[tsaubergine]

This PR is stacked on #5 and targets its branch: #2 → #3 → #4 → #5 → this PR.

This is Phase 2 of the Goby helm plan: goby_helm_ivp, which runs ivpico::helm::Helm (#4) in Goby3.

goby_helm_ivp (src/bin/goby/helm_ivp)

• Application: a goby::zeromq::SingleThreadApplication that iterates the helm at loop_freq (default 4 Hz, pHelmIvP's AppTick). Time comes from goby's SystemClock, so time warp works as in MOOS.
• Groups (src/bin/goby/groups.h, constexpr, ivpico::helm::*):
  • in: navigation, variable, command;
  • out: solution, status (every loop), posting, behavior_event, life_event, visualization, offboard_message, objective_function, configuration.
• Config (HelmIvPConfig, in goby3's style):
  • app, and interprocess (also from GOBY_INTERPROCESS);
  • loop_freq;
  • helm, which is ivp.interface.HelmConfig; helm.ownship defaults to interprocess.platform;
  • frontseat.
• Frontseat bridge (frontseat { enable: true }):
  • NodeStatus becomes the vehicle's Navigation: degrees to radians, speed over ground and over water;
  • each Solution becomes a DesiredCourse, with zeros during an allstop as pHelmIvP posts;
  • a HelmStateReport goes out every loop: DRIVE → HELM_DRIVE, PARK → HELM_PARK, otherwise HELM_NOT_RUNNING.
• Geodesy: lat/lon ↔ x/y uses goby's datum (app.geodesy), which must be set at startup.
• Logging and health:
  • behavior warnings and errors go to glog.is_warn(), events to is_verbose();
  • health is FAILED (with the config warnings) when MALCONFIG, and DEGRADED (with the halt message) when a behavior halts the helm.
• No poke app: goby zeromq publish publishes Variables and Commands once libivpico_interface.so is loaded (-l or GOBY_TOOL_LOAD_SHARED_LIBRARY).

Alpha example (launch/goby/alpha)

goby3-examples' frontseat_basic_sim, with goby_helm_ivp in place of MOOSDB and pHelmIvP. deploy.sh deploys it with goby zeromq publish. I ran it for 40 s at warp 10: the helm drove the simulated vehicle around the survey (820 DesiredCourses) and then parked at the end, as pHelmIvP does in s1_alpha. goby_liaison is commented out in the launch file, because it comes from goby3-gui, which init.sh doesn't install.

Test (ctest goby_helm_ivp, when Goby3 is found)

src/test/goby/test_goby_helm_ivp.sh:

1. runs gobyd and the app, with a constant-heading behavior and a datum;
2. publishes one frontseat NodeStatus with goby zeromq publish;
3. checks for a DesiredCourse with heading 90, HELM_DRIVE, and Status DRIVE.

Other changes

• find_package(Protobuf) and find_package(openocean_messages) move to the top-level CMakeLists, since src/bin now needs them too.
• README: repository structure and a "Goby app" section.

Notes

• cfg() isn't valid until goby's base classes are constructed, so the app sets its loop frequency in its constructor body. Passing cfg().loop_freq() to the base constructor read garbage and crashed now and then in Thread::set_loop_frequency. The second commit's message says that fix is in it, but it actually went in with the first commit.
• Still to come in Phase 2: the closed-loop mission runs under Goby (ivpico_mission_check), in a follow-up PR.

Test plan

• ctest: all 11 tests pass: helm_libs, helm, 8 × replay_*, and goby_helm_ivp (3/3 runs).
• The alpha example runs end to end with Goby 3.6.1 on Ubuntu 24.04.
• CI on all four jobs (Goby3 from packages.gobysoft.org).

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