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Fix steering controllers library kinematics #1150

Merged
merged 12 commits into from
Jul 3, 2024
Merged

Fix steering controllers library kinematics #1150

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aa34f02
Fix IK
christophfroehlich May 28, 2024
35f34d8
Fix controller tests and add notes
christophfroehlich May 28, 2024
21afbc5
Improve tests for other steering types
christophfroehlich May 28, 2024
8809f62
Improve odometry of overdetermined measurements
christophfroehlich May 28, 2024
0209540
Remove debug output
christophfroehlich May 28, 2024
f7486dd
Use std:: namespace for trigonometric functions
christophfroehlich Jun 8, 2024
8729f9e
Use the full name
christophfroehlich Jun 19, 2024
5eba4e4
Merge commit 'b81be48fb1b6101a3c601c0ea11c5393e5a7026e' into fix/stee…
christophfroehlich Jun 19, 2024
37b8f0a
Fix method name
christophfroehlich Jun 19, 2024
1504bc5
Add helper function
christophfroehlich Jun 19, 2024
fe2ba4b
Add default value to avoid breaking API
christophfroehlich Jun 20, 2024
3fa39cc
Merge branch 'master' into fix/steering_controllers_library_kinematics
destogl Jul 3, 2024
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10 changes: 10 additions & 0 deletions steering_controllers_library/include/steering_controllers_library/steering_odometry.hpp
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Expand Up @@ -231,6 +231,16 @@ class SteeringOdometry
*/
double convert_twist_to_steering_angle(const double v_bx, const double omega_bz);

/**
* \brief Calculates linear velocity of a robot with double traction axle
* \param right_traction_wheel_vel Right traction wheel velocity [rad/s]
* \param left_traction_wheel_vel Left traction wheel velocity [rad/s]
* \param steer_pos Steer wheel position [rad]
*/
double get_lin_velocity_double_traction_axle(
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const double right_traction_wheel_vel, const double left_traction_wheel_vel,
const double steer_pos);

/**
* \brief Reset linear and angular accumulators
*/
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31 changes: 26 additions & 5 deletions steering_controllers_library/src/steering_odometry.cpp
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Expand Up @@ -129,13 +129,26 @@ bool SteeringOdometry::update_from_velocity(
return update_odometry(linear_velocity, angular_velocity, dt);
}

double SteeringOdometry::get_lin_velocity_double_traction_axle(
const double right_traction_wheel_vel, const double left_traction_wheel_vel,
const double steer_pos)
{
double turning_radius = wheelbase_ / std::tan(steer_pos);
// overdetermined, we take the average
double vel_r = right_traction_wheel_vel * wheel_radius_ * turning_radius /
(turning_radius + wheel_track_ * 0.5);
double vel_l = left_traction_wheel_vel * wheel_radius_ * turning_radius /
(turning_radius - wheel_track_ * 0.5);
return (vel_r + vel_l) * 0.5;
}

bool SteeringOdometry::update_from_velocity(
const double right_traction_wheel_vel, const double left_traction_wheel_vel,
const double steer_pos, const double dt)
{
double linear_velocity =
(right_traction_wheel_vel + left_traction_wheel_vel) * wheel_radius_ * 0.5;
steer_pos_ = steer_pos;
double linear_velocity = get_lin_velocity_double_traction_axle(
right_traction_wheel_vel, left_traction_wheel_vel, steer_pos_);

const double angular_velocity = tan(steer_pos_) * linear_velocity / wheelbase_;

Expand All @@ -146,9 +159,17 @@ bool SteeringOdometry::update_from_velocity(
const double right_traction_wheel_vel, const double left_traction_wheel_vel,
const double right_steer_pos, const double left_steer_pos, const double dt)
{
steer_pos_ = (right_steer_pos + left_steer_pos) * 0.5;
double linear_velocity =
(right_traction_wheel_vel + left_traction_wheel_vel) * wheel_radius_ * 0.5;
// overdetermined, we take the average
const double right_steer_pos_est = std::atan(
wheelbase_ * std::tan(right_steer_pos) /
(wheelbase_ - wheel_track_ / 2 * std::tan(right_steer_pos)));
const double left_steer_pos_est = std::atan(
wheelbase_ * std::tan(left_steer_pos) /
(wheelbase_ + wheel_track_ / 2 * std::tan(left_steer_pos)));
steer_pos_ = (right_steer_pos_est + left_steer_pos_est) * 0.5;
Comment on lines +162 to +169
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Calculations are fine, but I thin we can split it a little to re-use and improve readability having "atan" and "tan" at the same line is a little confusing.

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Nah that's fine since this is following the docs.


double linear_velocity = get_lin_velocity_double_traction_axle(
right_traction_wheel_vel, left_traction_wheel_vel, steer_pos_);
const double angular_velocity = steer_pos_ * linear_velocity / wheelbase_;

return update_odometry(linear_velocity, angular_velocity, dt);
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4 changes: 2 additions & 2 deletions steering_controllers_library/test/test_steering_odometry.cpp
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Expand Up @@ -36,7 +36,7 @@ TEST(TestSteeringOdometry, ackermann_odometry)
odom.set_wheel_params(1., 1., 1.);
odom.set_odometry_type(steering_odometry::ACKERMANN_CONFIG);
ASSERT_TRUE(odom.update_from_velocity(1., 1., .1, .1, .1));
EXPECT_NEAR(odom.get_linear(), 1.0, 1e-3);
EXPECT_NEAR(odom.get_linear(), 1.002, 1e-3);
EXPECT_NEAR(odom.get_angular(), .1, 1e-3);
EXPECT_NEAR(odom.get_x(), .1, 1e-3);
EXPECT_NEAR(odom.get_heading(), .01, 1e-3);
Expand Down Expand Up @@ -226,7 +226,7 @@ TEST(TestSteeringOdometry, tricycle_odometry)
odom.set_wheel_params(1., 1., 1.);
odom.set_odometry_type(steering_odometry::TRICYCLE_CONFIG);
ASSERT_TRUE(odom.update_from_velocity(1., 1., .1, .1));
EXPECT_NEAR(odom.get_linear(), 1.0, 1e-3);
EXPECT_NEAR(odom.get_linear(), 1.002, 1e-3);
EXPECT_NEAR(odom.get_angular(), .1, 1e-3);
EXPECT_NEAR(odom.get_x(), .1, 1e-3);
EXPECT_NEAR(odom.get_heading(), .01, 1e-3);
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