Control of Leaning Dynamics for Three-wheeled Vehicles : Experimental evaluation of two control strategies

Abstract: Three‐wheelers are popular in fuel efficient contests but do not see much commercial success. This could be because three‐wheelers are easier to tip over than four wheeled vehicles. One way to counteract the tipping over is to introduce leaning dynamics on three‐wheeled vehicles so that they lean in corners like bicycles and motorcycles can. For this project a small radio‐controlled three‐wheeler was built with a mechanical system to handle the leaning dynamics for the front wheel pair. For the leaning control two different controllers were programmed to be compared, one relying on feedback from an accelerometer. The other calculates the desired angle based on a mechanical model with feedback from a potentiometer that measures the current leaning angle. These controllers where tested indoors on a smooth surface and outdoors on a rough surface to compare the two. Both controllers performed well indoors but the controller relying on feedback from the potentiometer was more stable than the one relying on the accelerometer. Testing outdoors on a rough surface amplified the differences. That test showed that the controller using an accelerometer was so unstable it barely could provide any leaning at all while the one using a potentiometer delivered very similar result as indoors. This was probably due to the accelerometers sensitivity to vibration. The controller using the accelerometer for feedback was slower and more unstable but can keep the vehicle leveled on leaning ground since it measures the actual acceleration the vehicle experiences. The controller using a potentiometer for feedback was faster and more stable but only uses the leaning dynamic while turning without taking other accelerations into account.