Motion Control State Interface

Basic State Switching Interface

Switching between basic robot states is achieved by sending corresponding commands, as shown below (state values are noted in parentheses).

Key commands:

Command	Code	Value	Type	Function
Stand/Sit	0x21010202	-	0	Switch between sitting and standing
Stop STOP	0x21020C0E	-	0	Trigger software emergency stop
Home	0x21010C05	-	0	Initialize robot joints

Axis Command Interface

Axis commands are outputs from the left and right joystick X and Y axes, with a value range of [-32767, 32767]. Axis commands should be sent at a frequency no lower than 20Hz. The axis command timeout is 250ms; when the robot doesn’t receive axis commands for more than 250ms, it will automatically stop moving.

Axis Commands in In-Place Mode

In in-place mode, the client sends axis commands to the motion host to control the robot’s body posture. If no axis command is received for more than one second, the system considers the command expired and the robot returns to normal standing posture. If the axis command value is within the dead zone, it is treated as 0.

Command Name	Code	Type	Dead Zone	Function
Adjust roll angle	0x21010131	0	[-12553, 12553]	Positive value rolls right
Adjust pitch angle	0x21010130	0	[-6553, 6553]	Positive value looks down
Adjust body height	0x21010102	0	[-20000, 20000]	Positive value raises body
Adjust yaw angle	0x21010135	0	[-9553, 9553]	Positive value rotates right

Axis Commands in Mobile Mode

In mobile mode, axis commands control the robot’s movement direction and speed. When the axis command value is within the dead zone, it is treated as 0 and the robot stops. The sign of the axis command determines the speed direction.

Command Name	Code	Type	Dead Zone	Function
Lateral movement	0x21010131	0	[-12553, 12553]	Desired linear velocity on y-axis, positive right
Forward/backward	0x21010130	0	[-6553, 6553]	Desired linear velocity on x-axis, positive forward
Left/right turn	0x21010135	0	[-9553, 9553]	Desired angular velocity, positive right turn

Stop Command

During robot movement, if the axis command is 0, the robot will stop moving.

Motion Mode Switching Interface

Command Name	Code	Value	Type
Posture mode	0x21010D05	-	0
Motion mode	0x21010D06	-	0

Gait Switching Interface

Gait can be adjusted when the robot is in motion mode.

Command	Code	Value	Type	Function
Low gear flat ground gait	0x21010300	-	0	Switch to low-speed gait
Medium gear flat ground gait	0x21010307	-	0	Switch to medium-speed gait
High gear flat ground gait	0x21010303	-	0	Switch to high-speed gait
Crawl gear flat ground gait	0x21010406	-	0	Switch to low-speed crawl gait, or from crawl to normal low-speed
Grip RUG gait	0x21010402	-	0	Switch to grip gait
Normal RUG gait	0x21010401	-	0	Switch to normal gait
High-step RUG gait	0x21010407	-	0	Switch to high-step gait

The robot’s current gait can be read via the robot_gait_state field. For state value definitions, see State Machine Overview and Implementation.

Velocity Interface

Velocity commands are complex commands. Each velocity command carries double-precision floating-point data values and must be sent when the robot is in navigation mode.

Command Name	Code	Type	Value Range
Angular velocity (rad/s)	0x0141	1	[-1.5, 1.5]
Robot x-axis linear velocity (m/s)	0x0140	1	[-1.0, 1.0]
Robot y-axis linear velocity (m/s)	0x0145	1	[-0.5, 0.5]

Robot State Information

The command code for robot state information:

Code	Type	Data Content	Send Frequency
0x0901	1	Struct RobotStateUpload (see below)	50 Hz

struct RobotStateUpload{
    int robot_basic_state;
    int robot_gait_state;
    double rpy[3];
    double rpy_vel[3];
    double xyz_acc[3];
    double pos_world[3];
    double vel_world[3];
    double vel_body[3];
    unsigned touch_down_and_stair_trot;
    bool is_charging;
    unsigned error_state;
    int robot_motion_state;
    double battery_level;
    int task_state;
    bool is_robot_need_move;
    bool zero_position_flag;
    double ultrasound[2];
};

Field descriptions:

Field	Type	Description
robot_basic_state	int	Robot basic motion state
robot_gait_state	int	Robot current gait
rpy[3]	double	IMU angle information
rpy_vel[3]	double	IMU angular velocity information
xyz_acc[3]	double	IMU acceleration information
pos_world[3]	double	Robot pose in world coordinate system
vel_world[3]	double	Robot velocity in world coordinate system
vel_body[3]	double	Robot velocity in body coordinate system
touch_down_and_stair_trot	unsigned	Invalid data, placeholder only
is_charging	bool	Invalid data, placeholder only
error_state	unsigned	Invalid data, placeholder only
robot_motion_state	int	Robot motion action state
battery_level	double	Battery level as decimal fraction
task_state	int	Invalid data, placeholder only
is_robot_need_move	bool	Balance state when affected by external force
zero_position_flag	bool	Homing flag
ultrasound[2]	double	Ultrasonic data

Robot Basic Motion State

Value	Robot Basic Motion State
1	Lying down
4	Preparing to stand
5	Standing up
6	Force control
7	Lying down in progress
8	Loss-of-control protection
9	Posture adjustment
11	Performing turn-over
17	Homing
18	Performing backflip
20	Performing wave

Note: For basic state transition relationships, refer to Basic State Switching Interface.

Robot Gait

Value	Gait
0	Flat ground low-speed gait
2	General obstacle-crossing gait
4	Flat ground medium-speed gait
5	Flat ground high-speed gait
6	Grip obstacle-crossing gait
12	Moonwalk gait
13	High-step obstacle-crossing gait

IMU Angle Information

double rpy[3] = {roll, pitch, yaw};

Element	Description
roll	IMU roll angle in world coordinate system (°)
pitch	IMU pitch angle in world coordinate system (°)
yaw	IMU yaw angle in world coordinate system (°)

IMU Angular Velocity Information

double rpy_vel[3] = {roll_vel, pitch_vel, yaw_vel};

Element	Description
roll_vel	IMU roll angular velocity in world coordinate system (rad/s)
pitch_vel	IMU pitch angular velocity in world coordinate system (rad/s)
yaw_vel	IMU yaw angular velocity in world coordinate system (rad/s)

IMU Acceleration Information

double xyz_acc[3] = {x_acc, y_acc, z_acc};

Element	Description
x_acc	IMU acceleration on world x-axis (m/s²)
y_acc	IMU acceleration on world y-axis (m/s²)
z_acc	IMU acceleration on world z-axis (m/s²)

World Coordinate System Pose

double pos_world[3] = {x, y, yaw};

Element	Description
x	Robot x-axis position in world coordinate system (m)
y	Robot y-axis position in world coordinate system (m)
yaw	Robot yaw angle in world coordinate system (rad)

World Coordinate System Velocity

double vel_world[3] = {x_vel, y_vel, yaw_vel};

Element	Description
x_vel	Robot velocity on world x-axis (m/s)
y_vel	Robot velocity on world y-axis (m/s)
yaw_vel	Robot yaw angular velocity in world coordinate system (rad/s)

Body Coordinate System Velocity

double vel_body[3] = {x_vel, y_vel, yaw_vel};

Element	Description
x_vel	Robot velocity on body x-axis (m/s)
y_vel	Robot velocity on body y-axis (m/s)
yaw_vel	Robot yaw angular velocity in body coordinate system (rad/s)

Robot Motion Action State

Value	Robot Motion Action State
0	Robot is in the state corresponding to robot_basic_state
1	Robot is stepping with gait corresponding to robot_gait_state
2	Robot is performing body twist
4	Robot is performing twist jump
11	Robot is performing forward jump

Note: The robot’s complete state is determined by robot_basic_state, robot_gait_state, and robot_motion_state together.

Balance State

Value	Balance State
0	Can maintain balance
1	Cannot maintain balance, stepping to adjust posture

Homing State

Value	Homing State
0	Homing not completed or exited homing state
1	Homing completed

Ultrasonic Data

double ultrasound[2] = {forward_distance, backward_distance};

Element	Description
forward_distance	Distance to obstacle in front of robot (m)
backward_distance	Distance to obstacle behind robot (m)

Note: Ultrasonic effective range is [0.28m, 4.50m]. When obstacle distance is less than 0.28m, it displays 0.28m; when greater than 4.50m, it displays 4.50m.