frc971/control_loops/drivetrain/ssdrivetrain.cc

#include "frc971/control_loops/drivetrain/ssdrivetrain.h"

#include "aos/common/controls/polytope.h"
#include "aos/common/commonmath.h"
#include "aos/common/logging/matrix_logging.h"

#include "frc971/control_loops/state_feedback_loop.h"
#include "frc971/control_loops/coerce_goal.h"
#include "frc971/control_loops/drivetrain/drivetrain.q.h"
#include "frc971/control_loops/drivetrain/drivetrain_config.h"

namespace frc971 {
namespace control_loops {
namespace drivetrain {

using ::frc971::control_loops::DoCoerceGoal;

void DrivetrainMotorsSS::ScaleCapU(Eigen::Matrix<double, 2, 1> *U) {
  output_was_capped_ =
      ::std::abs((*U)(0, 0)) > 12.0 || ::std::abs((*U)(1, 0)) > 12.0;

  if (output_was_capped_) {
    *U *= 12.0 / kf_->U_uncapped().lpNorm<Eigen::Infinity>();
  }
}

// This intentionally runs the U-capping code even when it's unnecessary to help
// make it more deterministic. Only running it when one or both sides want
// out-of-range voltages could lead to things like running out of CPU under
// certain situations, which would be bad.
void DrivetrainMotorsSS::PolyCapU(Eigen::Matrix<double, 2, 1> *U) {
  output_was_capped_ =
      ::std::abs((*U)(0, 0)) > 12.0 || ::std::abs((*U)(1, 0)) > 12.0;

  const Eigen::Matrix<double, 7, 1> error = kf_->R() - kf_->X_hat();

  LOG_MATRIX(DEBUG, "U_uncapped", *U);

  Eigen::Matrix<double, 2, 2> position_K;
  position_K << kf_->K(0, 0), kf_->K(0, 2), kf_->K(1, 0), kf_->K(1, 2);
  Eigen::Matrix<double, 2, 2> velocity_K;
  velocity_K << kf_->K(0, 1), kf_->K(0, 3), kf_->K(1, 1), kf_->K(1, 3);

  Eigen::Matrix<double, 2, 1> position_error;
  position_error << error(0, 0), error(2, 0);
  // drive_error = [total_distance_error, left_error - right_error]
  const auto drive_error = T_inverse_ * position_error;
  Eigen::Matrix<double, 2, 1> velocity_error;
  velocity_error << error(1, 0), error(3, 0);
  LOG_MATRIX(DEBUG, "error", error);


  Eigen::Matrix<double, 2, 1> U_integral;
  U_integral << kf_->X_hat(4, 0), kf_->X_hat(5, 0);

  const ::aos::controls::HPolytope<2> pos_poly(
      U_poly_, position_K * T_,
      -velocity_K * velocity_error + U_integral - kf_->ff_U());

  Eigen::Matrix<double, 2, 1> adjusted_pos_error;
  {
    const auto &P = drive_error;

    Eigen::Matrix<double, 1, 2> L45;
    L45 << ::aos::sign(P(1, 0)), -::aos::sign(P(0, 0));
    const double w45 = 0;

    Eigen::Matrix<double, 1, 2> LH;
    if (::std::abs(P(0, 0)) > ::std::abs(P(1, 0))) {
      LH << 0, 1;
    } else {
      LH << 1, 0;
    }
    const double wh = LH.dot(P);

    Eigen::Matrix<double, 2, 2> standard;
    standard << L45, LH;
    Eigen::Matrix<double, 2, 1> W;
    W << w45, wh;
    const Eigen::Matrix<double, 2, 1> intersection = standard.inverse() * W;

    bool is_inside_h, is_inside_45;
    const auto adjusted_pos_error_h =
        DoCoerceGoal(pos_poly, LH, wh, drive_error, &is_inside_h);
    const auto adjusted_pos_error_45 =
        DoCoerceGoal(pos_poly, L45, w45, intersection, &is_inside_45);
    if (pos_poly.IsInside(intersection)) {
      adjusted_pos_error = adjusted_pos_error_h;
    } else {
      if (is_inside_h) {
        if (adjusted_pos_error_h.norm() > adjusted_pos_error_45.norm() ||
            adjusted_pos_error_45.norm() > intersection.norm()) {
          adjusted_pos_error = adjusted_pos_error_h;
        } else {
          adjusted_pos_error = adjusted_pos_error_45;
        }
      } else {
        adjusted_pos_error = adjusted_pos_error_45;
      }
    }
  }

  *U = -U_integral + velocity_K *velocity_error +
       position_K *T_ *adjusted_pos_error + kf_->ff_U();

  if (!output_was_capped_) {
    if ((*U - kf_->U_uncapped()).norm() > 0.0001) {
      LOG(FATAL, "U unnecessarily capped\n");
    }
  }
}

DrivetrainMotorsSS::DrivetrainMotorsSS(const DrivetrainConfig &dt_config,
                                       StateFeedbackLoop<7, 2, 3> *kf,
                                       double *integrated_kf_heading)
    : dt_config_(dt_config),
      kf_(kf),
      U_poly_(
          (Eigen::Matrix<double, 4, 2>() << 1, 0, -1, 0, 0, 1, 0, -1)
              .finished(),
          (Eigen::Matrix<double, 4, 1>() << 12.0, 12.0, 12.0, 12.0).finished()),
      linear_profile_(::aos::controls::kLoopFrequency),
      angular_profile_(::aos::controls::kLoopFrequency),
      integrated_kf_heading_(integrated_kf_heading) {
  ::aos::controls::HPolytope<0>::Init();
  T_ << 1, 1, 1, -1;
  T_inverse_ = T_.inverse();
  unprofiled_goal_.setZero();
}

void DrivetrainMotorsSS::SetGoal(
    const ::frc971::control_loops::DrivetrainQueue::Goal &goal) {
  unprofiled_goal_ << goal.left_goal, goal.left_velocity_goal, goal.right_goal,
      goal.right_velocity_goal, 0.0, 0.0, 0.0;

  use_profile_ =
      !kf_->Kff().isZero(0) &&
      (goal.linear.max_velocity != 0.0 && goal.linear.max_acceleration != 0.0 &&
       goal.angular.max_velocity != 0.0 &&
       goal.angular.max_acceleration != 0.0);
  linear_profile_.set_maximum_velocity(goal.linear.max_velocity);
  linear_profile_.set_maximum_acceleration(goal.linear.max_acceleration);
  angular_profile_.set_maximum_velocity(goal.angular.max_velocity);
  angular_profile_.set_maximum_acceleration(goal.angular.max_acceleration);
}

// (left + right) / 2 = linear
// (right - left) / width = angular

Eigen::Matrix<double, 2, 1> DrivetrainMotorsSS::LeftRightToLinear(
    const Eigen::Matrix<double, 7, 1> &left_right) const {
  Eigen::Matrix<double, 2, 1> linear;
  linear << (left_right(0, 0) + left_right(2, 0)) / 2.0,
      (left_right(1, 0) + left_right(3, 0)) / 2.0;
  return linear;
}

Eigen::Matrix<double, 2, 1> DrivetrainMotorsSS::LeftRightToAngular(
    const Eigen::Matrix<double, 7, 1> &left_right) const {
  Eigen::Matrix<double, 2, 1> angular;
  angular << (left_right(2, 0) - left_right(0, 0)) /
                 (dt_config_.robot_radius * 2.0),
      (left_right(3, 0) - left_right(1, 0)) / (dt_config_.robot_radius * 2.0);
  return angular;
}

Eigen::Matrix<double, 4, 1> DrivetrainMotorsSS::AngularLinearToLeftRight(
    const Eigen::Matrix<double, 2, 1> &linear,
    const Eigen::Matrix<double, 2, 1> &angular) const {
  Eigen::Matrix<double, 2, 1> scaled_angle = angular * dt_config_.robot_radius;
  Eigen::Matrix<double, 4, 1> state;
  state << linear(0, 0) - scaled_angle(0, 0), linear(1, 0) - scaled_angle(1, 0),
      linear(0, 0) + scaled_angle(0, 0), linear(1, 0) + scaled_angle(1, 0);
  return state;
}

void DrivetrainMotorsSS::Update(bool enable_control_loop) {
  Eigen::Matrix<double, 2, 1> wheel_heading = LeftRightToAngular(kf_->X_hat());

  const double gyro_to_wheel_offset =
      wheel_heading(0, 0) - *integrated_kf_heading_;

  if (enable_control_loop) {
    // Update profiles.
    Eigen::Matrix<double, 2, 1> unprofiled_linear =
        LeftRightToLinear(unprofiled_goal_);
    Eigen::Matrix<double, 2, 1> unprofiled_angular =
        LeftRightToAngular(unprofiled_goal_);

    Eigen::Matrix<double, 2, 1> next_linear;
    Eigen::Matrix<double, 2, 1> next_angular;

    if (use_profile_) {
      next_linear = linear_profile_.Update(unprofiled_linear(0, 0),
                                           unprofiled_linear(1, 0));
      next_angular = angular_profile_.Update(unprofiled_angular(0, 0),
                                             unprofiled_angular(1, 0));
    } else {
      next_angular = unprofiled_angular;
      next_linear = unprofiled_linear;
    }

    const double wheel_compensation_offset =
        gyro_to_wheel_offset * dt_config_.robot_radius;
    const double scaled_angle_delta =
        (gyro_to_wheel_offset - last_gyro_to_wheel_offset_) *
        dt_config_.robot_radius;

    kf_->mutable_next_R().block<4, 1>(0, 0) =
        AngularLinearToLeftRight(next_linear, next_angular);

    kf_->mutable_next_R().block<3, 1>(4, 0) =
        unprofiled_goal_.block<3, 1>(4, 0);

    kf_->mutable_next_R(0, 0) -= wheel_compensation_offset;
    kf_->mutable_next_R(2, 0) += wheel_compensation_offset;

    if (!use_profile_) {
      kf_->mutable_R() = kf_->next_R();
    } else {
      kf_->mutable_R(0, 0) -= scaled_angle_delta;
      kf_->mutable_R(2, 0) += scaled_angle_delta;
    }

    // Run the controller.
    Eigen::Matrix<double, 2, 1> U = kf_->ControllerOutput();

    kf_->mutable_U_uncapped() = kf_->mutable_U() = U;
    ScaleCapU(&kf_->mutable_U());

    // Now update the feed forwards.
    kf_->UpdateFFReference();

    // Now, move the profile if things didn't go perfectly.
    if (use_profile_ &&
        (kf_->U() - kf_->U_uncapped()).lpNorm<Eigen::Infinity>() > 1e-4) {
      // kf_->R() is in wheel coordinates, while the profile is in absolute
      // coordinates.  Convert back...
      linear_profile_.MoveCurrentState(LeftRightToLinear(kf_->R()));

      LOG(DEBUG, "Saturated while moving\n");

      Eigen::Matrix<double, 2, 1> absolute_angular =
          LeftRightToAngular(kf_->R());
      absolute_angular(0, 0) -= gyro_to_wheel_offset;
      angular_profile_.MoveCurrentState(absolute_angular);
    }
  } else {
    Eigen::Matrix<double, 2, 1> wheel_linear = LeftRightToLinear(kf_->X_hat());
    Eigen::Matrix<double, 2, 1> next_angular = wheel_heading;
    next_angular(0, 0) = *integrated_kf_heading_;

    unprofiled_goal_.block<4, 1>(0, 0) =
        AngularLinearToLeftRight(wheel_linear, next_angular);

    auto current_linear = LeftRightToLinear(unprofiled_goal_);
    auto current_angular = LeftRightToAngular(unprofiled_goal_);
    linear_profile_.MoveCurrentState(current_linear);
    angular_profile_.MoveCurrentState(current_angular);

    kf_->mutable_next_R().block<4, 1>(0, 0) = kf_->X_hat().block<4, 1>(0, 0);
    kf_->mutable_R().block<4, 1>(0, 0) = kf_->X_hat().block<4, 1>(0, 0);
  }
  last_gyro_to_wheel_offset_ = gyro_to_wheel_offset;
}

void DrivetrainMotorsSS::SetOutput(
    ::frc971::control_loops::DrivetrainQueue::Output *output) const {
  if (output) {
    output->left_voltage = kf_->U(0, 0);
    output->right_voltage = kf_->U(1, 0);
    output->left_high = true;
    output->right_high = true;
  }
}

void DrivetrainMotorsSS::PopulateStatus(
    ::frc971::control_loops::DrivetrainQueue::Status *status) const {
  Eigen::Matrix<double, 2, 1> profiled_linear =
      LeftRightToLinear(kf_->next_R());
  Eigen::Matrix<double, 2, 1> profiled_angular =
      LeftRightToAngular(kf_->next_R());

  profiled_angular(0, 0) -= last_gyro_to_wheel_offset_;

  Eigen::Matrix<double, 4, 1> profiled_gyro_left_right =
      AngularLinearToLeftRight(profiled_linear, profiled_angular);

  status->profiled_left_position_goal = profiled_gyro_left_right(0, 0);
  status->profiled_left_velocity_goal = profiled_gyro_left_right(1, 0);
  status->profiled_right_position_goal = profiled_gyro_left_right(2, 0);
  status->profiled_right_velocity_goal = profiled_gyro_left_right(3, 0);
}

}  // namespace drivetrain
}  // namespace control_loops
}  // namespace frc971