本文主要是介绍Apollo9.0 Lattice Planner算法源码学习,希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
一、概述
主文件:lattice_planner.cc,相关路径如下:
modules\planning\planners\lattice\lattice_planner.cc
modules\planning\planners\lattice\lattice_planner.h
主程序函数:
Status LatticePlanner::Plan(const TrajectoryPoint& planning_start_point,Frame* frame,ADCTrajectory* ptr_computed_trajectory) {}
二、主程序学习(详细注释)
/******************************************************************************* Copyright 2017 The Apollo Authors. All Rights Reserved.** Licensed under the Apache License, Version 2.0 (the "License");* you may not use this file except in compliance with the License.* You may obtain a copy of the License at** http://www.apache.org/licenses/LICENSE-2.0** Unless required by applicable law or agreed to in writing, software* distributed under the License is distributed on an "AS IS" BASIS,* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.* See the License for the specific language governing permissions and* limitations under the License.*****************************************************************************//*** @file**/#include "modules/planning/planners/lattice/lattice_planner.h"#include <limits>
#include <memory>
#include <utility>
#include <vector>#include "cyber/common/log.h"
#include "cyber/common/macros.h"
#include "cyber/time/clock.h"
#include "modules/common/math/cartesian_frenet_conversion.h"
#include "modules/common/math/path_matcher.h"
#include "modules/planning/planners/lattice/behavior/collision_checker.h"
#include "modules/planning/planners/lattice/behavior/path_time_graph.h"
#include "modules/planning/planners/lattice/behavior/prediction_querier.h"
#include "modules/planning/planners/lattice/trajectory_generation/backup_trajectory_generator.h"
#include "modules/planning/planners/lattice/trajectory_generation/lattice_trajectory1d.h"
#include "modules/planning/planners/lattice/trajectory_generation/trajectory1d_generator.h"
#include "modules/planning/planners/lattice/trajectory_generation/trajectory_combiner.h"
#include "modules/planning/planners/lattice/trajectory_generation/trajectory_evaluator.h"
#include "modules/planning/planning_base/gflags/planning_gflags.h"
#include "modules/planning/planning_base/math/constraint_checker/constraint_checker.h"namespace apollo {
namespace planning {using apollo::common::ErrorCode;
using apollo::common::PathPoint;
using apollo::common::Status;
using apollo::common::TrajectoryPoint;
using apollo::common::math::CartesianFrenetConverter;
using apollo::common::math::PathMatcher;
using apollo::cyber::Clock;namespace {//---------该函数将输入的参考线进行离散化---------//
//---------输入:为ReferencePoint类型的vector----//
//---------输出:为PathPoint类型的vector---------//
std::vector<PathPoint> ToDiscretizedReferenceLine(const std::vector<ReferencePoint>& ref_points) {double s = 0.0;std::vector<PathPoint> path_points;for (const auto& ref_point : ref_points) {PathPoint path_point; //-----Pathpoint相当于定义的一种结构体,包含了很多路径点信息path_point.set_x(ref_point.x());path_point.set_y(ref_point.y());path_point.set_theta(ref_point.heading());path_point.set_kappa(ref_point.kappa());path_point.set_dkappa(ref_point.dkappa());if (!path_points.empty()) {double dx = path_point.x() - path_points.back().x();double dy = path_point.y() - path_points.back().y();s += std::sqrt(dx * dx + dy * dy); //-----s的计算方式:以直代曲!}path_point.set_s(s);path_points.push_back(std::move(path_point));}return path_points;
}//---------该函数将计算规划起点的Frenet坐标(状态)---------//
//---------其中调用了Cartesian 转 Frenet坐标的函数---------//
void ComputeInitFrenetState(const PathPoint& matched_point,const TrajectoryPoint& cartesian_state,std::array<double, 3>* ptr_s,std::array<double, 3>* ptr_d) {CartesianFrenetConverter::cartesian_to_frenet(matched_point.s(), matched_point.x(), matched_point.y(),matched_point.theta(), matched_point.kappa(), matched_point.dkappa(),cartesian_state.path_point().x(), cartesian_state.path_point().y(),cartesian_state.v(), cartesian_state.a(),cartesian_state.path_point().theta(),cartesian_state.path_point().kappa(), ptr_s, ptr_d);
}} // namespace/*-----------------------------------------------
以下的planner函数就是规划主函数
输入为:planning_start_point 规划起点;frame 一次规划所需要的所有环境信息
ptr_computed_trajectory 待规划的轨迹??
-----------------------------------------------*/
Status LatticePlanner::Plan(const TrajectoryPoint& planning_start_point,Frame* frame,ADCTrajectory* ptr_computed_trajectory) {size_t success_line_count = 0;size_t index = 0;
/*-----------------------------------------------
由于一个规划帧开始之前有定位和导航routing模块都会得到若干
条参考线,因此规划开始之前要根据给定的cost计算每条参考
线的cost,然后选择其中cost最低的一条进行离散化。SetPriorityCost
-----------------------------------------------*/for (auto& reference_line_info : *frame->mutable_reference_line_info()) {if (index != 0) {reference_line_info.SetPriorityCost(FLAGS_cost_non_priority_reference_line);} else {reference_line_info.SetPriorityCost(0.0);}/*-----------------------------------------------PlanOnReferenceLine()该函数为Lattice算法中最重要的函数,即:在选定cost最优的参考线之后,在该参考线上进行规划!-----------------------------------------------*/auto status =PlanOnReferenceLine(planning_start_point, frame, &reference_line_info);if (status != Status::OK()) {if (reference_line_info.IsChangeLanePath()) {AERROR << "Planner failed to change lane to "<< reference_line_info.Lanes().Id();} else {AERROR << "Planner failed to " << reference_line_info.Lanes().Id();}} else {success_line_count += 1;}++index;}if (success_line_count > 0) {return Status::OK();}return Status(ErrorCode::PLANNING_ERROR,"Failed to plan on any reference line.");
}/*-----------------------------------------------
对每一条参考线都会执行以下规划(?)
以下为PlanOnReferenceLine()的具体实现,分为7个步骤:
1、离散化参考线上的点,并计算s的值(目的:以直代曲,
为了在进行坐标转化以及计算障碍物距离自车的s坐标的时
候可以使用,如制作index2s表格,即根据参考线上点的索
引号映射到s值的表)
2、在参考线上计算“规划起点”的匹配点
3、根据匹配点,计算Frenet坐标系的S-L值
4、计算障碍物的S-T图(斜率表示速度)
5、生成纵横向采样路径
6、计算cost值,进行碰撞检测(依据S-T图)和动力学约束检测
7、优选出cost值最小的trajectory
-----------------------------------------------*/
Status LatticePlanner::PlanOnReferenceLine(const TrajectoryPoint& planning_init_point, Frame* frame,ReferenceLineInfo* reference_line_info) {static size_t num_planning_cycles = 0;static size_t num_planning_succeeded_cycles = 0;double start_time = Clock::NowInSeconds();double current_time = start_time;ADEBUG << "Number of planning cycles: " << num_planning_cycles << " "<< num_planning_succeeded_cycles;++num_planning_cycles;reference_line_info->set_is_on_reference_line();// 1. obtain a reference line and transform it to the PathPoint format.// 以下为参考线离散化的过程:auto ptr_reference_line =std::make_shared<std::vector<PathPoint>>(ToDiscretizedReferenceLine(reference_line_info->reference_line().reference_points()));// 2. compute the matched point of the init planning point on the reference// line.// 以下将计算规划起点的匹配点// 该函数的实现是在 path_matcher.cc 文件里面PathPoint matched_point = PathMatcher::MatchToPath(*ptr_reference_line, planning_init_point.path_point().x(),planning_init_point.path_point().y());// 3. according to the matched point, compute the init state in Frenet frame
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