CN110525534A - A kind of small vehicle chassis structure and its control method using complicated landform - Google Patents

Abstract

The invention discloses a small vehicle chassis structure for complex terrain, comprising: a chassis; a plurality of mecanum wheel sets, which are symmetrically and rotatably supported on both sides of the chassis, and the mecanum wheel sets include: planetary frame; a sun gear, which is arranged at the center of one side of the planet carrier; a plurality of planet gears, which are evenly arranged on the same side of the planet carrier in the circumferential direction of the sun gear, and meshed with the sun gear; a plurality of first A sprocket, which is arranged on the other side of the planet carrier, and is coaxially arranged in one-to-one correspondence with the planetary wheels; a plurality of second sprockets, which are respectively arranged on all the first sprockets The other side of the planet carrier; a chain, which sequentially connects the first sprocket and the second sprocket; a plurality of Mecanum wheels, which are arranged on the other side of the planet carrier, and are connected to the second The sprockets are arranged in one-to-one correspondence and coaxially; the output end of the power mechanism is coaxially connected with the sun gear for driving the sun gear to rotate.

Description

A small vehicle chassis structure and control method for complex terrain

technical field

The present invention relates to the technical field of vehicle chassis structure, and more specifically, the present invention relates to a small vehicle chassis structure and its control method applied in complex terrain.

Background technique

In recent years, in many fields such as disaster relief, anti-terrorism, and logistics, we need ground robots with good performance to perform tasks such as detection, investigation, and transportation. This kind of robot is small and flexible, has good passability, can enter and exit various complex terrain environments, and can realize different functions by carrying different upper-loading platforms, and is very popular in the market. At present, traditional wheel-driven or crawler-driven small vehicle chassis are still used in the market, but this type of chassis does not have omnidirectional mobility, and it is still inconvenient to use in some narrow environments. Moreover, due to the small size of the chassis itself, when traveling in environments such as ruins and stairs, the obstacle-surpassing ability of the chassis is even more tested.

Contents of the invention

The present invention designs and develops a small-scale vehicle chassis structure that applies to complex terrains. A plurality of mecanum wheel sets are arranged on symmetrical and rotatable supports on both sides of the chassis, and a two-degree-of-freedom planetary gear train is set in the mecanum wheel sets. , so that the chassis can and can perform various gestures on the ground, improving the vehicle's passability in a small space and the ability to climb over obstacles.

The invention designs and develops a control method for the chassis structure of a small vehicle using complex terrain, which can control the driving state of each mecanum wheel set according to the driving road conditions.

The present invention can also control the torque and distribution coefficient of the power mechanism on both sides of the front and rear axles according to the condition of the driving road surface and the driving state of the vehicle, so as to improve the driving stability of the vehicle.

The technical scheme provided by the invention is:

A small vehicle chassis structure for complex terrain applications, including:

chassis; and

A plurality of mecanum wheel sets, which are symmetrically and rotatably supported on both sides of the chassis, and the mecanum wheel sets include:

Planet carrier;

The sun gear is arranged at the center of one side of the planet carrier and can rotate along its own axis;

A plurality of planetary gears, which are evenly arranged in the circumferential direction of the sun gear and meshed with the sun gear, and the planetary gears can revolve around the sun gear axially and drive the planet carrier to rotate, and can also rotate around their own axial direction ;

A plurality of first sprockets, which are arranged on the other side of the planet carrier, and are coaxially arranged in one-to-one correspondence with the planetary wheels, and the first sprockets move synchronously with the corresponding planetary wheels;

A plurality of second sprockets, which are respectively arranged on the other side of the planet carrier between the first sprockets, and can rotate around their own axes;

a chain, which sequentially connects the first sprocket and the second sprocket, and is under tension;

Wherein, the first sprocket and the second sprocket are respectively located on both sides of the chain;

A plurality of Mecanum wheels, which are arranged on the other side of the planet carrier, and are coaxially arranged in one-to-one correspondence with the second sprocket, and the Mecanum wheels are synchronized with the corresponding second sprocket sports;

The power mechanism, whose output end is coaxially fixedly connected with the sun gear, is used to drive the sun gear to rotate.

Preferably, the planet carrier includes:

first shelf;

a second shelf, which is arranged parallel to and spaced apart from the first shelf;

Wherein, the structures of the first shelf and the second shelf are consistent, and both are triangular plate structures; and

The sun gear and the planetary gear are arranged on the outer surface of the first frame, the first sprocket, the second sprocket and the chain are arranged between the first frame and the second frame, so The mecanum wheel is arranged on the outside of the second shelf.

Preferably, it also includes:

The sun gear shaft is fixed through the sun gear, and one end is rotatably arranged at the center of the outer surface of the first frame, and the other end is fixedly connected to the output end of the power mechanism;

a plurality of planet shafts, which can rotate through the first frame plate and the second frame plate, and correspond to the planet wheels one by one;

Wherein, the planetary gear is coaxially fixed on the planetary shaft outside the first frame, and the first sprocket is coaxially fixed on the first frame and the second frame. between the plates on said planet shaft;

a plurality of sprocket shafts, which can rotate through the first frame plate and the second frame plate, and correspond to the second sprocket wheels one by one;

Wherein, the second sprocket is coaxially fixed on the sprocket shaft between the first shelf and the second shelf, and the Mecanum wheel is fixed on the second on the sprocket shaft on the outside of the frame plate.

Preferably, the power mechanism also includes:

Bearing seats, which are arranged at intervals outside the first frame plate, and the center can rotate through the output end of the power mechanism;

Wherein, the sun gear and the planetary gear are arranged between the first carrier plate and the bearing seat, and the planetary shaft can rotate the bearing seat.

Preferably, a slope angle sensor is also included, which is arranged on the chassis and used to detect the slope of the bottom surface of the vehicle.

Preferably, there are 4 mecanum wheel sets, and the symmetrical rotatable supports are arranged on the chassis; each of the mecanum wheel sets is provided with 3 mecanum wheels, and is surrounded by an equilateral triangle.

A control method for a small vehicle chassis structure applied to complex terrain, comprising:

When the vehicle is running on flat ground without obstacles, the planetary wheel only rotates around its own axis, and drives the mecanum wheel to rotate itself through the first sprocket and the second sprocket to drive the vehicle;

When the vehicle encounters an obstacle, the planetary wheel rotates around its own axis and also revolves around the sun gear axis, driving the planetary carrier to drive the mecanum wheel set to rotate, driving the vehicle forward and over the obstacle;

Wherein, when the vehicle is running, only two mecanum wheels in each mecanum wheel set are grounded at the same time.

Preferably, when the vehicle is running at a constant speed on flat ground without obstacles, the torques controlling the power mechanisms on both sides of the front and rear axles satisfy:

in, H is the inclination angle of the vehicle in the horizontal direction, H is the height of the center of mass when the vehicle is placed horizontally; L is the distance between the front and rear axles of the vehicle; b is the distance between the center of mass in the horizontal direction and the axis of the rear axle when the vehicle is placed horizontally; G is the height of the vehicle when it is working The total gravity, M _A1 and M _A2 are the torques of the power mechanism on the left and right sides of the front axle respectively; M _B1 and M _B2 are the torques of the power mechanism on the left and right sides of the rear axle respectively; r _c is the axis of the mecanum wheel when the planetary gear train revolves The radius of gyration around the center of the planetary gear train;

And control the front and rear axle torque distribution coefficient s to satisfy:

Among them, the maximum climbing ability of the vehicle Satisfy:

Among them, i _g is the transmission ratio of the planetary gear set; i _s is the transmission ratio of the sprocket set; d is the diameter of the mecanum wheel.

Preferably, when the vehicle starts or accelerates on a flat ground without obstacles, the torque of the power mechanism on both sides of the control front and rear axles satisfies:

Among them, L is the distance between the front and rear axles of the vehicle; G is the total gravity of the vehicle when it is working; M _A1 and M _A2 are the torques of the left and right power mechanisms of the front axle respectively; M _B1 and M _B2 are the torques of the left and right power mechanisms of the rear axle respectively. r _c is the rotation radius of the axis of the mecanum wheel around the center of the planetary gear system when the planetary gear train revolves, d is the diameter of the mecanum wheel, i _g is the transmission ratio of the planetary gear set; i _s is the transmission ratio of the sprocket set, H is the height of the center of mass when the vehicle is placed horizontally;

And control the front and rear axle torque distribution coefficient s to satisfy:

And control the acceleration a of the vehicle to satisfy:

Among them, m ₀ is the total mass of the vehicle when it is working.

Preferably, when the vehicle runs at a constant speed on flat ground, starts or accelerates, the rotational speed of the Mecanum wheel set is controlled to satisfy:

ω _i =ω _i1 =ω _i2 =ω _i3 , i=1,2,3,4;

Among them, _ω1 is the rotational speed _of the left front mecanum wheel set, _ω2 is the rotational speed of the right front mecanum wheel set, ω3 is the rotational speed of the left rear mecanum wheel set, and _ω4 is the rotational speed of the right rear mecanum wheel set Rotational speed; R is the ground contact radius of the mecanum wheel; Y is half of the front and rear wheelbase; X is half the distance between the ground contact points of the left and right wheels; ω _i is the speed of the _i -th mecanum wheel set; The speed of the first mecanum wheel in the mecanum wheel group, ω _i2 is the speed of the second mecanum wheel in the i-th mecanum wheel group, ω _i3 is the speed of the i-th mecanum wheel group The rotational speed of the third mecanum wheel, V _X is the lateral speed of the vehicle, V _Y is the longitudinal speed of the vehicle, and ω _o is the angular velocity of the vehicle.

Preferably, when the vehicle runs into an obstacle, the torque of the power mechanism controlling the front and rear axles on both sides satisfies:

in, H is the inclination angle of the vehicle in the horizontal direction, H is the height of the center of mass when the vehicle is placed horizontally; L is the distance between the front and rear axles of the vehicle; b is the distance between the center of mass in the horizontal direction and the axis of the rear axle when the vehicle is placed horizontally; G is the height of the vehicle when it is working The total gravity, M _A1 and M _A2 are the torques of the power mechanism on the left and right sides of the front axle respectively; M _B1 and M _B2 are the torques of the power mechanism on the left and right sides of the rear axle respectively; r _c is the axis of the mecanum wheel when the planetary gear train revolves The radius of gyration around the center of the planetary gear train;

And control the front and rear axle torque distribution coefficient s to satisfy:

Beneficial effects of the present invention:

(1) The small vehicle chassis structure designed and developed by the present invention applies complex terrain, and a plurality of mecanum wheel sets are arranged on symmetrical and rotatable supports on both sides of the chassis, so that the chassis can and can perform movements of various postures on the ground, Including forward and backward translation, spin, lateral movement, oblique travel, turning, etc., improve the passability of the vehicle in a small space and the ability to overcome obstacles, and realize movement in complex environments such as good roads, stairs, and ruins.

(2) The chassis of this vehicle is equipped with a two-degree-of-freedom planetary gear system connected to the Mecanum wheel set. With the mechanical characteristics of the planetary gear system itself, it can realize normal driving on flat ground, automatically identify obstacles encountered and support the chassis to overcome obstacles. No complicated sensors and control systems are required. Compared with the traditional ground robot chassis, the invention improves the passability in a narrow space and the ability to climb over obstacles.

(3) The control method of the small-sized vehicle chassis structure designed and developed by the present invention, which applies complex terrain, can control the driving state of each mecanum wheel set according to the driving road conditions. It can also control the torque and distribution coefficient of the power mechanism on both sides of the front and rear axles according to the driving road conditions and the driving state of the vehicle, so as to improve the driving stability of the vehicle.

Description of drawings

Fig. 1 is a structural schematic diagram of the chassis structure of a small vehicle applying complex terrain according to the present invention.

Fig. 2 is a structural schematic diagram of the Mecanum wheel set of the present invention.

Fig. 3 is a schematic diagram of the arrangement structure of the sun gear and the planetary gear of the present invention.

Fig. 4 is a schematic diagram of the arrangement structure of the sprocket set according to the present invention.

Fig. 5 is a schematic diagram of the working state of the vehicle in the present invention when it overcomes obstacles.

Fig. 6 is a schematic diagram of the coordinate system for analyzing the movement of the chassis mecanum wheel according to the present invention.

Fig. 7 is a schematic diagram of the coordinate system for analyzing the movement of the chassis mecanum wheel according to the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings, so that those skilled in the art can implement it with reference to the description.

As shown in Figure 1, the present invention provides a small-sized vehicle chassis structure that applies complex terrain. There are four power mechanisms 110 in the vehicle chassis 100. Due to the use of Mecanum wheel drive, in order to accurately control the posture of the vehicle body, the power mechanism is selected as servo motor. The motor is integrated with a gearbox with a suitable transmission ratio. The power supply adopts a lithium battery pack and is fixed on the frame. A slope toe sensor is also provided on the chassis 100 for detecting the slope of the road on which the vehicle is running.

In the vehicle chassis 100, the power transmission route is the motor-planetary gear train-Mecanum wheel. There are 4 sets of motors 110 and planetary gear trains 120; each set of planetary gear trains 120 is connected with 3 mecanum wheels 130 (collectively referred to as mecanum wheel sets), and the three mecanum wheels 130 form an equilateral triangle , there are 12 mecanum wheels 130 on the chassis 100 . The planetary gear train 120 includes a planetary gear set and a sprocket set, which are respectively arranged on two adjacent and parallel planes, and there is a planetary carrier 140 between the two planes.

As shown in FIG. 2 , the planetary carrier 140 includes a first carrier plate 141 and a second carrier plate 142 arranged parallel to each other at intervals, both of which have the same structure and are triangular plate-shaped structures.

The planetary gear system 120 includes a sun gear 121, which is rotatably arranged at the center outside the first frame plate 141 through a sun gear shaft 122. The sun gear shaft 122 is fixed through the center of the sun gear 121, and one end is rotatably arranged on the first frame. In the center of the outer surface of the plate 141, a plurality of planetary gears 123 are evenly arranged on the same side of the first shelf plate 141 in the circumferential direction of the sun gear 121 through the planetary shaft 124, and are meshed with the 121 sun gear, and the planetary gear 123 can rotate around the sun gear 121 axis. It revolves in the same direction and drives the planet carrier 140 to rotate, and can also rotate around its own axis. The planet shaft 124 can rotate through the first frame plate 141 and the second frame plate 142, and the planet wheel 123 is coaxially fixed on the planet shaft 124 outside the first frame plate 141, as shown in FIG. 3 Show.

The planetary gear train 120 also includes a sprocket set, as shown in FIG. The wheels 123 correspond one-to-one and are coaxially fixed on the planetary shaft 124 between the first frame plate 141 and the second frame plate 142, and the first sprocket 125 moves synchronously with the corresponding planetary wheel 123; a plurality of second chains The wheels 126 are respectively arranged on the other side of the planet carrier 140 between the first sprockets 125 (that is, between the first frame plate 141 and the second frame plate 142 ) through the sprocket shafts 127 , and can rotate around their own axes. The sprocket shaft 127 can rotate through the first frame plate 141 and the second frame plate 142, and corresponds to the second sprocket 126 one by one, and the second sprocket 136 is coaxially fixed on the first frame On the sprocket shaft 127 between the plate 141 and the second frame plate 142 , the mecanum wheel 130 is fixed on the sprocket shaft 127 outside the second frame plate 142 and moves synchronously with the corresponding second sprocket 126 . The chain 128 connects the first sprocket 125 and the second sprocket 126 in sequence, and is in a tensioned state, and the first sprocket 125 and the second sprocket 126 are located on both sides of the chain 128 .

The output shaft 111 of the servo motor 110 is splined to the sun gear shaft 122 for driving the sun gear 121 to rotate. In this embodiment, it also includes a bearing seat 129, which is arranged at intervals outside the first frame plate 141, and the center can rotate through the output shaft of the servo motor 110, and the output shaft can rotate freely in the bearing seat 129; the planet One end of the shaft 124 outside the first frame plate 141 can rotate through the bearing seat 129 . The sun gear 121 and the planet gear 123 are arranged between the first frame plate 141 and the bearing housing 129 .

The planetary gear train 120 mounted on the chassis of this vehicle has two degrees of freedom of rotation of the planetary gear 123 and revolution of the planetary gear 123 when driven. When driving, the power is input from the output shaft of the motor reducer to the sun gear 121, and the sun gear 121 meshes with the planetary gear 123, and the two degrees of freedom of the planetary gear 121, rotation or revolution, are not rigidly constrained. The revolution of the planetary gear 123 will drive the rotation of the planet carrier 140, and at the same time drive the three peripheral Mecanum wheels 130 to revolve around the central axis of the planetary gear train 120; The three second sprockets 126 are driven to rotate, and the second sprockets 126 drive the connected mecanum wheel 130 to rotate around its own axis through the sprocket shaft 127 .

Therefore, when the vehicle is running on flat ground, due to the low output torque of the motor, the orbital torque of the planetary wheel is smaller than the constraint caused by the gravity of the vehicle body, so the planetary wheel cannot revolve, and the rotation of the planetary wheel drives the rotation of the mecanum wheel through the chain transmission to drive the vehicle drive forward. When the vehicle encounters an obstacle, the output torque of the motor increases, and the revolution torque of the planetary gear also increases. When it is greater than the constraint brought by the gravity of the vehicle, the planetary gear starts to revolve, and at the same time drives the planetary carrier and the Mecanum wheel to revolve , to drive the vehicle forward and over obstacles.

Mecanum wheel 130 is composed of spokes and many small rollers fixed on the periphery, and the angle between the wheels and rollers is 45°. Each wheel has three degrees of freedom, one is to rotate around the axis of the wheel, the second is to rotate around the axis of the roller, and the third is to rotate around the contact point between the wheel and the ground. The wheel is driven by the sprocket shaft of the second sprocket in the planetary train, so the remaining two degrees of freedom are free to move. Three Mecanum wheels with the same option are installed on each group of planetary gear trains, and the three wheels are fixedly connected by the second sprockets connected respectively through the chain. When used on flat ground, each set of planetary gear trains has two mecanum wheels grounded and the other suspended. Therefore, when the vehicle travels on flat ground, eight traveling wheels are grounded. The Mecanum wheels on two adjacent sets of planetary gear trains have different directions of rotation. Due to the unique structure of the mecanum wheel, it can move omnidirectionally in a good road environment, and switch between straight, lateral, and oblique motion states arbitrarily. When driving on roads with poor adhesion coefficients such as mud and sand, the multiple grounded rollers on each Mecanum wheel form a deep tire pattern, which can increase the adhesion coefficient.

The small vehicle chassis structure designed and developed by the present invention applies to complex terrain, and a plurality of mecanum wheel sets are arranged on symmetrical and rotatable supports on both sides of the chassis, so that the chassis can and can perform movements of various postures on the ground, including forward and backward translation , spin, lateral movement, oblique travel, turning, etc., improve the passability of the vehicle in a small space and the ability to climb over obstacles, and realize movement in complex environments such as good roads, stairs, and ruins. The chassis of this vehicle is equipped with a two-degree-of-freedom planetary gear system connected to the Mecanum wheel set. With the mechanical characteristics of the planetary gear system itself, it can realize normal driving on flat ground, automatically identify obstacles encountered and support the chassis to overcome obstacles, without complicated procedures. Sensors and control systems. Compared with the traditional ground robot chassis, the invention improves the passability in a narrow space and the ability to climb over obstacles.

The present invention also provides a control method for a small vehicle chassis structure applying complex terrain, including:

(1) When the vehicle travels on flat ground without obstacles, the planetary wheel only rotates around its own axis, and drives the mecanum wheel to rotate through the first sprocket and the second sprocket to drive the vehicle;

(2) When the vehicle encounters an obstacle (as shown in Figure 5), the planetary wheel rotates around its own axis and also revolves around the axis of the sun gear, driving the planetary carrier to drive the mecanum wheel set to rotate, driving the vehicle forward and overturning obstacle;

Wherein, when the vehicle is running, only two mecanum wheels in each mecanum wheel set are grounded at the same time.

When the vehicle chassis is moving, the planetary gear train has two degrees of freedom of rotation and revolution at the same time, wherein the degree of freedom of rotation is unconstrained, and the degree of freedom of revolution is constrained by the reaction force between the vehicle's own gravity and the ground. When the revolution torque of the chassis planetary gear system is greater than the torque generated by the reaction force between the vehicle's own gravity and the ground, the planetary gear system starts to revolve.

When the vehicle is required to drive on flat ground, in order to ensure stable driving, the degree of freedom of revolution of the planetary gear train must be restricted, and only the rotation of the planetary gear drives the Mecanum wheel to drive the vehicle forward. Therefore, when driving on level ground, it is necessary to limit (control) the output torque of the four motors of the vehicle, so as to avoid the excessive output torque of individual motors and the excessive revolution torque of the planetary gear system, which will make the corresponding planetary gear system revolve and the vehicle will become bumpy.

In order to ensure the safety of use, when driving downhill in rough terrain, the front axle motor should be driven, and the rear axle motor should be slightly braked to provide the vehicle with the torque to turn backwards and prevent the vehicle from turning forward.

(1.1) When the vehicle is running on flat ground at a constant speed without obstacles, assuming that the ground adhesion coefficient is good and there is no sliding friction between the mecanum wheel and the ground, the speed v of the vehicle when driving on flat ground is:

Among them: n is the rotational speed of the motor output shaft; i _g is the transmission ratio of the planetary gear set; i _s is the transmission ratio of the sprocket set; d is the diameter of the mecanum wheel.

Since it is necessary to limit (control) the output torque of the motor when the vehicle is running on flat ground, and the output torque of the motor on a good road mainly depends on the ground slope and the acceleration of the vehicle (the acceleration of the vehicle at a constant speed is 0), it is necessary to explore whether the vehicle does not occur in the planetary gear train. The maximum climbing ability in the case of revolution, and the cooperative work mode of the front and rear axle motors required to meet the largest possible climbing degree.

On the slope road, the influence of the degree of inclination of the road surface on the road surface pressure of the front and rear axles of the vehicle is:

in: F _A is the normal pressure of the ground on the front axle; F _B is the normal pressure of the ground on the rear axle; H is the height of the center of mass when the vehicle is placed horizontally; L is the distance between the front and rear axles of the vehicle ; b is the distance between the center of mass in the horizontal direction and the axis of the rear axle when placed horizontally; G is the total gravity of the vehicle when it is working.

After simplification, we can get:

When the planetary gear train of the front and rear axles is at the critical value of revolution, the relationship between the motor torque and the normal pressure of the corresponding shaft is:

Among them: M _A1max and M _A2max are the critical torques of the motors on the left and right sides of the front axle when the planetary gear train starts to revolve; M _B1max and M _B2max are the critical torques of the left and right motors on the rear axle when the planetary gear train starts to revolve; r _c is the radius of gyration of the axis of the mecanum wheel around the center of the planetary gear train when the planetary gear train revolves.

Therefore, if the inclination angle of the vehicle in the horizontal direction is known That is to say, the maximum torque that can be generated by the front and rear axle motors when the planetary gear train does not revolve can be calculated.

when When the angle reaches the maximum value that the vehicle can climb, that is, when When , the driving force of the vehicle is equal to the sliding force along the slope:

Arranged to get:

In summary, It can represent the maximum climbing ability of the vehicle. And in order to make full use of the driving force of the vehicle and increase the driving force as much as possible under the premise of avoiding the revolution of the planetary gear train, it is necessary to control the front and rear motors cooperatively. The optimal torque distribution coefficient s of the front and rear axle motors is the control target, and the parameter s is used to control Front and rear axle motor torque output. The calculation process of s is:

Therefore, when the vehicle is running at a constant speed on flat ground without obstacles, the torque of the power mechanism (servo motor) on both sides of the front and rear axles should be controlled to satisfy:

Among them, M _A1 and M _A2 are the torques of the left and right power mechanisms of the front axle respectively; M _B1 and M _B2 are the torques of the left and right power mechanisms of the rear axle respectively;

And control the front and rear axle torque distribution coefficient s to satisfy:

(1.2) When the vehicle accelerates on flat ground without obstacles, the output torque of the motor is also related to the acceleration of the vehicle. In order to avoid the planetary gear system from revolving and causing bumps, it is necessary to limit the maximum acceleration of the vehicle and control the front and rear of the vehicle during acceleration. shaft motor torque.

When the vehicle accelerates forward with acceleration a, the normal pressure relationship between the front and rear axles and the ground is:

Among them: m ₀ is the total mass of the vehicle when it is working.

The relationship between the acceleration a and the motor drive torque is:

In the limit state before the planetary carrier of the front and rear axles revolves, the relationship between the motor torque and the normal pressure of the corresponding axle is:

After sorting out, it can be obtained that in the critical situation where the planetary gear train is about to revolve:

To sum up, when the vehicle starts or accelerates on flat ground, the front and rear axle motors are controlled cooperatively, and the front and rear axle torque distribution coefficient s is the control target, and s is:

The torque of the motor can be fully utilized, and the vehicle can start and move forward at the maximum acceleration a when the planetary carrier does not revolve. a _max is:

Therefore, when the vehicle starts or accelerates on a flat ground without obstacles, the torque of the power mechanism on both sides of the front and rear axles should be controlled to satisfy:

And control the front and rear axle torque distribution coefficient s to satisfy:

(1.3) When the vehicle runs at a constant speed or accelerates on flat ground, there are four sets of eight Mecanum wheels in total that touch the ground, and the Mecanum wheels can move the vehicle chassis in all directions. The mecanum wheels are arranged in an O shape, and by controlling the speed of the four sets of wheels, the vehicle can reach the states of forward, lateral, oblique, and spin, as shown in Figures 6 and 7. Control the speed of the Mecanum wheel set to satisfy:

ω _i =ω _i1 =ω _i2 =ω _i3 , i=1,2,3,4;

Among them, _ω1 is the rotational speed _of the left front mecanum wheel set, _ω2 is the rotational speed of the right front mecanum wheel set, ω3 is the rotational speed of the left rear mecanum wheel set, and _ω4 is the rotational speed of the right rear mecanum wheel set Rotational speed; R is the ground contact radius of the mecanum wheel; Y is half of the front and rear wheelbase; X is half the distance between the ground contact points of the left and right wheels; ω _i is the speed of the _i -th mecanum wheel set; The speed of the first mecanum wheel in the mecanum wheel group, ω _i2 is the speed of the second mecanum wheel in the i-th mecanum wheel group, ω _i3 is the speed of the i-th mecanum wheel group The rotational speed of the third mecanum wheel, V _X is the longitudinal speed of the vehicle, V _Y is the lateral speed of the vehicle, and ω _o is the spin angular velocity of the vehicle.

Further, the rotational speed of the corresponding motor output shaft is determined as the rotational speed of the mecanum wheel multiplied by the transmission ratio of the sprocket and the gear.

The above formula is the inverse solution equation of the movement of the chassis under ideal conditions, and the angular velocity of each group of mecanum wheels of the vehicle under ideal conditions can be obtained only by knowing the translational velocity and rotational velocity of the center of motion of the vehicle in all directions. Therefore, when controlling the movement of the vehicle, it is necessary to take the traveling speed and spin angular velocity of the vehicle on the X-axis (horizontal) and Y-axis (longitudinal) as the control target. After the target is determined, the controller uses the above formula to calculate each mecanum wheel set The target speed of the motor and the target speed of the corresponding motor, and output control signals to each motor.

(2.1) When the vehicle encounters an obstacle (it is in a state of low speed and low acceleration when crossing the obstacle, so the influence of acceleration is not considered), the power mechanism (servo motor) needs to provide enough torque to make the planetary gear train revolve and overcome the obstacle , the torque of the power mechanism on both sides of the front and rear axles should be controlled to satisfy:

in, H is the inclination angle of the vehicle in the horizontal direction, H is the height of the center of mass when the vehicle is placed horizontally; L is the distance between the front and rear axles of the vehicle; b is the distance between the center of mass in the horizontal direction and the axis of the rear axle when the vehicle is placed horizontally; G is the height of the vehicle when it is working The total gravity, M _A1 and M _A2 are the torques of the power mechanism on the left and right sides of the front axle respectively; M _B1 and M _B2 are the torques of the power mechanism on the left and right sides of the rear axle respectively; r _c is the axis of the mecanum wheel when the planetary gear train revolves The radius of gyration around the center of the planetary gear train;

In order to avoid mutual interference between the front and rear axle motors, the torque distribution coefficient s of the front and rear axles is controlled to satisfy:

The control method designed and developed by the invention for the chassis structure of a small vehicle applying complex terrain can control the running state of each mecanum wheel set according to the running road conditions. It can also control the torque and distribution coefficient of the power mechanism on both sides of the front and rear axles according to the driving road conditions and the driving state of the vehicle, so as to improve the driving stability of the vehicle.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. A small vehicle chassis structure for use with complex terrain, comprising:

a chassis; and

a plurality of Mecanum wheel sets symmetrically and rotatably supported on both sides of the chassis, the Mecanum wheel sets comprising:

a planet carrier;

a sun gear which is arranged at the center of one side of the planet carrier and can rotate along the axial direction of the sun gear;

the planet gears are uniformly arranged in the circumferential direction of the sun gear and are meshed with the sun gear, and the planet gears can revolve around the sun gear in the axial direction and drive the planet carrier to rotate and can also rotate around the self axial direction;

the first chain wheels are arranged on the other side of the planet carrier, correspond to the planet wheels one by one and are coaxially arranged, and the first chain wheels and the corresponding planet wheels synchronously move;

the second chain wheels are respectively arranged on the other side of the planet carrier between the first chain wheels and can rotate around the axial direction of the second chain wheels;

a chain which is connected with the first chain wheel and the second chain wheel in sequence and is in a tensioning state;

the first chain wheel and the second chain wheel are respectively positioned on two sides of the chain;

the Mecanum wheels are arranged on the other side of the planet carrier, correspond to the second chain wheels one by one and are coaxially arranged, and the Mecanum wheels and the corresponding second chain wheels synchronously move;

and the output end of the power mechanism is coaxially and fixedly connected with the sun wheel and is used for driving the sun wheel to rotate.

2. A compact vehicle chassis structure using complex terrain according to claim 1, wherein the carrier comprises:

a first frame plate;

the second frame plate is parallel to the first frame plate and arranged at intervals;

the first frame plate and the second frame plate are consistent in structure and are both triangular plate-shaped structures; and

sun gear and planet wheel set up first frame plate lateral surface, first sprocket, second sprocket and chain setting are in first frame plate with between the second frame plate, mecanum wheel sets up the second frame plate outside.

3. A small-sized vehicle chassis structure for applying a complex terrain according to claim 2, further comprising:

the sun wheel shaft fixedly penetrates through the sun wheel, one end of the sun wheel shaft is rotatably arranged in the center of the outer side face of the first frame plate, and the other end of the sun wheel shaft is fixedly connected with the output end of the power mechanism;

the planet shafts can rotatably penetrate through the first carrier plate and the second carrier plate and correspond to the planet wheels one by one;

the planet wheels are coaxially and fixedly arranged on the planet shaft positioned on the outer side of the first frame plate, and the first chain wheel is coaxially and fixedly arranged on the planet shaft positioned between the first frame plate and the second frame plate;

the chain wheel shafts can rotatably penetrate through the first frame plate and the second frame plate and correspond to the second chain wheels one by one;

the second chain wheel is coaxially and fixedly arranged on the chain wheel shaft between the first frame plate and the second frame plate, and the Mecanum wheel is fixedly arranged on the chain wheel shaft on the outer side of the second frame plate.

4. A small vehicle chassis structure using a complex terrain as set forth in claim 3, wherein the power mechanism further comprises:

the bearing seats are arranged on the outer side of the first frame plate at intervals, and the centers of the bearing seats can rotatably penetrate through the output end of the power mechanism;

wherein the sun gear and the planet gear are arranged between the first frame plate and the bearing seat, and the planet shaft can rotate the bearing seat.

5. A compact vehicle chassis structure for complex terrain applications as claimed in claim 1, 2, 3 or 4 wherein there are 4 of said Mecanum wheel sets and symmetrically rotatable supports are provided on said chassis; each Mecanum wheel set is provided with 3 Mecanum wheels and encloses an equilateral triangle.

6. A method of controlling a chassis structure of a small vehicle utilizing complex terrain, comprising:

when the vehicle runs on the flat ground without obstacles, the planet wheels only rotate around the self axial direction, and the first chain wheel and the second chain wheel drive the Mecanum wheel to rotate to drive the vehicle to run;

when the vehicle runs in an obstacle, the planet wheel axially rotates and also axially revolves around the sun wheel, the planet carrier is driven to drive the Mecanum wheel set to rotate, and the vehicle is driven to move forwards and cross the obstacle;

wherein, when the vehicle is traveling, only 2 and only 2 of the Mecanum wheel sets are simultaneously grounded.

7. The control method of a chassis structure of a small vehicle using a complex terrain as set forth in claim 6, wherein the torque of the power unit controlling both sides of the front and rear axles satisfies:

wherein,is the inclination angle of the vehicle in the horizontal direction, and H is the height of the mass center when the vehicle is horizontally placed; l is the distance between the front axle and the rear axle of the vehicle; b is the distance between the center of mass and the axis of the rear axle in the horizontal direction when the rear axle is horizontally placed; g is the total gravity of the vehicle during operation, M_A1、M_A2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the front shaft are respectively; m_B1、M_B2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the rear shaft are respectively; r is_cThe radius of gyration of the Mecanum wheel axis around the planet wheel train center when the planet wheel train revolves;

and controlling the torque distribution coefficient s of the front and rear shafts to satisfy:

wherein the maximum climbing capability of the vehicleSatisfies the following conditions:

wherein i_gIs the planetary gear set transmission ratio; i.e. i_sThe transmission ratio of the chain wheel set is set; d is the Mecanum wheel diameter.

8. A control method of a chassis structure of a small vehicle using a complex terrain as set forth in claim 6, wherein when the vehicle starts or runs with acceleration without obstacles, the torques of the power units controlling both sides of the front and rear axles are satisfied:

wherein L is the distance between the front axle and the rear axle of the vehicle; g is the total gravity of the vehicle during operation, M_A1、M_A2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the front shaft are respectively; m_B1、M_B2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the rear shaft are respectively; r is_cThe radius of rotation of a Mecanum wheel axis around the center of the planetary gear train during the revolution of the planetary gear train, d is the diameter of the Mecanum wheel, i_gIs the planetary gear set transmission ratio; i.e. i_sIs the transmission ratio of the chain wheel set, and H is the height of the mass center when the vehicle is horizontally placed;

and controlling the torque distribution coefficient s of the front and rear shafts to satisfy:

and controlling the acceleration a of the vehicle to satisfy:

wherein m is₀Is the total mass of the vehicle when in operation.

9. The method for controlling a chassis structure of a small vehicle using complex terrains as claimed in claim 7 or 8, wherein when the vehicle is started at a constant speed or is driven at an accelerated speed on a flat ground, the rotation speed of the Mecanum wheel set is controlled to satisfy the following conditions:

ω_i＝ω_i1＝ω_i2＝ω_i3，i＝1，2，3，4；

wherein, ω is₁Is the rotational speed, omega, of the left front Mecanum wheel set₂For the speed of rotation, omega, of the right front Mecanum wheel set₃Is the rotation speed, omega, of the left rear Mecanum wheel set₄The rotation speed of the rear right Mecanum wheel group; r is the grounding radius of the Mecanum wheel; y is half of the wheelbase; x is half of the distance between the grounding points of the left and right wheels, omega_iFor the speed of the ith Mecanum wheel set, ω_i1For the speed, ω, of the first Mecanum wheel in the ith Mecanum wheel set_i2For the speed, ω, of the second Mecanum wheel of the ith Mecanum wheel set_i3For the speed of rotation of the third Mecanum wheel of the ith Mecanum wheel set, V_XFor the transverse running speed of the vehicle, V_YAs the longitudinal running speed, ω, of the vehicle_oIs the vehicle spin angular velocity.

10. The control method of a chassis structure of a small vehicle using a complex terrain as set forth in claim 6, wherein the torque of the power mechanism controlling both sides of the front and rear axles satisfies:

wherein,is the inclination angle of the vehicle in the horizontal direction, and H is the height of the mass center when the vehicle is horizontally placed; l is the distance between the front axle and the rear axle of the vehicle; b is the distance between the center of mass and the axis of the rear axle in the horizontal direction when the rear axle is horizontally placed; g is the total gravity of the vehicle during operation, M_A1、M_A2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the front shaft are respectively; m_B1、M_B2The torque of the power mechanism at the left side and the torque of the power mechanism at the right side of the rear shaft are respectively; r is_cThe radius of gyration of the Mecanum wheel axis around the planet wheel train center when the planet wheel train revolves;

and controlling the torque distribution coefficient s of the front and rear shafts to satisfy: