CN105798932A - Control method for exoskeleton system in walking state - Google Patents

Abstract

The invention belongs to the technical field of automatic control, and relates to a control method for an exoskeleton system in the walking state. According to the control method, a traditional single parameter control manner is mainly improved; and the control method is mainly characterized in that gaits of the exoskeleton system in the walking state are particularly divided into five continuous gaits including leg withdrawing, pre-supporting, land contact, dynamic state supporting and steady state supporting, and the five continuous gaits are controlled. The control method has the beneficial effects that the walking gaits are divided, the traditional single parameter whole-process control manner is improved into a manner that multiple parameters jointly participate in control, movement of the exoskeleton system becomes mild, and the control method is more suitable for the natural running form of the human body.

Description

A kind of control method for exoskeleton system walking states

Technical field

The invention belongs to automatic control technology field, relate to a kind of control method for exoskeleton system walking states.

Background technology

In rescue and relief work or mountain environment, people generally require and carry substantial amounts of equipment and goods and materials, so can affect gait of march, travel distance and maneuverability, therefore, various countries accelerate to develop the ectoskeleton portable force aid system meeting human engineering, to realize reducing physical consumption, improve heavy burden ability and maneuverability.The main control method of current assistance exoskeleton system is for adopting hydraulic control system, and be controlled in conjunction with PID control method, PID control method needs first to provide control parameter, the method that PID conventional at present controls generally to adopt a parameter whole-process control exoskeleton system from the beginning to the end, but actually people is in the process of walking, the variation of center of gravity also can be driven while being subjected to displacement, if whole process is controlled by identical control parameter, the action that can cause exoskeleton system seems stiff, does not meet the feature of normal human's walking.

Summary of the invention

The purpose of the present invention, it is simply that for the problems referred to above, it is provided that a kind of control method for exoskeleton system walking states.

The technical scheme is that a kind of control method for exoskeleton system walking states, including exoskeleton system, the power source of described exoskeleton system is by the hydraulic cylinder of servo valve control；Described exoskeleton system at least also includes being positioned at the pressure transducer in vola, being positioned at the angular transducer at knee joint place and be positioned at the inertial sensor of leg；Then described control method comprises the following steps:

A. exoskeleton system gait under walking states is specifically divided into 5 continuous print gaits: receive lower limb, support in advance, contact to earth, dynamic support and stable state support；Wherein, stablize last gait that holding state is walking step state, be also the initial gait of walking step state；When stable state supports, hydraulic cylinder supports whole heavy burdens；When exoskeleton system starts to walk, enter step b；

B. receiving under lower limb gait, servo valve standard-sized sheet, exoskeleton system drives human body to carry out receiving lower limb, enters step c after receiving lower limb release；

C. supporting in advance under gait, the control electric current of servo valve is calculated by equation below 1:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Step d is entered after paying support release in advance；

D. contacting to earth under gait, the control electric current of servo valve is calculated by equation below 3:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Contact to earth and enter step e after release；

E., under dynamic support step, the control electric current of servo valve is calculated by equation below 4:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Entering stable state after dynamic support release to support, exoskeleton system completes the travelling control of a gait.

Beneficial effects of the present invention is, by the division to walking step state, the mode of traditional single parameter whole-process control is improved to the mode that multiple parameter participates in controlling jointly so that the movement of exoskeleton system becomes submissive, more conforms to the operation form of human body natural.

Accompanying drawing explanation

The walking step state that Fig. 1 is the present invention divides schematic diagram；

Fig. 2 is the control matched curve schematic diagram supporting gait in advance；

Fig. 3 is the hydraulic cylinder length simulation curve schematic diagram supporting gait in advance；

Fig. 4 is the control matched curve schematic diagram of gait of contacting to earth；

Fig. 5 is the hydraulic cylinder length simulation curve schematic diagram of gait of contacting to earth；

Fig. 6 is the control matched curve schematic diagram of dynamic support gait；

Fig. 7 is the hydraulic cylinder length simulation curve schematic diagram of dynamic support gait；

Fig. 8 is the hydraulic cylinder vertical force simulation curve schematic diagram of dynamic support gait；

Fig. 9 is level walking hydraulic cylinder length entirety simulation curve schematic diagram.

Detailed description of the invention

Below in conjunction with accompanying drawing, technical scheme is described in detail:

The present invention mainly says that traditional single parameter control mode improves, as it is shown in figure 1, mainly exoskeleton system gait under walking states is specifically divided into 5 continuous print gaits: receive lower limb, support in advance, contact to earth, dynamic support and stable state support and be respectively controlled.

Receiving lower limb stage control servo valve standard-sized sheet, allow model machine receive lower limb in advance, people's lower limb is followed model machine and is received lower limb, and people adapts to machine.Owing to being single-action hydraulic cylinder, do not carry out relevant control.

According to kinesiology's rule, pre-driving phase should be stretched one's legs more slowly, so needing the dynamic controlled quentity controlled variable little to servo valve in advance, select servo valve position control, soft stretching one's legs with people, help people to shift to an earlier date power-assisted, auxiliary people completes the transfer adjustment of the center of gravity when both legs switch；The expectation curve that control process adopts as in figure 2 it is shown, expectation curve input is emulated, constantly adjust control parameter until actual hydraulic pressure cylinder length to follow desired length respond well, obtain simulation figure shown in Fig. 3.Concrete grammar is:

Adopting servo valve position control, the PID control instruction of employing is as follows:

$K_{PID}\left(s\right)=(250+70/s)\×\frac{1+0.225s}{1+0.033s}$

The control electric current of servo valve is calculated by equation below 1:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

The stage hydraulic cylinder of contacting to earth needs to provide a support force of a preliminary support human bady gravitational and load, this stage control to need certain accuracy to react human body walking rule, so adopting position control.The expectation curve that control process adopts matched curve as shown in Figure 4, by emulating the simulation curve schematic diagram that can obtain as shown in Figure 5；Concrete grammar is:

The PID control instruction adopted is:

$K_{PID}\left(s\right)=(350+10/s)\×\frac{1+0.225s}{1+0.033s}$

Contacting to earth under gait, the control electric current of servo valve is calculated by equation below 3:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Dynamic support stage hydraulic cylinder needs quick and precisely good support major part to bear a heavy burden, what therefore this stage employing position control, power controlled is warm, wherein the expectation curve of position control is as shown in Figure 6, can obtain simulation curve simulation curve figure as shown in Figure 7 and Figure 8 by emulating；

The PID control instruction that this stage adopts is:

K_PID(s)=0.25 × K_{PID position}(s)+0.75×K_{PID power}(s)

Under dynamic support step, the control electric current of servo valve is calculated by equation below 4:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Entering stable state after dynamic support release to support, exoskeleton system completes the travelling control of a gait.

The flat Simulation of walking schematic diagram that above-mentioned step is monolithically fabricated is as shown in Figure 9.

Claims (1)

1., for a control method for exoskeleton system walking states, including exoskeleton system, the power source of described exoskeleton system is by the hydraulic cylinder of servo valve control；Described exoskeleton system at least also includes being positioned at the pressure transducer in vola, being positioned at the angular transducer at knee joint place and be positioned at the inertial sensor of leg；Then described control method comprises the following steps:

A. exoskeleton system gait under walking states is specifically divided into 5 continuous print gaits: receive lower limb, support in advance, contact to earth, dynamic support and stable state support；Wherein, stablize last gait that holding state is walking step state, be also the initial gait of walking step state；When stable state supports, hydraulic cylinder supports whole heavy burdens；When exoskeleton system starts to walk, enter step b；

B. receiving under lower limb gait, servo valve standard-sized sheet, exoskeleton system drives human body to carry out receiving lower limb, enters step c after receiving lower limb release；

C. supporting in advance under gait, the control electric current of servo valve is calculated by equation below 1:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Step d is entered after paying support release in advance；

D. contacting to earth under gait, the control electric current of servo valve is calculated by equation below 3:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Contact to earth and enter step e after release；

E., under dynamic support step, the control electric current of servo valve is calculated by equation below 4:

Wherein, I_ctrlFor servo valve control input current, Y_expRepresenting the desired length of hydraulic cylinder, Y represents the physical length of hydraulic cylinder, and s is the unit second；Y_expEquation below 2 can be passed through calculate:

θ_kRepresent that the knee joint angle obtained measured by angular transducer；Dist1 represents that hydraulic cylinder thigh junction point is to knee joint bearing distance；Dist2 represents that hydraulic cylinder shank junction point is to knee joint bearing distance；

Entering stable state after dynamic support release to support, exoskeleton system completes the travelling control of a gait.