update mpc class

mpc_pybullet_demo/mpcpy/cvxpy_mpc.py

@@ -63,6 +63,8 @@ class MPC:
         self.action_len = M
         self.state_cost = Q
         self.action_cost = R
+        self.u_bounds = np.array([P.MAX_ACC, P.MAX_STEER])
+        self.du_bounds = np.array([P.MAX_D_ACC, P.MAX_D_STEER])
 
     def optimize_linearized_model(
         self,
@@ -71,7 +73,7 @@ class MPC:
         C,
         initial_state,
         target,
-        time_horizon=10,
+        control_horizon=10,
         Q=None,
         R=None,
         verbose=False,
@@ -85,7 +87,7 @@ class MPC:
         :param Q:
         :param R:
         :param target:
-        :param time_horizon:
+        :param control_horizon:
         :param verbose:
         :return:
         """
@@ -97,45 +99,37 @@ class MPC:
             R = self.action_cost
 
         # Create variables
-        x = opt.Variable((self.state_len, time_horizon + 1), name="states")
-        u = opt.Variable((self.action_len, time_horizon), name="actions")
+        x = opt.Variable((self.state_len, control_horizon + 1), name="states")
+        u = opt.Variable((self.action_len, control_horizon), name="actions")
+        cost = 0
+        constr = []
 
-        # Loop through the entire time_horizon and append costs
-        cost_function = []
-
-        for t in range(time_horizon):
-
-            _cost = opt.quad_form(target[:, t + 1] - x[:, t + 1], Q) + opt.quad_form(
-                u[:, t], R
-            )
-
-            _constraints = [
-                x[:, t + 1] == A @ x[:, t] + B @ u[:, t] + C,
-                u[0, t] >= -P.MAX_ACC,
-                u[0, t] <= P.MAX_ACC,
-                u[1, t] >= -P.MAX_STEER,
-                u[1, t] <= P.MAX_STEER,
-            ]
-            # opt.norm(target[:, t + 1] - x[:, t + 1], 1) <= 0.1]
+        for k in range(control_horizon):
+            cost += opt.quad_form(target[:, k] - x[:, k], Q)
+            cost += opt.quad_form(u[:, k], R)
 
             # Actuation rate of change
-            if t < (time_horizon - 1):
-                _cost += opt.quad_form(u[:, t + 1] - u[:, t], R * 1)
-                _constraints += [opt.abs(u[0, t + 1] - u[0, t]) / P.DT <= P.MAX_D_ACC]
-                _constraints += [opt.abs(u[1, t + 1] - u[1, t]) / P.DT <= P.MAX_D_STEER]
+            if k < (control_horizon - 1):
+                cost += opt.quad_form(u[:, k + 1] - u[:, k], self.P)
 
-            if t == 0:
-                # _constraints += [opt.norm(target[:, time_horizon] - x[:, time_horizon], 1) <= 0.01,
-                #                x[:, 0] == initial_state]
-                _constraints += [x[:, 0] == initial_state]
+            # Kinematics Constrains
+            constr += [x[:, k + 1] == A @ x[:, k] + B @ u[:, k] + C]
 
-            cost_function.append(
-                opt.Problem(opt.Minimize(_cost), constraints=_constraints)
-            )
+            # Actuation rate of change limit
+            if t < (control_horizon - 1):
+                constr += [opt.abs(u[0, k + 1] - u[0, k]) / P.DT <= self.du_bounds[0]]
+                constr += [opt.abs(u[1, k + 1] - u[1, k]) / P.DT <= self.du_bounds[1]]
 
-        # Add final cost
-        problem = sum(cost_function)
+        # Final Point tracking
+        # cost += opt.quad_form(x[:, -1] - target[:,-1], Qf)
 
-        # Minimize Problem
-        problem.solve(verbose=verbose, solver=opt.OSQP)
+        # initial state
+        constr += [x[:, 0] == initial_state]
+
+        # actuation magnitude
+        constr += [opt.abs(u[:, 0]) <= self.u_bounds[0]]
+        constr += [opt.abs(u[:, 1]) <= self.u_bounds[1]]
+
+        prob = opt.Problem(opt.Minimize(cost), constr)
+        solution = prob.solve(solver=opt.OSQP, warm_start=True, verbose=False)
         return x, u