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Overview

Driver mode allows you to manually control the robot using keyboard inputs. The control system implements a differential drive model with velocity limiting and friction simulation.

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Keyboard Controls

The robot is controlled using the WASD keys:

W Key

Move forward - increases linear velocity

S Key

Move backward - decreases linear velocity

A Key

Turn left - increases angular velocity

D Key

Turn right - decreases angular velocity

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Velocity Limits

The driver system enforces maximum velocity constraints to ensure realistic robot behavior: 
const MAX_VEL: f32 = 4.0;   // Maximum linear velocity
const MAX_AVEL: f32 = 0.07; // Maximum angular velocity

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Linear Velocity

  • Maximum forward/backward speed: 4.0 units/s
  • Acceleration per keypress: 0.2 units/s
  • Friction deceleration: 0.07 units/s when no input

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Angular Velocity

  • Maximum turning speed: 0.07 rad/s
  • Turning acceleration: 0.0076 rad/s
  • Friction deceleration: 0.005 rad/s when no input

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Differential Drive

Mars-RS uses a differential drive model that converts linear and angular velocities into left and right wheel velocities: 
let vr = (2.0 * vel.0 - track * vel.1) / 2.0;
let vl = vr + (track * vel.1);

robot.step((vl, vr));
Where:
  • vel.0 is the linear velocity
  • vel.1 is the angular velocity
  • track is the robot’s track width (distance between wheels)
  • vl and vr are the left and right wheel velocities

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Friction Simulation

The driver mode includes friction to make the robot feel more realistic: 
// Linear friction
vel.0 = if absv > 0.07 {vel.0 - sgnv * 0.07} else {0.0};

// Angular friction
vel.1 = if absv1 > 0.005 {vel.1 - sgnv1 * 0.005} else {0.0};
This means the robot will gradually slow down when no keys are pressed, eventually coming to a complete stop.
The friction values are tuned to provide smooth control while preventing the robot from sliding too much.

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Switching Modes

To enter driver mode:
  1. Press the T key to toggle between Driver and Auton modes
  2. Click the Driver button in the UI
Driver mode is the default mode when Mars-RS starts up.

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Implementation Details

The driver code is located in src/driver.rs:43-77. The main drive function:
  1. Calculates absolute values and signs of current velocities
  2. Clamps velocities to maximum limits
  3. Applies friction to slow down the robot
  4. Processes WASD key inputs
  5. Converts to differential drive wheel velocities
  6. Updates robot position

Autonomous Mode

Learn about autonomous movement algorithms

Path Creation

Create paths for autonomous execution

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