fix bug in control thread

Author: zzx9636

ROS_Core/src/Labs/Lab1/cfg/planner.cfg

@@ -5,6 +5,6 @@ from dynamic_reconfigure.parameter_generator_catkin import *
 
 gen = ParameterGenerator()
 
-gen.add("latency",  double_t,    0, "Latency compensation for control", 0.05, -1, 1)
+gen.add("latency",  double_t,    0, "Latency compensation for control", 0.25, -1, 1)
 
 exit(gen.generate("racecar_planner", "racecar_planner", "planner"))

ROS_Core/src/Labs/Lab1/scripts/traj_planner.py

@@ -222,7 +222,7 @@ def control_thread(self):
         '''
         Main control thread to publish control command
         '''
-        rate = rospy.Rate(50)
+        rate = rospy.Rate(40)
         u_queue = queue.Queue()
 
         # values to keep track of the previous control command
@@ -234,7 +234,7 @@ def dyn_step(x, u, dt):
             dx = np.array([x[2]*np.cos(x[3]),
                         x[2]*np.sin(x[3]),
                         u[0],
-                        x[2]*np.tan(u[1]*1.05)/0.257,
+                        x[2]*np.tan(u[1]*1.1)/0.257,
                         0
                         ])
             x_new = x + dx*dt
@@ -258,10 +258,11 @@ def dyn_step(x, u, dt):
             # check if there is new state available
             if self.control_state_buffer.new_data_available:
                 odom_msg = self.control_state_buffer.readFromRT()
-                t_prev = odom_msg.header.stamp.to_sec()
+                t_slam = odom_msg.header.stamp.to_sec()
 
                 u = np.zeros(3)
-                while not u_queue.empty() and u_queue.queue[0][-1] < t_prev:
+                u[-1] = t_slam
+                while not u_queue.empty() and u_queue.queue[0][-1] < t_slam:
                     u = u_queue.get() # remove old control commands
 
                 # get the state from the odometry message
@@ -277,27 +278,26 @@ def dyn_step(x, u, dt):
                             psi,
                             u[1]
                         ])
-                
-                # update the state buffer for the planning thread
-                plan_state = np.append(state_cur, t_act)
-                self.plan_state_buffer.writeFromNonRT(plan_state)
-                
-                # update the current state use past control command
+               
+                # predict the current state use past control command
                 for i in range(u_queue.qsize()):
                     u_next = u_queue.queue[i]
-                    dt = u_next[-1] - t_prev
+                    dt = u_next[-1] - u[-1]
                     state_cur = dyn_step(state_cur, u, dt)
                     u = u_next
-                    t_prev = u[-1]
 
-                # update the cur state with the most recent control command
-                state_cur = dyn_step(state_cur, u, t_act - t_prev)
+                # predict the cur state with the most recent control command
+                state_cur = dyn_step(state_cur, u, t_act - u[-1])
+                
+                # update the state buffer for the planning thread
+                plan_state = np.append(state_cur, t_act)
+                self.plan_state_buffer.writeFromNonRT(plan_state)
 
             # if there is no new state available, we do one step forward integration to predict the state
             elif prev_state is not None:
                 t_prev = prev_u[-1]
                 dt = t_act - t_prev
-                # predict the state when the control command is executed
+                # predict the state using the last control command is executed
                 state_cur = dyn_step(prev_state, prev_u, dt)
 
             # Generate control command from the policy
@@ -310,20 +310,20 @@ def dyn_step(x, u, dt):
 
                 if state_ref is not None:
                     accel, steer_rate = self.compute_control(state_cur, state_ref, u_ref, K)
-                    steer = max(-0.35, min(0.35, prev_u[1] + steer_rate*dt))
+                    steer = max(-0.37, min(0.37, prev_u[1] + steer_rate*dt))
                 else:
                     # reset the policy buffer if the policy is not valid
                     rospy.logwarn("Try to retrieve a policy beyond the horizon! Reset the policy buffer!")
                     self.policy_buffer.reset()
 
             # generate control command
-            if self.simulation:
-                throttle_pwm = accel
-                steer_pwm = steer
-            else:
+            if not self.simulation and state_cur is not None:
                 # If we are using robot,
                 # the throttle and steering angle needs to convert to PWM signal
                 throttle_pwm, steer_pwm = self.pwm_converter.convert(accel, steer, state_cur[2])
+            else:
+                throttle_pwm = accel
+                steer_pwm = steer                
 
             # publish control command
             servo_msg = ServoMsg()

ROS_Core/src/Labs/Lab1/scripts/utils/generate_pwm.py

@@ -45,7 +45,7 @@ def convert(self, accel: float, steer: float, v: float):
             v_bounded = v
 
         # negative pwm means turn left (positive steering angle)
-        steer_pwm = -np.clip(steer/0.35, -1, 1)
+        steer_pwm = -np.clip(steer/0.37, -1, 1)
         accel_bounded = np.sign(accel)*min(abs(accel), 2+v)
 
         # Generate Input vector