前言
这篇文章我开始和大家一起探讨机器人SLAM建图与自主导航 ，在前面的内容中，我们介绍了差速轮式机器人的概念及应用，谈到了使用Gazebo平台搭建仿真环境的教程，主要是利用gmapping slam算法，生成一张二维的仿真环境地图 。我们也会在这篇文章中继续介绍并使用这片二维的仿真环境地图，用于我们的演示。
教程
SLAM算法的引入
（1）SLAM：Simultaneous Localization and Mapping，中文是即时定位与地图构建，所谓的SLAM算法准确说是能实现SLAM功能的算法，而不是某一个具体算法。
（2）现在各种机器人研发和商用化非常火 ，所有的自主机器人都绕不开一个问题，即在陌生环境中，需要知道周边是啥样（建图），需要知道我在哪（定位），于是有了SLAM 课题的研究。SLAM在室内机器人，自动驾驶汽车建图，VR/AR穿戴等领域都有广泛的应用。
（3）SLAM算法根据依赖的传感器不同，可以分为激光SLAM和视觉SLAM，前者是激光雷达，后者是能提供深度信息的摄像头，如双目摄像头，红外摄像头等。除此之外，SLAM算法通常还依赖里程计提供距离信息，否则地图很难无缝的拼接起来，很容易跑飞。一个经典的SLAM 流程框架如下，其中回环检测时为了判断机器人有没有来过之前的位置。
整体视觉SLAM的流程图
gmapping算法的基本原理
（1）现在ROS里有一系列SLAM算法包，如：gmapping ，hector（不需要里程计，比较特别），谷歌开源的cartographer（效率高），rtabmap（前面是二维的，这是三维建图）等。
（2）gmapping是基于激光雷达的，需要里程计信息，创建二维格栅地图。其中IMU信息可以没有 。
（3）ros中激光雷达数据消息是 sensor_msgs/LaserScan ，内容如下：
（4）ros中里程计数据消息是 nav_msgs/Odometry 。
（5）gmapping 发布的地图meta数据：
（6）gmapping 发布的地图栅格数据
mbot_navigation
（1）ubuntu20.04 + ros noetic下，安装gmapping和保存地图文件的map_server
sudo apt-get install ros-noetic-gmapping sudo apt-get install ros-noetic-map-server // 补充：这是安装hector sudo apt-get install ros-noetic-hector-slam
（2）创建 mbot_navigation 和相关文件
cd ~/catkin_ws/src catkin_create_pkg mbot_navigation geometry_msgs move_base_msgs actionlib roscpp rospy cd mbot_navigation mkdir launch maps rviz touch launch/gmapping.launch
（3）调用gmapping算法，只需要写launch文件就行了，不用编码。gmapping.launch
<launch> // mbot_gazebo 会通过发/scan topic，传出lidar数据 <arg name="scan_topic" default="scan" /> // gammping一大堆参数，这里都是从他的demo里扣出来的，不用改。 // 如果想用的好，可以尝试修改，甚至改一些代码，这就是算法（调参）工程师！ <node pkg="gmapping" type="slam_gmapping" name="slam_gmapping" output="screen" clear_params="true"> // mbot_gazebo 会通过发/odom topic，传出里程计数据 <param name="odom_frame" value="odom"/> <param name="map_update_interval" value="5.0"/> <!-- Set maxUrange < actual maximum range of the Laser --> <param name="maxRange" value="5.0"/> <param name="maxUrange" value="4.5"/> <param name="sigma" value="0.05"/> <param name="kernelSize" value="1"/> <param name="lstep" value="0.05"/> <param name="astep" value="0.05"/> <param name="iterations" value="5"/> <param name="lsigma" value="0.075"/> <param name="ogain" value="3.0"/> <param name="lskip" value="0"/> <param name="srr" value="0.01"/> <param name="srt" value="0.02"/> <param name="str" value="0.01"/> <param name="stt" value="0.02"/> <param name="linearUpdate" value="0.5"/> <param name="angularUpdate" value="0.436"/> <param name="temporalUpdate" value="-1.0"/> <param name="resampleThreshold" value="0.5"/> <param name="particles" value="80"/> <param name="xmin" value="-1.0"/> <param name="ymin" value="-1.0"/> <param name="xmax" value="1.0"/> <param name="ymax" value="1.0"/> <param name="delta" value="0.05"/> <param name="llsamplerange" value="0.01"/> <param name="llsamplestep" value="0.01"/> <param name="lasamplerange" value="0.005"/> <param name="lasamplestep" value="0.005"/> <remap from="scan" to="$(arg scan_topic)"/> </node> // 保存的rviz配置文件 <node pkg="rviz" type="rviz" name="rviz" args="-d $(find mbot_navigation)/rviz/map.rviz"/> </launch>
（4）连同mbot_gazebo，一起编译运行
cd ~/catkin_ws catkin_make -DCATKIN_WHITELIST_PACKAGES="mbot_navigation;mbot_gazebo" source devel/setup.bash // 打开仿真环境 roslaunch mbot_gazebo mbot_gazebo.launch //再开一个窗口，打开gmapping roslaunch mbot_navigation gmapping.launch // 控制机器人行动，进行建图 roslaunch mbot_gazebo mbot_teletop.launch // 建图完成后，新开窗口，执行map_server，保存生成的地图 cd ~/catkin_ws/src/mbot_navigation/maps rosrun map_server map_saver -f gmapping_save
最终保存下来的地图
总结
在github上面的访问地址：https://github.com/Jieshoudaxue/ros_senior/tree/main/mbot_navigation/config/move_base
代码示例：
#include <ros/ros.h> #include <list> #include <geometry_msgs/Pose.h> #include <move_base_msgs/MoveBaseAction.h> #include <actionlib/client/simple_action_client.h> geometry_msgs::Pose createPose(double px, double py, double pz, double ox, double oy, double oz, double ow) { geometry_msgs::Pose pose; pose.position.x = px; pose.position.y = py; pose.position.z = pz; pose.orientation.x = ox; pose.orientation.y = oy; pose.orientation.z = oz; pose.orientation.w = ow; return pose; } int main(int argc, char** argv) { ros::init(argc, argv, "move_test"); actionlib::SimpleActionClient<move_base_msgs::MoveBaseAction> move_base_client("move_base", true); ROS_INFO("Waiting for move_base action server..."); move_base_client.waitForServer(); ROS_INFO("connected to move base server"); std::vector<geometry_msgs::Pose> target_list; target_list.push_back(createPose(6.543, 4.779, 0.000, 0.000, 0.000, 0.645, 0.764)); target_list.push_back(createPose(5.543, -4.779, 0.000, 0.000, 0.000, 0.645, 0.764)); target_list.push_back(createPose(-5.543, 4.779, 0.000, 0.000, 0.000, 0.645, 0.764)); target_list.push_back(createPose(-5.543, -4.779, 0.000, 0.000, 0.000, 0.645, 0.764)); for (uint8_t i = 0; i < target_list.size(); i ++) { ros::Time start_time = ros::Time::now(); ROS_INFO("going to %u goal, position: (%f, %f)", i, target_list[i].position.x, target_list[i].position.y); move_base_msgs::MoveBaseGoal goal; goal.target_pose.header.frame_id = "map"; goal.target_pose.header.stamp = ros::Time::now(); goal.target_pose.pose = target_list[i]; move_base_client.sendGoal(goal); move_base_client.waitForResult(); if (move_base_client.getState() == actionlib::SimpleClientGoalState::SUCCEEDED) { ros::Duration running_time = ros::Time::now() - start_time; ROS_INFO("go to %u goal succeeded, running time %f sec", i, running_time.toSec()); } else { ROS_INFO("goal failed"); } } return 0; }
# YOLOv5 🚀 by Ultralytics, GPL-3.0 license """ YOLO-specific modules Usage: $ python path/to/models/yolo.py --cfg yolov5s.yaml """ import argparse import sys from copy import deepcopy from pathlib import Path FILE = Path(__file__).resolve() ROOT = FILE.parents[1] # YOLOv5 root directory if str(ROOT) not in sys.path: sys.path.append(str(ROOT)) # add ROOT to PATH # ROOT = ROOT.relative_to(Path.cwd()) # relative from models.common import * from models.experimental import * from utils.autoanchor import check_anchor_order from utils.general import LOGGER, check_version, check_yaml, make_divisible, print_args from utils.plots import feature_visualization from utils.torch_utils import fuse_conv_and_bn, initialize_weights, model_info, scale_img, select_device, time_sync try: import thop # for FLOPs computation except ImportError: thop = None class Detect(nn.Module): stride = None # strides computed during build onnx_dynamic = False # ONNX export parameter def __init__(self, nc=80, anchors=(), ch=(), inplace=True): # detection layer super().__init__() self.nc = nc # number of classes self.no = nc + 5 # number of outputs per anchor self.nl = len(anchors) # number of detection layers self.na = len(anchors[0]) // 2 # number of anchors self.grid = [torch.zeros(1)] * self.nl # init grid self.anchor_grid = [torch.zeros(1)] * self.nl # init anchor grid self.register_buffer('anchors', torch.tensor(anchors).float().view(self.nl, -1, 2)) # shape(nl,na,2) self.m = nn.ModuleList(nn.Conv2d(x, self.no * self.na, 1) for x in ch) # output conv self.inplace = inplace # use in-place ops (e.g. slice assignment) def forward(self, x): z = [] # inference output for i in range(self.nl): x[i] = self.m[i](x[i]) # conv bs, _, ny, nx = x[i].shape # x(bs,255,20,20) to x(bs,3,20,20,85) x[i] = x[i].view(bs, self.na, self.no, ny, nx).permute(0, 1, 3, 4, 2).contiguous() if not self.training: # inference if self.onnx_dynamic or self.grid[i].shape[2:4] != x[i].shape[2:4]: self.grid[i], self.anchor_grid[i] = self._make_grid(nx, ny, i) y = x[i].sigmoid() if self.inplace: y[..., 0:2] = (y[..., 0:2] * 2 - 0.5 + self.grid[i]) * self.stride[i] # xy y[..., 2:4] = (y[..., 2:4] * 2) ** 2 * self.anchor_grid[i] # wh else: # for YOLOv5 on AWS Inferentia https://github.com/ultralytics/yolov5/pull/2953 xy = (y[..., 0:2] * 2 - 0.5 + self.grid[i]) * self.stride[i] # xy wh = (y[..., 2:4] * 2) ** 2 * self.anchor_grid[i] # wh y = torch.cat((xy, wh, y[..., 4:]), -1) z.append(y.view(bs, -1, self.no)) return x if self.training else (torch.cat(z, 1), x) def _make_grid(self, nx=20, ny=20, i=0): d = self.anchors[i].device if check_version(torch.__version__, '1.10.0'): # torch>=1.10.0 meshgrid workaround for torch>=0.7 compatibility yv, xv = torch.meshgrid([torch.arange(ny, device=d), torch.arange(nx, device=d)], indexing='ij') else: yv, xv = torch.meshgrid([torch.arange(ny, device=d), torch.arange(nx, device=d)]) grid = torch.stack((xv, yv), 2).expand((1, self.na, ny, nx, 2)).float() anchor_grid = (self.anchors[i].clone() * self.stride[i]) \ .view((1, self.na, 1, 1, 2)).expand((1, self.na, ny, nx, 2)).float() return grid, anchor_grid class Model(nn.Module): def __init__(self, cfg='yolov5s.yaml', ch=3, nc=None, anchors=None): # model, input channels, number of classes super().__init__() if isinstance(cfg, dict): self.yaml = cfg # model dict else: # is *.yaml import yaml # for torch hub self.yaml_file = Path(cfg).name with open(cfg, encoding='ascii', errors='ignore') as f: self.yaml = yaml.safe_load(f) # model dict # Define model ch = self.yaml['ch'] = self.yaml.get('ch', ch) # input channels if nc and nc != self.yaml['nc']: LOGGER.info(f"Overriding model.yaml nc={self.yaml['nc']} with nc={nc}") self.yaml['nc'] = nc # override yaml value if anchors: LOGGER.info(f'Overriding model.yaml anchors with anchors={anchors}') self.yaml['anchors'] = round(anchors) # override yaml value self.model, self.save = parse_model(deepcopy(self.yaml), ch=[ch]) # model, savelist self.names = [str(i) for i in range(self.yaml['nc'])] # default names self.inplace = self.yaml.get('inplace', True) # Build strides, anchors m = self.model[-1] # Detect() if isinstance(m, Detect): s = 256 # 2x min stride m.inplace = self.inplace m.stride = torch.tensor([s / x.shape[-2] for x in self.forward(torch.zeros(1, ch, s, s))]) # forward m.anchors /= m.stride.view(-1, 1, 1) check_anchor_order(m) self.stride = m.stride self._initialize_biases() # only run once # Init weights, biases initialize_weights(self) self.info() LOGGER.info('') def forward(self, x, augment=False, profile=False, visualize=False): if augment: return self._forward_augment(x) # augmented inference, None return self._forward_once(x, profile, visualize) # single-scale inference, train def _forward_augment(self, x): img_size = x.shape[-2:] # height, width s = [1, 0.83, 0.67] # scales f = [None, 3, None] # flips (2-ud, 3-lr) y = [] # outputs for si, fi in zip(s, f): xi = scale_img(x.flip(fi) if fi else x, si, gs=int(self.stride.max())) yi = self._forward_once(xi)[0] # forward # cv2.imwrite(f'img_{si}.jpg', 255 * xi[0].cpu().numpy().transpose((1, 2, 0))[:, :, ::-1]) # save yi = self._descale_pred(yi, fi, si, img_size) y.append(yi) y = self._clip_augmented(y) # clip augmented tails return torch.cat(y, 1), None # augmented inference, train def _forward_once(self, x, profile=False, visualize=False): y, dt = [], [] # outputs for m in self.model: if m.f != -1: # if not from previous layer x = y[m.f] if isinstance(m.f, int) else [x if j == -1 else y[j] for j in m.f] # from earlier layers if profile: self._profile_one_layer(m, x, dt) x = m(x) # run y.append(x if m.i in self.save else None) # save output if visualize: feature_visualization(x, m.type, m.i, save_dir=visualize) return x def _descale_pred(self, p, flips, scale, img_size): # de-scale predictions following augmented inference (inverse operation) if self.inplace: p[..., :4] /= scale # de-scale if flips == 2: p[..., 1] = img_size[0] - p[..., 1] # de-flip ud elif flips == 3: p[..., 0] = img_size[1] - p[..., 0] # de-flip lr else: x, y, wh = p[..., 0:1] / scale, p[..., 1:2] / scale, p[..., 2:4] / scale # de-scale if flips == 2: y = img_size[0] - y # de-flip ud elif flips == 3: x = img_size[1] - x # de-flip lr p = torch.cat((x, y, wh, p[..., 4:]), -1) return p def _clip_augmented(self, y): # Clip YOLOv5 augmented inference tails nl = self.model[-1].nl # number of detection layers (P3-P5) g = sum(4 ** x for x in range(nl)) # grid points e = 1 # exclude layer count i = (y[0].shape[1] // g) * sum(4 ** x for x in range(e)) # indices y[0] = y[0][:, :-i] # large i = (y[-1].shape[1] // g) * sum(4 ** (nl - 1 - x) for x in range(e)) # indices y[-1] = y[-1][:, i:] # small return y def _profile_one_layer(self, m, x, dt): c = isinstance(m, Detect) # is final layer, copy input as inplace fix o = thop.profile(m, inputs=(x.copy() if c else x,), verbose=False)[0] / 1E9 * 2 if thop else 0 # FLOPs t = time_sync() for _ in range(10): m(x.copy() if c else x) dt.append((time_sync() - t) * 100) if m == self.model[0]: LOGGER.info(f"{'time (ms)':>10s} {'GFLOPs':>10s} {'params':>10s} {'module'}") LOGGER.info(f'{dt[-1]:10.2f} {o:10.2f} {m.np:10.0f} {m.type}') if c: LOGGER.info(f"{sum(dt):10.2f} {'-':>10s} {'-':>10s} Total") def _initialize_biases(self, cf=None): # initialize biases into Detect(), cf is class frequency # https://arxiv.org/abs/1708.02002 section 3.3 # cf = torch.bincount(torch.tensor(np.concatenate(dataset.labels, 0)[:, 0]).long(), minlength=nc) + 1. m = self.model[-1] # Detect() module for mi, s in zip(m.m, m.stride): # from b = mi.bias.view(m.na, -1) # conv.bias(255) to (3,85) b.data[:, 4] += math.log(8 / (640 / s) ** 2) # obj (8 objects per 640 image) b.data[:, 5:] += math.log(0.6 / (m.nc - 0.999999)) if cf is None else torch.log(cf / cf.sum()) # cls mi.bias = torch.nn.Parameter(b.view(-1), requires_grad=True) def _print_biases(self): m = self.model[-1] # Detect() module for mi in m.m: # from b = mi.bias.detach().view(m.na, -1).T # conv.bias(255) to (3,85) LOGGER.info( ('%6g Conv2d.bias:' + '%10.3g' * 6) % (mi.weight.shape[1], *b[:5].mean(1).tolist(), b[5:].mean())) # def _print_weights(self): # for m in self.model.modules(): # if type(m) is Bottleneck: # LOGGER.info('%10.3g' % (m.w.detach().sigmoid() * 2)) # shortcut weights def fuse(self): # fuse model Conv2d() + BatchNorm2d() layers LOGGER.info('Fusing layers... ') for m in self.model.modules(): if isinstance(m, (Conv, DWConv)) and hasattr(m, 'bn'): m.conv = fuse_conv_and_bn(m.conv, m.bn) # update conv delattr(m, 'bn') # remove batchnorm m.forward = m.forward_fuse # update forward self.info() return self def info(self, verbose=False, img_size=640): # print model information model_info(self, verbose, img_size) def _apply(self, fn): # Apply to(), cpu(), cuda(), half() to model tensors that are not parameters or registered buffers self = super()._apply(fn) m = self.model[-1] # Detect() if isinstance(m, Detect): m.stride = fn(m.stride) m.grid = list(map(fn, m.grid)) if isinstance(m.anchor_grid, list): m.anchor_grid = list(map(fn, m.anchor_grid)) return self def parse_model(d, ch): # model_dict, input_channels(3) LOGGER.info(f"\n{'':>3}{'from':>18}{'n':>3}{'params':>10} {'module':<40}{'arguments':<30}") anchors, nc, gd, gw = d['anchors'], d['nc'], d['depth_multiple'], d['width_multiple'] na = (len(anchors[0]) // 2) if isinstance(anchors, list) else anchors # number of anchors no = na * (nc + 5) # number of outputs = anchors * (classes + 5) layers, save, c2 = [], [], ch[-1] # layers, savelist, ch out for i, (f, n, m, args) in enumerate(d['backbone'] + d['head']): # from, number, module, args m = eval(m) if isinstance(m, str) else m # eval strings for j, a in enumerate(args): try: args[j] = eval(a) if isinstance(a, str) else a # eval strings except NameError: pass n = n_ = max(round(n * gd), 1) if n > 1 else n # depth gain if m in [Conv, GhostConv, Bottleneck, GhostBottleneck, SPP, SPPF, DWConv, MixConv2d, Focus, CrossConv, BottleneckCSP, C3, C3TR, C3SPP, C3Ghost]: c1, c2 = ch[f], args[0] if c2 != no: # if not output c2 = make_divisible(c2 * gw, 8) args = [c1, c2, *args[1:]] if m in [BottleneckCSP, C3, C3TR, C3Ghost]: args.insert(2, n) # number of repeats n = 1 elif m is nn.BatchNorm2d: args = [ch[f]] elif m is Concat: c2 = sum(ch[x] for x in f) elif m is Detect: args.append([ch[x] for x in f]) if isinstance(args[1], int): # number of anchors args[1] = [list(range(args[1] * 2))] * len(f) elif m is Contract: c2 = ch[f] * args[0] ** 2 elif m is Expand: c2 = ch[f] // args[0] ** 2 else: c2 = ch[f] m_ = nn.Sequential(*(m(*args) for _ in range(n))) if n > 1 else m(*args) # module t = str(m)[8:-2].replace('__main__.', '') # module type np = sum(x.numel() for x in m_.parameters()) # number params m_.i, m_.f, m_.type, m_.np = i, f, t, np # attach index, 'from' index, type, number params LOGGER.info(f'{i:>3}{str(f):>18}{n_:>3}{np:10.0f} {t:<40}{str(args):<30}') # print save.extend(x % i for x in ([f] if isinstance(f, int) else f) if x != -1) # append to savelist layers.append(m_) if i == 0: ch = [] ch.append(c2) return nn.Sequential(*layers), sorted(save) if __name__ == '__main__': parser = argparse.ArgumentParser() parser.add_argument('--cfg', type=str, default='yolov5s.yaml', help='model.yaml') parser.add_argument('--device', default='', help='cuda device, i.e. 0 or 0,1,2,3 or cpu') parser.add_argument('--profile', action='store_true', help='profile model speed') parser.add_argument('--test', action='store_true', help='test all yolo*.yaml') opt = parser.parse_args() opt.cfg = check_yaml(opt.cfg) # check YAML print_args(FILE.stem, opt) device = select_device(opt.device) # Create model model = Model(opt.cfg).to(device) model.train() # Profile if opt.profile: img = torch.rand(8 if torch.cuda.is_available() else 1, 3, 640, 640).to(device) y = model(img, profile=True) # Test all models if opt.test: for cfg in Path(ROOT / 'models').rglob('yolo*.yaml'): try: _ = Model(cfg) except Exception as e: print(f'Error in {cfg}: {e}') # Tensorboard (not working https://github.com/ultralytics/yolov5/issues/2898) # from torch.utils.tensorboard import SummaryWriter # tb_writer = SummaryWriter('.') # LOGGER.info("Run 'tensorboard --logdir=models' to view tensorboard at http://localhost:6006/") # tb_writer.add_graph(torch.jit.trace(model, img, strict=False), []) # add model graph
