I am trying to solve a non-linear optimization problem using Gekko. Despite defining one of the variables as an integer, Gekko still returns a float. I tried writing a random, simpler optimization problem (shown below), and the same thing happened. Why is this and how can I get Gekko to solve for an integer value?

I have a problem to optimize the motion of a spacecraft. It starts relative to point O, moving in an undisturbed near-Earth circular orbit with a radius of 6871 km. The gravitational parameter of the Earth is equal to 3.9860044∙10^14 m^3/s^2. The problem is to fly in dt = 86400 seconds from a point in phase space r0 = (10 km, 100 km, -5 km)^T, v0 = (1 m/s, -10 m/s, 3 m/s)^T to the origin, that is, to the point rf = 0, vf = 0. The initial mass of the spacecraft is equal to 1000 kg, the specific impulse of the spacecraft propulsion system is 220 seconds (2157.463 m/s), and the thrust is varied in range from 0.362 to 100 N. I am trying to minimize the propellant mass index to carry out the meeting between two spacecraft to solve the problem of orbital transfer and spacecraft meeting. Consider the HCW equations as a mathematical model.

I have a problem to optimize the motion of a spacecraft. It starts relative to point O, moving in an undisturbed near-Earth circular orbit with a radius of 6871 km. The gravitational parameter of the Earth is equal to 3.9860044∙10^14 m^3/s^2. The problem is to fly in dt = 86400 seconds from a point in phase space r0 = (10 km, 100 km, -5 km)^T, v0 = (1 m/s, -10 m/s, 3 m/s)^T to the origin, that is, to the point rf = 0, vf = 0. The initial mass of the spacecraft is equal to 1000 kg, the specific impulse of the spacecraft propulsion system is 220 seconds (2157.463 m/s), and the thrust is varied in range from 0.362 to 100 N. I am trying to minimize the propellant mass index to carry out the meeting between two spacecraft to solve the problem of orbital transfer and spacecraft meeting. Consider the HCW equations as a mathematical model.

I have a problem to optimize the motion of a spacecraft. It starts relative to point O, moving in an undisturbed near-Earth circular orbit with a radius of 6871 km. The gravitational parameter of the Earth is equal to 3.9860044∙10^14 m^3/s^2. The problem is to fly in dt = 86400 seconds from a point in phase space r0 = (10 km, 100 km, -5 km)^T, v0 = (1 m/s, -10 m/s, 3 m/s)^T to the origin, that is, to the point rf = 0, vf = 0. The initial mass of the spacecraft is equal to 1000 kg, the specific impulse of the spacecraft propulsion system is 220 seconds (2157.463 m/s), and the thrust is varied in range from 0.362 to 100 N. I am trying to minimize the propellant mass index to carry out the meeting between two spacecraft to solve the problem of orbital transfer and spacecraft meeting. Consider the HCW equations as a mathematical model.

I have a problem to optimize the motion of a spacecraft. It starts relative to point O, moving in an undisturbed near-Earth circular orbit with a radius of 6871 km. The gravitational parameter of the Earth is equal to 3.9860044∙10^14 m^3/s^2. The problem is to fly in dt = 86400 seconds from a point in phase space r0 = (10 km, 100 km, -5 km)^T, v0 = (1 m/s, -10 m/s, 3 m/s)^T to the origin, that is, to the point rf = 0, vf = 0. The initial mass of the spacecraft is equal to 1000 kg, the specific impulse of the spacecraft propulsion system is 220 seconds (2157.463 m/s), and the thrust is varied in range from 0.362 to 100 N. I am trying to minimize the propellant mass index to carry out the meeting between two spacecraft to solve the problem of orbital transfer and spacecraft meeting. Consider the HCW equations as a mathematical model.

I am very new to the Gekko Package in python. My target is to maximize 'Q_factor' from the trained TensorFlow model (.keras) I already have.

I am using GEKKO in Python to estimate trajectory of a bouncing ball. For that i need to estimate 2 variables: e_1(coefficient_of_restitution) and q_1(horizontal_velocity loss at each bounce).
I have written the following code for it but the parameters dose not seems to be updated, although the solver is executed successfully. The initial value of parameters are same as the final optimized value of parameters e_1= 0.8 and q_1= 1.

I have a problem to optimize the motion of a spacecraft. It starts relative to point O, moving in an undisturbed near-Earth circular orbit with a radius of 6871 km. The gravitational parameter of the Earth is equal to 3.9860044∙10^14 m^3/s^2. The problem is to fly in dt = 86400 seconds from a point in phase space r0 = (10 km, 100 km, -5 km)^T, v0 = (1 m/s, -10 m/s, 3 m/s)^T to the origin, that is, to the point rf = 0, vf = 0. The initial mass of the spacecraft is equal to 1000 kg, the specific impulse of the spacecraft propulsion system is 220 seconds (2157.463 m/s), and the thrust is varied in range from 0.362 to 100 N. I am trying to minimize the propellant mass index to carry out the rendezvous between two spacecraft to solve the problem of orbital transfer and spacecraft rendezvous and docking.

Here is a simple delayed system, or say a DDE

I have previously successfully solved a mechanical system using the gekko package. However, without having changed anything in my code, I now get the following error message: