The movementPID field configures the feedback control that is used to calculate the actual forces applied to the Rigidbody at any given point in time. Specifically, it configures a generalized PID Controller (Proportional/Integral/Derivative controller) that can be tuned to provide a wide range of physics behaviors.
The proportional term (P) controls how quickly the hovercraft reaches the correct velocity. The derivative term (D) influences how quickly the vehicle recovers from speed changes caused by outside influences (such as collisions).
Although it looks complicated at first glance, HoverKit includes the ability to automatically determine the starting values that can be used for your vehicle, and with a little experimentation it quickly becomes obvious how to tweak the values to achieve the behavior you desire.
This value determines how quickly the vehicle will adjust to arrive at the proper physics solution for moving at the desired speed, with higher numbers achieving the correct velocity faster than lower numbers. For instance, higher numbers might result in achieving maximum speed within a very short time (great for racing), while lower numbers might result in taking much longer to achieve maximum speed (more appropriate for tanks).
From 100% to 200% of the vehicle’s Rigidbody mass will provide a good starting point for experimentation, or use the Estimate Forces button to generate default values.
In the case of the HoverMovement component, the dFactor value provides control over how quickly the system responds to external conditions like a collision, with higher numbers resulting in faster recovery, while lower numbers can result in a more pronounced loss of speed.
This value will typically be much lower than the P value, often not more than 5% of the P value.