CN105182748A - Space tether robot target capture stable control method - Google Patents

Abstract

The invention discloses a space tether robot target capture stable control method which comprises the following steps: 1) establishing a space tether robot target capture kinetic equation; 2) calculating correction amount e of expected pose of a space tether robot; 3) estimating uncertainty of a system model of the space tether robot; and 4) calculating stable control force and control moment Q of the space tether robot. The impedance control method is adopted in the invention, so that influence due to impact force in the capture process can be reduced. The uncertainty of the space tether robot model is estimated through a neural network, so that compensation control can be carried out on influence due to uncertainty effectively; overshoot is small in the control process; convergence time is shorter; and control precision is higher.

Description

A kind of space rope system robot target arrests stable control method

[technical field]

The invention belongs to Spacecraft Control technical field of research, be specifically related to a kind of space rope system robot target and arrest stable control method.

[background technology]

Robot of space rope system, due to features such as it are flexible, safety, fuel consumption are low, has and acts on widely in On-orbit servicing, can carry out the operations such as inert satellite relief, space trash cleaning, auxiliary change rail.

According to the flow of task of robot of space rope system, can be divided into release, approach target, target is arrested, target operates double teacher after arresting rear stable and target acquistion, wherein target arrests stability contorting is one of main research of robot of space rope system.Robot of space rope system approaches and arrests near position to target, and need to close up operation paw and arrest target, this is one of core missions of robot of space rope system.In target capture process, because operation paw closes up the factors such as relative linear velocity between speed and target and relative angle speed, whole capture process may be caused due to collision to become unstable, even can cause treating that capture target goes out to operate paw and arrests envelope, cause arresting mission failure.In addition, owing to treating may spinning of capture target self, whole capture process can be caused more difficult.Therefore, design suitable target and arrest stable control method, ensureing the stability contorting of robot of space rope system in target capture process, is very significant.

It is one of the core missions of robot of space rope system that target is arrested, and the stability contorting in target capture process directly affects the success or failure of space rope system robot task, and it becomes the research emphasis of space rope system robot field.

[summary of the invention]

The object of the present invention is to provide one can be widely used in space rope system robot target and arrest stable control method, this control method can in realize target capture process, robot of space rope system pose stable, realizes arresting the success of target.

For achieving the above object, the technical solution adopted in the present invention comprises the following steps:

1) set up space rope system robot target and arrest kinetics equation;

2) the correction e of robot of space rope system expected pose is calculated;

3) estimation space rope system robot system model uncertainty

4) the robot stabilized control of computer memory rope system and control moment Q.

The present invention further improves and is

Described step 1) in, space rope system robot target is arrested kinetics equation and is:

$M\stackrel{\·\·}{\mathrm{\ξ}}+N\stackrel{\·}{\mathrm{\ξ}}+G=Q+\mathrm{\τ}$

Wherein, l is spatial tether length; α is spatial tether face interior angle; β is exterior angle, spatial tether face; θ and ψ is space rope system robot pose angle; M is system inertia matrix; N nonlinear velocity continuous item; G gravity continuous item; Q is space rope system robot controlling power and control moment; τ is spatial tether distracter.

Described step 2) in, the method calculating the correction e of robot of space rope system expected pose is:

$e=\underset{i=1}{\overset{n}{\Σ}}{e}_i$

Wherein, n is the contact-impact point quantity of robot of space rope system and target;

$e_i\left(s\right)=\frac{-F_{ei}}{M_d{s}^2+B_{d}s+K_d}$

S is Laplace operator, F _eibe i-th contact-impact power, recorded by force snesor, M _d, B _dand K _dfor the inertia matrix at capture target position, damping matrix and stiffness matrix.

Described step 3) in, estimation space rope system robot system model uncertainty concrete grammar be:

$\widehat{\mathrm{\ρ}}={\widehat{\mathrm{\Θ}}}^T{\mathrm{\Φ}}_{\mathrm{\ρ}}$

Wherein, for RBF neural export weights, its more new law be f _ρfor any positive definite matrix, k _ρ>0 is design parameter, ξ _dfor expecting system state, Λ is any positive definite matrix, Φ _ρfor radial basis function output valve.

Described step 4) in, the robot stabilized control of computer memory rope system and control moment Q:

$Q=Kr+M_0({\stackrel{\·\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}\stackrel{\·}{e})+N_0({\stackrel{\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}e)+G_0+\widehat{\mathrm{\ρ}}+\mathrm{\η}$

Wherein, K is positive definite matrix, M ₀, N ₀and G ₀be respectively the nominal value of matrix M, N and G in system dynamics equation, η=(η _δ+ η _τ) sgn (r) is robust item, sgn () is sign function, for the upper bound of RBF neural evaluated error, η _τfor the spatial tether interference upper limit.

Compared with prior art, the present invention has following beneficial effect:

Present invention employs impedance adjustment, the impact that the impact force in capture process is brought can be reduced.Estimated space rope system robot model uncertainty by neural network, effectively can compensate control to the impact that uncertainty is brought, and in control procedure, overshoot is less, convergence time is shorter, and control accuracy is higher.

[accompanying drawing explanation]

Fig. 1 is that space rope system of the present invention robot target arrests schematic diagram.

Wherein: 1-treats capture target; Robot of 2-space rope system; 3-spatial tether; 4-space platform; The 5-earth.

[embodiment]

Below in conjunction with accompanying drawing, the present invention is described in further detail:

See Fig. 1, the present invention includes following steps:

The first step: set up space rope system robot target and arrest kinetics equation:

$M\stackrel{\·\·}{\mathrm{\ξ}}+N\stackrel{\·}{\mathrm{\ξ}}+G=Q+\mathrm{\τ}$

Wherein, l is spatial tether length, and α is spatial tether face interior angle, and β is exterior angle, spatial tether face, θ and ψ is space rope system robot pose angle; M is system inertia matrix; N nonlinear velocity continuous item; G gravity continuous item; Q is space rope system robot controlling power and control moment; τ is spatial tether distracter.

Second step: the correction e calculating robot of space rope system expected pose

The correction of robot of space rope system expected pose meets following relational expression:

Wherein, i is the contact-impact point in target capture process.

The correction e of expected pose can be expressed as:

3rd step: estimation space rope system robot system model uncertainty

Indeterminate neural network is utilized to be expressed as:

Wherein, Φ _ρfor radial basis function output valve, for RBF neural exports weights, the weights of design adaptive updates rule is:

Wherein, F _ρfor any positive definite matrix, k _ρ>0 is design parameter.

When estimating space rope system robot model uncertainty, there is evaluated error in RBF neural meanwhile, consider the impact of tether interference τ, η is to evaluated error in design suppress with the impact of tether interference τ, design η is:

η＝(η _δ+η _τ)·sgn(r)

Wherein, sgn () is sign function, for RBF neural evaluated error the upper bound, η _τfor the upper bound of spatial tether interference τ.

4th step: the robot stabilized control of computer memory rope system and control moment Q

$Q=Kr+M_0({\stackrel{\·\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}\stackrel{\·}{e})+N_0({\stackrel{\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}e)+G_0+\widehat{\mathrm{\ρ}}+\mathrm{\η}$

Wherein, M ₀, N ₀and G ₀for nominal system matrix.

Above content is only and technological thought of the present invention is described; protection scope of the present invention can not be limited with this; every technological thought proposed according to the present invention, any change that technical scheme basis is done, within the protection domain all falling into claims of the present invention.

Claims (5)

1. space rope system robot target arrests a stable control method, it is characterized in that, comprises the following steps:

1) set up space rope system robot target and arrest kinetics equation;

2) the correction e of robot of space rope system expected pose is calculated;

3) estimation space rope system robot system model uncertainty

4) the robot stabilized control of computer memory rope system and control moment Q.

2. space rope system according to claim 1 robot target arrests stable control method, it is characterized in that, described step 1) in, space rope system robot target is arrested kinetics equation and is:

$M\stackrel{\·\·}{\mathrm{\ξ}}+N\stackrel{\·}{\mathrm{\ξ}}+G=Q+\mathrm{\τ}$

Wherein, l is spatial tether length; α is spatial tether face interior angle; β is exterior angle, spatial tether face; θ and ψ is space rope system robot pose angle; M is system inertia matrix; N nonlinear velocity continuous item; G gravity continuous item; Q is space rope system robot controlling power and control moment; τ is spatial tether distracter.

3. space rope system according to claim 1 robot target arrests stable control method, it is characterized in that, described step 2) in, the method calculating the correction e of robot of space rope system expected pose is:

$e=\underset{i=1}{\overset{n}{\Σ}}{e}_i$

Wherein, n is the contact-impact point quantity of robot of space rope system and target;

$e_i\left(s\right)=\frac{-F_{ei}}{M_d{s}^2+B_{d}s+K_d}$

S is Laplace operator, F _eibe i-th contact-impact power, recorded by force snesor, M _d, B _dand K _dfor the inertia matrix at capture target position, damping matrix and stiffness matrix.

4. space rope system according to claim 1 robot target arrests stable control method, it is characterized in that, described step 3) in, estimation space rope system robot system model uncertainty concrete grammar be:

$\widehat{\mathrm{\ρ}}={\widehat{\mathrm{\Θ}}}^T{\mathrm{\Φ}}_{\mathrm{\ρ}}$

Wherein, for RBF neural export weights, its more new law be f _ρfor any positive definite matrix, k _ρ>0 is design parameter, ξ _dfor expecting system state, Λ is any positive definite matrix, Φ _ρfor radial basis function output valve.

5. space rope system according to claim 1 robot target arrests stable control method, it is characterized in that, described step 4) in, the robot stabilized control of computer memory rope system and control moment Q:

$Q=Kr+M_0({\stackrel{\·\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}\stackrel{\·}{e})+N_0({\stackrel{\·}{\mathrm{\ξ}}}_d+\mathrm{\Λ}e)+G_0+\widehat{\mathrm{\ρ}}+\mathrm{\η}$

Wherein, K is positive definite matrix, M ₀, N ₀and G ₀be respectively the nominal value of matrix M, N and G in system dynamics equation, η=(η _δ+ η _τ) sgn (r) is robust item, sgn () is sign function, for the upper bound of RBF neural evaluated error, η _τfor the spatial tether interference upper limit.