Chris, I see no reason reinventing the wheel like Harry suggests given that the PathFollowerDriver already implements these PID controllers (one for lateral control, the other for longitudinal control) and you can adjust all parameters (including setting the appropriate gain to 0 to make it a PD controller).
The reason for the behavior you see is simply because the PID gains must be properly set for the vehicle and type of maneuvers you attempt to implement. I estimated the values we have in our demos a long time ago for a HMMWV-type vehicle. We simply used the same or similar values for other vehicles, with more or less success. Obviously, the dynamics of the M113 vehicle are too different from that of a HMMWV for the same set of controller gains to work similarly well. The demos we provide are for illustration only. It is implied that a user would need to make appropriate adjustments (for example in PID controller gains) when changing the vehicle and/or scenario. You can get ballpark estimates of the gain values by considering a simple scalar 2nd order ODE mockup model of the vehicle yaw dynamics. --Radu From: 'Harry ZHANG' via ProjectChrono <[email protected]> Sent: Sunday, 24 August 2025 18:53 To: ProjectChrono <[email protected]> Subject: [chrono] Re: Steering Controller Question Hi Chris, I did similar demo before, controlling M113 tracked vehicle to follow sine shape path with PID method, the video link is (https://uwmadison.box.com/s/j93bhbnkwbdh996bi9k7stk1gisas1g2). Is this demo what you want to do (to some extend))? In this demo, I implemented a basic PD controller in the simulation loop given the information of predefined sine-shape trajectory and vehicle's current state while I am not sure about the reason why it's not working well with PathFollowerDriver (might because of the tracked vehicle's skid steering mechanism is different from the ones one wheeled vehicle), I would recommend trying to implement a basic PID controller, which you could easily adjust PID gains given over/under damped scenarios. From experience (demo I shared above), it would work fine with a customized PID controller. Best, Harry On Wednesday, August 13, 2025 at 8:31:11 AM UTC-5 [email protected]<mailto:[email protected]> wrote: Hi all, I have been testing some of Project Chrono's features with their vehicle module and I was curious if anyone can explain this abnormality. I created a file that creates a PathFollowerDriver component on the M113 tracked vehicle to test how the PID controller works. I started with a straight line path first and was able to get some pretty solid results with the chosen gains. When I transitioned the same gains to a more complicated path (the Double Lane Change Path) the previous gains that I had were too harsh and veered the M113 off of the desired path. Comparing that to the wheeled vehicle, no matter the maneuver chosen, the same gains can be used and the wheeled vehicle would be able to follow the path from beginning to end with little difficulty. My first thought as to why this may be happening is because of the time step difference in simulations (2e-3 in the wheeled vs. 5e-4 in the tracked), but I was wondering if anyone else may have some thoughts behind what may be going on. Thank you, Chris -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/7600dd11-a7b8-4e50-9120-9b86e46829c8n%40googlegroups.com<https://urldefense.com/v3/__https:/groups.google.com/d/msgid/projectchrono/7600dd11-a7b8-4e50-9120-9b86e46829c8n*40googlegroups.com?utm_medium=email&utm_source=footer__;JQ!!Mak6IKo!ISC0Jm4_uECvakm47H_xdTjWI0VJX4rMGT7JxNvkQ-NvNQB-IeG6gyCyBjxJ12UWi4-PIM5nxKknvre4xBhCtYSCmKY$>. -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/CH3PPF46CDC21851BC216388E549BA9752BA73EA%40CH3PPF46CDC2185.namprd06.prod.outlook.com.
