Systems and methods for controlling a radio-controlled two-wheeled vehicle
A radio-controlled (RC) motorcycle is disclosed with a chassis, a rear wheel, and a steerable front wheel assembly. The motorcycle includes an attitude estimator that uses rotation and acceleration data from an IMU to estimate an inertial attitude of the motorcycle. A receiver is connected to a control processor and receives a steering input from an RC transmitter. The control processor determines a desired roll angle based at least in part on the steering input from the receiver; determines a reported roll angle from the attitude estimate; and controls a steering angle of the front wheel assembly to reduce the difference (or reduce error) between the desired roll angle and the reported roll angle.
1 . A radio-controlled (RC) motorcycle, comprising:
a chassis, comprising a rear wheel and a steerable front wheel assembly;
an inertial measurement unit (IMU) comprising one or more angular rate sensors configured to output rotation data associated with rotation of the RC motorcycle about one or more axes, and one or more acceleration sensors configured to output acceleration data associated with acceleration of the RC motorcycle along one or more axes;
an attitude estimator, configured to calculate an attitude estimate of the RC motorcycle using the rotation and acceleration data from the IMU;
a receiver;
a brake coupled to the rear wheel; and
a control processor, electrically connected to the receiver configured to:
receive a steering input from an RC transmitter;
receive an attitude estimate from the attitude estimator;
determine a target roll angle based at least in part on the steering input from the receiver;
determine a reported roll angle from the attitude estimate;
control a steering angle of the front wheel assembly to reduce error between the target roll angle and the reported roll angle;
store a pitch angle activation threshold, maximum pitch rotation rate threshold, and target pitch angle;
determine a reported pitch angle and a reported pitch rotation rate based on data from the attitude estimator and inertial measurement unit;
compare the pitch angle activation threshold and maximum pitch rotation rate threshold to the reported pitch angle and the reported pitch rotation rate respectively; and
when either the pitch angle activation threshold or the maximum pitch rotation rate threshold are exceeded, control the RC motorcycle to avoid flipping over.
2 . The RC motorcycle of claim 1 , wherein the control processor is further configured to:
store a maximum roll angle; and
control the steering angle to prevent the RC motorcycle from exceeding the maximum roll angle.
3 . The RC motorcycle of claim 1 , wherein the control processor is further configured to determine an upright input based on the steering input from the RC transmitter.
4 . The RC motorcycle of claim 3 , wherein the upright input is determined based on the steering input being indicative of a centered steering input on the transmitter, and wherein the control processor, based at least in part on the upright input, is further configured to control the RC motorcycle to maintain an upright position.
5 . The RC motorcycle of claim 1 , wherein the control processor is further configured to stabilize a yaw angle.
6 . The RC motorcycle of claim 5 , wherein the yaw angle is stabilized by a closed-loop control system in the control processor that adds stabilization corrections to the steering angle based on a reported yaw rotation from the inertial measurement unit.
7 . The RC motorcycle of claim 1 , wherein the control processor is further configured to stabilize a pitch angle.
8 . The RC motorcycle of claim 1 , wherein controlling the RC motorcycle to avoid flipping over comprises a closed-loop control system that reduces a throttle or applies the brake to reduce an error between the target pitch angle and the reported pitch angle.
9 . The RC motorcycle of claim 8 , wherein the target pitch angle is selected to be near a balance point of the RC motorcycle about a pitch rotation axis, allowing the RC motorcycle to maintain the target pitch angle.
10 . The RC motorcycle of claim 1 , further comprising:
an angle limiter configured to maintain the RC motorcycle at a minimum roll angle relative to ground;
wherein the control processor is further configured to:
determine the reported roll angle is close to the minimum roll angle;
receive a throttle input from the receiver; and
control the steering angle to stand the motorcycle up.
11 . A control processor for an RC vehicle, configured to:
receive angular rotation data associated with rotation of the RC vehicle about one or more axes and acceleration data associated with acceleration of the RC vehicle along one or more axes;
calculate a roll angle estimate of the RC vehicle, based on the rotation data and the acceleration data;
receive steering command data from a controller associated with the RC vehicle; calculate a target roll angle, based on the steering command data;
control the steering angle of at least one wheel of the RC vehicle to reduce error between the target roll angle and the roll angle estimate; and
determine a self-level input based on the steering input from the RC transmitter;
wherein the self-level input is determined based on the steering input being indicative of a centered steering input on the transmitter.
12 . The control processor for an RC vehicle of claim 11 , wherein the control processor is further configured to:
store a maximum roll angle; and
control the steering angle to prevent the RC vehicle from exceeding the maximum roll angle.
13 . The control processor for an RC vehicle of claim 11 , wherein the control processor is further configured to stabilize a yaw angle.
14 . The control processor for an RC vehicle of claim 13 , wherein the yaw angle is stabilized by a closed-loop control system in the control processor that adds stabilization corrections to the steering angle based on a reported yaw rotation.
15 . The control processor for an RC vehicle of claim 11 , wherein the control processor is further configured to:
store a pitch angle activation threshold, maximum pitch rotation rate threshold, and target pitch angle;
determine a reported pitch angle and a reported pitch rotation rate based on data from the attitude estimator;
compare the pitch angle activation threshold and maximum pitch rotation rate threshold to the reported pitch angle and the reported pitch rotation rate respectively; and
when either the pitch angle activation threshold or the maximum pitch rotation rate threshold are exceeded, control the RC vehicle to avoid flipping over.
16 . The control processor for an RC vehicle of claim 15 , wherein controlling the RC vehicle to avoid flipping over comprises a closed-loop control system that reduces throttle or applies the brake to reduce error between the target pitch angle and the reported pitch angle.
17 . The control processor for an RC vehicle of claim 16 , wherein the target pitch angle is selected to be near a balance point of the RC vehicle about a pitch rotation axis.