ROS package for radio based follow me function

This package was created as part of a master's thesis. It enables a robot to autonomously follow a human using Ultra-wideband Two-way Ranging and Bluetooth Angle of Arrival measurements. This package contains nodes for localizing the human, drivers for the sensors are in separate packages (UWB, Bluetooth).

Usage

Several config files have to be edited based on the used sensor configuration:

1. In config/twr.yaml enter the fixed frame (has to already exist and be connected to the tf tree), the name of the frame that marks the position of the human, whether the localisation should operate in 3D or in 2D and the ID of the UWB module that the human carries. The next parameters are lists, each element describes one of the UWB modules mounted on the robot. id has to match the ID set in the firmware of the UWB module. positions contains three numbers per module, these are the x, y and z coordinates of the module in the fixed coordinate frame defined earlier. Parameter calibration allows to set a calibration polynomial for each module separately, this polynomial can have arbitrary degree (has to be the same for all modules) and is used to correct the range measurements that the corresponding module publishes.

2. config/aoa.yaml again contains the fixed frame as a parameter. The next parameter is mode, it defines how will be the most relevant AoA measurement selected (if multiple are available). It can be set to RSSI or external, the default one is RSSI. RSSI uses just the signal strength, which might not be a reliable indicator of the measurement quality. external uses an estimate from other localisation system (i.e. UWB TWR) to select the antenna array that has the human in range. This estimate has the form of a tf frame defined in parameter estimate_frame. Parameter positions again defines where are the AoA antennas mounted with respect to the fixed frame, but since they are directional, orientation has to be provided too (as quaternion). A tf frame for each antenna is created, parameter frames defines how these frames should be named.

The last step is to prepare the launch files. In launch/aoa.launch and launch/twr.launch configure the driver for each sensor by specifying the port to which it is connected. In the main launch file launch/radio.launch set the desired gap between the robot and human and set the available sensor systems (tdoa_available, twr_available and bt_aoa_available)

Once all of the preceding steps are complete, the system is ready to be used. It can be started with the launch/radio.launch launch file.