Revert "improve sensor fusion" -- DO NOT MERGE
This reverts commit bdf277355dcd647bd5d27b38fc107243a2247a02.
This reverts commit dc5b63e40ee697324d39fe105d6f12c2bb031fc6.
it might be responsible for a regression that makes the
rotation vector spin.
Bug: 7267330
Change-Id: Ifb10e933537e70c1d85a7ba73a7e3ae59002fe62
diff --git a/services/sensorservice/Fusion.cpp b/services/sensorservice/Fusion.cpp
index 93d6127..b88a647 100644
--- a/services/sensorservice/Fusion.cpp
+++ b/services/sensorservice/Fusion.cpp
@@ -201,15 +201,15 @@
// q11 = su^2.dt
//
- const float dT2 = dT*dT;
- const float dT3 = dT2*dT;
-
- // variance of integrated output at 1/dT Hz (random drift)
- const float q00 = gyroVAR * dT + 0.33333f * biasVAR * dT3;
+ // variance of integrated output at 1/dT Hz
+ // (random drift)
+ const float q00 = gyroVAR * dT;
// variance of drift rate ramp
const float q11 = biasVAR * dT;
- const float q10 = 0.5f * biasVAR * dT2;
+
+ const float u = q11 / dT;
+ const float q10 = 0.5f*u*dT*dT;
const float q01 = q10;
GQGt[0][0] = q00; // rad^2
@@ -220,22 +220,6 @@
// initial covariance: Var{ x(t0) }
// TODO: initialize P correctly
P = 0;
-
- // it is unclear how to set the initial covariance. It does affect
- // how quickly the fusion converges. Experimentally it would take
- // about 10 seconds at 200 Hz to estimate the gyro-drift with an
- // initial covariance of 0, and about a second with an initial covariance
- // of about 1 deg/s.
- const float covv = 0;
- const float covu = 0.5f * (float(M_PI) / 180);
- mat33_t& Pv = P[0][0];
- Pv[0][0] = covv;
- Pv[1][1] = covv;
- Pv[2][2] = covv;
- mat33_t& Pu = P[1][1];
- Pu[0][0] = covu;
- Pu[1][1] = covu;
- Pu[2][2] = covu;
}
bool Fusion::hasEstimate() const {
@@ -373,11 +357,6 @@
mat34_t Fusion::getF(const vec4_t& q) {
mat34_t F;
-
- // This is used to compute the derivative of q
- // F = | [q.xyz]x |
- // | -q.xyz |
-
F[0].x = q.w; F[1].x =-q.z; F[2].x = q.y;
F[0].y = q.z; F[1].y = q.w; F[2].y =-q.x;
F[0].z =-q.y; F[1].z = q.x; F[2].z = q.w;
@@ -389,18 +368,10 @@
const vec4_t q = x0;
const vec3_t b = x1;
const vec3_t we = w - b;
+ const vec4_t dq = getF(q)*((0.5f*dT)*we);
+ x0 = normalize_quat(q + dq);
- // q(k+1) = O(we)*q(k)
- // --------------------
- //
- // O(w) = | cos(0.5*||w||*dT)*I33 - [psi]x psi |
- // | -psi' cos(0.5*||w||*dT) |
- //
- // psi = sin(0.5*||w||*dT)*w / ||w||
- //
- //
// P(k+1) = Phi(k)*P(k)*Phi(k)' + G*Q(k)*G'
- // ----------------------------------------
//
// G = | -I33 0 |
// | 0 I33 |
@@ -421,26 +392,13 @@
const mat33_t wx(crossMatrix(we, 0));
const mat33_t wx2(wx*wx);
const float lwedT = length(we)*dT;
- const float hlwedT = 0.5f*lwedT;
const float ilwe = 1/length(we);
const float k0 = (1-cosf(lwedT))*(ilwe*ilwe);
const float k1 = sinf(lwedT);
- const float k2 = cosf(hlwedT);
- const vec3_t psi(sinf(hlwedT)*ilwe*we);
- const mat33_t O33(crossMatrix(-psi, k2));
- mat44_t O;
- O[0].xyz = O33[0]; O[0].w = -psi.x;
- O[1].xyz = O33[1]; O[1].w = -psi.y;
- O[2].xyz = O33[2]; O[2].w = -psi.z;
- O[3].xyz = psi; O[3].w = k2;
Phi[0][0] = I33 - wx*(k1*ilwe) + wx2*k0;
Phi[1][0] = wx*k0 - I33dT - wx2*(ilwe*ilwe*ilwe)*(lwedT-k1);
- x0 = O*q;
- if (x0.w < 0)
- x0 = -x0;
-
P = Phi*P*transpose(Phi) + GQGt;
checkState();
@@ -467,12 +425,7 @@
K[1] = transpose(P[1][0])*LtSi;
// update...
- // P = (I-K*H) * P
- // P -= K*H*P
- // | K0 | * | L 0 | * P = | K0*L 0 | * | P00 P10 | = | K0*L*P00 K0*L*P10 |
- // | K1 | | K1*L 0 | | P01 P11 | | K1*L*P00 K1*L*P10 |
- // Note: the Joseph form is numerically more stable and given by:
- // P = (I-KH) * P * (I-KH)' + K*R*R'
+ // P -= K*H*P;
const mat33_t K0L(K[0] * L);
const mat33_t K1L(K[1] * L);
P[0][0] -= K0L*P[0][0];