1. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationship:
d
_
pulses
,
opt
=
arg
\ue89e
\ue89e
max
d
_
pulses
\ue89e
Var
S
\ue8a0
(
d
_
pulses
)
–
(
Cov
S
\ue8a0
(
d
_
pulses
,
t
)
)
2
Var
S
\ue8a0
(
t
_
)
wherein:
dpulses,opt is optimized positions of the transmitters in a sequence in which the transmitters transmit;
dpulses is positions of the transmitters in a sequence in which the transmitters transmit;
t is transmission instants;
VarS is sample variance; and
CovS is sample covariance.
2. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationships:
|CovWS(dpulses,x,t,\u03c1)|=minimal
|CovWS(dpulses,y,t,\u03c1)|=minimal
wherein:
dpulses,x is X positions of the transmitters in a sequence in which the transmitters transmit;
dpulses,y is Y positions of the transmitters in the sequence in which the transmitters transmit;
t is transmission instants;
\u03c1 is transmission energies;
CovWS is weighted sample covariance, wherein
Cov
WS
\ue8a0
(
x
_
,
y
_
,
w
_
)
:=
E
WS
\ue8a0
(
x
_
–
E
WS
\ue8a0
(
x
_
,
w
_
)
\xb7
1
_
\u2297
y
_
–
E
WS
\ue8a0
(
y
_
,
w
_
)
\xb7
1
_
,
w
_
)
\ue89e
E
WS
\ue8a0
(
x
_
,
w
_
)
:=
1
\u2211
j
=
1
K
\ue89e
\ue89e
wj
\ue89e
\u2211
i
=
1
K
\ue89e
\ue89e
xi
\xb7
wi
wherein:
w is weight vector;
EWS is weighted sample mean; and
is element-wise multiplication.
3. The method as recited in claim 2, wherein an optimization of the following mathematical relationships is carried out:
CovWS(dpulses,x,t,\u03c1)=0
CovWS(dpulses,y,t,\u03c1)=0.
4. A method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
providing at least two transmitters having different activation time frames; and
activating the transmitters a different number of times in the respective activation time frames of the transmitters such that a common center instant for the transmitters is provided for the activation time frames of the transmitters.
5. The method as recited in claim 4, wherein one of the transmitters is activated with a time offset from a second one of the transmitters, the respectively later-activated transmitter being activated, in a boundary region of the respective activation time frame, at least one less time than the other transmitter, the other transmitter being not activated the same number of times at the beginning and at the end of the respective activation time frame.
6. The method as recited in claim 5, wherein a discrete Fourier transform is carried out for signal evaluation, and wherein sampled values of the later-activated transmitter are made up by way of zero paddings to the number of sampled values of the other transmitter, and wherein by using an amplitude factor, (i) a phase difference in the sampled signals of the two transmitters is corrected, and (ii) the sampled signals of the two transmitters are equalized.
7. The method as recited in claim 6, wherein a transmission-ramp-based radar modulation is used for the signals of the transmitters.
8. The method as recited in claim 1, wherein the MIMO radar is situated in a motor vehicle, and wherein the method is used to identify at least one of the following variables: distance, relative velocity, and angle.
9. A non-transitory computer-readable data storage medium storing a computer program having program codes which, when executed on a computer, performs a method for operating a MIMO radar such that an influence of an object motion on an angle estimate is substantially eliminated, the method comprising:
identifying a time multiplex schema having a transmission sequence and transmission instants of transmitters of the MIMO radar by optimizing the following mathematical relationship:
d
_
pulses
,
opt
=
arg
\ue89e
\ue89e
max
d
_
pulses
\ue89e
Var
S
\ue8a0
(
d
_
pulses
)
–
(
Cov
S
\ue8a0
(
d
_
pulses
,
t
)
)
2
Var
S
\ue8a0
(
t
_
)
wherein:
dpulses,opt is optimized positions of the transmitters in a sequence in which the transmitters transmit;
dpulses is positions of the transmitters in a sequence in which the transmitters transmit;
t is transmission instants;
VarS is sample variance; and
CovS is sample covariance.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An electric power steering apparatus, comprising a torque detection unit comprising:
a torque detection element comprising a pair of detection coils of which impedances change in accordance with torque;
a torque detection portion comprising a monitoring portion which monitors the torque detection element; and
a shortcircuit failure detection portion which detects a shortcircuit failure occurring between a main torque signal line and a sub torque signal line of the detection coils, wherein
the shortcircuit failure detection portion detects the shortcircuit failure occurring between the main torque signal line and the sub torque signal line by comparing a main torque signal and a sub torque signal, which are outputted from the torque detection portion when an abnormal condition is intentionally set in the monitoring portion.
2. The electric power steering apparatus according to claim 1, wherein the torque detection unit further comprises a reference voltage generation circuit which outputs a particular reference voltage, which differs from a standard reference voltage, to the monitoring portion and
when a test mode, in which a torque detection circuit is tested, is set, the abnormal condition is intentionally set in the monitoring portion by setting the particular reference voltage therein.
3. The electric power steering apparatus according to claim 2, wherein the particular reference voltage, which is set in the monitoring portion when the test mode is set, exceeds the standard reference voltage.
4. The electric power steering apparatus according to claim 1, wherein the monitoring portion is configured so that when an abnormal condition is set therein by intentionally setting the particular reference voltage therein, the sub torque signal line is grounded.
5. The electric power steering apparatus according to claim 1, wherein the shortcircuit failure detection portion determines that the shortcircuit failure occurring between the main torque signal line and the sub torque signal line occurs in a case where a test mode is set, where an abnormal condition is set in the monitoring portion by setting a particular reference voltage exceeding a standard reference voltage therein, and where a main torque signal voltage and a sub torque signal voltage outputted from the torque detection portion are equal to each other.
6. The electric power steering apparatus according to claim 1, wherein when the shortcircuit failure is detected, the torque detection unit changes a mode thereof into a fail safe mode.