simondlevy
Why computeVelocities returns doubled distance?
in vehicles.py distance calculates as:
dxyMillimeters = self.wheelRadiusMillimeters * \
(math.radians(leftDiffDegrees) + math.radians(rightDiffDegrees))
Obviously, if two 1mm radius wheels rotate by 1rad we get 2mm distanse instead of one.
yet return value described as
dxyMillimeters forward distance traveled, in millimeters
As far as I understand, rotation is also doubled, but I'm not sure. Maybe CoreSLAM uses doubled value, maybe degrees should be halved, maybe it's just error, I don't know. So, why?
There is similar code in the C++ code and based on testing, the calculated distance and rotation didn't seem correct.
poseChange.dtheta_degrees = this->wheel_radius_mm / this->half_axle_length_mm *
(right_diff_degrees - left_diff_degrees);
When I modified Robot::extractOdometry() of my robot to calculate degrees rotate of each wheel to be 1/2, the calculations seems much closer physical measurements. I too would love to know if this is a bug, or something I'm not understanding.
This is legacy code that I haven't looked at in years. If you want to modify and do a pull request, that'd be great. Maybe an optional scaling parameter would be the best solution.
