I want to custom my statespace like the example"Motion Planning with RRT for Fixed-Wing UAV",but the following error occurs"Abstract classes cannot be instantiated."

 properties (SetAccess = protected)%设置属性的特性为保护特性
        %UniformDistribution - Uniform distribution for sampling
        UniformDistribution %采样时利用均匀分布
        
        %NormalDistribution - Normal distribution for sampling
        NormalDistribution %采样时利用正态分布
        
        %WorkspaceGoalRegion Bounding box for goal region
        WorkspaceGoalRegion %设置该属性的目的是：当采样到目标区域（逼近目标）时表示搜索成功
        
        %DubinsPathSettings Dubin Path Settings for path planning
        DubinsPathSettings
        
        %AirSpeed Air speed configuration used in the state space
        AirSpeed %state space里定义airspeed配置  
        uavModelName
        Height
        Temp
        Sound
        Press
        AirDensity
    end
    properties (Constant)%常量
        %DefaultMaxRollAngle Default values for Max Roll Angle
        DefaultMaxRollAngle=pi/6 %默认最大滚动角
        
        %DefaultAirSpeed Default values for AirSpeed
        DefaultAirSpeed=20 %默认空速
        
        %DefaultFlightPathAngleLimit Default values for FlightPathAngleLimit
        DefaultFlightPathAngleLimit= [-0.1 0.1] %默认飞行路径角度限制
        
        %DefaultRandomDefaultRandomStateBounds Default values for State Bounds
        DefaultRandomDefaultRandomStateBounds = ...
            [-40, 50; ...
            -40, 50; ...
            -40 50; ...
            -pi,pi] %默认状态边界
        DefalutuavModelName='multirotor'
        DefalutHeight=65
        DefalutTemp=287.7275
        DefalutSound=340.0446
        DefalutPress=1.0055e+05
        DefalutAirDensity=1.2174
        
    end
    
    methods
        function obj = myCustomUAVStateSpace(varargin)
            %State Space Constructor for myCustomUAVStateSpace object
            name = 'myCustomUAVStateSpace';
            numStateVariables = 9;
            %没有在methods里定义DefaultRandomStateBounds,只是在properties定义了默认随机状态边界，用圆点表示法调用状态边界属性
            % Call the constructor of the base class
            [e-mail](name, numStateVariables, myCustomUAVStateSpace.DefaultRandomStateBounds);
            
            % Create the probability distributions for sampling.
            obj.NormalDistribution = matlabshared.tracking.internal.NormalDistribution(numStateVariables);
            obj.UniformDistribution = matlabshared.tracking.internal.UniformDistribution(numStateVariables);
            
            if nargin ~= 0
                [mxRoll,arspeed,flightpathangle,uavName,height,temp,sound,press,airdensity]=myCustomUAVStateSpace.parseStateSpaceConstuctor(varargin{:});
                
            end
            if (nargin ==0)
                mxRoll=obj.DefaultMaxRollAngle;
                arspeed=obj.DefaultAirSpeed;
                flightpathangle=obj.DefaultFlightPathAngleLimit;
                uavName=obj.DefalutuavModelName;
                height=obj.DefalutHeight;
                temp=obj.DefalutTemp;
                sound=obj.DefalutSound;
                press=obj.DefalutPress;
                airdensity=obj.DefalutAirDensity;
                %bounds=obj.DefaultRandomDefaultRandomStateBounds;
            end

            obj.AirSpeed = arspeed;
            obj.uavModelName=uavName;
            obj.Height=height;
            obj.Temp=temp;
            obj.Sound=sound;
            obj.Press=press;
            obj.AirDensity=airdensity;
            obj.DubinsPathSettings=uavDubinsConnection('MaxRollAngle',mxRoll,'AirSpeed',arspeed,'FlightPathAngleLimit',flightpathangle);
            %obj.DefaultRandomStateBounds = bounds;
            
        end

Answer 1

[Jianxin Sun]

Hi Wenjun,

The error you received is about missing implmenetation in your state space class. In this example, the UAV state space inherits from nav.StateSpace class, which requires the following methods to be implemented:

    methods (Abstract)
        %DISTANCE Distance between two states
        dist = distance(obj, state1, state2)
        %INTERPOLATE Interpolate between two states
        state = interpolate(obj, state1, state2, ratios)
        %sampleGaussian Sample state using Gaussian distribution
        state = sampleGaussian(obj, meanState, stdDev)
        %sampleUniform Sample state using uniform distribution
        state = sampleUniform(obj, varargin)
        %enforceStateBounds Ensure that state lies within state bounds
        boundedState = enforceStateBounds(obj, state)
        %COPY Create deep copy of state space object
        copyObj = copy(obj)
    end
    
    

You can take the ExampleHelperUAVStateSpace implementation as an example.

Thanks,

Jianxin

Answer 2

[Wenjun Li]

Hi Jianxin,

Thank you for your patience! I tried to modify my state space as your suggested, but I still get the same error"Abstract classes cannot be instantiated".Then this is my modifications ：

function copyObj = copy(obj)
            %copyObj copies one object to another
            copyObj=myCustomUAVStateSpace;
            copyObj.DubinsPathSettings=copy(obj.DubinsPathSettings);
            copyObj.WorkspaceGoalRegion=obj.WorkspaceGoalRegion;
            copyObj.PWGRGuidedSampling=obj.PWGRGuidedSampling;
            copyObj.AirSpeed=obj.AirSpeed;
            copyObj.uavModelName=obj.uavModelName;
            copyObj.Height=obj.Height;
            copyObj.Temp=obj.Temp;
            copyObj.Sound=obj.Sound;
            copyObj.Press=obj.Press;
            copyObj.AirDensity=obj.AirDensity;
            copyObj.DefaultRandomStateBounds = obj.DefaultRandomStateBounds;
            copyObj.UniformDistribution = obj.UniformDistribution.copy;
            copyObj.NormalDistribution = obj.NormalDistribution.copy;
        end
    end
methods (Static, Access = protected)
        function [mxRoll,arspeed,flightpathangle,bnds,uavName,height,temp,sound,press,airdensity] = parseStateSpaceConstuctor(varargin)
            %parseConstructor Parses the inputs to the constructor
            p = matlabshared.autonomous.core.internal.NameValueParser({'MaxRollAngle', 'AirSpeed','FlightPathAngleLimit','Bounds','uavModelName','Height','Temp','Sound','Press','AirDensity'},...
                {myCustomUAVStateSpace.DefaultMaxRollAngle, myCustomUAVStateSpace.DefaultAirSpeed,myCustomUAVStateSpace.DefaultFlightPathAngleLimit,myCustomUAVStateSpace.DefaultRandomDefaultRandomStateBounds,myCustomUAVStateSpace.DefalutuavModelName,myCustomUAVStateSpace.DefalutHeight,myCustomUAVStateSpace.DefalutTemp,myCustomUAVStateSpace.DefalutSound,myCustomUAVStateSpace.DefalutPress,myCustomUAVStateSpace.DefalutAirDensity});
            if nargin == 0
                p.parse(varargin{:});
            else
                p.parse(varargin{1:end});
            end
            mxRoll = p.parameterValue('MaxRollAngle');
            arspeed = p.parameterValue('AirSpeed');
            flightpathangle=p.parameterValue('FlightPathAngleLimit');
            bnds=p.parameterValue('Bounds');
            uavName=p.parameterValue('uavModelName');
            height=p.parameterValue('Height');
            temp=p.parameterValue('Temp');
            sound=p.parameterValue('Sound');
            press=p.parameterValue('Press');
            airdensity=p.parameterValue('AirDensity');
        end
    end
end

Your answer will be very important to my future work, I would be very grateful if you could reply my question.

Thanks,

Wenjun

[Jianxin Sun]

Hi Wenjun,

Please run the following command to view all the missing function implementation in your class:

meta.abstractDetails('myCustomUAVStateSpace')

You will need to implement all the mehtods listed by the output.

Thanks,

Jianxin

[Wenjun Li]

Hi Jianxin,

Thank you so much!I have solved the problem by using your suggestion.But when I use my customized state space to perform navigation,the following errors occurs:

ss=myCustomUAVStateSpace("MaxRollAngle",pi/6,...
    "AirSpeed",25,...
    "FlightPathAngleLimit",[-0.1,0.1],...
    "Bounds",[-40,50;-40,50;-40,50;-inf,Inf;-Inf,Inf;-Inf,Inf;-Inf,Inf],...
    "Sound",340.0,...
    "Press",1.0055e+05,...
    "AirDensity",1.2174);

Error using StateSpace

Expected StateBounds to be of size 7x2, but it is of size 1x1.

Error in nav.StateSpace/validateStateBounds (line 277)

validateattributes(bounds, {'double'}, ...

Error in nav.StateSpace/set.StateBounds (line 113)

obj.StateBoundsInternal = obj.validateStateBounds(bounds, ...

Error in myCustomUAVStateSpace (line 109)

obj.StateBounds = bounds;

But I define bounds of 7*2, I don't understand why this problem occurs？I would appreciate if you could help me with this question.Please forgive me for interrupting again and again.I'm looking forward your reply!

Thanks,

Wenjun