sample
Description
Examples
Sample SE(2) State Space Using Gaussian State Sampler
Sample an SE(2) state space using a Gaussian state sampler, and observe the impact of the sampler parameter values on the sampling results.
Set the seed value to ensure you generate the same results.
rng(50,"twister");
Create a simple occupancy map with a narrow passage.
map = binaryOccupancyMap; occupied = [5*ones(9,1),[1; 2; 3; 4; 5; 7; 8; 9; 10]]; setOccupancy(map,occupied,1); figure(Position=[0, 0, 200, 200]) show(map)
Define the lower and upper limits of the state space variables x
, y
, and theta
from the occupancy map.
x = map.XWorldLimits; y = map.YWorldLimits; theta = [-pi pi];
Create a state space SE(2) object using the specified state space variables. Check the validity of states in the input state space by using a state validator. Set the validation distance to 0.01.
ss = stateSpaceSE2([x; y; theta]); sv = validatorOccupancyMap(ss,Map=map); sv.ValidationDistance = 0.01;
Sample State Space Using Gaussian State Sampler
Create a Gaussian state sampler with default parameter values. By default:
The maximum number of attempts that the sampler must take for finding the state samples is set to 10.
The standard deviation values along the and directions are set to 0.1, 0.1, and 0.0628, respectively.
sampler_orig = stateSamplerGaussian(sv)
sampler_orig = stateSamplerGaussian with properties: StateSpace: [1x1 stateSpaceSE2] StateValidator: [1x1 validatorOccupancyMap] StandardDeviation: [0.1000 0.1000 0.0628] MaxAttempts: 10
Generate 40 samples for motion planning from the input state space.
states_orig = sample(sampler_orig,40);
You can generate optimal samples by modifying the maximum number of attempts and standard deviation values. If the samples are scattered all over the input space, increase the maximum number of attempts and the standard deviation values to concentrate the state samples around the obstacle boundary.
Vary Maximum Number of Attempts
Create copies of the original state sampler object and modify the maximum number of attempts, property of the sampler, MaxAttempts,
to study its impact on the sampling results. Set the standard deviation values to default values.
Set the maximum number of attempts to find valid samples to 100, and generate 40 new samples from the input state space.
sampler_2 = copy(sampler_orig); sampler_2.MaxAttempts = 100; states_2 = sample(sampler_2,40);
Set the maximum number of attempts to find valid samples to 200, and generate 40 new samples from the input state space.
sampler_3 = copy(sampler_orig); sampler_3.MaxAttempts = 200; states_3 = sample(sampler_3,40);
Display the results using the helperDisplayStates
helper function. Note that, as the number of attempts increases, the samples concentrate more around the obstacle boundary.
helperDisplayStates(map,states_orig,sampler_2,states_2,sampler_3,states_3,"MaxAttempts");
Vary Standard Deviation
Create copies of the original state sampler object and modify the standard deviation, property of the sampler, StandardDeviation,
to study its impact on the sampling results. Set the maximum number of attempts to 200.
Generate 40 samples with the default standard deviation values.
sampler_orig.MaxAttempts = 200; states_orig = sample(sampler_orig,40);
Set the standard deviation values to [0.01 0.01 0.06]. Generate 40 new samples from the input state space.
sampler_4 = copy(sampler_orig); sampler_4.StandardDeviation = [0.01 0.01 0.06]; states_4 = sample(sampler_4,40);
Set the standard deviation values to [0.5 0.5 0.06]
. Generate 40 new samples from the input state space.
sampler_5 = copy(sampler_orig); sampler_5.StandardDeviation = [0.5 0.5 0.06]; states_5 = sample(sampler_5,40);
Display the results using the helperDisplayStates
helper function. Note that, as you increase the standard deviation values, the samples concentrate more around the obstacle boundary. However, if the standard deviation values are greater than the width of the narrow passages in the input space, the sampler generates incorrect results.
helperDisplayStates(map,states_orig,sampler_4,states_4,sampler_5,states_5,"Std.Deviation");
Helper Function
helperDisplayStates
displays results using a custom figure window.
function helperDisplayStates(map,states_orig,sampler_2,states_2,sampler_3,states_3,select) if select == "MaxAttempts" title_1 = "MaxAttempts = 10 (Default value)"; title_2 = strcat("MaxAttempts = ",num2str(sampler_2.MaxAttempts)); title_3 = strcat("MaxAttempts = ",num2str(sampler_3.MaxAttempts)); elseif select == "Std.Deviation" title_1 = "StandardDeviation = [0.1 0.1 0.06] (Default value)"; title_2 = strcat("StandardDeviation = [0.01 0.01 0.06]"); title_3 = strcat("StandardDeviation = [0.5 0.5 0.06]"); end fig_1 = figure(Position=[0 0 700 300]); movegui("center") panel_1 = uipanel(fig_1, ... Position=[0 0 0.33 1], ... Title=title_1); hPlot1 = axes(panel_1); show(map,Parent=hPlot1); hold on; plot(states_orig(:,1),states_orig(:,2),plannerLineSpec.state{:}) hold off panel_2 = uipanel(fig_1, ... Position=[0.33 0 0.33 1], ... Title=title_2); hPlot2 = axes(panel_2); show(map,Parent=hPlot2); hold on; plot(states_2(:,1),states_2(:,2),plannerLineSpec.state{:}) hold off panel_3 = uipanel(fig_1, ... Position=[0.66 0 0.33 1], ... Title=title_3); hPlot3 = axes(panel_3); show(map,Parent=hPlot3); hold on; plot(states_3(:,1),states_3(:,2),plannerLineSpec.state{:}) hold off end
Input Arguments
sampler
— State sampler object
stateSamplerGaussian
object
State sampler object, specified as a stateSamplerGaussian
object.
numsamples
— Number of samples
1
(default) | positive integer
Number of samples, specified as a positive integer.
Data Types: double
Output Arguments
states
— State samples
M-by-N matrix of real values
State samples, returned as an M-by-N matrix of
real values. M is the number of states. N is the
number of state variables. Each row of the matrix specifies the state variables
corresponding to the input state space model. For example, for the SE(2) state space
model, N is 3 and each row is of the form [x
,
y
, theta
].
Data Types: double
Version History
Introduced in R2023b
MATLAB 命令
您点击的链接对应于以下 MATLAB 命令:
请在 MATLAB 命令行窗口中直接输入以执行命令。Web 浏览器不支持 MATLAB 命令。
Select a Web Site
Choose a web site to get translated content where available and see local events and offers. Based on your location, we recommend that you select: .
You can also select a web site from the following list:
How to Get Best Site Performance
Select the China site (in Chinese or English) for best site performance. Other MathWorks country sites are not optimized for visits from your location.
Americas
- América Latina (Español)
- Canada (English)
- United States (English)
Europe
- Belgium (English)
- Denmark (English)
- Deutschland (Deutsch)
- España (Español)
- Finland (English)
- France (Français)
- Ireland (English)
- Italia (Italiano)
- Luxembourg (English)
- Netherlands (English)
- Norway (English)
- Österreich (Deutsch)
- Portugal (English)
- Sweden (English)
- Switzerland
- United Kingdom (English)