ardupilot/APMrover2/AP_MotorsUGV.cpp

/*
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <AP_HAL/AP_HAL.h>
#include "SRV_Channel/SRV_Channel.h"
#include "AP_MotorsUGV.h"
#include "Rover.h"

extern const AP_HAL::HAL& hal;

// parameters for the motor class
const AP_Param::GroupInfo AP_MotorsUGV::var_info[] = {
    // @Param: PWM_TYPE
    // @DisplayName: Output PWM type
    // @Description: This selects the output PWM type as regular PWM, OneShot, Brushed motor support using PWM (duty cycle) with separated direction signal, Brushed motor support with separate throttle and direction PWM (duty cyle)
    // @Values: 0:Normal,1:OneShot,2:OneShot125,3:Brushed,4:BrushedBiPolar
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("PWM_TYPE", 1, AP_MotorsUGV, _pwm_type, PWM_TYPE_NORMAL),

    // @Param: PWM_FREQ
    // @DisplayName: Output PWM freq for brushed motors
    // @Description: Output PWM freq for brushed motors
    // @Units: kHz
    // @Range: 1 20
    // @Increment: 1
    // @User: Advanced
    // @RebootRequired: True
    AP_GROUPINFO("PWM_FREQ", 2, AP_MotorsUGV, _pwm_freq, 16),

    // @Param: SAFE_DISARM
    // @DisplayName: Motor PWM output disabled when disarmed
    // @Description: Disables motor PWM output when disarmed
    // @Values: 0:PWM enabled while disarmed, 1:PWM disabled while disarmed
    // @User: Advanced
    AP_GROUPINFO("SAFE_DISARM", 3, AP_MotorsUGV, _disarm_disable_pwm, 0),

    // @Param: THR_SLEWRATE
    // @DisplayName: Throttle slew rate
    // @Description: maximum percentage change in throttle per second. A setting of 10 means to not change the throttle by more than 10% of the full throttle range in one second. A value of zero means no limit. A value of 100 means the throttle can change over its full range in one second. Note that for some NiMH powered rovers setting a lower value like 40 or 50 may be worthwhile as the sudden current demand on the battery of a big rise in throttle may cause a brownout.
    // @Units: %/s
    // @Range: 0 100
    // @Increment: 1
    // @User: Standard
    AP_GROUPINFO("SLEWRATE", 4, AP_MotorsUGV, _slew_rate, 100),

    AP_GROUPEND
};

AP_MotorsUGV::AP_MotorsUGV(AP_ServoRelayEvents &relayEvents) :
        _relayEvents(relayEvents)
{
    AP_Param::setup_object_defaults(this, var_info);
}

void AP_MotorsUGV::init()
{
    // setup servo ouput
    setup_servo_output();

    // setup pwm type
    setup_pwm_type();

    // set safety output
    setup_safety_output();
}

/*
  work out if skid steering is available
 */
bool AP_MotorsUGV::have_skid_steering() const
{
    if (SRV_Channels::function_assigned(SRV_Channel::k_throttleLeft) &&
        SRV_Channels::function_assigned(SRV_Channel::k_throttleRight)) {
        return true;
    }
    return false;
}

void AP_MotorsUGV::output(bool armed, float dt)
{
    // soft-armed overrides passed in armed status
    if (!hal.util->get_soft_armed()) {
        armed = false;
    }

    // ensure steering and throttle are within limits
    _steering = constrain_float(_steering, -4500.0f, 4500.0f);
    _throttle = constrain_float(_throttle, -100.0f, 100.0f);

    slew_limit_throttle(dt);

    // output for regular steering/throttle style frames
    output_regular(armed, _steering, _throttle);

    // output for skid steering style frames
    output_skid_steering(armed,  _steering, _throttle);

    // send values to the PWM timers for output
    SRV_Channels::calc_pwm();
    hal.rcout->cork();
    SRV_Channels::output_ch_all();
    hal.rcout->push();
    _last_throttle = _throttle;
}

// output to regular steering and throttle channels
void AP_MotorsUGV::output_regular(bool armed, float steering, float throttle)
{
    // always allow steering to move
    SRV_Channels::set_output_scaled(SRV_Channel::k_steering, steering);

    // output to throttle channels
    if (armed) {
        // handle armed case
        SRV_Channels::set_output_scaled(SRV_Channel::k_throttle, throttle);
    } else {
        // handle disarmed case
        if (_disarm_disable_pwm) {
            SRV_Channels::set_output_limit(SRV_Channel::k_throttle, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
        } else {
            SRV_Channels::set_output_limit(SRV_Channel::k_throttle, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
        }
    }
}

// output to skid steering channels
void AP_MotorsUGV::output_skid_steering(bool armed, float steering, float throttle)
{
    // handle simpler disarmed case
    if (!armed) {
        if (_disarm_disable_pwm) {
            SRV_Channels::set_output_limit(SRV_Channel::k_throttleLeft, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
            SRV_Channels::set_output_limit(SRV_Channel::k_throttleRight, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
        } else {
            SRV_Channels::set_output_limit(SRV_Channel::k_throttleLeft, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
            SRV_Channels::set_output_limit(SRV_Channel::k_throttleRight, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
        }
        return;
    }

    // skid steering mixer
    float steering_scaled = steering / 4500.0f; // steering scaled -1 to +1
    float throttle_scaled = throttle / 100.0f;  // throttle scaled -1 to +1

    // apply constraints
    steering_scaled = constrain_float(steering_scaled, -1.0f, 1.0f);
    throttle_scaled = constrain_float(throttle_scaled, -1.0f, 1.0f);

    // check for saturation and scale back throttle and steering proportionally
    const float saturation_value = fabsf(steering_scaled) + fabsf(throttle_scaled);
    if (saturation_value > 1.0f) {
        steering_scaled = steering_scaled / saturation_value;
        throttle_scaled = throttle_scaled / saturation_value;
    }

    // add in throttle
    float motor_left = throttle_scaled;
    float motor_right = throttle_scaled;

    // deal with case of turning on the spot
    if (is_zero(throttle_scaled)) {
        // full possible range is not used to keep response equivalent to non-zero throttle case
        motor_left += steering_scaled * 0.5f;
        motor_right -= steering_scaled * 0.5f;
    } else {
        // add in steering
        const float dir = is_positive(throttle_scaled) ? 1.0f : -1.0f;
        if (is_negative(steering_scaled)) {
            // moving left all steering to right wheel
            motor_right -= dir * steering_scaled;
        } else {
            // turning right, all steering to left wheel
            motor_left += dir * steering_scaled;
        }
    }
    if (_pwm_type == PWM_TYPE_BRUSHED) {
        const bool dirLeft = is_positive(motor_left);
        const bool dirRight = is_positive(motor_right);
        _relayEvents.do_set_relay(0, dirLeft);
        _relayEvents.do_set_relay(1, dirRight);
        motor_left = fabsf(motor_left);
        motor_right = fabsf(motor_right);
    }
    SRV_Channels::set_output_scaled(SRV_Channel::k_throttleLeft,  1000.0f * motor_left);
    SRV_Channels::set_output_scaled(SRV_Channel::k_throttleRight, 1000.0f * motor_right);
}

// slew limit throttle for one iteration
void AP_MotorsUGV::slew_limit_throttle(float dt)
{
    if (_use_slew_rate && (_slew_rate > 0)) {
        float temp = _slew_rate * dt * 0.01f * 100.0f;  // TODO : get THROTTLE MIN and THROTTLE MAX
        if (temp < 1.0f) {
            temp = 1.0f;
        }
        _throttle = constrain_int16(_throttle, _last_throttle - temp, _last_throttle + temp);
    }
}

// setup servo output
void AP_MotorsUGV::setup_servo_output()
{
    // k_steering are limited to -45;45 degree
    SRV_Channels::set_angle(SRV_Channel::k_steering, SERVO_MAX);

    // k_throttle are in power percent so -100 ... 100
    SRV_Channels::set_angle(SRV_Channel::k_throttle, 100);

    // skid steering left/right throttle as -1000 to 1000 values
    SRV_Channels::set_angle(SRV_Channel::k_throttleLeft,  1000);
    SRV_Channels::set_angle(SRV_Channel::k_throttleRight, 1000);
}

// setup pwm output type
void AP_MotorsUGV::setup_pwm_type()
{
    switch (_pwm_type) {
    case PWM_TYPE_ONESHOT:
    case PWM_TYPE_ONESHOT125:
        // tell HAL to do immediate output
        hal.rcout->set_output_mode(AP_HAL::RCOutput::MODE_PWM_ONESHOT);
        break;
    case PWM_TYPE_BRUSHED:
    case PWM_TYPE_BRUSHEDBIPOLAR:
        hal.rcout->set_output_mode(AP_HAL::RCOutput::MODE_PWM_BRUSHED);
        /*
         * Group 0: channels 0 1
         * Group 1: channels 4 5 6 7
         * Group 2: channels 2 3
         */
        // TODO : See if we can seperate frequency between groups
        hal.rcout->set_freq((1UL << 0), static_cast<uint16_t>(_pwm_freq * 1000));  // Steering group
        hal.rcout->set_freq((1UL << 2), static_cast<uint16_t>(_pwm_freq * 1000));  // Throttle group
        break;
    default:
        // do nothing
        break;
    }
}

// setup output in case of main CPU failure
void AP_MotorsUGV::setup_safety_output()
{
    if (_pwm_type == PWM_TYPE_BRUSHED) {
        // set trim to min to set duty cycle range (0 - 100%) to servo range
        SRV_Channels::set_trim_to_min_for(SRV_Channel::k_throttleLeft);
        SRV_Channels::set_trim_to_min_for(SRV_Channel::k_throttleRight);
        SRV_Channels::setup_failsafe_trim_all();
    }
    if (_pwm_type == PWM_TYPE_BRUSHEDBIPOLAR) {
        SRV_Channels::setup_failsafe_trim_all();
    }

    if (_disarm_disable_pwm) {
        // throttle channels output zero pwm (i.e. no signal)
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttle, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttleLeft, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttleRight, SRV_Channel::SRV_CHANNEL_LIMIT_ZERO_PWM);
    } else {
        // throttle channels output trim values (because rovers will go backwards if set to MIN)
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttle, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttleLeft, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
        SRV_Channels::set_safety_limit(SRV_Channel::k_throttleRight, SRV_Channel::SRV_CHANNEL_LIMIT_TRIM);
    }
}