5.1.2 Locomotion Control

The locomotion control interfaces provide the core functions for controlling the robot’s walking and running velocities.

Control Functions

• Supports locomotion control based on lateral velocity, forward velocity, and yaw rate (angular velocity around the vertical axis).

• Supports dynamic management and priority arbitration of multiple control input sources.

Locomotion Control Topic

Topic Name	Data Type	Description	QoS	Frequency
/aima/mc/locomotion/velocity	McLocomotionVelocity	Locomotion control(switch to Stable Stand first)	-	-

• McLocomotionVelocity ros2-msg @ mc/motion/McLocomotionVelocity.msg

  # Locomotion control
  # Topic: /aima/mc/locomotion/velocity
  
  MessageHeader header             # Message header
  string source                    # Input source name, custom for secondary development. Do not reuse names used by other modules; see notes below.
  float64 forward_velocity         # Forward/backward velocity (m/s), forward is positive
  float64 lateral_velocity         # Lateral velocity (m/s), left is positive
  float64 angular_velocity         # Yaw rate (rad/s), counterclockwise is positive
  

  Note that here the developer is the publisher of locomotion control messages, which may conflict with locomotion commands from other native system modules (such as the remote controller).

  The motion control system provides a multi-input management mechanism that arbitrates conflicting commands in real time based on priority.

  Developers must register a custom input source and use it in the source field of locomotion commands.

  For details, see the next section MC Control Signal Configuration.

  Locomotion start threshold constraints:

  When the robot is stationary, the first step requires the commanded target velocity to exceed a certain threshold. After the robot is already moving, smaller target velocities can be used. The target velocity is composed from forward_velocity, lateral_velocity, and angular_velocity. Reference threshold values for using a single control component are given in the table below.

  Target velocity type	Start threshold	Notes
  forward_velocity	0.09	Forward/backward
  lateral_velocity	0.60	Absolute value; left/right both valid
  angular_velocity	0.03	Absolute value; clockwise/counterclockwise both valid

Important

The thresholds may vary among releases, always check them and tune your code when the firmware changed

Programming Examples

For detailed programming examples and code explanations, refer to:

• C++ Examples:

  • Robot Locomotion Control

  • Register Secondary Development Input Source

• Python Examples:

  • Control robot locomotion

  • Register custom input source

Safety Notes

Warning

Motion Control Constraints

• Ensure the robot is in a safe state before switching motion modes.

• An input source must be registered before performing locomotion control.

• It is recommended to test locomotion control code in a simulation environment first.

Note

Best Practices

• Implement motion state monitoring and exception handling.

• Implement safety checks around locomotion control.

• Ensure velocity commands are smooth and continuous.