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kuka_simulation.cc
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kuka_simulation.cc
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/// @file
///
/// Implements a simulation of the KUKA iiwa arm. Like the driver for the
/// physical arm, this simulation communicates over LCM using lcmt_iiwa_status
/// and lcmt_iiwa_command messages. It is intended to be a be a direct
/// replacement for the KUKA iiwa driver and the actual robot hardware.
#include <memory>
#include <gflags/gflags.h>
#include "drake/common/drake_assert.h"
#include "drake/common/find_resource.h"
#include "drake/examples/kuka_iiwa_arm/iiwa_common.h"
#include "drake/examples/kuka_iiwa_arm/iiwa_lcm.h"
#include "drake/examples/kuka_iiwa_arm/kuka_torque_controller.h"
#include "drake/geometry/scene_graph.h"
#include "drake/lcmt_iiwa_command.hpp"
#include "drake/lcmt_iiwa_status.hpp"
#include "drake/multibody/parsing/parser.h"
#include "drake/systems/analysis/simulator.h"
#include "drake/systems/controllers/inverse_dynamics_controller.h"
#include "drake/systems/controllers/state_feedback_controller_interface.h"
#include "drake/systems/framework/diagram.h"
#include "drake/systems/framework/diagram_builder.h"
#include "drake/systems/framework/leaf_system.h"
#include "drake/systems/lcm/lcm_interface_system.h"
#include "drake/systems/lcm/lcm_publisher_system.h"
#include "drake/systems/lcm/lcm_subscriber_system.h"
#include "drake/systems/primitives/demultiplexer.h"
#include "drake/systems/primitives/discrete_derivative.h"
#include "drake/visualization/visualization_config_functions.h"
DEFINE_double(simulation_sec, std::numeric_limits<double>::infinity(),
"Number of seconds to simulate.");
DEFINE_string(urdf, "", "Name of urdf to load");
DEFINE_double(target_realtime_rate, 1.0,
"Playback speed. See documentation for "
"Simulator::set_target_realtime_rate() for details.");
DEFINE_bool(torque_control, false, "Simulate using torque control mode.");
DEFINE_double(sim_dt, 3e-3,
"The time step to use for MultibodyPlant model "
"discretization.");
namespace drake {
namespace examples {
namespace kuka_iiwa_arm {
namespace {
using multibody::MultibodyPlant;
using systems::Context;
using systems::Demultiplexer;
using systems::StateInterpolatorWithDiscreteDerivative;
using systems::Simulator;
using systems::controllers::InverseDynamicsController;
using systems::controllers::StateFeedbackControllerInterface;
int DoMain() {
systems::DiagramBuilder<double> builder;
// Adds a plant.
auto [plant, scene_graph] = multibody::AddMultibodyPlantSceneGraph(
&builder, FLAGS_sim_dt);
const char* kModelPath =
"drake/manipulation/models/iiwa_description/"
"urdf/iiwa14_polytope_collision.urdf";
const std::string urdf =
(!FLAGS_urdf.empty() ? FLAGS_urdf : FindResourceOrThrow(kModelPath));
auto iiwa_instance =
multibody::Parser(&plant, &scene_graph).AddModels(urdf).at(0);
plant.WeldFrames(plant.world_frame(), plant.GetFrameByName("base"));
plant.Finalize();
// TODO(sammy-tri) Add a floor.
// Creates and adds LCM publisher for visualization.
auto lcm = builder.AddSystem<systems::lcm::LcmInterfaceSystem>();
visualization::ApplyVisualizationConfig({}, &builder, nullptr, nullptr,
nullptr, nullptr, lcm);
// Since we welded the model to the world above, the only remaining joints
// should be those in the arm.
const int num_joints = plant.num_positions();
DRAKE_DEMAND(num_joints % kIiwaArmNumJoints == 0);
const int num_iiwa = num_joints / kIiwaArmNumJoints;
// Adds a iiwa controller.
StateFeedbackControllerInterface<double>* controller = nullptr;
if (FLAGS_torque_control) {
VectorX<double> stiffness, damping_ratio;
SetTorqueControlledIiwaGains(&stiffness, &damping_ratio);
stiffness = stiffness.replicate(num_iiwa, 1).eval();
damping_ratio = damping_ratio.replicate(num_iiwa, 1).eval();
controller = builder.AddSystem<KukaTorqueController<double>>(
plant, stiffness, damping_ratio);
} else {
VectorX<double> iiwa_kp, iiwa_kd, iiwa_ki;
SetPositionControlledIiwaGains(&iiwa_kp, &iiwa_ki, &iiwa_kd);
iiwa_kp = iiwa_kp.replicate(num_iiwa, 1).eval();
iiwa_kd = iiwa_kd.replicate(num_iiwa, 1).eval();
iiwa_ki = iiwa_ki.replicate(num_iiwa, 1).eval();
controller = builder.AddSystem<InverseDynamicsController<double>>(
plant, iiwa_kp, iiwa_ki, iiwa_kd,
false /* without feedforward acceleration */);
}
// Create the command subscriber and status publisher.
auto command_sub = builder.AddSystem(
systems::lcm::LcmSubscriberSystem::Make<drake::lcmt_iiwa_command>(
"IIWA_COMMAND", lcm));
command_sub->set_name("command_subscriber");
auto command_receiver =
builder.AddSystem<IiwaCommandReceiver>(num_joints);
command_receiver->set_name("command_receiver");
auto plant_state_demux = builder.AddSystem<Demultiplexer>(
2 * num_joints, num_joints);
plant_state_demux->set_name("plant_state_demux");
auto desired_state_from_position = builder.AddSystem<
StateInterpolatorWithDiscreteDerivative>(
num_joints, kIiwaLcmStatusPeriod,
true /* suppress_initial_transient */);
desired_state_from_position->set_name("desired_state_from_position");
auto status_pub = builder.AddSystem(
systems::lcm::LcmPublisherSystem::Make<lcmt_iiwa_status>(
"IIWA_STATUS", lcm, kIiwaLcmStatusPeriod /* publish period */));
status_pub->set_name("status_publisher");
auto status_sender = builder.AddSystem<IiwaStatusSender>(num_joints);
status_sender->set_name("status_sender");
builder.Connect(command_sub->get_output_port(),
command_receiver->get_message_input_port());
builder.Connect(plant_state_demux->get_output_port(0),
command_receiver->get_position_measured_input_port());
builder.Connect(command_receiver->get_commanded_position_output_port(),
desired_state_from_position->get_input_port());
builder.Connect(desired_state_from_position->get_output_port(),
controller->get_input_port_desired_state());
builder.Connect(plant.get_state_output_port(iiwa_instance),
plant_state_demux->get_input_port(0));
builder.Connect(plant_state_demux->get_output_port(0),
status_sender->get_position_measured_input_port());
builder.Connect(plant_state_demux->get_output_port(1),
status_sender->get_velocity_estimated_input_port());
builder.Connect(command_receiver->get_commanded_position_output_port(),
status_sender->get_position_commanded_input_port());
builder.Connect(plant.get_state_output_port(),
controller->get_input_port_estimated_state());
builder.Connect(controller->get_output_port_control(),
plant.get_actuation_input_port(iiwa_instance));
builder.Connect(controller->get_output_port_control(),
status_sender->get_torque_commanded_input_port());
builder.Connect(controller->get_output_port_control(),
status_sender->get_torque_measured_input_port());
// TODO(sammy-tri) Add a low-pass filter for simulated external torques.
// This would slow the simulation significantly, however. (see #12631)
builder.Connect(
plant.get_generalized_contact_forces_output_port(iiwa_instance),
status_sender->get_torque_external_input_port());
builder.Connect(status_sender->get_output_port(),
status_pub->get_input_port());
// Connect the torque input in torque control
if (FLAGS_torque_control) {
KukaTorqueController<double>* torque_controller =
dynamic_cast<KukaTorqueController<double>*>(controller);
DRAKE_DEMAND(torque_controller != nullptr);
builder.Connect(command_receiver->get_commanded_torque_output_port(),
torque_controller->get_input_port_commanded_torque());
}
auto sys = builder.Build();
Simulator<double> simulator(*sys);
simulator.set_publish_every_time_step(false);
simulator.set_target_realtime_rate(FLAGS_target_realtime_rate);
simulator.Initialize();
// Simulate for a very long time.
simulator.AdvanceTo(FLAGS_simulation_sec);
return 0;
}
} // namespace
} // namespace kuka_iiwa_arm
} // namespace examples
} // namespace drake
int main(int argc, char* argv[]) {
gflags::ParseCommandLineFlags(&argc, &argv, true);
return drake::examples::kuka_iiwa_arm::DoMain();
}