Twist

Represents 3D linear velocity and 3D angular velocity. Used for full 6-DOF velocity representation in odometry, navigation, and force/torque control. For 2D mobile robots, prefer the simpler CmdVel.

When to Use

Use Twist when you need full 3D velocity: drones, underwater vehicles, manipulator end-effectors, or any system that moves in all six degrees of freedom. Also used as a component of Odometry and TwistWithCovariance.

ROS2 Equivalent

geometry_msgs/Twist — identical field layout (linear [x, y, z] + angular [x, y, z]).

Rust Example

use horus::prelude::*;

// Drone velocity: 1 m/s forward, 0.5 m/s up, yawing at 0.1 rad/s
let twist = Twist {
    linear: [1.0, 0.0, 0.5],        // [x, y, z] m/s
    angular: [0.0, 0.0, 0.1],       // [roll, pitch, yaw] rad/s
    timestamp_ns: 0,
};

let topic: Topic<Twist> = Topic::new("velocity")?;
topic.send(twist);

Python Example

import horus

twist = horus.Twist(
    linear=[1.0, 0.0, 0.5],
    angular=[0.0, 0.0, 0.1],
)

Fields

TwistWithCovariance

For uncertainty-aware systems (EKF, navigation stacks), use the covariance variant:

let twist_cov = TwistWithCovariance {
    twist: Twist { linear: [1.0, 0.0, 0.0], angular: [0.0, 0.0, 0.1], timestamp_ns: 0 },
    covariance: [0.0; 36],  // 6x6 row-major: [vx, vy, vz, wx, wy, wz]
};

CmdVel vs Twist

Related Types

• CmdVel — Simplified 2D velocity command
• Odometry — Combines pose + twist for localization
• Accel — Linear + angular acceleration