Make battery failsafe limits configurable

src/modules/systemlib/battery.cpp

@@ -48,6 +48,8 @@ Battery::Battery() :
 	_param_n_cells(this, "N_CELLS"),
 	_param_capacity(this, "CAPACITY"),
 	_param_v_load_drop(this, "V_LOAD_DROP"),
+	_param_low_thr(this, "LOW_THR"),
+	_param_crit_thr(this, "CRIT_THR"),
 	_voltage_filtered_v(0.0f),
 	_throttle_filtered(0.0f),
 	_discharged_mah(0.0f),
@@ -162,13 +164,11 @@ Battery::estimateRemaining(float voltage_v, float throttle_normalized)
 void
 Battery::determineWarning()
 {
-	// TODO: Determine threshold or make params.
-
 	// Smallest values must come first
-	if (_remaining < 0.09f) {
+	if (_remaining < _param_crit_thr.get()) {
 		_warning = battery_status_s::BATTERY_WARNING_CRITICAL;
 
-	} else if (_remaining < 0.18f) {
+	} else if (_remaining < _param_low_thr.get()) {
 		_warning = battery_status_s::BATTERY_WARNING_LOW;
 	}
 }

src/modules/systemlib/battery.h

@@ -101,6 +101,8 @@ private:
 	control::BlockParamInt _param_n_cells;
 	control::BlockParamFloat _param_capacity;
 	control::BlockParamFloat _param_v_load_drop;
+	control::BlockParamFloat _param_low_thr;
+	control::BlockParamFloat _param_crit_thr;
 
 	float _voltage_filtered_v;
 	float _throttle_filtered;

src/modules/systemlib/battery_params.c

@@ -66,6 +66,36 @@ PARAM_DEFINE_FLOAT(BAT_V_EMPTY, 3.4f);
  */
 PARAM_DEFINE_FLOAT(BAT_V_CHARGED, 4.2f);
 
+/**
+ * Low threshold
+ *
+ * Sets the threshold (between 0 and 1, which is equivalent to between 0 and 100%)
+ * when the battery will be reported as low. This has to be higher than the critical
+ * threshold.
+ *
+ * @group Battery Calibration
+ * @decimal 2
+ * @min 0.15
+ * @max 0.5
+ * @increment 0.01
+ */
+PARAM_DEFINE_FLOAT(BAT_LOW_THR, 0.18f);
+
+/**
+ * Critical threshold
+ *
+ * Sets the threshold (between 0 and 1, which is equivalent to between 0 and 100%)
+ * when the battery will be reported as critically low. This has to be lower than
+ * the low threshold. This threshold commonly will trigger RTL or landing.
+ *
+ * @group Battery Calibration
+ * @decimal 2
+ * @min 0.05
+ * @max 0.14
+ * @increment 0.01
+ */
+PARAM_DEFINE_FLOAT(BAT_CRIT_THR, 0.09f);
+
 /**
  * Voltage drop per cell on 100% load
  *