🛡️ SENTINELARM-6 (v3.9.2)

High-Performance ESP32 Robotic Controller with Dual-Core Safety Architecture.

📖 Overview

SentinelArm-6 is a firmware designed for 6-DOF robotic arms that prioritizes safety and smooth motion. Unlike standard Arduino sketches, this firmware utilizes FreeRTOS to separate motion control from safety monitoring onto different CPU cores.

It features Adaptive Collision Detection, ignoring the natural current spikes of motor startup (Inrush Current) while instantly detecting physical obstructions during movement.

✨ Key Features

🧠 Dual-Core Architecture

• Core 0 (Safety Task): High-frequency monitoring of current sensors (ACS712 & INA219).
• Core 1 (Motion Task): Inverse kinematics, command parsing, and cubic interpolation.

🛡️ Advanced Safety Systems

• Dynamic Deviation Check: Detects collisions by monitoring unexpected current spikes.
• Inrush Grace Period (New in v3.9.2): 300ms blind window prevents false E-Stops.
• Absolute Current Limiter: Hard E-Stop if current exceeds 5.0A (configurable).

🌊 Cinematic Motion Control

• Cubic Ease-In-Out acceleration/deceleration.
• Hybrid Drive Engine for Stepper + Servos.

💾 Persistence

• EEPROM storage for last position, calibration, and thresholds.

🛠️ Hardware Configuration

Pinout Map (ESP32 Dev Module)

Component	ESP32 Pin	Protocol	Notes
Stepper DIR	GPIO16	Digital	Base Motor Direction
Stepper STEP	GPIO17	Digital	Step Pulse
Stepper EN	GPIO4	Digital	Active LOW
Microsteps	18,19,23	Digital	MS1, MS2, MS3
Servo Driver	21 (SDA), 22 (SCL)	I2C	PCA9685 @ 0x40
Main Sensor	GPIO34	Analog	ACS712
Gripper Sensor	21,22	I2C	INA219 @ 0x41
Fan Control	GPIO26	PWM	12V Fan
Global Enable	GPIO13	Digital	Cuts motor power

Bill of Materials

• ESP32-WROOM-32
• PCA9685 16-Channel PWM Driver
• A4988/DRV8825 Stepper Driver
• ACS712 + INA219 Sensors
• 1× NEMA17 Stepper + 5× Servos (MG996R/RDS3115)

🚀 Serial Communication Protocol

• Baud: 921600
• Header: 0xA5

Commands

ID	Function	Payload
'M'	Move	Target Angles [6], Speed Factor
'H'	Home	Move to rest position
'G'	Gripper	Target Current Limit
'E'	E-Stop Release	Unlock motors
'S'	Save Pose	Save to EEPROM
'D'	Set Deviation	Sensitivity value
'T'	Set Threshold	Max amps
'R'	Report	Return config

💾 Installation

Prerequisites

• VS Code + PlatformIO.
• Clone the repository.

Build Instructions

1. Open platformio.ini.
2. Connect ESP32 via USB.
3. Upload using PlatformIO.
4. Power motors after ESP32 boots.

Calibration

During the first 3 seconds, the ACS712 baseline is measured.

⚠️ Do NOT move the robot during this time.

📊 Performance Tuning (v3.9.2)

• For false E-Stops → increase Deviation Threshold (D command > 1.0).
• Heavy motors? Increase DEVIATION_GRACE_PERIOD_MS.

📜 License

Distributed under the MIT License. See LICENSE for details.

Author: Farouk Jamali