PM Re Architecture (again 2.0)

Background

I’m working on it

Reasoning Behind Restructuring

We are once again restructuring path manager! The current goal is to restructure PM so that it focuses more on path management while AM will take care of movement such as calculating roll, pitch, yaw, and adjusting throttle.

State Machine Changes

Some state names have been renamed to better reflect what is happening within the state. resetVariables has been renamed to FlightStageSelectorMode where PM will figure out what stage of flight needs to be executed.

The coordinateTurnElevation state has been removed as it previously calculated roll, pitch, yaw, etc which has been passed onto AM. Now, the desired heading is calculated in one of the flight modes and is passed to AM to make movement calculations.

Main Structure of PM

A diagram of the general flow of Path Manager, including its modes, stages, and states can be found below.

PM has been sectioned into to main modes: CommsWithSystemManagerMode, and FlightStageSelectorMode. Within CommsWithSystemManagerMode, PM will get the relevant instructions and information from AM, TM, and Sensor Fusion. This retrieval process is separated into three stages CommsWithAMStage, CommsWithTMStage, CommsWithSFStage where PM will get information from both managers and sensor fusion respectively. Note: The stages originally created to get information from AM, TM, and SF have been combined into one stage within CommsWithSystemManagerMode.

PM will check if the drone is under manual control by receiving a WaypointType . If it is not under manual control, it will enter FlightStageSelectorMode, the main part of the state machine. Within this mode, PM will change flight states if triggered to do so. While flying, PM may enter any of the following flight states: Disarmed, Takeoff, Cruising, Landing, and Landed. Note: a Preflight state may be added. If we are in the Disarmed state or Landed state PM will go back to the start. However, if we are in Takeoff, Cruising, or Landing, PM will execute their respective stages.

Important Structs

Note: These will all be coming from System Manager in a single packet

SM → PM

typedef struct CommandsFromSM{
    WaypointType waypoint_type;  // not necessary  
} CommandsFromSM;

where WaypointType is defined as

enum WaypointType {PATH_FOLLOW = 0, ORBIT_FOLLOW, HOVER_WAYPOINT, TAKEOFF_WAYPOINT, LANDING_WAYPOINT, TRANSITION_WAYPOINT, MANUAL_WAYPOINT};

PM → AM Struct:

typedef struct CommandsForAM_t{
2  WaypointType waypoint_type;  // not necessary
3
4  // heading unit vector and magnitude
5  float dist_x; 
6  float dist_y; 
7  float dist_z; 
8  float magnitude; // Magnitude distance to waypoint target
9  float heading; // heading at target waypoint
10  double speed_target; // Target velocity of drone approaching target
11} CommandsForAM;

AM → PM Struct:

AM will send to PM an armed flag to signal that we are ready to fly. Additional information TBD

typedef struct CommandsFromAM{
    bool armed;  
} CommandsFromAM;

TM → PM Struct:

CV will be sending a list of waypoints during Cruise and Search (sent through TM and SM) where a single waypoint is defined in the TelemWaypointData struct below. The start_landing flag will be signaled when a landing pad is found.

struct TelemWaypointData {    
  double longitude;  //    
  double lattiude;   
  uint8_t waypoint_id; 
};

typedef struct CommandsFromTM{
    bool start_landing;
    uint8_t num_waypoints; // number of waypoints in the list 
    TelemWaypointData waypoints[num_waypoints]; 
} CommandsFromTM;