calcMain.m

function state =   calcMain(parameters, state, i)
% CALCMAIN  Calculates trajectory values at each point in time.
% calcMain gets called at each iteration and handles the states of the 
% trajectory via a passed state input argument.
% state.mode = 1 -- Acceleration
% state.mode = 2 -- Deceleration
% state.mode = 3 -- Max Frequency
% @author      Rafael Anderka, Lorenzo Principe

    % Calculate state-specific variables
    switch state.mode
        case 1 % Acceleration
            % Calculations assume optimal frequency
            state.frequency(i)      = calcOptimalFrequency(state.velocity(i - 1), parameters);
            state.DSLIMForce(i)     = calcFx(state.frequency(i), state.velocity(i - 1), parameters);
            state.brakesForce(i)    = 0;
            state.phase(i)          = state.phase(i - 1) + 2 * pi * state.frequency(i) * parameters.dt;
            state.powerLoss(i)      = calcPl(state.frequency(i), state.velocity(i - 1), parameters);
        case 2 % Deceleration using EmBrakes            
            state.frequency(i)      = 0;
            state.DSLIMForce(i)     = 0;
            state.brakesForce(i)    = calcBrakingForce(state.velocity(i-1), parameters);  
            state.phase(i)          = state.phase(i - 1);
            state.powerLoss(i)      = 0;
        case 3 % Max RPM
            state.frequency(i)      = parameters.maxFrequency;
            state.DSLIMForce(i)     = calcFx(state.frequency(i), state.velocity(i - 1), parameters);
            state.brakesForce(i)    = 0;
            state.phase(i)          = state.phase(i - 1) + 2 * pi * state.frequency(i) * parameters.dt;
            state.powerLoss(i)      = calcPl(state.frequency(i), state.velocity(i - 1), parameters);
    end
    
    % Calculate air drag
    state.drag(i) = calcDrag(state.velocity(i-1), parameters);
    
    % Calculate rolling friction
    state.rollFriction(i) = calcRollFriction(parameters);
    
    % Calculate net force
    state.fx(i) = state.DSLIMForce(i) + state.brakesForce(i) + state.drag(i) + state.rollFriction(i);

    % Calculate acceleration
    state.acceleration(i) = state.fx(i) / parameters.mass;
    
    % Calculate velocity and distance
    state.velocity(i) = state.velocity(i - 1) + parameters.dt * state.acceleration(i);
    state.distance(i) = state.distance(i - 1) + parameters.dt * state.velocity(i);
    
    % Calculate power and efficiency
    state.power(i) = state.fx(i) * state.velocity(i); % Power output = force * velocity
    state.powerInput(i) = state.power(i) + state.powerLoss(i); % ignoring inertia
    state.efficiency(i) = state.power(i) / state.powerInput(i);

    % Calculate synchronous speed and slip
    state.velocitySync(i) = state.frequency(i) * parameters.limLength / parameters.polePairs;
    state.slip(i) = (state.velocitySync(i) - state.velocity(i)) / state.velocitySync(i);
    if (isinf(state.slip(i)))
        state.slip(i) = 0;
    end
end