Proposed TrafficUpdate changes

The original requirements are here: https://code.asam.net/simulation/proposal/osi/-/blob/master/subchapters/1-4_requirements.adoc#user-content-provide-interface-for-traffic-participants

These changes satisfy all requirements from (1), (2), (3), and (4).

It doesn't address 5-7 as they are largely orthogonal.

Signed-off-by: Caspar de Haes <caspar.dehaes@five.ai>

Author: caspar-ai

osi_object.proto

@@ -436,6 +436,50 @@ message MovingObject
         // through.
         //
         optional double ground_clearance = 6;
+
+        // Detailed wheel data.
+        //
+        // \note OSI uses singular instead of plural for repeated field names.
+        //
+        repeated WheelData wheel = 7;
+
+        // \brief Information for a single wheel.
+        //
+        message WheelData
+        {
+            // The axle which contains this wheel.  A value of 0 represents the
+            // front-most axle of the vehicle with higher numbers incrementing
+            // towards the rear-most axle.
+            //
+            optional uint32 axle = 1;
+
+            // The index of the wheel on the axle, counting in the direction
+            // of positive-y, i.e. right-to-left.
+            //
+            // For example, on a standard 2-axle, 4-wheel car, the rear-right
+            // wheel would be (axle=1, index=0).
+            //
+            optional uint32 index = 2;
+
+            // Steering angle with positive values indicating a clockwise
+            // rotation about the z-axis.  Must be zero for non-steering
+            // wheels.
+            //
+            optional double steer_angle = 3;
+
+            // Rotation of the wheel about the axle in radians per second.
+            //
+            optional double rotation_rate = 4;
+
+            // Current rotation about the axle.  Rotation angle
+            // increases as the vehicle moves forward (x-positive) and
+            // decreases as the vehicle moves backwards.
+            //
+            // \note This value doesn't wrap but permanently increases or
+            // decreases.
+            //
+            optional double rotation_angle = 5;
+        }
     }
 
     //

osi_trafficupdate.proto

@@ -38,13 +38,63 @@ message TrafficUpdate
     //
     optional Timestamp timestamp = 2;
 
-    // Updated moving object
+    // Updated traffic participant data
     //
-    // \note Only the following members are considered in updates: id, base member 
-    // without dimension and base_polygon and the vehicle_classification.light_state.
-    // All other members can be left undefined and will be
-    // ignored by the receiver of this message.
+    repeated TrafficParticipantUpdate traffic = 3;
+
+    // \brief Data for a single traffic participant to update the simulator.
+    //
+    // It includes an immediate update for the current timestamp reported in
+    // parent traffic update message which can include the full detail of a
+    // moving object message.
+    //
+    // The future trajectory is deliberately more sparse as much of the detail
+    // won't be known for all future points.
     //
-    optional MovingObject update = 3;
+    message TrafficParticipantUpdate
+    {
+        // Updated moving object
+        //
+        // \note Only the following members are considered in updates: id, base member 
+        // without dimension and base_polygon and the vehicle_classification.light_state.
+        // All other members can be left undefined and will be
+        // ignored by the receiver of this message.
+        //
+        optional MovingObject update = 1;
+
+        // The future trajectory message is to allow traffic participants to
+        // indicate to the simulator their current expectations of where they plan to
+        // be in the future.
+        //
+        // \note Traffic participants aren't required to stick precisely to this future
+        // trajectory.  It is to allow the simulator to provide realistic agent
+        // behaviours without performing prediction for all external traffic
+        // participants.
+        //
+        repeated FutureTrajectoryNode future_trajectory = 2;
+
+        //
+        // \brief The future node is a single point in time as part of a future
+        // trajectory which defines the pose, velocity, acceleration, etc. at
+        // that point.
+        // See the FutureTrajectory message for details and context.
+        //
+        message FutureTrajectoryNode
+        {
+            // The future timestamp for the trajectory node. Zero time is arbitrary
+            // but must be identical for all messages. Zero time does not need to
+            // coincide with the UNIX epoch. Recommended is the starting time point of
+            // the simulation.
+            //
+            // \note This must be in the future compared to the timestamp in the top
+            // level traffic update message.
+            //
+            optional Timestamp timestamp = 1;
 
+            // Traffic participant data for the future trajectory node.
+            //
+            // \note Dimensions and base polygon are ignored.
+            optional BaseMoving future_point = 2;
+        }
+    }
 }