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Integrating Perception, Planning, and Control in Autonomous Robots

Integrating Perception, Planning, and Control in Autonomous Robots

Autonomous robots need to continuously answer three questions:

  1. What is around me? — Perception
  2. What should I do? — Planning
  3. How do I physically do it? — Control

These systems become powerful when integrated into a closed feedback loop.

The Autonomy Loop

       ┌───────────────┐
       │    Sensors    │
       └───────┬───────┘
               ↓
       ┌───────────────┐
       │  Perception   │
       └───────┬───────┘
               ↓
       ┌───────────────┐
       │ World / State │
       └───────┬───────┘
               ↓
       ┌───────────────┐
       │   Planning    │
       └───────┬───────┘
               ↓
       ┌───────────────┐
       │   Control     │
       └───────┬───────┘
               ↓
            Robot
               │
               └──── feedback ────→ Sensors
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1. Perception

Perception converts sensor measurements into estimates.

For example:

Camera Frame
     ↓
Object Detector
     ↓
Person: 0.96
Box: 0.91
Chair: 0.87
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For navigation, perception may generate obstacles:

Obstacle A → x=2.0, y=0.5
Obstacle B → x=3.2, y=-1.1
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Always associate detections with timestamps and, where possible, uncertainty.

2. State Estimation

Planning should not consume isolated detections. It needs a coherent state.

Combine:

IMU
Wheel Odometry
GPS
LiDAR
Camera
     ↓
Sensor Fusion
     ↓
Robot Pose + Velocity
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The state estimator should continuously update the robot's belief about its position and motion.

3. Planning

Planning transforms the current state and goal into a desired behavior.

State + Goal + Environment
            ↓
         Planner
            ↓
      Desired Path
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For navigation systems, Nav2 provides planning and control infrastructure for ROS 2 robots. Nav2 documentation

4. Control

The controller follows the planned trajectory.

For a differential-drive robot:

Desired Path
     ↓
Controller
     ↓
linear velocity
angular velocity
     ↓
Motor Driver
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A controller should operate at a predictable frequency and enforce physical limits.

5. Connect Everything with ROS 2

A simplified ROS graph could be:

camera_node
     ↓
/image
     ↓
perception_node
     ↓
/detections
     ↓
world_model_node
     ↓
/world_state
     ↓
planner_node
     ↓
/planned_path
     ↓
controller_node
     ↓
/cmd_vel
     ↓
base_controller
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ROS 2 topics are appropriate for continuous streams such as sensor data and robot state. Actions are useful for long-running navigation or other behaviors requiring feedback. ROS 2 interfaces

6. Avoid Blocking the Control Loop

Suppose object detection takes 200 ms.

Do not make the motor control loop wait for inference:

Bad:
Control → wait for AI → Control
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Instead:

Perception: asynchronous
Planning: asynchronous
Control: deterministic
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The controller should continue operating with the latest valid state.

7. Add Confidence and Freshness

A perception result should have:

value
confidence
timestamp
source
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For example:

Detection(
    label="person",
    confidence=0.94,
    timestamp=123456789
)
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Reject stale information when it is no longer safe to use.

8. Add Recovery Behaviors

Autonomous systems should expect failures.

Examples:

Path blocked
   ↓
Replan
   ↓
Still blocked?
   ↓
Recovery behavior
   ↓
Stop / Request Help
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Recovery behavior is part of autonomy—not an afterthought.

9. Example Control Pipeline

A mobile robot can implement:

def control(state, path):
    target = select_target(path, state.pose)

    linear = compute_linear_velocity(state, target)
    angular = compute_angular_velocity(state, target)

    linear = clamp(linear, -MAX_V, MAX_V)
    angular = clamp(angular, -MAX_W, MAX_W)

    return linear, angular
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The controller receives a safe representation of the planned path and produces bounded commands.

10. Measure End-to-End Latency

Measure:

Sensor timestamp
      ↓
Perception timestamp
      ↓
Planning timestamp
      ↓
Control timestamp
      ↓
Actuator timestamp
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The important metric is not just model inference time. It is the age of the information when the actuator receives the command.

11. Simulation and Testing

Start with recorded data or simulation:

Recorded Sensors
       ↓
Perception
       ↓
Planning
       ↓
Control
       ↓
Simulation
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Then move to:

Simulation → Hardware-in-the-Loop → Real Robot
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Test edge cases such as missing detections, moving obstacles, localization loss, and planner failures.

Conclusion

Perception, planning, and control should be treated as a continuous feedback system.

Perception tells the robot what it believes is happening. Planning chooses an appropriate response. Control turns that response into physical motion. The loop repeats as new sensor information arrives.

The key engineering principle is to keep the control layer predictable while allowing AI-heavy perception and reasoning components to evolve independently.

Useful Links

Website: www.v-modal.com
SDK Flutter: https://github.com/v-modal/vmodal_sdk_flutter
SDK Android: https://github.com/v-modal/vmodal_sdk_android
Discord: https://discord.gg/K72z28KUx

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