SITL: add battery model evaluation example

libraries/SITL/examples/EvaluateBatteryModel/EvaluateBatteryModel.cpp

@@ -0,0 +1,87 @@
+#include <AP_HAL/AP_HAL.h>
+
+#include <SITL/SIM_Battery.h>
+#include <SITL/SIM_Frame.h>
+
+#include <stdio.h>
+
+/* run with:
+    ./waf configure --board linux
+    ./waf build --targets examples/EvaluateBatteryModel
+    ./build/linux/examples/EvaluateBatteryModel Tools/autotest/models/Callisto.json 50
+*/
+
+void setup();
+void loop();
+
+const AP_HAL::HAL& hal = AP_HAL::get_HAL();
+
+// helper to give access to protected functions
+class Frame_helper : public SITL::Frame {
+public:
+    using SITL::Frame::Frame;
+
+    void public_load_frame_params(const char *model_json) {
+        load_frame_params(model_json);
+    }
+
+    float get_capacity() { return model.battCapacityAh; }
+    float get_max_volt() { return model.maxVoltage; }
+    float get_resistance() { return model.refBatRes; }
+
+};
+
+Frame_helper frame {nullptr, 0, nullptr};
+SITL::Battery battery;
+
+void setup(void)
+{
+    uint8_t argc;
+    char * const *argv;
+
+    hal.util->commandline_arguments(argc, argv);
+
+    if (argc <= 2) {
+        ::printf("pass .json model definition path and current draw\n");
+        exit(0);
+    }
+
+    // parse JSON vehicle definition
+    frame.public_load_frame_params(argv[1]);
+
+    // parse current draw
+    const float current = strtof(argv[2], NULL);
+
+    const float amp_hour_capacity = frame.get_capacity();
+    const float resistance = frame.get_resistance();
+    const float max_voltage = frame.get_max_volt();
+    const float min_voltage = max_voltage * 0.7;
+
+    ::printf("Simulating %0.2fv, %0.2f ah battery with resistance of %f\n", max_voltage, amp_hour_capacity, resistance);
+    ::printf("Voltage from %0.2f to %0.2f with constant current draw of %0.2f\n", max_voltage, min_voltage, current);
+
+    // setup battery model
+    battery.setup(amp_hour_capacity, resistance, max_voltage);
+    battery.init_voltage(max_voltage);
+
+    uint64_t time = 0;
+    hal.scheduler->stop_clock(time);
+    const double time_step = 0.05;
+
+    ::printf("time, voltage\n");
+    while (battery.get_voltage() >= min_voltage) {
+        battery.set_current(current);
+
+        ::printf("%0.2f, %0.2f\n", time * 1.0e-6, battery.get_voltage());
+
+        time += time_step*1e6;
+        hal.scheduler->stop_clock(time);
+    }
+}
+
+void loop(void)
+{
+    exit(0);
+}
+
+AP_HAL_MAIN();

libraries/SITL/examples/EvaluateBatteryModel/wscript

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+# encoding: utf-8
+
+def build(bld):
+
+    if bld.env.BOARD != 'linux':
+        return
+
+    source = bld.path.ant_glob('*.cpp')
+    source.append('../../../../libraries/SITL/SIM_Battery.cpp')
+    source.append('../../../../libraries/SITL/SIM_Frame.cpp')
+
+    bld.env.DEFINES.append("USE_PICOJSON=1")
+
+    bld.ap_program(
+        use='ap',
+        program_groups=['examples'],
+        source=source,
+    )
+