engineering/modules/robotics/robotics.h

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/**
******************************************************************************
* @file robotics.cpp/h
* @brief Robotic toolbox on STM32. STM32机器人学库
* @author Spoon Guan
* @ref [1] SJTU ME385-2, Robotics, Y.Ding
* [2] Bruno Siciliano, et al., Robotics: Modelling, Planning and
* Control, Springer, 2010.
* [3] R.Murry, Z.X.Li, and S.Sastry, A Mathematical Introduction
* to Robotic Manipulation, CRC Press, 1994.
******************************************************************************
* Copyright (c) 2023 Team JiaoLong-SJTU
* All rights reserved.
******************************************************************************
*/
#ifndef ROBOTICS_H
#define ROBOTICS_H
#include "utils.h"
#include "matrix.h"
namespace robotics {
// rotation matrix(R) -> RPY([yaw;pitch;roll])
Matrixf<3, 1> r2rpy(Matrixf<3, 3> R);
// RPY([yaw;pitch;roll]) -> rotation matrix(R)
Matrixf<3, 3> rpy2r(Matrixf<3, 1> rpy);
// rotation matrix(R) -> angle vector([r;θ])
Matrixf<4, 1> r2angvec(Matrixf<3, 3> R);
// angle vector([r;θ]) -> rotation matrix(R)
Matrixf<3, 3> angvec2r(Matrixf<4, 1> angvec);
// rotation matrix(R) -> quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)]
Matrixf<4, 1> r2quat(Matrixf<3, 3> R);
// quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)] -> rotation matrix(R)
Matrixf<3, 3> quat2r(Matrixf<4, 1> quat);
// quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)] -> RPY([yaw;pitch;roll])
Matrixf<3, 1> quat2rpy(Matrixf<4, 1> q);
// RPY([yaw;pitch;roll]) -> quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)]
Matrixf<4, 1> rpy2quat(Matrixf<3, 1> rpy);
// quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)] -> angle vector([r;θ])
Matrixf<4, 1> quat2angvec(Matrixf<4, 1> q);
// angle vector([r;θ]) -> quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)]
Matrixf<4, 1> angvec2quat(Matrixf<4, 1> angvec);
// homogeneous transformation matrix(T) -> rotation matrix(R)
Matrixf<3, 3> t2r(Matrixf<4, 4> T);
// rotation matrix(R) -> homogeneous transformation matrix(T)
Matrixf<4, 4> r2t(Matrixf<3, 3> R);
// homogeneous transformation matrix(T) -> translation vector(p)
Matrixf<3, 1> t2p(Matrixf<4, 4> T);
// translation vector(p) -> homogeneous transformation matrix(T)
Matrixf<4, 4> p2t(Matrixf<3, 1> p);
// rotation matrix(R) & translation vector(p) -> homogeneous transformation
// matrix(T)
Matrixf<4, 4> rp2t(Matrixf<3, 3> R, Matrixf<3, 1> p);
// homogeneous transformation matrix(T) -> RPY([yaw;pitch;roll])
Matrixf<3, 1> t2rpy(Matrixf<4, 4> T);
// inverse of homogeneous transformation matrix(T^-1=[R',-R'P;0,1])
Matrixf<4, 4> invT(Matrixf<4, 4> T);
// RPY([yaw;pitch;roll]) -> homogeneous transformation matrix(T)
Matrixf<4, 4> rpy2t(Matrixf<3, 1> rpy);
// homogeneous transformation matrix(T) -> angle vector([r;θ])
Matrixf<4, 1> t2angvec(Matrixf<4, 4> T);
// angle vector([r;θ]) -> homogeneous transformation matrix(T)
Matrixf<4, 4> angvec2t(Matrixf<4, 1> angvec);
// homogeneous transformation matrix(T) -> quaternion,
// [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)]
Matrixf<4, 1> t2quat(Matrixf<4, 4> T);
// quaternion, [q0;q1;q2;q3]=[cos(θ/2);rsin(θ/2)] -> homogeneous transformation
// matrix(T)
Matrixf<4, 4> quat2t(Matrixf<4, 1> quat);
// homogeneous transformation matrix(T) -> twist coordinates vector ([p;rθ])
Matrixf<6, 1> t2twist(Matrixf<4, 4> T);
// twist coordinates vector ([p;rθ]) -> homogeneous transformation matrix(T)
Matrixf<4, 4> twist2t(Matrixf<6, 1> twist);
// joint type: R-revolute joint, P-prismatic joint
typedef enum joint_type {
R = 0,
P = 1,
} Joint_Type_e;
// DenavitHartenberg(DH) method
struct DH_t {
// forward kinematic
Matrixf<4, 4> fkine();
// DH parameter
float theta;
float d;
float a;
float alpha;
Matrixf<4, 4> T;
};
class Link {
public:
Link(){};
Link(float theta, float d, float a, float alpha, Joint_Type_e type = R,
float offset = 0, float qmin = 0, float qmax = 0, float m = 1,
Matrixf<3, 1> rc = matrixf::zeros<3, 1>(),
Matrixf<3, 3> I = matrixf::zeros<3, 3>());
Link(const Link& link);
Link& operator=(Link link);
float qmin() { return qmin_; }
float qmax() { return qmax_; }
Joint_Type_e type() { return type_; }
float m() { return m_; }
Matrixf<3, 1> rc() { return rc_; }
Matrixf<3, 3> I() { return I_; }
Matrixf<4, 4> T(float q); // forward kinematic
public:
// kinematic parameter
DH_t dh_;
float offset_;
// limit(qmin,qmax), no limit if qmin<=qmax
float qmin_;
float qmax_;
// joint type
Joint_Type_e type_;
// dynamic parameter
float m_; // mass
Matrixf<3, 1> rc_; // centroid(link coordinate)
Matrixf<3, 3> I_; // inertia tensor(3*3)
};
template <uint16_t _n = 1>
class Serial_Link {
public:
Serial_Link(Link links[_n]) {
for (int i = 0; i < _n; i++)
links_[i] = links[i];
gravity_ = matrixf::zeros<3, 1>();
gravity_[2][0] = -9.81f;
}
Serial_Link(Link links[_n], Matrixf<3, 1> gravity) {
for (int i = 0; i < _n; i++)
links_[i] = links[i];
gravity_ = gravity;
}
// forward kinematic: T_n^0
// param[in] q: joint variable vector
// param[out] T_n^0
Matrixf<4, 4> fkine(Matrixf<_n, 1> q) {
T_ = matrixf::eye<4, 4>();
for (int iminus1 = 0; iminus1 < _n; iminus1++)
T_ = T_ * links_[iminus1].T(q[iminus1][0]);
return T_;
}
// forward kinematic: T_k^0
// param[in] q: joint variable vector
// param[in] k: joint number
// param[out] T_k^0
Matrixf<4, 4> fkine(Matrixf<_n, 1> q, uint16_t k) {
if (k > _n)
k = _n;
Matrixf<4, 4> T = matrixf::eye<4, 4>();
for (int iminus1 = 0; iminus1 < k; iminus1++)
T = T * links_[iminus1].T(q[iminus1][0]);
return T;
}
// T_k^k-1: homogeneous transformation matrix of link k
// param[in] q: joint variable vector
// param[in] kminus: joint number k, input k-1
// param[out] T_k^k-1
Matrixf<4, 4> T(Matrixf<_n, 1> q, uint16_t kminus1) {
if (kminus1 >= _n)
kminus1 = _n - 1;
return links_[kminus1].T(q[kminus1][0]);
}
// jacobian matrix, J_i = [J_pi;j_oi]
// param[in] q: joint variable vector
// param[out] jacobian matix J_6*n
Matrixf<6, _n> jacob(Matrixf<_n, 1> q) {
Matrixf<3, 1> p_e = t2p(fkine(q)); // p_e
Matrixf<4, 4> T_iminus1 = matrixf::eye<4, 4>(); // T_i-1^0
Matrixf<3, 1> z_iminus1; // z_i-1^0
Matrixf<3, 1> p_iminus1; // p_i-1^0
Matrixf<3, 1> J_pi;
Matrixf<3, 1> J_oi;
for (int iminus1 = 0; iminus1 < _n; iminus1++) {
// revolute joint: J_pi = z_i-1x(p_e-p_i-1), J_oi = z_i-1
if (links_[iminus1].type() == R) {
z_iminus1 = T_iminus1.block<3, 1>(0, 2);
p_iminus1 = t2p(T_iminus1);
T_iminus1 = T_iminus1 * links_[iminus1].T(q[iminus1][0]);
J_pi = vector3f::cross(z_iminus1, p_e - p_iminus1);
J_oi = z_iminus1;
}
// prismatic joint: J_pi = z_i-1, J_oi = 0
else {
z_iminus1 = T_iminus1.block<3, 1>(0, 2);
T_iminus1 = T_iminus1 * links_[iminus1].T(q[iminus1][0]);
J_pi = z_iminus1;
J_oi = matrixf::zeros<3, 1>();
}
J_[0][iminus1] = J_pi[0][0];
J_[1][iminus1] = J_pi[1][0];
J_[2][iminus1] = J_pi[2][0];
J_[3][iminus1] = J_oi[0][0];
J_[4][iminus1] = J_oi[1][0];
J_[5][iminus1] = J_oi[2][0];
}
return J_;
}
// inverse kinematic, numerical solution(Newton method)
// param[in] T: homogeneous transformation matrix of end effector
// param[in] q: initial joint variable vector(q0) for Newton method's
// iteration
// param[in] tol: tolerance of error (norm(error of twist vector))
// param[in] max_iter: maximum iterations, default 30
// param[out] q: joint variable vector
Matrixf<_n, 1> ikine(Matrixf<4, 4> Td,
Matrixf<_n, 1> q = matrixf::zeros<_n, 1>(),
float tol = 1e-4f, uint16_t max_iter = 50) {
Matrixf<4, 4> T;
Matrixf<3, 1> pe, we;
Matrixf<6, 1> err, new_err;
Matrixf<_n, 1> dq;
float step = 1;
for (int i = 0; i < max_iter; i++) {
T = fkine(q);
pe = t2p(Td) - t2p(T);
// angvec(Td*T^-1), transform angular vector(T->Td) in world coordinate
we = t2twist(Td * invT(T)).block<3, 1>(3, 0);
for (int i = 0; i < 3; i++) {
err[i][0] = pe[i][0];
err[i + 3][0] = we[i][0];
}
if (err.norm() < tol)
return q;
// adjust iteration step
Matrixf<6, _n> J = jacob(q);
for (int j = 0; j < 5; j++) {
dq = matrixf::inv(J.trans() * J) * (J.trans() * err) * step;
if (dq[0][0] == INFINITY) // J'*J singular
{
dq = matrixf::inv(J.trans() * J + 0.1f * matrixf::eye<_n, _n>()) *
J.trans() * err * step;
// SVD<6, _n> JTJ_svd(J.trans() * J);
// dq = JTJ_svd.solve(err) * step * 5e-2f;
q += dq;
for (int i = 0; i < _n; i++) {
if (links_[i].type() == R)
q[i][0] = math::loopLimit(q[i][0], -PI, PI);
}
break;
}
T = fkine(q + dq);
pe = t2p(Td) - t2p(T);
we = t2twist(Td * invT(T)).block<3, 1>(3, 0);
for (int i = 0; i < 3; i++) {
new_err[i][0] = pe[i][0];
new_err[i + 3][0] = we[i][0];
}
if (new_err.norm() < err.norm()) {
q += dq;
for (int i = 0; i < _n; i++) {
if (links_[i].type() == robotics::Joint_Type_e::R) {
q[i][0] = math::loopLimit(q[i][0], -PI, PI);
}
}
break;
} else {
step /= 2.0f;
}
}
if (step < 1e-3f)
return q;
}
return q;
}
// (Reserved function) inverse kinematic, analytic solution(geometric method)
Matrixf<_n, 2> (*ikine_analytic)(Matrixf<4, 4> T);
// (Reserved function) check inverse kinematic , analytic solution(geometric method)
// 检查解析解是否存在
bool (*ikine_analytic_check)(Matrixf<4, 4> T);
// inverse dynamic, Newton-Euler method
// param[in] q: joint variable vector
// param[in] qv: dq/dt
// param[in] qa: d^2q/dt^2
// param[in] he: load on end effector [f;μ], default 0
Matrixf<_n, 1> rne(Matrixf<_n, 1> q,
Matrixf<_n, 1> qv = matrixf::zeros<_n, 1>(),
Matrixf<_n, 1> qa = matrixf::zeros<_n, 1>(),
Matrixf<6, 1> he = matrixf::zeros<6, 1>()) {
// forward propagation
// record each links' motion state in matrices
// [ωi] angular velocity
Matrixf<3, _n + 1> w = matrixf::zeros<3, _n + 1>();
// [βi] angular acceleration
Matrixf<3, _n + 1> b = matrixf::zeros<3, _n + 1>();
// [pi] position of joint
Matrixf<3, _n + 1> p = matrixf::zeros<3, _n + 1>();
// [vi] velocity of joint
Matrixf<3, _n + 1> v = matrixf::zeros<3, _n + 1>();
// [ai] acceleration of joint
Matrixf<3, _n + 1> a = matrixf::zeros<3, _n + 1>();
// [aci] acceleration of mass center
Matrixf<3, _n + 1> ac = matrixf::zeros<3, _n + 1>();
// temperary vectors
Matrixf<3, 1> w_i, b_i, p_i, v_i, ai, ac_i;
// i & i-1 coordinate convert to 0 coordinate
Matrixf<4, 4> T_0i = matrixf::eye<4, 4>();
Matrixf<4, 4> T_0iminus1 = matrixf::eye<4, 4>();
Matrixf<3, 3> R_0i = matrixf::eye<3, 3>();
Matrixf<3, 3> R_0iminus1 = matrixf::eye<3, 3>();
// unit vector of z-axis
Matrixf<3, 1> ez = matrixf::zeros<3, 1>();
ez[2][0] = 1;
for (int i = 1; i <= _n; i++) {
T_0i = T_0i * T(q, i - 1); // T_i^0
R_0i = t2r(T_0i); // R_i^0
R_0iminus1 = t2r(T_0iminus1); // R_i-1^0
// ω_i = ω_i-1+qv_i*R_i-1^0*ez
w_i = w.col(i - 1) + qv[i - 1][0] * R_0iminus1 * ez;
// β_i = β_i-1+ω_i-1x(qv_i*R_i-1^0*ez)+qa_i*R_i-1^0*ez
b_i = b.col(i - 1) +
vector3f::cross(w.col(i - 1), qv[i - 1][0] * R_0iminus1 * ez) +
qa[i - 1][0] * R_0iminus1 * ez;
p_i = t2p(T_0i); // p_i = T_i^0(1:3,4)
// v_i = v_i-1+ω_ix(p_i-p_i-1)
v_i = v.col(i - 1) + vector3f::cross(w_i, p_i - p.col(i - 1));
// a_i = a_i-1+β_ix(p_i-p_i-1)+ω_ix(ω_ix(p_i-p_i-1))
ai = a.col(i - 1) + vector3f::cross(b_i, p_i - p.col(i - 1)) +
vector3f::cross(w_i, vector3f::cross(w_i, p_i - p.col(i - 1)));
// ac_i = a_i+β_ix(R_0^i*rc_i^i)+ω_ix(ω_ix(R_0^i*rc_i^i))
ac_i =
ai + vector3f::cross(b_i, R_0i * links_[i - 1].rc()) +
vector3f::cross(w_i, vector3f::cross(w_i, R_0i * links_[i - 1].rc()));
for (int row = 0; row < 3; row++) {
w[row][i] = w_i[row][0];
b[row][i] = b_i[row][0];
p[row][i] = p_i[row][0];
v[row][i] = v_i[row][0];
a[row][i] = ai[row][0];
ac[row][i] = ac_i[row][0];
}
T_0iminus1 = T_0i; // T_i-1^0
}
// backward propagation
// record each links' force
Matrixf<3, _n + 1> f = matrixf::zeros<3, _n + 1>(); // joint force
Matrixf<3, _n + 1> mu = matrixf::zeros<3, _n + 1>(); // joint moment
// temperary vector
Matrixf<3, 1> f_iminus1, mu_iminus1;
// {T,R',P}_i^i-1
Matrixf<4, 4> T_iminus1i;
Matrixf<3, 3> RT_iminus1i;
Matrixf<3, 1> P_iminus1i;
// I_i-1(in 0 coordinate)
Matrixf<3, 3> I_i;
// joint torque
Matrixf<_n, 1> torq;
// load on end effector
for (int row = 0; row < 3; row++) {
f[row][_n] = he.block<3, 1>(0, 0)[row][0];
mu[row][_n] = he.block<3, 1>(3, 0)[row][0];
}
for (int i = _n; i > 0; i--) {
T_iminus1i = T(q, i - 1); // T_i^i-1
P_iminus1i = t2p(T_iminus1i); // P_i^i-1
RT_iminus1i = t2r(T_iminus1i).trans(); // R_i^i-1'
R_0iminus1 = R_0i * RT_iminus1i; // R_i-1^0
// I_i^0 = R_i^0*I_i^i*(R_i^0)'
I_i = R_0i * links_[i - 1].I() * R_0i.trans();
// f_i-1 = f_i+m_i*ac_i-m_i*g
f_iminus1 = f.col(i) + links_[i - 1].m() * ac.col(i) -
links_[i - 1].m() * gravity_;
// μ_i-1 = μ_i+f_ixrc_i-f_i-1xrc_i-1->ci+I_i*b_i+ω_ix(I_i*ω_i)
mu_iminus1 = mu.col(i) +
vector3f::cross(f.col(i), R_0i * links_[i - 1].rc()) -
vector3f::cross(f_iminus1, R_0i * (RT_iminus1i * P_iminus1i +
links_[i - 1].rc())) +
I_i * b.col(i) + vector3f::cross(w.col(i), I_i * w.col(i));
// τ_i = μ_i-1'*(R_i-1^0*ez)
torq[i - 1][0] = (mu_iminus1.trans() * R_0iminus1 * ez)[0][0];
for (int row = 0; row < 3; row++) {
f[row][i - 1] = f_iminus1[row][0];
mu[row][i - 1] = mu_iminus1[row][0];
}
R_0i = R_0iminus1;
}
return torq;
}
private:
Link links_[_n];
Matrixf<3, 1> gravity_;
Matrixf<4, 4> T_;
Matrixf<6, _n> J_;
};
Matrixf<5, 2> my_analytic_ikine(Matrixf<4, 4> T);
bool check_ikine(Matrixf<4, 4> T);
Matrixf<3,2> spherical_wrist_ikine(const Matrixf<3,3>& R,float theta_1,float theta_2);
}; // namespace robotics
#endif // ROBOTICS_H