Contacts - 6D Loop contacts

CHANGELOG.md

@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+* Added 6D loop contacts to account for contacts between parts of the robot in https://github.com/loco-3d/crocoddyl/pull/1309
 * Fixed the inequality constraints' feasibility computation by incorporating bounds into the calculation in https://github.com/loco-3d/crocoddyl/pull/1307
 * Improved the action factory used for unit testing in https://github.com/loco-3d/crocoddyl/pull/1300
 * Ignore ruff issues in ipython notebook files in https://github.com/loco-3d/crocoddyl/pull/1297

bindings/python/crocoddyl/multibody/contacts/contact-6d-loop.cpp

@@ -0,0 +1,242 @@
+///////////////////////////////////////////////////////////////////////////////
+// BSD 3-Clause License
+//
+// Copyright (C) 2019-2024, LAAS-CNRS, University of Edinburgh
+//                          Heriot-Watt University
+// Copyright note valid unless otherwise stated in individual files.
+// All rights reserved.
+///////////////////////////////////////////////////////////////////////////////
+
+#include "crocoddyl/multibody/contacts/contact-6d-loop.hpp"
+
+#include "python/crocoddyl/multibody/multibody.hpp"
+#include "python/crocoddyl/utils/copyable.hpp"
+
+namespace crocoddyl {
+namespace python {
+
+void exposeContact6DLoop() {
+  bp::register_ptr_to_python<boost::shared_ptr<ContactModel6DLoop> >();
+
+  bp::class_<ContactModel6DLoop, bp::bases<ContactModelAbstract> >(
+      "ContactModel6DLoop",
+      "Rigid 6D contact model.\n\n"
+      "It defines a rigid 6D contact models based on acceleration-based "
+      "holonomic constraints.\n"
+      "The calc and calcDiff functions compute the contact Jacobian and drift "
+      "(holonomic constraint) or\n"
+      "the derivatives of the holonomic constraint, respectively.",
+      bp::init<boost::shared_ptr<StateMultibody>, int, pinocchio::SE3, int,
+               pinocchio::SE3, pinocchio::ReferenceFrame, std::size_t,
+               bp::optional<Eigen::Vector2d> >(
+          bp::args("self", "state", "joint1_id", "joint1_placement",
+                   "joint2_id", "joint2_placement", "type", "nu", "gains"),
+          "Initialize the contact model.\n\n"
+          ":param state: state of the multibody system\n"
+          ":param joint1_id: Parent joint id of the first contact frame\n"
+          ":param joint1_placement: Placement of the first contact frame with "
+          "respect to the parent joint\n"
+          ":param joint2_id: Parent joint id of the second contact frames\n"
+          ":param joint2_placement: Placement of the second contact frame with "
+          "respect to the parent joint\n"
+          ":param type: reference frame of contact (must be pinocchio::LOCAL)\n"
+          ":param nu: dimension of control vector\n"
+          ":param gains: gains of the contact model (default "
+          "np.matrix([0.,0.]))"))
+      .def("calc", &ContactModel6DLoop::calc, bp::args("self", "data", "x"),
+           "Compute the 6D loop-contact Jacobian and drift.\n\n"
+           "The rigid contact model throught acceleration-base holonomic "
+           "constraint\n"
+           "of the contact frame placement.\n"
+           ":param data: contact data\n"
+           ":param x: state point (dim. state.nx)")
+      .def("calcDiff", &ContactModel6DLoop::calcDiff,
+           bp::args("self", "data", "x"),
+           "Compute the derivatives of the 6D loop-contact holonomic "
+           "constraint.\n\n"
+           "The rigid contact model throught acceleration-base holonomic "
+           "constraint\n"
+           "of the contact frame placement.\n"
+           "It assumes that calc has been run first.\n"
+           ":param data: cost data\n"
+           ":param x: state point (dim. state.nx)")
+      .def("updateForce", &ContactModel6DLoop::updateForce,
+           bp::args("self", "data", "force"),
+           "Convert the Lagrangian into a stack of spatial forces.\n\n"
+           ":param data: cost data\n"
+           ":param force: force vector (dimension 6)")
+      .def("updateForceDiff", &ContactModel6DLoop::updateForceDiff,
+           bp::args("self", "data", "df_dx", "df_du"),
+           "Update the force derivatives.\n\n"
+           ":param data: cost data\n"
+           ":param df_dx: Jacobian of the force with respect to the state\n"
+           ":param df_du: Jacobian of the force with respect to the control")
+      .def("createData", &ContactModel6DLoop::createData,
+           bp::with_custodian_and_ward_postcall<0, 2>(),
+           bp::args("self", "data"),
+           "Create the 6D loop-contact data.\n\n"
+           "Each contact model has its own data that needs to be allocated. "
+           "This function\n"
+           "returns the allocated data for a predefined cost.\n"
+           ":param data: Pinocchio data\n"
+           ":return contact data.")
+      .add_property(
+          "joint1_id",
+          bp::make_function(&ContactModel6DLoop::get_joint1_id,
+                            bp::return_value_policy<bp::return_by_value>()),
+          "Parent joint id of the first contact frame")
+      .add_property(
+          "joint1_placement",
+          bp::make_function(&ContactModel6DLoop::get_joint1_placement,
+                            bp::return_value_policy<bp::return_by_value>()),
+          "Placement of the first contact frame with respect to the parent "
+          "joint")
+      .add_property(
+          "joint2_id",
+          bp::make_function(&ContactModel6DLoop::get_joint2_id,
+                            bp::return_value_policy<bp::return_by_value>()),
+          "Parent joint id of the second contact frame")
+      .add_property(
+          "joint2_placement",
+          bp::make_function(&ContactModel6DLoop::get_joint2_placement,
+                            bp::return_value_policy<bp::return_by_value>()),
+          "Placement of the second contact frame with respect to the parent "
+          "joint")
+      .add_property(
+          "gains",
+          bp::make_function(&ContactModel6DLoop::get_gains,
+                            bp::return_value_policy<bp::return_by_value>()),
+          "Baumegarte stabilisation gains (Kp, Kd)")
+      .def(CopyableVisitor<ContactModel6DLoop>());
+
+  bp::register_ptr_to_python<boost::shared_ptr<ContactData6DLoop> >();
+
+  bp::class_<ContactData6DLoop, bp::bases<ContactDataAbstract> >(
+      "ContactData6DLoop", "Data for 6DLoop contact.\n\n",
+      bp::init<ContactModel6DLoop*, pinocchio::Data*>(
+          bp::args("self", "model", "data"),
+          "Create 6D loop-contact data.\n\n"
+          ":param model: 6D loop-contact model\n"
+          ":param data: Pinocchio data")[bp::with_custodian_and_ward<
+          1, 2, bp::with_custodian_and_ward<1, 3> >()])
+      .add_property(
+          "v1_partial_dq",
+          bp::make_getter(&ContactData6DLoop::v1_partial_dq,
+                          bp::return_internal_reference<>()),
+          "Jacobian of the spatial velocity of the first contact frame wrt q")
+      .add_property("a1_partial_dq",
+                    bp::make_getter(&ContactData6DLoop::a1_partial_dq,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the spatial acceleration of the first contact "
+                    "frame wrt q")
+      .add_property("a1_partial_dv",
+                    bp::make_getter(&ContactData6DLoop::a1_partial_dv,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the spatial acceleration of the first contact "
+                    "frame wrt v")
+      .add_property(
+          "v2_partial_dq",
+          bp::make_getter(&ContactData6DLoop::v2_partial_dq,
+                          bp::return_internal_reference<>()),
+          "Jacobian of the spatial velocity of the second contact frame wrt q")
+      .add_property("a2_partial_dq",
+                    bp::make_getter(&ContactData6DLoop::a2_partial_dq,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the spatial acceleration of the second "
+                    "contact frame wrt q")
+      .add_property("a2_partial_dv",
+                    bp::make_getter(&ContactData6DLoop::a2_partial_dv,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the spatial acceleration of the second "
+                    "contact frame wrt v")
+      .add_property("da0_dx",
+                    bp::make_getter(&ContactData6DLoop::da0_dx,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the acceleration drift wrt x")
+      .add_property("da0_dq_t1",
+                    bp::make_getter(&ContactData6DLoop::da0_dq_t1,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the acceleration drift wrt q - part 1")
+      .add_property("da0_dq_t2",
+                    bp::make_getter(&ContactData6DLoop::da0_dq_t2,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the acceleration drift wrt q - part 2")
+      .add_property("da0_dq_t3",
+                    bp::make_getter(&ContactData6DLoop::da0_dq_t3,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the acceleration drift wrt q - part 3")
+      .add_property("f1Xj1",
+                    bp::make_getter(&ContactData6DLoop::f1Xj1,
+                                    bp::return_internal_reference<>()),
+                    "Inverse of the placement of the first contact frame in "
+                    "the joint frame - "
+                    "Action Matrix")
+      .add_property("f2Xj2",
+                    bp::make_getter(&ContactData6DLoop::f2Xj2,
+                                    bp::return_internal_reference<>()),
+                    "Inverse of the placement of the second contact frame in "
+                    "the joint frame "
+                    "- Action Matrix")
+      .add_property("f1Mf2",
+                    bp::make_getter(&ContactData6DLoop::f1Mf2,
+                                    bp::return_internal_reference<>()),
+                    "Relative placement of the contact frames")
+      .add_property("f1Xf2",
+                    bp::make_getter(&ContactData6DLoop::f1Xf2,
+                                    bp::return_internal_reference<>()),
+                    "Relative placement of the contact frames - Action Matrix")
+      .add_property("f1Jf1",
+                    bp::make_getter(&ContactData6DLoop::f1Jf1,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the first contact frame")
+      .add_property("f2Jf2",
+                    bp::make_getter(&ContactData6DLoop::f2Jf2,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the second frame in the joint frame")
+      .add_property("j1Jj1",
+                    bp::make_getter(&ContactData6DLoop::j1Jj1,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the first joint in the joint frame")
+      .add_property("j2Jj2",
+                    bp::make_getter(&ContactData6DLoop::j2Jj2,
+                                    bp::return_internal_reference<>()),
+                    "Jacobian of the second contact frame")
+      .add_property("f1vf1",
+                    bp::make_getter(&ContactData6DLoop::f1vf1,
+                                    bp::return_internal_reference<>()),
+                    "Velocity of the first contact frame")
+      .add_property("f2vf2",
+                    bp::make_getter(&ContactData6DLoop::f2vf2,
+                                    bp::return_internal_reference<>()),
+                    "Velocity of the second contact frame")
+      .add_property(
+          "f1vf2",
+          bp::make_getter(&ContactData6DLoop::f1vf2,
+                          bp::return_internal_reference<>()),
+          "Velocity of the second contact frame in the first contact frame")
+      .add_property("f1af1",
+                    bp::make_getter(&ContactData6DLoop::f1af1,
+                                    bp::return_internal_reference<>()),
+                    "Acceleration of the first contact frame")
+      .add_property("f2af2",
+                    bp::make_getter(&ContactData6DLoop::f2af2,
+                                    bp::return_internal_reference<>()),
+                    "Acceleration of the second contact frame")
+      .add_property(
+          "f1af2",
+          bp::make_getter(&ContactData6DLoop::f1af2,
+                          bp::return_internal_reference<>()),
+          "Acceleration of the second contact frame in the first contact frame")
+      .add_property("joint1_f",
+                    bp::make_getter(&ContactData6DLoop::joint1_f,
+                                    bp::return_internal_reference<>()),
+                    "Force at the first joint")
+      .add_property("joint2_f",
+                    bp::make_getter(&ContactData6DLoop::joint2_f,
+                                    bp::return_internal_reference<>()),
+                    "Force at the second joint")
+      .def(CopyableVisitor<ContactData6DLoop>());
+}
+
+}  // namespace python
+}  // namespace crocoddyl

bindings/python/crocoddyl/multibody/multibody.cpp

@@ -56,6 +56,7 @@ void exposeMultibody() {
   exposeContact2D();
   exposeContact3D();
   exposeContact6D();
+  exposeContact6DLoop();
   exposeImpulse3D();
   exposeImpulse6D();
 }

bindings/python/crocoddyl/multibody/multibody.hpp

@@ -61,6 +61,7 @@ void exposeContact1D();
 void exposeContact2D();
 void exposeContact3D();
 void exposeContact6D();
+void exposeContact6DLoop();
 void exposeImpulse3D();
 void exposeImpulse6D();
 void exposeMultibody();

include/crocoddyl/multibody/contact-base.hpp

@@ -94,8 +94,9 @@ class ContactModelAbstractTpl {
    * @param[in] data   Contact data
    * @param[in] force  Contact force
    */
-  void updateForceDiff(const boost::shared_ptr<ContactDataAbstract>& data,
-                       const MatrixXs& df_dx, const MatrixXs& df_du) const;
+  virtual void updateForceDiff(
+      const boost::shared_ptr<ContactDataAbstract>& data, const MatrixXs& df_dx,
+      const MatrixXs& df_du) const;
 
   /**
    * @brief Set the stack of spatial forces to zero