High Level Command — C++ Example

Source: rbq_sdk/cpp/example/src/rbq_high_level.cpp

Publishes HighLevelCommand messages at 50 Hz over DDS.
Gait selection is done from the terminal; velocity setpoints come from a joystick.

Overview

Three concurrent actors run together:

Actor	Rate	Role
Control loop thread	50 Hz	Publishes `HighLevelCommand` with the current gait + velocity
Joystick loop thread	100 Hz	Polls the joystick and updates atomic velocity globals
Main thread (terminal)	blocking	Reads gait names/IDs from stdin and updates the target gait

At startup the control loop also publishes switchControlMode = true once, which enables EXT_JOY mode on the robot stack — without this the HighLevelCommand topic is ignored.

Prerequisites

RBQ SDK built and installed — see C++ SDK Overview.
A Linux joystick device at /dev/input/js* (the joystick is required to start the program).
Robot stack running (simulation or hardware).

Build

From rbq_sdk/cpp/example/:

bash

bash scripts/setup.bash
bash scripts/build.bash

Binary: bin/rbq_high_level

Run

bash

./bin/rbq_high_level <networkInterface> [joystickPath]
# e.g.
./bin/rbq_high_level eth0
./bin/rbq_high_level eth0 /dev/input/js1

The joystick auto-detection follows the same logic as the Sport Client (Joystick) example.

Terminal commands

At the > prompt type either a gait name or a numeric gait ID.

list              # print the example's built-in list
standing          # switch to STANDING by name
3                 # switch to TROTTING by ID
waving            # switch to WAVING by name

Supported gaits

Name	ID	Description
`sitting`	0	Robot sits on the ground
`standing`	1	Neutral standing posture (default at startup)
`trotting`	3	MPC trot gait
`trot_stairs`	4	Stair-adaptive trot
`waving`	5	Slow walk gait
`docking`	10	Auto-docking sequence

The example's built-in list also prints internal gaits that are not supported. Use only the gaits in the table above.

Joystick velocity controls

Axis	Maps to	Max value
Left stick Y (forward)	`vel_x`	±1.2 m/s
Left stick X (lateral)	`vel_y`	±0.5 m/s
Right stick X (yaw)	`omega_z`	±60 deg/s

A deadzone of 0.12 is applied before scaling.

Note on omega_z units: HighLevelCommand.omega_z is sent in degrees per second.
The on-robot QuadWalk multiplies by D2R internally, so the SDK side sends raw deg/s values (e.g. 60 deg/s ≈ 1.05 rad/s of yaw).

DDS topics used

Direction	Topic	Message type
Publish	`rt/rbq/cmd/high_level`	`rbq_msgs::msg::dds_::HighLevelCommand_`
Publish	`rt/rbq/cmd/switch_control_mode`	`std_msgs::msg::dds_::Bool_`

Key implementation notes

gait_transition flag: Set to true only on the single tick immediately following a gait change, using std::atomic<bool>::exchange(). This ensures the QuadWalk gaitTimer is triggered exactly once rather than continuously.
switchControlMode: Published once at startup (after a 200 ms delay to let DDS subscribers connect). If not published, the robot ignores HighLevelCommand and stays in joystick mode.
Timing: The control loop uses clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, ...) for precise 20 ms scheduling. If the loop runs late, it resets timeNext to the current time rather than chasing a drifting target.

High Level Command — C++ Example ​

Overview ​

Prerequisites ​

Build ​

Run ​

Terminal commands ​

Supported gaits ​

Joystick velocity controls ​

DDS topics used ​

Key implementation notes ​

See also ​