Rover: PILOT_STEER_TYPE replaces SKID_STEER_IN

new options allow controlling vehicle's heading while reversing
skid-steering vehicles rotate in opposite direction when backing up

APMrover2/Parameters.cpp

@@ -142,12 +142,12 @@ const AP_Param::Info Rover::var_info[] = {
     // @User: Standard
     GSCALAR(throttle_cruise,        "CRUISE_THROTTLE",    50),
 
-    // @Param: SKID_STEER_IN
+    // @Param: PILOT_STEER_TYPE
-    // @DisplayName: Skid steering input
+    // @DisplayName: Pilot input steering type
     // @Description: Set this to 1 for skid steering input rovers (tank track style in RC controller). When enabled, servo1 is used for the left track control, servo3 is used for right track control
-    // @Values: 0:Disabled, 1:SkidSteeringInput
+    // @Values: 0:Default,1:Two Paddles Input,2:Direction reversed when backing up,3:Direction unchanged when backing up
     // @User: Standard
-    GSCALAR(skid_steer_in,           "SKID_STEER_IN",     0),
+    GSCALAR(pilot_steer_type, "PILOT_STEER_TYPE", 0),
 
     // @Param: FS_ACTION
     // @DisplayName: Failsafe Action

APMrover2/Parameters.h

@@ -129,7 +129,7 @@ public:
         k_param_throttle_cruise,
         k_param_throttle_slewrate_old,  // unused
         k_param_throttle_reduction,     // unused
-        k_param_skid_steer_in,
+        k_param_pilot_steer_type,
         k_param_skid_steer_out_old, // unused
 
         // failsafe control
@@ -238,7 +238,7 @@ public:
     // Throttle
     //
     AP_Int8     throttle_cruise;
-    AP_Int8     skid_steer_in;
+    AP_Int8     pilot_steer_type;
 
     // failsafe control
     AP_Int8     fs_action;

APMrover2/defines.h

@@ -121,5 +121,12 @@ enum aux_switch_pos {
     AUX_SWITCH_HIGH
 };
 
+enum pilot_steer_type_t {
+    PILOT_STEER_TYPE_DEFAULT = 0,
+    PILOT_STEER_TYPE_TWO_PADDLES = 1,
+    PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING = 2,
+    PILOT_STEER_TYPE_DIR_UNCHANGED_WHEN_REVERSING = 3,
+};
+
 #define AUX_SWITCH_PWM_TRIGGER_HIGH 1800   // pwm value above which the ch7 or ch8 option will be invoked
 #define AUX_SWITCH_PWM_TRIGGER_LOW  1200   // pwm value below which the ch7 or ch8 option will be disabled

APMrover2/mode.cpp

@@ -24,6 +24,49 @@ bool Mode::enter()
     return _enter();
 }
 
+void Mode::get_pilot_desired_steering_and_throttle(float &steering_out, float &throttle_out)
+{
+    // apply RC skid steer mixing
+    switch ((enum pilot_steer_type_t)rover.g.pilot_steer_type.get())
+    {
+        case PILOT_STEER_TYPE_DEFAULT:
+        default: {
+            // by default regular and skid-steering vehicles reverse their rotation direction when backing up
+            // (this is the same as PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING below)
+            throttle_out = rover.channel_throttle->get_control_in();
+            steering_out = rover.channel_steer->get_control_in();
+            break;
+        }
+
+        case PILOT_STEER_TYPE_TWO_PADDLES: {
+            // convert the two radio_in values from skid steering values
+            // left paddle from steering input channel, right paddle from throttle input channel
+            // steering = left-paddle - right-paddle
+            // throttle = average(left-paddle, right-paddle)
+            const float left_paddle = rover.channel_steer->norm_input();
+            const float right_paddle = rover.channel_throttle->norm_input();
+
+            throttle_out = 0.5f * (left_paddle + right_paddle) * 100.0f;
+
+            const float steering_dir = is_negative(throttle_out) ? -1 : 1;
+            steering_out = steering_dir * (left_paddle - right_paddle) * 4500.0f;
+            break;
+        }
+
+        case PILOT_STEER_TYPE_DIR_REVERSED_WHEN_REVERSING:
+            throttle_out = rover.channel_throttle->get_control_in();
+            steering_out = rover.channel_steer->get_control_in();
+            break;
+
+        case PILOT_STEER_TYPE_DIR_UNCHANGED_WHEN_REVERSING: {
+            throttle_out = rover.channel_throttle->get_control_in();
+            const float steering_dir = is_negative(throttle_out) ? -1 : 1;
+            steering_out = steering_dir * rover.channel_steer->get_control_in();
+            break;
+        }
+    }
+}
+
 // set desired location
 void Mode::set_desired_location(const struct Location& destination, float next_leg_bearing_cd)
 {

APMrover2/mode.h

@@ -91,6 +91,10 @@ protected:
     // subclasses override this to perform any required cleanup when exiting the mode
     virtual void _exit() { return; }
 
+    // decode pilot steering held in channel_steer, channel_throttle and return in steer_out and throttle_out arguments
+    // steering_out is in the range -4500 ~ +4500, throttle_out is in the range -100 ~ +100
+    void get_pilot_desired_steering_and_throttle(float &steering_out, float &throttle_out);
+
     // calculate steering angle given a desired lateral acceleration
     void calc_steering_from_lateral_acceleration(bool reversed = false);
 

APMrover2/mode_manual.cpp

@@ -8,9 +8,11 @@ void ModeManual::update()
         g2.motors.set_throttle(0.0f);
         g2.motors.set_steering(0.0f);
     } else {
+        float desired_steering, desired_throttle;
+        get_pilot_desired_steering_and_throttle(desired_steering, desired_throttle);
         // copy RC scaled inputs to outputs
-        g2.motors.set_throttle(channel_throttle->get_control_in());
+        g2.motors.set_throttle(desired_throttle);
-        g2.motors.set_steering(channel_steer->get_control_in());
+        g2.motors.set_steering(desired_steering);
     }
 
     // mark us as in_reverse when using a negative throttle to stop AHRS getting off

APMrover2/mode_steering.cpp

@@ -3,8 +3,11 @@
 
 void ModeSteering::update()
 {
+    float desired_steering, desired_throttle;
+    get_pilot_desired_steering_and_throttle(desired_steering, desired_throttle);
+
     // convert pilot throttle input to desired speed (up to twice the cruise speed)
-    float target_speed = channel_throttle->get_control_in() * 0.01f * calc_speed_max(g.speed_cruise, g.throttle_cruise * 0.01f);
+    float target_speed = desired_steering * 0.01f * calc_speed_max(g.speed_cruise, g.throttle_cruise * 0.01f);
 
     // get speed forward
     float speed;
@@ -17,7 +20,7 @@ void ModeSteering::update()
     }
 
     // determine if pilot is requesting pivot turn
-    bool is_pivot_turning = g2.motors.have_skid_steering() && is_zero(target_speed) && (channel_steer->get_control_in() != 0);
+    bool is_pivot_turning = g2.motors.have_skid_steering() && is_zero(target_speed) && (!is_zero(desired_steering));
 
     // In steering mode we control lateral acceleration directly.
     // For pivot steering vehicles we use the TURN_MAX_G parameter
@@ -33,7 +36,7 @@ void ModeSteering::update()
     max_g_force = constrain_float(max_g_force, 0.1f, g.turn_max_g * GRAVITY_MSS);
 
     // convert pilot steering input to desired lateral acceleration
-    lateral_acceleration = max_g_force * (channel_steer->get_control_in() / 4500.0f);
+    lateral_acceleration = max_g_force * (desired_steering / 4500.0f);
 
     // reverse target lateral acceleration if backing up
     bool reversed = false;

APMrover2/radio.cpp

@@ -113,43 +113,6 @@ void Rover::read_radio()
     // check that RC value are valid
     control_failsafe(channel_throttle->get_radio_in());
 
-    // apply RC skid steer mixing
-    if (g.skid_steer_in) {
-        // convert the two radio_in values from skid steering values
-        /*
-          mixing rule:
-          steering = motor1 - motor2
-          throttle = 0.5*(motor1 + motor2)
-          motor1 = throttle + 0.5*steering
-          motor2 = throttle - 0.5*steering
-        */          
-
-        const float left_input = channel_steer->norm_input();
-        const float right_input = channel_throttle->norm_input();
-        const float throttle_scaled = 0.5f * (left_input + right_input);
-        float steering_scaled = constrain_float(left_input - right_input, -1.0f, 1.0f);
-
-        // flip the steering direction if requesting the vehicle reverse (to be consistent with separate steering-throttle frames)
-        if (is_negative(throttle_scaled)) {
-            steering_scaled = -steering_scaled;
-        }
-
-        int16_t steer = channel_steer->get_radio_trim();
-        int16_t thr   = channel_throttle->get_radio_trim();
-        if (steering_scaled > 0.0f) {
-            steer += steering_scaled * (channel_steer->get_radio_max() - channel_steer->get_radio_trim());
-        } else {
-            steer += steering_scaled * (channel_steer->get_radio_trim() - channel_steer->get_radio_min());
-        }
-        if (throttle_scaled > 0.0f) {
-            thr += throttle_scaled * (channel_throttle->get_radio_max() - channel_throttle->get_radio_trim());
-        } else {
-            thr += throttle_scaled * (channel_throttle->get_radio_trim() - channel_throttle->get_radio_min());
-        }
-        channel_steer->set_pwm(steer);
-        channel_throttle->set_pwm(thr);
-    }
-
     // check if we try to do RC arm/disarm
     rudder_arm_disarm_check();
 }