CN105938499A - Coordinate system establishment method of 3D biped robot - Google Patents

Abstract

The invention relates to a coordinate system establishment method of a 3D biped robot. The method comprises the steps of establishment of a robot inertial coordinate system, a reference coordinate system and coordinate systems of all connecting rods. The inertial coordinate system is fixed on a foot for a support leg when the robot takes its first step. The x-axis direction of the foot is aligned with the forward direction of the foot for the support leg. The y-axis direction points to the outside of a robot body. The z-axis direction is vertical to a foot panel. The reference coordinate system varies with the walking of the robot. In the single-leg support period of an ith step, the reference coordinate system is fixed on the foot of the support leg. The x-axis direction of the foot is aligned with the forward direction of the foot for the support leg. The y-axis direction points to the outside of a robot body. The z-axis direction is vertical to the foot panel. The coordinate systems of all connecting rods are established according to an HD method. The coordinate system establishment method cannot only describe the 3D spatial movement of the 3D biped robot in a complicated road condition but also conveniently demonstrate the kinematic characteristics of the walking state of the robot.

Description

A kind of establishment of coordinate system method of 3D biped robot

Technical field

The invention belongs to robotics, be specifically related to the establishment of coordinate system side of a kind of 3D biped robot Method.

Background technology

3D biped robot is to have multivariant Higher Dimensional Nonlinear Systems.In early stage, people are right for realizing The gait planning of biped robot and control, often move the 3d space of 3D biped robot and solve Coupling, two the independent plane motions being decomposed in forward plane and lateral plane, set up phase the most respectively The kinesiology answered and kinetic model.But, Grizzle teaches at Asymptotically stable Point out in walking of a five-link underactuated 3-D bipedal robot, 3D biped Robot is when carrying out 3d space walking, and its spatial degrees of freedom can couple.Therefore, plane motion is carried out Decoupling can cause the inaccurate of kinesiology and kinetic model, and then cause gait planning and control Error.And to set up accurate motion and the kinetic model that can describe 3D biped robot's space motion, The most important thing is to set up the coordinate system that can describe robot 3d space motion.

Currently, with respect to the foundation of 3D biped robot's space coordinates mostly in reference to article Human-like Walking:Optimal motion of a bipedal robot with toe-rotation motion institute The method carried.In the method, the inertial coodinate system of robot keeps constant, and reference frame initial point is fixed At supporting leg, and each change in coordinate axis direction is always parallel with the coordinate axes of inertial coodinate system, it addition, robot Link rod coordinate system be based on DH method set up.But, based on this establishment of coordinate system method, carrying out 3D Still there is also some inconveniences: firstly, since be somebody's turn to do when the Kinematic Model of biped robot and analysis In method, reference frame will be always parallel with inertial coodinate system, and the coordinate system that therefore the method is set up is the suitableeest Together in the robot walking in smooth-riding surface, it is difficult to be suitable for the reality in the lives such as sand ground, slope, step Road conditions are walked；Secondly as the foundation of reference frame is pre-determined in the method, with robot Walking states is unrelated, and therefore this establishment of coordinate system method is difficult to disclose some kinesiologys of robot ambulation state Feature.

Summary of the invention

In order to overcome the problems referred to above, the invention provides a kind of establishment of coordinate system method of 3D biped robot, The method can not only describe 3D biped robot and move at the 3d space of complex road condition, moreover it is possible to disclose easily The kinematics character of robot ambulation state.

The technical purpose of the present invention is achieved through the following technical solutions:

A kind of establishment of coordinate system method of 3D biped robot, for robot 3d space kinetic coordinate system Set up, including inertial coodinate system { I}, reference frame { R_iAnd each link rod coordinate system { q_kFoundation, Wherein i represents the i-th step of robot ambulation, k=0, and 1,2...n, n represent robot degree of freedom number.

Further, described inertial coodinate system the sole of supporting leg when I} is fixed on the robot ambulation first step, Its x-axis direction is consistent with supporting leg sole direction of advance, and y-axis is pointed to outside robot health, hangs down in z-axis direction Straight in sole plane.

Further, described reference frame { R_iThe walking of random device people and change, the monopodia in the i-th step props up The support phase, reference frame { R_iIt is fixed on the sole of supporting leg, its x-axis direction and supporting leg sole direction of advance Unanimously, y-axis is pointed to outside robot health, and z-axis direction is perpendicular to sole plane.

Further, described each link rod coordinate system { q_kFoundation be based on DH parametric method, wherein, coordinate system {q₀And the i-th step reference frame { R_iOverlap.

The beneficial effects of the present invention is: the establishment of coordinate system method of a kind of 3D biped robot provided by the present invention The 3d space motion of biped robot can be described, kinesiology and dynamic accurately can be set up based on the method Mechanical model, thus reduce 3D biped robot's gait planning and the error of control；Additionally, the present invention Establishment of coordinate system method can disclose the kinematics character of 3D biped robot's cycle gait easily: biped machine Next step foothold of device people be always at the rectangle frame that robot step-length and step width formed to angle point；And And it is expected that for the cycle walking 3D biped robot, its footprint walking is along space The half that corner dimension is robot yaw angle in straight line, this straight line and inertial coodinate system x-axis direction.Therefore, Use the establishment of coordinate system method of the present invention, more hold for carrying out the programming personnel of robot gait planning The kinematics of readily understood robot gait, thus reduce programming difficulty, improve work efficiency.

Accompanying drawing explanation

Fig. 1 represents that 3D biped robot's left foot supports structural model and the link rod coordinate system of phase；

Fig. 2 represents that 3D biped robot's right crus of diaphragm supports structural model and the link rod coordinate system of phase；

Fig. 3 is inertial coodinate system and the reference frame schematic diagram of 3D biped robot；

The rectangle frame that drawing reference numeral: 1-is made up of robot step-length and step width, 2-robot ambulation footprint.

Detailed description of the invention

The invention provides a kind of establishment of coordinate system method of 3D biped robot, for robot 3d space The foundation of kinetic coordinate system, including inertial coodinate system { I}, reference frame { R_iAnd each link rod coordinate system {q_kFoundation.

It is described in further detail below in conjunction with drawings and Examples.

3D biped robot involved by the embodiment of the present invention is as depicted in figs. 1 and 2.Assume the robot first step Support for left foot, and assume yaw angle q₀It is always maintained at not due to the impact of frictional force in the monopodia support phase Become, thus robot sole keeps geo-stationary with ground always.Therefore, robot supports at each monopodia The sole position of phase and direction can represent with its footprint.

The foundation of inertial coodinate system involved in the present invention and reference frame is as shown in Figure 3: inertial coordinate { I} is fixed on first step supporting leg sole (representing with its footprint), its x-axis direction and sole direction of advance in system Unanimously, z-axis direction is vertical with sole, and its y-axis is pointed to outside robot health.Described reference coordinate Being the walking of random device people and change, the monopodia in 2i step supports phase, reference frame { R_2iBe fixed on and prop up Support leg sole, x-axis direction is consistent with sole direction of advance, and z-axis direction is vertical with sole, and its y-axis Point to outside robot health；Equally, robot is also based on this in the foundation of 2i+1 step reference frame Rule.Wherein, A is robot direction of advance footprint.

Based on the reference frame set up above, we can disclose biped robot's cycle gait easily Kinematic relation and feature.As it is shown on figure 3, for cycle gait, we are it is clear that machine Next step foothold of people is always at the diagonal angle of the rectangle frame 1 that robot step-length L is formed with step width W1 Point；And can predict that next step direction of advance and rectangle frame angle on one side of sole is always equal to robot The yaw angle q of gait_st, this can from left and right lower limb support the phase land time yaw angle q_0swCalculating come Prove, may certify that, for cycle gait, yaw angle q when landing_0swEqual to q_stOr-q_st.This Outward, can also prove very easily based on the reference frame set up, for the 3D biped machine of cycle walking Device people, its footprint walking is the straight line along space, this straight line and inertial coodinate system x-axis direction Angle is q_st/2.Here simple proof is as follows:

Assume reference frame { R_2i+1Initial point at reference frame { R_2i-1Position coordinates under } is (X, Y), Can be obtained by the geometrical relationship in figure two

$tan\left(\mathrm{\θ}\right)=\frac{Y}{X}=-\frac{W_1-W_{1}cos\left(q_{st}\right)+Lsin\left(q_{st}\right)}{L\cos \left(q_{st}\right)+W_{1}sin\left(q_{st}\right)+L}=-tan\left(\frac{q_{st}}{2}\right),$

Such that it is able to prove that robot ambulation direction is q with the angle in inertial coodinate system x-axis direction_st/2。

Robot involved by present example has 8 degree of freedom, its corresponding link rod coordinate system { q_k, K=0,1,2 ... 8, foundation as depicted in figs. 1 and 2, the foundation of each link rod coordinate system is in accordance with DH method, The homogeneous transition matrix of the most each adjacent links coordinate system is as follows, which describes each adjacent links coordinate Transformational relation between system:

$\begin{array}{cc}T_1^0=\left[\begin{array}{cccc}-\sin q_1& -\cos q_1& 0& 0\\ 0& 0& -1& 0\\ \cos q_1& -\sin q_1& 0& 0\\ 0& 0& 0& 1\end{array}\right]& T_2^1=\left[\begin{array}{cccc}\sin q_2& -\cos q_2& 0& 0\\ 0& 0& 1& 0\\ -\sin q_2& -\cos q_2& 0& 0\\ 0& 0& 0& 1\end{array}\right]\end{array}$

$\begin{array}{cc}T_3^2=\left[\begin{array}{cccc}\cos q_3& -\sin q_3& 0& L_1\\ 0& 0& -1& 0\\ -\sin q_3& \cos q_3& 0& 0\\ 0& 0& 0& 1\end{array}\right]& T_4^3=\left[\begin{array}{cccc}\cos q_4& -\sin q_4& 0& L_2\\ \sin q_4& \cos q_4& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right]\end{array}$

$\begin{array}{cc}T_5^4=\left[\begin{array}{cccc}\sin q_5& \cos q_5& 0& 0\\ 0& 0& 1& 0\\ \cos q_5& -\sin q_5& 0& 0\\ 0& 0& 0& 1\end{array}\right]& T_6^5=\left[\begin{array}{cccc}-\sin q_6& -\cos q_6& 0& W\\ -\cos q_6& \sin q_6& 0& 0\\ 0& 0& -1& 0\\ 0& 0& 0& 1\end{array}\right]\end{array}$

$\begin{array}{cc}T_7^6=\left[\begin{array}{cccc}\cos q_7& -\sin q_7& 0& 0\\ 0& 0& 1& 0\\ -\sin q_7& -\cos q_7& 0& 0\\ 0& 0& 0& 1\end{array}\right]& T_8^7=\left[\begin{array}{cccc}\cos q_8& -\sin q_8& 0& L_2\\ \sin q_8& \cos q_8& 0& 0\\ 0& 0& 1& 0\\ 0& 0& 0& 1\end{array}\right]\end{array}$

So far, the foundation of 3D biped robot's coordinate system it is complete.

Enumerating of above-described embodiment only the technology of the present invention design way of realization, protection scope of the present invention is not Being only limitted to above-described embodiment, protection scope of the present invention may extend to those skilled in the art according to the present invention's Technology conceives thinkable equivalent technologies means.

Claims (4)

1. the establishment of coordinate system method of 3D biped robot, for robot 3d space kinetic coordinate system Foundation, it is characterised in that: include inertial coodinate system { I}, reference frame { R_iAnd each connecting rod coordinate { q_k} Foundation, wherein i represents the i-th step of robot ambulation, k=0, and 1,2...n, n represent robot degree of freedom Number.

2. the establishment of coordinate system method of the 3D biped robot as described in claim 1, it is characterised in that: Described inertial coodinate system the sole of supporting leg when I} is fixed on the robot ambulation first step, its x-axis direction with Support leg sole direction of advance is consistent, and y-axis is pointed to outside robot health, and z-axis direction is perpendicular to sole plane.

3. the establishment of coordinate system method of the 3D biped robot as described in claim 1, it is characterised in that: Described reference frame { R_iThe walking of random device people and change, the monopodia in the i-th step supports phase, reference coordinate System { R_iIt being fixed on the sole of supporting leg, its x-axis direction is consistent with supporting leg sole direction of advance, and y-axis is pointed to Outside robot health, z-axis direction is perpendicular to sole plane.

4. the establishment of coordinate system method of the 3D biped robot as described in claim any one of 1-3, it is special Levy and be: described each link rod coordinate system { q_kFoundation be based on DH parametric method, wherein, coordinate system { q₀With I-th step reference frame { R_iOverlap.