Motor - Weber-State-Submarine-Project/Submarine GitHub Wiki
Hardware ESC Motor Documentation
This section discusses the hardware implementation of the ESC motor controllers, including their connections, operation, and challenges encountered during integration.
TD1.2E 12V Underwater Thruster
Specifications
| Parameter | Value |
|---|---|
| Thruster Size | 78mm x 112mm |
| Motor KV | 350KV |
| Rated Voltage | 12V - 14.8V |
| Thrust Forward | 1200g - 2500g |
| Rated Current | 5A - 13A |
| Power | 60W - 312W |
| Material | Nylon Injection Molding, Anti-Corrosion |
| Components | Deflecting Cover and Cap, Propeller, Motor, Cable |
| Cable Length | 50cm |
| Working Depth | 100m |
| Working Environment | Freshwater and seawater |
| PWM Signal Control | 48KHz |
| PWM Range | 1ms - 2ms |
| Reverse Range | 1ms - 1.5ms |
| Forward Range | 1.5ms - 2ms |
| Neutral Stop | 1.5ms |
How ESC Motors Work
ESC motors are typically controlled via an ESC controller connected to a receiver. In this project, the ESC controllers are instead controlled by a Raspberry Pi 5, which generates PWM signals to determine the speed and direction of the motors. Before the motors can be controlled, the ESC controller must be armed. According to the datasheet, the arming sequence is as follows:
- Connect the wires and turn on the power.
- Send a 2ms or 1ms signal (max speed).
- Send a 1.5ms signal (stop signal).
Challenges with PWM
Software PWM
Initial attempts to control the ESC on a Raspberry Pi 4 used software-generated PWM signals, which were effective. However, after transitioning to the Raspberry Pi 5, these signals no longer worked reliably. It was determined that software-based PWM struggled to produce precise signals on the new hardware.
Hardware PWM
Attempts to utilize hardware PWM on the Raspberry Pi 5 were also unsuccessful due to the lack of support for the newer hardware in existing libraries.
Implementation of a PWM Hat
A hardware PWM hat was introduced to resolve the PWM signal issues. By connecting the PWM hat to the Raspberry Pi, it became possible to generate accurate signals required to arm and control the ESC motors.
Under-Volting the Motors
Although the ESC specifications recommend a minimum voltage of 12V, testing revealed that the motors could function at voltages as low as 8V. The current implementation uses 8.5V to reduce the boat's speed, allowing other sensors to capture data more effectively during navigation.
Pinout Diagram
Description: This pinout diagram illustrates the connections between the Raspberry Pi, ESCs (Electronic Speed Controllers), and the motors. It provides clear details on signal, power, and ground wiring to ensure accurate motor control and system functionality. Use this diagram as a guide during hardware setup and debugging.
Motor Mount
Description: The motor mount securely attaches the ESC motors to the boat, ensuring proper alignment and stability during operation.