HC-SR04 Ultrasonic Sensor

Authors: Daniel Rico-Aniles 

The Sensor Description

When the RPlidar

Hardware Architecture

The solution that has worked best for th 

Figure 2. Hardware architecture to control an ultrasonic sensor HC-SR04

Finite State Machine

STEP 1 - rplidar.launch Modification

The RPLidar Se

HC-SR04 with Configuration and Data Registers 

STEP 1 - rplidar.launch Modification

The RPLidar Se

VHDL Codes

STEP 3 - Hector-SLAM Mapping File  Modification

There are 2 important parameters in the Hector-SLAM mapping launch file that can help to avoid getting a map broken, map_update_distance_thresh and map_update_angle_thresh. These parameters determined how often the map is updated, the units are meters and radians for the distance and angle respectively.



The used parameter values are shown shown in Figure 4.

Figure 4 Map update parameter inside the Hector-SLAM mapping launch file.

Results

After doing the above stated modification it was possible to generate a correct map running Hector-SLAM and teleoperating the robot with a bluetooth controller. The generated map is shown in Figure 5.

IMPORTANT the parameters have to be tuned so that  the robot can  move in straight line or turn  at 100% the speed without breaking the map.

Figure 5 Successful map generation.