CN111208840B - Hovering control method of deep-sea underwater robot - Google Patents
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Abstract
The invention provides a hovering control method of a deep sea underwater robot, which adopts automatic switching of deep movement speed control and position control and automatic adjustment of a position control adjustment item to realize adjustment of depth deviation, thereby realizing the purpose of constant-depth hovering or constant-height hovering control. The speed control can enable the underwater robot to exert the maximum vertical control capability, the position control ensures the adjustment precision and response speed of the depth deviation, and the position control adjustment item can eliminate the vertical steady-state error. The invention can make the underwater robot overcome the influence of the residual buoyancy, realize the constant depth or constant height hovering, and reflect the residual buoyancy.
Description
Technical Field
The invention relates to a motion control method of a deep-sea underwater robot, in particular to a hovering control method of the deep-sea underwater robot.
Background
Currently, there are two main types of hovering control methods for a deep-sea underwater robot, one is to control the vertical motion of a carrier by generating direct power by an actuating mechanism, and the other is to control the vertical motion of the carrier by changing the gravity or buoyancy of the carrier.
Because the deep sea underwater robot has a large depth change range, the buoyancy of the carrier and gravity are unbalanced due to factors such as sea water density change, carrier compression and the like, namely the underwater robot carrier has certain residual buoyancy, the residual buoyancy is difficult to accurately calculate in advance, and in addition, the underwater robot carrier is in safety consideration, and certain residual buoyancy can be artificially reserved so as to avoid the danger of sitting on the bottom.
The deep sea underwater robot provided with the vertical propeller needs that the underwater robot can keep a certain depth motionless (fixed-depth hovering) or keep a certain height motionless (fixed-height hovering) from the water bottom for certain operation tasks, so that the operations of measuring, observing, recording and the like of environmental information or targets are completed. However, due to the influence of the residual buoyancy, the heave control of the underwater robot may oscillate or cause a problem error, resulting in a reduced quality of the hover control. Therefore, there is a need to find a deep sea underwater robot hover control method that can overcome the effects of residual buoyancy.
Disclosure of Invention
The invention aims to provide a hovering control method of a deep sea underwater robot, which adopts automatic switching of deep movement speed control and position control and automatic adjustment of a position control adjustment item to realize adjustment of depth deviation, thereby realizing the purpose of constant-depth hovering or constant-height hovering control.
The purpose of the invention is realized in the following way: the method comprises the following steps:
step one: the deviation generator gives a uniform depth deviation e d I.e. vertical position deviation in positive direction downwards; target value depth value d given by the planning system at constant-depth hover d And the depth value d measured by the robot depth gauge is differed to obtain a depth deviation e d :
e d ＝d d -d
Target value altitude value h given by the planning system at a fixed altitude hover d And the height difference from the water bottom height value h measured by the robot altimeter is obtained to obtain the height deviation e h :
e h ＝h d -h
Since the positive direction defined by the altitude information is opposite to the positive direction defined by the depth information, the altitude deviation is converted into the depth deviation when hovering at a fixed altitude, namely:
e d ＝-e h
then to the depth deviation e d Differentiation is carried out to obtain depthDeviation change rate e d ：
Step two: the switching controller is used for controlling the switching according to the depth deviation e d The absolute value of (a) automatically selects to use a speed controller or a position controller: when the depth deviates from e d The absolute value of (a) is greater than the threshold e y When, i.e. |e d |>e y When the speed controller is adopted, otherwise, the position controller is adopted;
step three: the speed controller adopts an integral algorithm and depth deviation e d Linear mapping to target heave velocity v d ：
v d ＝k v e d
Rate of change of deviation from depth e d Difference is made to obtain speed deviation e v ：
e v ＝v d -e` d
Pair e v After integral calculation, multiplying by integral coefficient k i As control output o, realize the control of hovering to the robot to fix depth or to fix height:
o(t)＝o(t-1)+k i e v (t)
step four: the position controller adopts a proportional differential algorithm and depth deviation e d Multiplying by integral coefficient k p Adding the depth deviation change rate e d Multiplying by a differential coefficient k d Output o as position controller l ：
o l (t)＝k p e d (t)+k d e` d (t)
Position controller output o l The robot is coupled with the position control adjustment item a to realize fixed-depth or fixed-height hovering control:
o(t)＝o l (t)+a(t)
when the speed controller is switched to the position controller, the last output of the speed controller is used as a position control adjustment item:
a(t)＝o(t)
when the position controller is switched to the speed controller, the last coupling value of the position controller output and the position control adjustment item is used as the integral initial value of the speed controller, and then the position controller output and the position control adjustment item are coupled to be 0:
o(t)＝a(t)，a(t)＝0
when the position controller is effective, the position control adjustment item is automatically adjusted according to the output of the position controller, and the adjustment rule is that if the variance of the output value of the position controller is smaller than the threshold D within a period of time y The position control adjustment term a accumulates the product of the current position controller output value o and the scaling parameter k:
a(t)＝a(t-1)+k*o(t)
when the depth deviation satisfies the control accuracy and remains stable, the magnitude of the position control adjustment term may be regarded as the magnitude of the remaining buoyancy.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the hovering control of the underwater robot is divided into two cases according to the size of the depth deviation, the speed control is adopted under the condition of larger depth deviation, the integration function of the speed control allows the vertical output to reach the maximum output value of an actuator, at the moment, the capability of resisting the residual buoyancy of the underwater robot can be exerted, and when the underwater robot vertically moves at a smaller speed, the control output of the underwater robot approaches to the residual buoyancy, and the speed of converging the depth deviation can be accelerated by taking the speed control as an adjustment item of the position control; position control is adopted under the condition of small depth deviation, so that the response speed and control precision of control can be ensured, and meanwhile, steady-state errors can be eliminated by a position control adjustment item; when the speed control and the position control are switched, the position control adjustment items exist, so that the control output is continuous, the impact can be avoided, and the continuity of the control output is ensured; the position control adjustment term also characterizes the actual residual buoyancy, providing a reference for adjusting the underwater robot ballast configuration or studying the interaction of the robot with the deep sea environment.
Drawings
FIG. 1 is a schematic diagram of a hover control method for a deep sea underwater robot;
FIG. 2 is a 1000 meter constant depth hover control curve;
FIG. 3 is a 5 meter high hover control curve.
Detailed Description
The invention is described in further detail below with reference to the drawings and the detailed description.
Referring to fig. 1 to 3, the invention is a hover control method for a deep sea underwater robot, comprising a deviation generator, a switching controller, a speed controller, a position control adjustment item, and a coupler;
the bias generator defines a uniform depth bias e d I.e. vertical position deviation in positive direction downwards; the target value depth value given by the planning system and the depth value measured by the robot depth meter are differed in the process of hovering at a fixed depth to obtain a depth deviation e d The method comprises the steps of carrying out a first treatment on the surface of the The target value altitude value given by the planning system and the altitude value measured by the robot altimeter are differed when the altitude is fixed and hovered, so as to obtain the altitude deviation e h Because the positive direction defined by the height information is opposite to the positive direction defined by the depth information, the controller inputs uniform depth deviation for the convenience of the subsequent controller design, and the height deviation is converted into the depth deviation when hovering at a fixed height, namely e d ＝-e h The method comprises the steps of carrying out a first treatment on the surface of the Then to the depth deviation e d Differentiation is carried out to obtain the depth deviation change rate e d ；
The switcher is based on the depth deviation e d Automatically selecting a speed controller or a position controller for use; when the depth deviates from e d The absolute value of (a) is greater than the threshold e y When, i.e. |e d |>e y When the speed controller is adopted, otherwise, position control is adopted;
the speed controller adopts an integral algorithm, and the depth deviation e d Linear mapping to target heave velocity v d Then the change rate e' is deviated from the depth d Difference is made to obtain speed deviation e v For e v After integral calculation, multiplying by integral coefficient k i As control output, realizing the control of fixed depth or fixed height hovering of the robot;
the position controller adopts a proportional differential algorithm, and is deepDegree deviation e d Multiplying by integral coefficient k p Adding the depth deviation change rate e d Multiplying by a differential coefficient k d As the output of the position controller, the output of the position controller is coupled with the position control adjustment item to realize the control of the fixed depth or fixed height hovering of the robot;
the position control adjustment item only participates in control when the position controller is effective; when the speed controller is switched to the position controller, the speed controller is finally output as a position control adjustment item; when the position controller is switched to the speed controller, taking the last coupling value of the position controller output and the position control adjustment item as the integral initial value of the speed controller, and then coupling the position controller output and the position control adjustment item to be 0; when the position controller is effective, the position control adjustment item is automatically adjusted according to the output of the position controller, and the adjustment rule is that if the variance of the output value of the position controller is smaller than the threshold D within a period of time y The position control adjustment term a adds up the product of the current position controller output value o and the proportional parameter k, namely a (t) =a (t-1) +k×o (t); when the depth deviation satisfies the control accuracy and remains stable, the magnitude of the position control adjustment term may be regarded as the magnitude of the remaining buoyancy.
The invention provides a hovering control method of a deep sea underwater robot, which is shown in fig. 1: the device comprises a deviation generator, a switching controller, a speed controller, a position control adjustment item and a coupler;
the bias generator defines a uniform depth bias e d I.e. vertical position deviation in positive direction downwards; target value depth value d given by the planning system at constant-depth hover d And the depth value d measured by the robot depth gauge is differed to obtain a depth deviation e d :
e d ＝d d -d
Target value altitude value h given by the planning system at a fixed altitude hover d And the height difference from the water bottom height value h measured by the robot altimeter is obtained to obtain the height deviation e h :
e h ＝h d -h
Because the positive direction defined by the height information is opposite to the positive direction defined by the depth information, the controller inputs uniform depth deviation for the convenience of the subsequent controller design, and the height deviation is converted into the depth deviation when hovering at a fixed height, namely:
e d ＝-e h
then to the depth deviation e d Differentiation is carried out to obtain the depth deviation change rate e d ：
The switching controller is used for controlling the switching according to the depth deviation e d Automatically selecting a speed controller or a position controller for use; when the depth deviates from e d The absolute value of (a) is greater than the threshold e y When, i.e. |e d |>e y When the speed controller is adopted, otherwise, position control is adopted;
the speed controller adopts an integral algorithm, and the depth deviation e d Linear mapping to target heave velocity v d ：
v d ＝k v e d
Then the change rate e' is deviated from the depth d Difference is made to obtain speed deviation e v ：
e v ＝v d -e` d
Pair e v After integral calculation, multiplying by integral coefficient k i As control output o, realize the control of hovering to the robot to fix depth or to fix height:
o(t)＝o(t-1)+k i e v (t)
the position controller adopts a proportional differential algorithm, and the depth deviation e d Multiplying by integral coefficient k p Adding the depth deviation change rate e d Multiplying by a differential coefficient k d Output o as position controller l ：
o l (t)＝k p e d (t)+k d e` d (t)
Position controller output o l Coupled with position control adjustment item aRealize the control of hovering of the robot to a fixed depth or a fixed height;
o(t)＝o l (t)+a(t)
the position control adjustment item only participates in control when the position controller is effective; when the speed controller is switched to the position controller, the last output of the speed controller is used as a position control adjustment item:
a(t)＝o(t)
when the position controller is switched to the speed controller, the last coupling value of the position controller output and the position control adjustment item is used as the integral initial value of the speed controller, and then the position controller output and the position control adjustment item are coupled to be 0:
o(t)＝a(t)，a(t)＝0
when the position controller is effective, the position control adjustment item is automatically adjusted according to the output of the position controller, and the adjustment rule is that if the variance of the output value of the position controller is smaller than the threshold D within a period of time y The position control adjustment term a accumulates the product of the current position controller output value o and the scaling parameter k:
a(t)＝a(t-1)+k*o(t)
when the depth deviation satisfies the control accuracy and remains stable, the magnitude of the position control adjustment term may be regarded as the magnitude of the remaining buoyancy.
FIG. 2 is a 1000 meter constant depth hover control curve in the sea, and FIG. 3 is a 5 meter constant height hover control curve in the sea.
In summary, the invention discloses a hovering control method of a deep sea underwater robot. The invention adopts automatic switching of deep movement speed control and position control and automatic adjustment of position control adjustment items to realize adjustment of depth deviation, thereby realizing the purpose of constant-depth hovering or constant-height hovering control. The speed control can enable the underwater robot to exert the maximum vertical control capability, the position control ensures the adjustment precision and response speed of the depth deviation, and the position control adjustment item can eliminate the vertical steady-state error. The invention can make the underwater robot overcome the influence of the residual buoyancy, realize the constant depth or constant height hovering, and reflect the residual buoyancy.
Claims (1)
1. A hovering control method of a deep sea underwater robot is characterized in that: the method comprises the following steps:
step one: the deviation generator gives a uniform depth deviation e d I.e. vertical position deviation in positive direction downwards; target value depth value d given by the planning system at constant-depth hover d And the depth value d measured by the robot depth gauge is differed to obtain a depth deviation e d :
e d ＝d d -d
Target value altitude value h given by the planning system at a fixed altitude hover d And the height difference from the water bottom height value h measured by the robot altimeter is obtained to obtain the height deviation e h :
e h ＝h d -h
Since the positive direction defined by the altitude information is opposite to the positive direction defined by the depth information, the altitude deviation is converted into the depth deviation when hovering at a fixed altitude, namely:
e d ＝-e h
then to the depth deviation e d Differentiation is carried out to obtain the depth deviation change rate e d ：
Step two: the switching controller is used for controlling the switching according to the depth deviation e d The absolute value of (a) automatically selects to use a speed controller or a position controller: when the depth deviates from e d The absolute value of (a) is greater than the threshold e y When, i.e. |e d |>e y When the speed controller is adopted, otherwise, the position controller is adopted;
step three: the speed controller adopts an integral algorithm and depth deviation e d Linear mapping to target heave velocity v d ：
v d ＝k v e d
Rate of change of deviation from depth e d Difference is made to obtain speed deviation e v ：
e v ＝v d -e` d
Pair e v After integral calculation, multiplying by integral coefficient k i As control output o, realize the control of hovering to the robot to fix depth or to fix height:
o(t)＝o(t-1)+k i e v (t)
step four: the position controller adopts a proportional differential algorithm and depth deviation e d Multiplying by integral coefficient k p Adding the depth deviation change rate e d Multiplying by a differential coefficient k d Output o as position controller l ：
o l (t)＝k p e d (t)+k d e` d (t)
Position controller output o l The robot is coupled with the position control adjustment item a to realize fixed-depth or fixed-height hovering control:
o(t)＝o l (t)+a(t)
when the speed controller is switched to the position controller, the last output of the speed controller is used as a position control adjustment item:
a(t)＝o(t)
when the position controller is switched to the speed controller, the last coupling value of the position controller output and the position control adjustment item is used as the integral initial value of the speed controller, and then the position controller output and the position control adjustment item are coupled to be 0:
o(t)＝a(t)，a(t)＝0
when the position controller is effective, the position control adjustment item is automatically adjusted according to the output of the position controller, and the adjustment rule is that if the variance of the output value of the position controller is smaller than the threshold D within a period of time y The position control adjustment term a accumulates the product of the current position controller output value o and the scaling parameter k:
a(t)＝a(t-1)+k*o(t)
when the depth deviation satisfies the control accuracy and remains stable, the magnitude of the position control adjustment term may be regarded as the magnitude of the remaining buoyancy.
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