Merge branch 'master' into vector_control

1 files changed, 133 insertions, 0 deletions

diff --git a/src/modules/systemlib/pwm_limit/pwm_limit.c b/src/modules/systemlib/pwm_limit/pwm_limit.c
new file mode 100644
index 000000000..cac3dc82a
--- /dev/null
+++ b/src/modules/systemlib/pwm_limit/pwm_limit.c
@@ -0,0 +1,133 @@
+/****************************************************************************
+ *
+ *   Copyright (C) 2013 PX4 Development Team. All rights reserved.
+ *   Author: Julian Oes <joes@student.ethz.ch>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name PX4 nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/**
+ * @file pwm_limit.c
+ *
+ * Lib to limit PWM output
+ *
+ * @author Julian Oes <joes@student.ethz.ch>
+ */
+
+#include "pwm_limit.h"
+#include <math.h>
+#include <stdbool.h>
+#include <drivers/drv_hrt.h>
+
+void pwm_limit_init(pwm_limit_t *limit)
+{
+	limit->state = LIMIT_STATE_OFF;
+	limit->time_armed = 0;
+	return;
+}
+
+void pwm_limit_calc(const bool armed, const unsigned num_channels, const uint16_t *disarmed_pwm, const uint16_t *min_pwm, const uint16_t *max_pwm, float *output, uint16_t *effective_pwm, pwm_limit_t *limit)
+{
+	/* first evaluate state changes */
+	switch (limit->state) {
+		case LIMIT_STATE_OFF:
+			if (armed)
+				limit->state = LIMIT_STATE_RAMP;
+			limit->time_armed = hrt_absolute_time();
+			break;
+		case LIMIT_STATE_INIT:
+			if (!armed)
+				limit->state = LIMIT_STATE_OFF;
+			else if (hrt_absolute_time() - limit->time_armed >= INIT_TIME_US)
+				limit->state = LIMIT_STATE_RAMP;
+			break;
+		case LIMIT_STATE_RAMP:
+			if (!armed)
+				limit->state = LIMIT_STATE_OFF;
+			else if (hrt_absolute_time() - limit->time_armed >= INIT_TIME_US + RAMP_TIME_US)
+				limit->state = LIMIT_STATE_ON;
+			break;
+		case LIMIT_STATE_ON:
+			if (!armed)
+				limit->state = LIMIT_STATE_OFF;
+			break;
+		default:
+			break;
+	}
+
+	unsigned progress;
+	uint16_t temp_pwm;
+
+	/* then set effective_pwm based on state */
+	switch (limit->state) {
+		case LIMIT_STATE_OFF:
+		case LIMIT_STATE_INIT:
+			for (unsigned i=0; i<num_channels; i++) {
+				effective_pwm[i] = disarmed_pwm[i];
+				output[i] = 0.0f;
+			}
+			break;
+		case LIMIT_STATE_RAMP:
+
+			progress = (hrt_absolute_time() - INIT_TIME_US - limit->time_armed)*10000 / RAMP_TIME_US;
+			for (unsigned i=0; i<num_channels; i++) {
+                
+				uint16_t ramp_min_pwm;
+                
+				/* if a disarmed pwm value was set, blend between disarmed and min */
+				if (disarmed_pwm[i] > 0) {
+
+					/* safeguard against overflows */
+					uint16_t disarmed = disarmed_pwm[i];
+					if (disarmed > min_pwm[i])
+						disarmed = min_pwm[i];
+
+					uint16_t disarmed_min_diff = min_pwm[i] - disarmed;
+					ramp_min_pwm = disarmed + (disarmed_min_diff * progress) / 10000;
+				} else {
+                    
+					/* no disarmed pwm value set, choose min pwm */
+					ramp_min_pwm = min_pwm[i];
+				}
+
+				effective_pwm[i] = output[i] * (max_pwm[i] - ramp_min_pwm)/2 + (max_pwm[i] + ramp_min_pwm)/2;
+				output[i] = (float)progress/10000.0f * output[i];
+			}
+			break;
+		case LIMIT_STATE_ON:
+			for (unsigned i=0; i<num_channels; i++) {
+				effective_pwm[i] = output[i] * (max_pwm[i] - min_pwm[i])/2 + (max_pwm[i] + min_pwm[i])/2;
+				/* effective_output stays the same */
+			}
+			break;
+		default:
+			break;
+	}
+	return;
+}