From b31cd1adb51b9832a7fc46fe3d1b0d44b330d1a8 Mon Sep 17 00:00:00 2001
From: Michael du Breuil <wicked.shell.scripts@gmail.com>
Date: Mon, 15 Apr 2019 17:29:36 -0700
Subject: [PATCH] AP_RangeFinder: Remove pre arm distance check

---
 libraries/AP_RangeFinder/RangeFinder.cpp      | 21 ----------------
 libraries/AP_RangeFinder/RangeFinder.h        | 10 --------
 .../AP_RangeFinder/RangeFinder_Backend.cpp    | 25 -------------------
 .../AP_RangeFinder/RangeFinder_Backend.h      |  2 --
 4 files changed, 58 deletions(-)

diff --git a/libraries/AP_RangeFinder/RangeFinder.cpp b/libraries/AP_RangeFinder/RangeFinder.cpp
index e27df7c000..696dae1eec 100644
--- a/libraries/AP_RangeFinder/RangeFinder.cpp
+++ b/libraries/AP_RangeFinder/RangeFinder.cpp
@@ -311,10 +311,6 @@ void RangeFinder::init(enum Rotation orientation_default)
             // present (although it may not be healthy)
             num_instances = i+1;
         }
-        // initialise pre-arm check variables
-        state[i].pre_arm_check = false;
-        state[i].pre_arm_distance_min = 9999;  // initialise to an arbitrary large value
-        state[i].pre_arm_distance_max = 0;
 
         // initialise status
         state[i].status = RangeFinder_NotConnected;
@@ -337,7 +333,6 @@ void RangeFinder::update(void)
                 continue;
             }
             drivers[i]->update();
-            drivers[i]->update_pre_arm_check();
         }
     }
 
@@ -631,22 +626,6 @@ uint8_t RangeFinder::range_valid_count_orient(enum Rotation orientation) const
     return backend->range_valid_count();
 }
 
-/*
-  returns true if pre-arm checks have passed for all range finders
-  these checks involve the user lifting or rotating the vehicle so that sensor readings between
-  the min and 2m can be captured
- */
-bool RangeFinder::pre_arm_check() const
-{
-    for (uint8_t i=0; i<num_instances; i++) {
-        // if driver is valid but pre_arm_check is false, return false
-        if ((drivers[i] != nullptr) && (params[i].type != RangeFinder_TYPE_NONE) && !state[i].pre_arm_check) {
-            return false;
-        }
-    }
-    return true;
-}
-
 const Vector3f &RangeFinder::get_pos_offset_orient(enum Rotation orientation) const
 {
     AP_RangeFinder_Backend *backend = find_instance(orientation);
diff --git a/libraries/AP_RangeFinder/RangeFinder.h b/libraries/AP_RangeFinder/RangeFinder.h
index eb7b63225f..93b18386d1 100644
--- a/libraries/AP_RangeFinder/RangeFinder.h
+++ b/libraries/AP_RangeFinder/RangeFinder.h
@@ -91,9 +91,6 @@ public:
         uint16_t voltage_mv;            // voltage in millivolts, if applicable, otherwise 0
         enum RangeFinder_Status status; // sensor status
         uint8_t  range_valid_count;     // number of consecutive valid readings (maxes out at 10)
-        bool     pre_arm_check;         // true if sensor has passed pre-arm checks
-        uint16_t pre_arm_distance_min;  // min distance captured during pre-arm checks
-        uint16_t pre_arm_distance_max;  // max distance captured during pre-arm checks
         uint32_t last_reading_ms;       // system time of last successful update from sensor
 
         const struct AP_Param::GroupInfo *var_info;
@@ -154,13 +151,6 @@ public:
         estimated_terrain_height = height;
     }
 
-    /*
-      returns true if pre-arm checks have passed for all range finders
-      these checks involve the user lifting or rotating the vehicle so that sensor readings between
-      the min and 2m can be captured
-     */
-    bool pre_arm_check() const;
-
     static RangeFinder *get_singleton(void) { return _singleton; }
 
 protected:
diff --git a/libraries/AP_RangeFinder/RangeFinder_Backend.cpp b/libraries/AP_RangeFinder/RangeFinder_Backend.cpp
index 901020a46d..04f7c6f4cf 100644
--- a/libraries/AP_RangeFinder/RangeFinder_Backend.cpp
+++ b/libraries/AP_RangeFinder/RangeFinder_Backend.cpp
@@ -79,28 +79,3 @@ void AP_RangeFinder_Backend::set_status(RangeFinder::RangeFinder_Status _status)
     }
 }
 
-/*
-  set pre-arm checks to passed if the range finder has been exercised through a reasonable range of movement
-      max distance sensed is at least 50cm > min distance sensed
-      max distance < 200cm
-      min distance sensed is within 10cm of ground clearance or sensor's minimum distance
- */
-void AP_RangeFinder_Backend::update_pre_arm_check()
-{
-    // return immediately if already passed or no sensor data
-    if (state.pre_arm_check || state.status == RangeFinder::RangeFinder_NotConnected || state.status == RangeFinder::RangeFinder_NoData) {
-        return;
-    }
-
-    // update min, max captured distances
-    state.pre_arm_distance_min = MIN(state.distance_cm, state.pre_arm_distance_min);
-    state.pre_arm_distance_max = MAX(state.distance_cm, state.pre_arm_distance_max);
-
-    // Check that the range finder has been exercised through a realistic range of movement
-    if (((state.pre_arm_distance_max - state.pre_arm_distance_min) >= RANGEFINDER_PREARM_REQUIRED_CHANGE_CM) &&
-         (state.pre_arm_distance_max < RANGEFINDER_PREARM_ALT_MAX_CM) &&
-         ((int16_t)state.pre_arm_distance_min < (MAX(params.ground_clearance_cm,params.min_distance_cm) + 10)) &&
-         ((int16_t)state.pre_arm_distance_min > (MIN(params.ground_clearance_cm,params.min_distance_cm) - 10))) {
-        state.pre_arm_check = true;
-    }
-}
diff --git a/libraries/AP_RangeFinder/RangeFinder_Backend.h b/libraries/AP_RangeFinder/RangeFinder_Backend.h
index 8e1f557ea1..01fdaa452f 100644
--- a/libraries/AP_RangeFinder/RangeFinder_Backend.h
+++ b/libraries/AP_RangeFinder/RangeFinder_Backend.h
@@ -33,8 +33,6 @@ public:
 
     virtual void handle_msg(mavlink_message_t *msg) { return; }
 
-    void update_pre_arm_check();
-
     enum Rotation orientation() const { return (Rotation)params.orientation.get(); }
     uint16_t distance_cm() const { return state.distance_cm; }
     uint16_t voltage_mv() const { return state.voltage_mv; }