Files
sunnypilot/selfdrive/controls/lib/latcontrol.py
Vasily Tarasov e9ef18d088 Interpolate ki/kp for steering PID loop (#200)
* Interpolate ki/kp for steering PID loop

Very much needed for the Volt port: car ping-pongs with low kp
on high speeeds, and the loop is unstable with high kp on
low speeds.

Also, removes "number or array?" logic from PIController,
now that all the callers use interpolation ofr ki/kp.

* Pass speed to steering PID loop for ki/kp interpolation

* Remove unused numbers import

old-commit-hash: 93f55f3ccf
2018-03-15 13:28:15 -07:00

112 lines
4.3 KiB
Python

import math
import numpy as np
from selfdrive.controls.lib.pid import PIController
from selfdrive.controls.lib.lateral_mpc import libmpc_py
from common.numpy_fast import interp
from common.realtime import sec_since_boot
from selfdrive.swaglog import cloudlog
# 100ms is a rule of thumb estimation of lag from image processing to actuator command
ACTUATORS_DELAY = 0.1
_DT = 0.01 # 100Hz
_DT_MPC = 0.05 # 20Hz
def calc_states_after_delay(states, v_ego, steer_angle, curvature_factor, steer_ratio):
states[0].x = v_ego * ACTUATORS_DELAY
states[0].psi = v_ego * curvature_factor * math.radians(steer_angle) / steer_ratio * ACTUATORS_DELAY
return states
def get_steer_max(CP, v_ego):
return interp(v_ego, CP.steerMaxBP, CP.steerMaxV)
class LatControl(object):
def __init__(self, VM):
self.pid = PIController((VM.CP.steerKpBP, VM.CP.steerKpV),
(VM.CP.steerKiBP, VM.CP.steerKiV),
k_f=VM.CP.steerKf, pos_limit=1.0)
self.last_cloudlog_t = 0.0
self.setup_mpc(VM.CP.steerRateCost)
def setup_mpc(self, steer_rate_cost):
self.libmpc = libmpc_py.libmpc
self.libmpc.init(steer_rate_cost)
self.mpc_solution = libmpc_py.ffi.new("log_t *")
self.cur_state = libmpc_py.ffi.new("state_t *")
self.mpc_updated = False
self.cur_state[0].x = 0.0
self.cur_state[0].y = 0.0
self.cur_state[0].psi = 0.0
self.cur_state[0].delta = 0.0
self.last_mpc_ts = 0.0
self.angle_steers_des = 0.0
self.angle_steers_des_mpc = 0.0
self.angle_steers_des_prev = 0.0
self.angle_steers_des_time = 0.0
def reset(self):
self.pid.reset()
def update(self, active, v_ego, angle_steers, steer_override, d_poly, angle_offset, VM, PL):
cur_time = sec_since_boot()
self.mpc_updated = False
if self.last_mpc_ts < PL.last_md_ts:
self.last_mpc_ts = PL.last_md_ts
self.angle_steers_des_prev = self.angle_steers_des_mpc
curvature_factor = VM.curvature_factor(v_ego)
l_poly = libmpc_py.ffi.new("double[4]", list(PL.PP.l_poly))
r_poly = libmpc_py.ffi.new("double[4]", list(PL.PP.r_poly))
p_poly = libmpc_py.ffi.new("double[4]", list(PL.PP.p_poly))
# account for actuation delay
self.cur_state = calc_states_after_delay(self.cur_state, v_ego, angle_steers, curvature_factor, VM.CP.steerRatio)
v_ego_mpc = max(v_ego, 5.0) # avoid mpc roughness due to low speed
self.libmpc.run_mpc(self.cur_state, self.mpc_solution,
l_poly, r_poly, p_poly,
PL.PP.l_prob, PL.PP.r_prob, PL.PP.p_prob, curvature_factor, v_ego_mpc, PL.PP.lane_width)
delta_desired = self.mpc_solution[0].delta[1]
self.cur_state[0].delta = delta_desired
self.angle_steers_des_mpc = float(math.degrees(delta_desired * VM.CP.steerRatio) + angle_offset)
self.angle_steers_des_time = cur_time
self.mpc_updated = True
# Check for infeasable MPC solution
nans = np.any(np.isnan(list(self.mpc_solution[0].delta)))
t = sec_since_boot()
if nans:
self.libmpc.init(VM.CP.steerRateCost)
self.cur_state[0].delta = math.radians(angle_steers) / VM.CP.steerRatio
if t > self.last_cloudlog_t + 5.0:
self.last_cloudlog_t = t
cloudlog.warning("Lateral mpc - nan: True")
if v_ego < 0.3 or not active:
output_steer = 0.0
self.pid.reset()
else:
# TODO: ideally we should interp, but for tuning reasons we keep the mpc solution
# constant for 0.05s.
#dt = min(cur_time - self.angle_steers_des_time, _DT_MPC + _DT) + _DT # no greater than dt mpc + dt, to prevent too high extraps
#self.angle_steers_des = self.angle_steers_des_prev + (dt / _DT_MPC) * (self.angle_steers_des_mpc - self.angle_steers_des_prev)
self.angle_steers_des = self.angle_steers_des_mpc
steers_max = get_steer_max(VM.CP, v_ego)
self.pid.pos_limit = steers_max
self.pid.neg_limit = -steers_max
steer_feedforward = self.angle_steers_des * v_ego**2 # proportional to realigning tire momentum (~ lateral accel)
output_steer = self.pid.update(self.angle_steers_des, angle_steers, check_saturation=(v_ego > 10), override=steer_override, feedforward=steer_feedforward, speed=v_ego)
self.sat_flag = self.pid.saturated
return output_steer