Motor dropout during Arcade Control (High turn, Low forward)

Programming Support
1

Hi everyone,

I’m having an issue with my 450 RPM (36:48) 6-motor drivetrain using Arcade Control.

The Issue: When I push the left stick (forward) slightly for low speed, but push the right stick (turn) fully for a high-speed spin, the motors on one side of the chassis stop spinning entirely.

Technical Details:

  • Hardware: 6x 11W Motors (600 RPM cartridges, 36:48 external).
  • Code: PROS chassis.arcade (or custom arcade logic).
  • Symptom: One side “dead” only when combining low linear and high angular velocity.

Is this likely a Voltage/Power Scaling issue in the arcade function, or is the motor triggering a Current Limit (2.5A) due to the high torque demand of a 450 RPM turn?Any advice?

#include "main.h"
#include "robot-config.hpp"

#include "drive.hpp"

// ---- Constants ---------------------------------------------------------------

// Curve intensity for exponential joystick mapping (3.0 ~ 8.0 recommended)
static constexpr double DRIVE_CURVE = 5.0;

// Task loop delay in milliseconds
static constexpr uint32_t TASK_DELAY_MS = 10;

static pros::Task *drive_task_handle = nullptr;

// ---- Helper Functions --------------------------------------------------------

double apply_curve(double input, double curve)
{
    if (input == 0.0)
        return 0.0;

    // Normalize input to [-1, 1]
    const double norm = input / 127.0;

    // Apply exponential curve, preserve sign
    const double curved = (std::exp(curve * std::abs(norm)) - 1.0) / (std::exp(curve) - 1.0);

    return std::copysign(curved * 127.0, input);
}

// ---- Task --------------------------------------------------------------------

void drive_task_fn(void *param)
{
    while (true)
    {
        // Read joystick axes
        const double throttle = master.get_analog(pros::E_CONTROLLER_ANALOG_LEFT_Y);
        const double turn = master.get_analog(pros::E_CONTROLLER_ANALOG_RIGHT_X);

        // Apply exponential curves
        const double c_throttle = apply_curve(throttle, DRIVE_CURVE);
        const double c_turn = apply_curve(turn, DRIVE_CURVE);

        // Arcade mixing
        double left_power = c_throttle + c_turn;
        double right_power = c_throttle - c_turn;

        // Clamp to [-127, 127]
        left_power = std::fmax(-127.0, std::fmin(127.0, left_power));
        right_power = std::fmax(-127.0, std::fmin(127.0, right_power));

        // Output to motor groups
        left_motors.move(static_cast<int32_t>(left_power));
        right_motors.move(static_cast<int32_t>(right_power));

        pros::delay(TASK_DELAY_MS);
    }
}

// ---- Public API --------------------------------------------------------------

void drive_start()
{
    if (drive_task_handle != nullptr)
        return; // already running
    drive_task_handle = new pros::Task(drive_task_fn, nullptr, "Drive Task");
}

void drive_stop()
{
    if (drive_task_handle != nullptr)
    {
        drive_task_handle->remove();
        delete drive_task_handle;
        drive_task_handle = nullptr;
    }

    left_motors.move(0);
    right_motors.move(0);
}