intermediate4_realtime_joint_floating.cpp

This tutorial runs real-time joint floating with gentle velocity damping, gravity compensation, and soft protection against position limits. This example is ideal for verifying the system's whole-loop real-timeliness, accuracy of the robot dynamics model, and joint torque control performance. If everything works well, all joints should float smoothly.

Copyright

Copyright (C) 2016-2024 Flexiv Ltd. All Rights Reserved.

Author

Flexiv

 
#include <flexiv/rdk/robot.hpp>
#include <flexiv/rdk/scheduler.hpp>
#include <flexiv/rdk/utility.hpp>
#include <spdlog/spdlog.h>
 
#include <iostream>
#include <string>
#include <thread>
#include <atomic>
 
using namespace flexiv;
 
namespace {
const std::vector<double> kFloatingDamping = {10.0, 10.0, 5.0, 5.0, 1.0, 1.0, 1.0};
 
std::atomic<bool> g_stop_sched = {false};
}
 
void PrintHelp()
{
    // clang-format off
    std::cout << "Required arguments: [robot SN]" << std::endl;
    std::cout << "    robot SN: Serial number of the robot to connect to. "
                 "Remove any space, for example: Rizon4s-123456" << std::endl;
    std::cout << "Optional arguments: None" << std::endl;
    std::cout << std::endl;
    // clang-format on
}
 
void PeriodicTask(rdk::Robot& robot)
{
    try {
        // Monitor fault on the connected robot
        if (robot.fault()) {
            throw std::runtime_error(
                "PeriodicTask: Fault occurred on the connected robot, exiting ...");
        }
 
        // Set 0 joint torques
        std::vector<double> target_torque(robot.info().DoF);
 
        // Add some velocity damping
        for (size_t i = 0; i < target_torque.size(); ++i) {
            target_torque[i] += -kFloatingDamping[i] * robot.states().dtheta[i];
        }
 
        // Send target joint torque to RDK server, enable gravity compensation and joint limits soft
        // protection
        robot.StreamJointTorque(target_torque, true, true);
 
    } catch (const std::exception& e) {
        spdlog::error(e.what());
        g_stop_sched = true;
    }
}
 
int main(int argc, char* argv[])
{
    // Program Setup
    // =============================================================================================
    // Parse parameters
    if (argc < 2 || rdk::utility::ProgramArgsExistAny(argc, argv, {"-h", "--help"})) {
        PrintHelp();
        return 1;
    }
    // Serial number of the robot to connect to. Remove any space, for example: Rizon4s-123456
    std::string robot_sn = argv[1];
 
    // Print description
    spdlog::info(
        ">>> Tutorial description <<<\nThis tutorial runs real-time joint floating with gentle "
        "velocity damping, gravity compensation, and soft protection against position limits. This "
        "example is ideal for verifying the system's whole-loop real-timeliness, accuracy of the "
        "robot dynamics model, and joint torque control performance. If everything works well, all "
        "joints should float smoothly.\n");
 
    try {
        // RDK Initialization
        // =========================================================================================
        // Instantiate robot interface
        rdk::Robot robot(robot_sn);
 
        // Clear fault on the connected robot if any
        if (robot.fault()) {
            spdlog::warn("Fault occurred on the connected robot, trying to clear ...");
            // Try to clear the fault
            if (!robot.ClearFault()) {
                spdlog::error("Fault cannot be cleared, exiting ...");
                return 1;
            }
            spdlog::info("Fault on the connected robot is cleared");
        }
 
        // Enable the robot, make sure the E-stop is released before enabling
        spdlog::info("Enabling robot ...");
        robot.Enable();
 
        // Wait for the robot to become operational
        while (!robot.operational()) {
            std::this_thread::sleep_for(std::chrono::seconds(1));
        }
        spdlog::info("Robot is now operational");
 
        // Move robot to home pose
        spdlog::info("Moving to home pose");
        robot.SwitchMode(rdk::Mode::NRT_PLAN_EXECUTION);
        robot.ExecutePlan("PLAN-Home");
        // Wait for the plan to finish
        while (robot.busy()) {
            std::this_thread::sleep_for(std::chrono::seconds(1));
        }
 
        // Real-time Joint Floating
        // =========================================================================================
        // Switch to real-time joint torque control mode
        robot.SwitchMode(rdk::Mode::RT_JOINT_TORQUE);
 
        // Create real-time scheduler to run periodic tasks
        rdk::Scheduler scheduler;
        // Add periodic task with 1ms interval and highest applicable priority
        scheduler.AddTask(
            std::bind(PeriodicTask, std::ref(robot)), "HP periodic", 1, scheduler.max_priority());
        // Start all added tasks
        scheduler.Start();
 
        // Block and wait for signal to stop scheduler tasks
        while (!g_stop_sched) {
            std::this_thread::sleep_for(std::chrono::milliseconds(1));
        }
        // Received signal to stop scheduler tasks
        scheduler.Stop();
 
    } catch (const std::exception& e) {
        spdlog::error(e.what());
        return 1;
    }
 
    return 0;
}