Allow updating robot gravity

include/ur_client_library/control/script_command_interface.h

@@ -91,6 +91,16 @@ class ScriptCommandInterface : public ReverseInterface
    */
   bool setPayload(const double mass, const vector3d_t* cog);
 
+  /*!
+   * \brief Set the gravity vector
+   *
+   * \param gravity Gravity, a vector [x, y, z] specifying the gravity vector (pointing towards
+   * the Earth's center) given in the robot's base frame
+   *
+   * \returns True, if the write was performed successfully, false otherwise.
+   */
+  bool setGravity(const vector3d_t* gravity);
+
   /*!
    * \brief Set the tool voltage.
    *
@@ -227,6 +237,7 @@ class ScriptCommandInterface : public ReverseInterface
     END_TOOL_CONTACT = 6,           ///< End detecting tool contact
     SET_FRICTION_COMPENSATION = 7,  ///< Set friction compensation
     FT_RTDE_INPUT_ENABLE = 8,       ///< Enable FT RTDE input
+    SET_GRAVITY = 9,                ///< Set gravity vector
   };
 
   /*!

include/ur_client_library/ur/ur_driver.h

@@ -596,6 +596,17 @@ class UrDriver
    */
   bool setPayload(const float mass, const vector3d_t& cog);
 
+  /*!
+   * \brief Set the gravity vector. Note: It requires the external control script to be running or
+   * the robot to be in headless mode.
+   *
+   * \param gravity Gravity, a vector [x, y, z] specifying the gravity vector (pointing towards
+   * the Earth's center) given in the robot's base frame
+   *
+   * \returns True on successful write.
+   */
+  bool setGravity(const vector3d_t& gravity);
+
   /*!
    * \brief Set the tool voltage. Note: It requires the external control script to be running or the robot to be in
    * headless mode.

resources/external_control.urscript

@@ -56,6 +56,7 @@ START_TOOL_CONTACT = 5
 END_TOOL_CONTACT = 6
 SET_FRICTION_COMPENSATION = 7
 FT_RTDE_INPUT_ENABLE = 8
+SET_GRAVITY = 9
 SCRIPT_COMMAND_DATA_DIMENSION = 28
 
 FREEDRIVE_MODE_START = 1
@@ -756,6 +757,9 @@ thread script_commands():
         mass = raw_command[2] / MULT_jointstate
         cog = [raw_command[3] / MULT_jointstate, raw_command[4] / MULT_jointstate, raw_command[5] / MULT_jointstate]
         set_payload(mass, cog)
+      elif command == SET_GRAVITY:
+        gravity = [raw_command[2] / MULT_jointstate, raw_command[3] / MULT_jointstate, raw_command[4] / MULT_jointstate]
+        set_gravity(gravity)
       elif command == SET_TOOL_VOLTAGE:
         tool_voltage = raw_command[2] / MULT_jointstate
         set_tool_voltage(tool_voltage)

src/control/script_command_interface.cpp

@@ -89,6 +89,31 @@ bool ScriptCommandInterface::setPayload(const double mass, const vector3d_t* cog
   return server_.write(client_fd_, buffer, sizeof(buffer), written);
 }
 
+bool ScriptCommandInterface::setGravity(const vector3d_t* gravity)
+{
+  const int message_length = 4;
+  uint8_t buffer[sizeof(int32_t) * MAX_MESSAGE_LENGTH];
+  uint8_t* b_pos = buffer;
+  int32_t val = htobe32(toUnderlying(ScriptCommand::SET_GRAVITY));
+  b_pos += append(b_pos, val);
+
+  for (auto const& grav_component : *gravity)
+  {
+    val = htobe32(static_cast<int32_t>(round(grav_component * MULT_JOINTSTATE)));
+    b_pos += append(b_pos, val);
+  }
+
+  // writing zeros to allow usage with other script commands
+  for (size_t i = message_length; i < MAX_MESSAGE_LENGTH; i++)
+  {
+    val = htobe32(0);
+    b_pos += append(b_pos, val);
+  }
+  size_t written;
+
+  return server_.write(client_fd_, buffer, sizeof(buffer), written);
+}
+
 bool ScriptCommandInterface::setToolVoltage(const ToolVoltage voltage)
 {
   const int message_length = 2;

src/ur/ur_driver.cpp

@@ -298,6 +298,26 @@ bool UrDriver::setPayload(const float mass, const vector3d_t& cog)
   }
 }
 
+bool UrDriver::setGravity(const vector3d_t& gravity)
+{
+  if (script_command_interface_->clientConnected())
+  {
+    return script_command_interface_->setGravity(&gravity);
+  }
+  else
+  {
+    URCL_LOG_WARN("Script command interface is not running. Falling back to sending plain script code. On e-Series "
+                  "robots this will only work, if the robot is in remote_control mode.");
+    std::stringstream cmd;
+    cmd.imbue(std::locale::classic());  // Make sure, decimal divider is actually '.'
+    cmd << "sec setup():" << std::endl
+        << " set_gravity([" << gravity[0] << ", " << gravity[1] << ", " << gravity[2] << "])" << std::endl
+        << "end";
+    return sendScript(cmd.str());
+    return true;
+  }
+}
+
 bool UrDriver::setToolVoltage(const ToolVoltage voltage)
 {
   // Test that the tool voltage is either 0, 12 or 24.