inverted_pendulum_controller.hpp

// Copyright 2026 Open Source Robotics Foundation, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#ifndef INVERTED_PENDULUM_CONTROLLER__INVERTED_PENDULUM_CONTROLLER_HPP_
#define INVERTED_PENDULUM_CONTROLLER__INVERTED_PENDULUM_CONTROLLER_HPP_
 
#include <string>
 
#include "controller_interface/controller_interface.hpp"
#include "rclcpp/rclcpp.hpp"
#include "rclcpp_lifecycle/state.hpp"
 
namespace inverted_pendulum_controller
{
 
class InvertedPendulumController : public controller_interface::ControllerInterface
{
public:
  InvertedPendulumController();
 
  controller_interface::CallbackReturn on_init() override;
 
  controller_interface::InterfaceConfiguration command_interface_configuration() const override;
  controller_interface::InterfaceConfiguration state_interface_configuration() const override;
 
  controller_interface::CallbackReturn on_configure(
    const rclcpp_lifecycle::State & previous_state) override;
  controller_interface::CallbackReturn on_activate(
    const rclcpp_lifecycle::State & previous_state) override;
  controller_interface::CallbackReturn on_deactivate(
    const rclcpp_lifecycle::State & previous_state) override;
 
  controller_interface::return_type update(
    const rclcpp::Time & time, const rclcpp::Duration & period) override;
 
  bool is_balancing() const { return balancing_; }
 
private:
  // Hardware interface names
  std::string motor_joint_state_name_;
  std::string motor_joint_vel_name_;
  std::string pendulum_joint_state_name_;
  std::string pendulum_joint_vel_name_;
  std::string motor_joint_command_name_;
 
  // Physical plant constants
  double m2_{0.014};      
  double l2_{0.051};      
  double L1_{0.062};      
  double J2_{4.447e-5};   
  double g_{9.80665};     
  double E_target_{0.0};  
 
  // Full-state LQR gains: u = -K * [q1, q1_dot, q2, q2_dot]
  double k_q1_{-5.000};
  double k_q1_vel_{-4.352};
  double k_q2_{418.238};
  double k_q2_vel_{33.281};
 
  // Energy-shaping swing-up parameters
  double k_e_{80.0};               
  double k_arm_{31.0};             
  double k_arm_vel_{6.0};          
  double swing_accel_max_{100.0};  
  double arm_zone_{2.0};           
  double swing_start_vel_{
    0.01};  
 
  // Mode transition & gating parameters
  double catch_angle_{0.20};  
  double fall_angle_{
    0.60};  
  double catch_cmd_fraction_{
    0.60};                       
  int catch_ramp_steps_{10};     
  int catch_ramp_remaining_{0};  
 
  // Actuator safety limit
  double motor_accel_max_{150.0};  
 
  // Operational state
  bool balancing_{false};
};
 
}  // namespace inverted_pendulum_controller
 
#endif  // INVERTED_PENDULUM_CONTROLLER__INVERTED_PENDULUM_CONTROLLER_HPP_