spec_reaction_wheel.md

Specification for ReactionWheel class

1. Overview

1. functions

• The ReactionWheel class simulates a reaction wheel.
• The ReactionWheel class generates torque caused by the reaction wheel.

2. files

• reaction_wheel.cpp, reaction_wheel.hpp: Definitions and declarations of the class
• reaction_wheel_ode.cpp, reaction_wheel_ode.hpp: Ordinary differential equation for RW emulation
• reaction_wheel.ini: Initialization file
• plot_reaction_wheel.py: An example of a Python script to plot reaction_wheel output

3. how to use

• Set the parameters in reaction_wheel.ini.
  • moment_of_inertia_kgm2: Moment of inertia of the rotor
  • max_output_torque_Nm: Maximum output torque
  • max_angular_velocity_rpm: Maximum angular velocity
  • Direction parameters
    • direction_determination_mode: Mode of direction definition
    • quaternion_b2c: Quaternion body to component (used in RW jitter)
    • direction_b: Rotation direction
  • position_b_m: Position of the wheel
  • dead_time_s: Dead time
  • time_constant_s: Time constant of the first-order control lag
  • Friction parameters
    • friction_order: Order of friction acceleration
    • friction_coefficients: Coefficients of friction acceleration
  • stop_limit_angular_velocity_rad_s: Stop limit angular velocity
  • initial_motor_drive_flag: Initial motor drive flag
  • initial_angular_velocity_rad_s: Initial angular velocity
  • Other parameters
    • Parameters for the Component class
    • Parameters for the PowerPort class
    • Parameters for the RwJitter class
• Create an instance by using the initialization function InitReactionWheel
• Use the SetDriveFlag, SetVelocityLimit_rpm, and SetTargetTorque_* to drive the reaction wheel.
• Use the GetAngularVelocity_* to get angular velocity information.

2. Explanation of Algorithm

1. MainRoutine

1. Overview

• The MainRoutine function calculates the generating torque including control lag and friction.

2. Inputs and Outputs

• TBW

3. Algorithm

• TBW

3. Results of verifications

• Case 1
  • Parameters: Default
  • Command: +20 rad/s2 -> -20 rad/s2 -> drive_flag = false.

• Case 2
  • Parameters: time_constant = 0, friction_coefficients = 1.0
  • Command: +20 rad/s2 -> -20 rad/s2 -> drive_flag = false.