-at: std::unique_ptr<ToolCommSetup> tool_comm_setup;
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:end-at: std::move(tool_comm_setup)
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Robot control loop
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------------------
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This example reads the robot's joint positions, increments / decrements the 5th axis and sends that
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back as a joint command for the next cycle. This way, the robot will move its wrist first until a
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positive limit and then back to 0.
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To read the joint data, the driver's RTDE client is used:
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.. literalinclude:: ../../examples/full_driver.cpp
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:language: c++
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:caption: examples/full_driver.cpp
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:linenos:
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:lineno-match:
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:start-at: // Once RTDE communication is started
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:end-before: // Open loop control
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The first read operation will initialize the target buffer with the current robot position. Next,
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the target joint configuration is calculated:
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.. literalinclude:: ../../examples/full_driver.cpp
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:language: c++
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:caption: examples/full_driver.cpp
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:linenos:
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:lineno-match:
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:start-at: // Open loop control
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:end-at: joint_target[5] += increment
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To send the control command, the robot's :ref:`reverse_interface` is used via the
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``writeJointCommand()`` function:
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.. literalinclude:: ../../examples/full_driver.cpp
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:language: c++
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:caption: examples/full_driver.cpp
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:linenos:
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:lineno-match:
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:start-at: // Setting the RobotReceiveTimeout
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:end-before: URCL_LOG_DEBUG("data_pkg:\n%s", data_pkg->toString().c_str());

‎examples/full_driver.cpp‎

Lines changed: 43 additions & 47 deletions
Original file line numberDiff line numberDiff line change
@@ -43,7 +43,6 @@ const std::string DEFAULT_ROBOT_IP = "192.168.56.101";
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const std::string SCRIPT_FILE = "resources/external_control.urscript";
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const std::string OUTPUT_RECIPE = "examples/resources/rtde_output_recipe.txt";
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const std::string INPUT_RECIPE = "examples/resources/rtde_input_recipe.txt";
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const std::string CALIBRATION_CHECKSUM = "calib_12788084448423163542";
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std::unique_ptr<UrDriver> g_my_driver;
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std::unique_ptr<DashboardClient> g_my_dashboard;
@@ -109,13 +108,7 @@ int main(int argc, char* argv[])
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std::unique_ptr<ToolCommSetup> tool_comm_setup;
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const bool headless = true;
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g_my_driver.reset(new UrDriver(robot_ip, SCRIPT_FILE, OUTPUT_RECIPE, INPUT_RECIPE, &handleRobotProgramState, headless,
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std::move(tool_comm_setup), CALIBRATION_CHECKSUM));
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// Once RTDE communication is started, we have to make sure to read from the interface buffer, as
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// otherwise we will get pipeline overflows. Therefor, do this directly before starting your main
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// loop.
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g_my_driver->startRTDECommunication();
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std::move(tool_comm_setup)));
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// Increment depends on robot version
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double increment_constant = 0.0005;
@@ -130,62 +123,65 @@ int main(int argc, char* argv[])
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bool passed_positive_part = false;
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URCL_LOG_INFO("Start moving the robot");
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urcl::vector6d_t joint_target = { 0, 0, 0, 0, 0, 0 };
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// Once RTDE communication is started, we have to make sure to read from the interface buffer, as
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// otherwise we will get pipeline overflows. Therefor, do this directly before starting your main
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// loop.
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g_my_driver->startRTDECommunication();
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while (!(passed_positive_part && passed_negative_part))
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{
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// Read latest RTDE package. This will block for a hard-coded timeout (see UrDriver), so the
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// robot will effectively be in charge of setting the frequency of this loop.
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// In a real-world application this thread should be scheduled with real-time priority in order
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// to ensure that this is called in time.
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std::unique_ptr<rtde_interface::DataPackage> data_pkg = g_my_driver->getDataPackage();
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if (data_pkg)
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if (!data_pkg)
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{
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// Read current joint positions from robot data
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if (!data_pkg->getData("actual_q", g_joint_positions))
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{
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// This throwing should never happen unless misconfigured
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std::string error_msg = "Did not find 'actual_q' in data sent from robot. This should not happen!";
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throw std::runtime_error(error_msg);
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}
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URCL_LOG_WARN("Could not get fresh data package from robot");
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return 1;
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}
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// Read current joint positions from robot data
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if (!data_pkg->getData("actual_q", g_joint_positions))
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{
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// This throwing should never happen unless misconfigured
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std::string error_msg = "Did not find 'actual_q' in data sent from robot. This should not happen!";
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throw std::runtime_error(error_msg);
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}
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if (first_pass)
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{
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joint_target = g_joint_positions;
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first_pass = false;
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}
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if (first_pass)
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{
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joint_target = g_joint_positions;
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first_pass = false;
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}
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// Open loop control. The target is incremented with a constant each control loop
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if (passed_positive_part == false)
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{
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increment = increment_constant;
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if (g_joint_positions[5] >= 2)
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{
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passed_positive_part = true;
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}
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}
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else if (passed_negative_part == false)
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// Open loop control. The target is incremented with a constant each control loop
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if (passed_positive_part == false)
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{
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increment = increment_constant;
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if (g_joint_positions[5] >= 2)
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{
167-
increment = -increment_constant;
168-
if (g_joint_positions[5] <= 0)
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{
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passed_negative_part = true;
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}
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passed_positive_part = true;
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}
173-
joint_target[5] += increment;
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// Setting the RobotReceiveTimeout time is for example purposes only. This will make the example running more
175-
// reliable on non-realtime systems. Use with caution in productive applications.
176-
bool ret = g_my_driver->writeJointCommand(joint_target, comm::ControlMode::MODE_SERVOJ,
177-
RobotReceiveTimeout::millisec(100));
178-
if (!ret)
165+
}
166+
else if (passed_negative_part == false)
167+
{
168+
increment = -increment_constant;
169+
if (g_joint_positions[5] <= 0)
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{
180-
URCL_LOG_ERROR("Could not send joint command. Is the robot in remote control?");
181-
return 1;
171+
passed_negative_part = true;
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}
183-
URCL_LOG_DEBUG("data_pkg:\n%s", data_pkg->toString().c_str());
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}
185-
else
174+
joint_target[5] += increment;
175+
// Setting the RobotReceiveTimeout time is for example purposes only. This will make the example running more
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// reliable on non-realtime systems. Use with caution in productive applications.
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bool ret = g_my_driver->writeJointCommand(joint_target, comm::ControlMode::MODE_SERVOJ,
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RobotReceiveTimeout::millisec(100));
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if (!ret)
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{
187-
URCL_LOG_WARN("Could not get fresh data package from robot");
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URCL_LOG_ERROR("Could not send joint command. Is the robot in remote control?");
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return 1;
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}
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URCL_LOG_DEBUG("data_pkg:\n%s", data_pkg->toString().c_str());
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}
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g_my_driver->stopControl();
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URCL_LOG_INFO("Movement done");

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