Road feeling feedback system and method for hinged hydraulic steer-by-wire vehicle

Abstract

The invention relates to a road feeling feedback system and method for a hinged type hydraulic steer-by-wire vehicle, the system comprises a hinged type hydraulic steering execution assembly, a road feeling feedback execution assembly and a steering control ECU, and the hinged type hydraulic steering execution assembly and the road feeling feedback execution assembly are connected through the steering control ECU; the hinged hydraulic steering execution assembly is used for collecting state variables when the vehicle runs; the steering control ECU is used for obtaining the expected transmission torque of a transmission shaft of the steering wheel according to state variables collected on the hinged type hydraulic steering execution assembly and adjusting the output torque of the road sensing torque motor according to the expected transmission torque of the transmission shaft of the steering wheel. The road feeling feedback execution assembly controls the road feeling feedback torque in real time through the output torque of a road feeling torque motor, and the steering hand feeling of a steering wheel during steering is fed back to a driver. Compared with the prior art, real-time customized smooth road feeling feedback can be carried out on the hinged hydraulic steer-by-wire vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of steering systems for construction machinery and equipment, and particularly to a road feel feedback system and method for an articulated hydraulically wire-controlled steering vehicle. Background Art

[0002] The steering system of articulated construction equipment uses hydraulic pressure to drive the telescopic movement of the steering cylinder to achieve steering. Typical equipment includes wheel loaders, heavy trucks, etc. The traditional steering scheme that uses a full hydraulic directional control valve to control double hydraulic cylinders has disadvantages such as steering delay and complex system. The wire-controlled steering system (Steer-by-Wire, SBW) that decouples mechanical physical connections is the development trend of engineering vehicles, and it has obvious advantages in terms of control flexibility, rich functions, space layout, and fuel consumption reduction.

[0003] The road feel feedback strategy of the wire-controlled steering system is one of the key technologies to ensure driving safety and comfort. The torque of the steering resistance that the driver needs to overcome when turning the steering wheel to control the vehicle steering process is called road feel. For conventional vehicles, the wire-controlled steering system takes the steering wheel angle, vehicle speed, and lateral acceleration as the main influencing factors of the steering wheel torque. For example, patent application CN105083373A discloses a wire-controlled steering road feel device and its control method based on parameter estimation. This method measures signals by sensors, estimates the current vehicle state variables through Kalman filtering, calculates the vehicle steering resistance torque, and compensates and corrects the steering road feel through vehicle speed, variable transmission ratio, and lateral acceleration to obtain the current ideal steering wheel torque value. This is not applicable to heavy-load construction equipment with wire-controlled steering in unstructured construction sites. The construction equipment is in a low-speed and heavy-load motion state, and there is a complex environment with rough roads. The reaction torque on the steering wheel should transmit the motion state of the whole vehicle and the force condition of the tires to the driver. In terms of torque transmission, the special driving scenario of a compound disturbance road surface easily causes the simple torque feedback steering wheel to hit the hand, resulting in a poor driving experience of the driver's road feel feedback. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art and provide a road feel feedback system and method for an articulated hydraulically wire-controlled steering vehicle, which can achieve accurate and smooth road feel feedback for the articulated hydraulically wire-controlled steering vehicle.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A road feeling feedback system for an articulated hydraulically steer-by-wire vehicle, comprising: an articulated hydraulic steering execution assembly, a road feeling feedback execution assembly, and a steering control ECU. The articulated hydraulic steering execution assembly includes a wheel speed encoder, a hydraulic proportional directional valve, a one-way overflow valve, a hydraulic pressure gauge, a steering execution cylinder, and a steering encoder. The articulated hydraulic steering execution assembly is used to collect state variables during vehicle driving. The road feeling feedback execution assembly includes a steering wheel, a road feeling torque motor, a steering wheel encoder, and a torque sensor. The articulated hydraulic steering execution assembly and the road feeling feedback execution assembly are connected through the steering control ECU. The steering control ECU is used to obtain the expected transmission torque of the transmission shaft of the steering wheel according to the state variables collected on the articulated hydraulic steering execution assembly, and adjust the output torque of the road feeling torque motor according to the expected transmission torque of the transmission shaft of the steering wheel. The road feeling feedback execution assembly is used to output a road feeling feedback torque in real time according to the output torque of the road feeling torque motor, and feedback the steering feel when the steering wheel is turned to the driver.

[0007] Further, the expected transmission torque of the transmission shaft of the steering wheel is:

[0008]

[0009] In the formula, is the expected transmission torque of the transmission shaft of the steering wheel, G is the driving preference gain coefficient, T p is the hydraulic load feedback torque, T c is the steering compensation torque, T damp is the damping torque, T at is the active return torque, T lim is the limit control torque, B sw is the inherent damping coefficient of the steering wheel, θ sw is the angle of the steering wheel, measured by the steering wheel encoder, T fric is the frictional torque.

[0010] Further, the hydraulic load feedback torque is calculated according to the hydraulic pressure measured by the hydraulic pressure gauge:

[0011] T p = k p (P l - P r )

[0012] In the formula, P l is the hydraulic pressure on the left-turn input side, P r is the hydraulic pressure on the right-turn input side, k p is the steering execution torque coefficient.

[0013] Further, the steering compensation torque is used to compensate for the surge of the nonlinear torque, and the steering compensation torque is:

[0014] T c =k c (A1L l +A2L r )(P l -P r )

[0015]

[0016]

[0017] In the formula, T c is the steering compensation torque, A1 is the cross-sectional area of the rodless cavity of the steering cylinder, A2 is the cross-sectional area of the rod cavity of the steering oil tank, L l is the lever arm of the left steering actuator cylinder mentioned above, L r is the lever arm of the right steering actuator cylinder mentioned above, θ is the vehicle steering angle, measured by the steering encoder, d f is the width of the front joint of the articulated hydraulic steering mechanism, d r is the width of the rear joint of the articulated hydraulic steering mechanism, h f is the length of the front vertical line of the articulated hydraulic steering mechanism, h r is the length of the rear vertical line of the articulated hydraulic steering mechanism.

[0018] Further, the damping torque is:

[0019]

[0020] B d =k damp v+b damp

[0021] In the formula, T damp is the damping torque, B d is the rotational damping coefficient, θ sw is the steering wheel rotation angle, measured by the steering wheel encoder, k damp and b damp are the linear synthesis coefficients of the rotational damping coefficient, and v is the vehicle driving speed, measured by the wheel speed encoder.

[0022] Further, the active return torque matches the steering wheel rotation angle and the vehicle driving speed:

[0023]

[0024] In the formula, T atThe active return torque is \(T_a\), the vehicle driving speed is \(v\), which is measured by the wheel speed encoder, and \(\theta\) sw is the steering wheel angle, \(k\) v is the return torque speed proportionality coefficient, \(k\) θ is the return torque angle proportionality coefficient.

[0025] Furthermore, the limit control torque is used to limit the maximum steering of the steering wheel, prompting the driver to reach the farthest steering angle and avoiding the steering wheel exceeding the steering range. The limit control torque is:

[0026]

[0027] \(\theta\) max \(=i(v,P)\theta\)

[0028] \(i(v,P)=i_0 + k\) vi \(v + k\) pi \(P\)

[0029] In the formula, \(T\) lim is the limit control torque, \(k\) lim is the limit torque proportionality coefficient, \(\theta\) sw is the steering wheel angle, \(\theta\) max is the maximum steering wheel angle, \(i(v,P)\) is the virtual steering transmission ratio, \(i_0\) is the basic steering ratio, \(k\) vi is the transmission ratio speed coefficient, \(v\) is the vehicle driving speed, \(k\) pi is the transmission ratio hydraulic load coefficient, \(P\) is the steering load hydraulic pressure, and \(\theta\) is the vehicle steering angle.

[0030] Furthermore, the road feel feedback torque is:

[0031]

[0032] \(T\) m \(=k\) m \(I\) m

[0033] In the formula, \(T\) fb is the road feel feedback torque, \(B\) sw is the inherent damping coefficient of the steering wheel, \(\theta\) sw is the steering wheel angle, \(T\) s is the transmission torque of the steering shaft of the steering wheel, \(T\) damp is the damping torque, \(T\) fric is the frictional torque, is the expected transmission torque of the steering shaft of the steering wheel, \(d(t)\) is the disturbance quantity, is the control function, \(T\) m is the output torque of the road feel torque motor, \(I\) m is the current of the road feel torque motor, \(k\)m is the torque constant of the road feel torque motor, is the angular acceleration output by the road feel torque motor, ω m is the angular velocity output by the road feel torque motor, θ m is the angle output by the road feel torque motor, t is time, g m is the transmission ratio.

[0034] Further, the dynamic scheme of the road feel feedback execution assembly follows the following steering wheel torque balance equation:

[0035]

[0036] In the formula, T sw is the torque applied by the driver to the steering wheel, J sw is the moment of inertia of the steering wheel, θ sw is the steering wheel angle, B sw is the inherent damping coefficient of the steering wheel, T s is the transmission torque of the transmission shaft of the steering wheel, measured by the torque sensor, T fric is the frictional torque.

[0037] According to another aspect of the present invention, a road feel feedback method for an articulated hydraulically steer-by-wire vehicle is provided. By using the above-mentioned road feel feedback system of the articulated hydraulically steer-by-wire vehicle for road feel feedback, the method includes the following steps:

[0038] Collect the state variables of the vehicle during driving through the articulated hydraulic steering execution assembly;

[0039] Obtain the expected transmission torque of the transmission shaft of the steering wheel according to the state variables;

[0040] Adjust the output torque of the road feel torque motor through the steering control ECU according to the expected transmission torque of the transmission shaft of the steering wheel, and then adjust the transmission torque of the transmission shaft of the steering wheel to realize the real-time output of the road feel feedback torque, and feedback the steering feel when the steering wheel is turned to the driver.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. The present invention collects the state variables of the vehicle during driving through the articulated hydraulic steering execution assembly, obtains the expected transmission torque of the transmission shaft of the steering wheel through the steering control ECU according to the state variables collected on the articulated hydraulic steering execution assembly, adjusts the output torque of the road feel torque motor according to the expected transmission torque of the transmission shaft of the steering wheel, and feeds back the steering feel when the steering wheel is turned to the driver through the road feel feedback execution assembly, realizing the real-time and accurate output of the road feel feedback torque.

[0043] 2. Based on the calculation and feedback model of the traditional road feeling feedback torque, the present invention filters the high-frequency hydraulic complex noise signals caused by fine bumps through a first-order low-pass filter, smooths the feedback torque of the reverse steering wheel, and uses a limiter to prevent torque mutation and avoid hitting the steering wheel, thereby constructing the expected transmission torque of the transmission shaft of the steering wheel and realizing the smooth output of the road feeling feedback torque. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 FIG. is a schematic structural diagram of a road feeling feedback system for an articulated hydraulic by-wire steering vehicle proposed by the present invention;

[0045] Figure 2 FIG. is a schematic physical structure diagram of a road feeling feedback system for an articulated hydraulic by-wire steering vehicle proposed by the present invention;

[0046] Figure 3 FIG. is a schematic flow diagram of a road feeling feedback method for an articulated hydraulic by-wire steering vehicle proposed by the present invention.

[0047] Legend: 1. Steering wheel; 2. Road feeling torque motor; 3. Steering wheel transmission structure; 4. Steering wheel encoder; 5. Torque sensor; 6. Steering control ECU; 7. Wheel speed encoder; 8. Hydraulic proportional directional valve; 9. Unidirectional overflow valve; 10. Hydraulic pressure gauge; 11. Steering actuator cylinder; 12. Steering encoder; 13. Articulated hydraulic steering actuator assembly; 14. Road feeling feedback actuator assembly. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives the detailed implementation manner and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0049] Abbreviations involved:

[0050] Electronic control unit: Electronic Control Unit, ECU

[0051] Proportional Integral Derivative: PID

[0052] Embodiment 1

[0053] This embodiment provides a road feeling feedback system for an articulated hydraulic by-wire steering vehicle, as Figure 1As shown in the figure, it includes: an articulated hydraulic steering actuator assembly 13, a road feel feedback actuator assembly 14, and a steering control ECU 6. The articulated hydraulic steering actuator assembly 13 includes a wheel speed encoder 7, a hydraulic proportional directional valve 8, a one-way overflow valve 9, a hydraulic pressure gauge 10, a steering actuator cylinder 11, and a steering encoder 12. The articulated hydraulic steering actuator assembly 13 is used to collect state variables during vehicle driving; the road feel feedback actuator assembly 14 includes a steering wheel 1, a road feel torque motor 2, a steering wheel encoder 4, and a torque sensor 5. The articulated hydraulic steering actuator assembly 13 and the road feel feedback actuator assembly 14 are connected through the steering control ECU 6. The steering control ECU 6 is used to obtain the expected driving torque of the transmission shaft of the steering wheel 1 according to the state variables collected on the articulated hydraulic steering actuator assembly 13, and adjust the output torque of the road feel torque motor 2 according to the expected driving torque of the transmission shaft of the steering wheel 1; the road feel feedback actuator assembly 14 is used to output a road feel feedback torque in real time according to the output torque of the road feel torque motor 2, and feedback the steering feel when the steering wheel 1 is turned to the driver.

[0054] The state variables include: the steering angle of the steering wheel 1, the vehicle driving speed, the hydraulic pressure on the steering input side, the vehicle steering angle, etc.

[0055] The physical structure schematic diagram of the road feel feedback system of an articulated hydraulic by-wire steering vehicle is as Figure 2 shown, and it also includes a hydraulic oil supply component and a communication line. The steering actuator cylinder 11 of the articulated hydraulic steering mechanism in this embodiment includes two steering actuator cylinders 11 on the left and right sides.

[0056] The expected driving torque of the transmission shaft of the steering wheel 1 is:

[0057]

[0058] In the formula, is the expected driving torque of the transmission shaft of the steering wheel 1, G is the driving preference gain coefficient, T p is the hydraulic load feedback torque, T c is the steering compensation torque, T damp is the damping torque, T at is the active return torque, T lim is the limit control torque, B sw is the inherent damping coefficient of the steering wheel 1, θ sw is the steering angle of the steering wheel 1, measured by the steering wheel encoder 4, T fric is the frictional torque.

[0059] The construction process of the expected driving torque of the transmission shaft of the steering wheel 1 is as follows:

[0060] The pre-set calculation feedback model of the road feel feedback torque is:

[0061] T fb =GT base +T damp -T at +T lim

[0062] Where G is the driving preference gain coefficient, T base is the feedback torque basis term, T damp is the damping torque, T at is the active self-aligning torque, T lim It is the limit control torque.

[0063] The steering feel is expressed as the resistance torque overcome by the driver driving the steering wheel, and the road feel feedback torque can be expressed as:

[0064]

[0065] Where, T fb is the road feedback torque, B sw is the inherent damping coefficient of steering wheel 1, θ sw is the steering angle of steering wheel 1, T s is the transmission torque of the transmission shaft of the steering wheel 1, T fric is the friction torque.

[0066] The expected transmission torque of the transmission shaft of the steering wheel 1 is obtained by combining the above two road feel feedback torque formulas.

[0067] The basic term of feedback torque is obtained after passing through multi-stage filters:

[0068] T base =Filter(T base_raw ,k)=Filter(T p -T c ,k)

[0069] Where, T base is the basic term of feedback torque, Filter() is a multi-level filtering function, T base_raw is the original unfiltered feedback torque basis term, k is the current iteration number, T p is the hydraulic load feedback torque, T c The steering compensation torque.

[0070] The torque is smoothed by multi-stage filters while retaining the steering feel caused by load or obstruction. The multi-stage filter consists of a low-pass filter and a limiter. A first-order low-pass filter is used to filter the high-frequency hydraulic complex noise signal caused by fine bumps, smooth the feedback torque of the reverse disc, and achieve comfortable driving:

[0071] T′ base (k) = αd T base_raw (k)+(1 - α d )T base (k - 1)

[0072]

[0073] f c =f min +k f v

[0074]

[0075] In the formula, T b ' ase (k) is the basic torque output by the first - order low - pass filter, α d is the smoothing coefficient, f c is the cut - off frequency, Δt is the sensor acquisition frequency, ΔT is the maximum torque amplitude of the limiter filter, f min is the lowest cut - off frequency, k f is the cut - off frequency speed coefficient, and v is the vehicle driving speed.

[0076] Among them, as the operating speed of the construction vehicle chassis increases, the cut - off frequency increases to retain more high - frequency road feelings. At the same time, a limiter is used to prevent torque mutations and avoid hitting the steering wheel 1.

[0077] The hydraulic load feedback torque is calculated according to the hydraulic pressure measured by the hydraulic pressure gauge 10:

[0078] T p =k p (P l -P r )

[0079] In the formula, P l is the hydraulic pressure on the left - turn input side, P r is the hydraulic pressure on the right - turn input side, and k p is the steering execution torque coefficient.

[0080] The steering compensation torque is used to compensate for the non - linear torque surge, and the steering compensation torque is:

[0081] T c =k c (A1L l +A2L r )(P l -P r )

[0082]

[0083] In the formula, T cis the steering compensation torque, A1 is the cross-sectional area of the rodless cavity of the steering cylinder, A2 is the cross-sectional area of the rod cavity of the steering cylinder, L l is the lever arm of the left steering actuator cylinder 11, L r is the lever arm of the right steering actuator cylinder 11, θ is the vehicle steering angle, measured by the steering encoder 12, d f is the front joint width of the articulated hydraulic steering mechanism, d r is the rear joint width of the articulated hydraulic steering mechanism, h f is the front vertical line length of the articulated hydraulic steering mechanism, h r is the rear vertical line length of the articulated hydraulic steering mechanism.

[0084] The damping torque is:

[0085]

[0086] B d = k damp v + b damp

[0087] In the formula, T damp is the damping torque, B d is the rotational damping coefficient, θ sw is the steering wheel 1 rotation angle, measured by the steering wheel encoder 4, k damp and b damp are the linear synthesis coefficients of the rotational damping coefficient, v is the vehicle driving speed, measured by the wheel speed encoder 7. k damp and b damp realize the adaptive adjustment of the damping coefficient with the vehicle speed. This damping term can improve the high-speed stability while ensuring the low-speed flexibility, reduce the safety risks caused by misoperations during high-speed movement, improve the vehicle steering stability, and reduce vehicle jitter.

[0088] The active return torque is responsible for driving the direction back to the straight-ahead driving state after stopping steering, reducing the driver's operation burden, enhancing the driving stability of the equipment, and preventing the direction from deviating. The active return torque is matched with the steering wheel rotation angle and the vehicle driving speed:

[0089]

[0090] In the formula, T at is the active return torque, v is the vehicle driving speed, measured by the wheel speed encoder 7, θ sw is the steering wheel 1 rotation angle, is the steering speed, k v is the return torque speed proportionality coefficient, k θ is the return torque angle proportionality coefficient.

[0091] The limit control torque is used to limit the maximum steering of the steering wheel 1, prompt the driver to reach the farthest steering angle, and avoid the steering wheel 1 exceeding the steering range. The limit control torque is as follows:

[0092]

[0093] θ max = i(v, P)θ

[0094] i(v, P) = i0 + k vi v + k pi P

[0095] In the formula, T lim is the limit control torque, k lim is the limit torque proportionality coefficient, θ sw is the steering angle of the steering wheel 1, θ max is the maximum steering angle of the steering wheel 1, i(v, P) is the virtual steering transmission ratio, i0 is the basic steering ratio, k vi is the transmission ratio speed coefficient, v is the vehicle driving speed, k pi is the transmission ratio hydraulic load coefficient, P is the steering load hydraulic pressure, and θ is the vehicle steering angle.

[0096] The dynamic scheme of the road feel feedback actuator assembly 14 follows the following steering wheel torque balance equation:

[0097]

[0098] In the formula, T sw is the torque applied by the driver to the steering wheel, J sw is the moment of inertia of the steering wheel, θ sw is the steering angle of the steering wheel, B sw is the inherent damping coefficient of the steering wheel 1, T s is the transmission torque of the transmission shaft of the steering wheel 1, measured by the torque sensor 5, T fric is the frictional torque.

[0099] The steering control ECU 6 is used to obtain the expected transmission torque of the transmission shaft of the steering wheel 1 according to the state variables collected on the articulated hydraulic steering actuator assembly 13, adjust the output torque of the road feel torque motor 2 according to the expected transmission torque of the transmission shaft of the steering wheel 1, and output the road feel feedback torque in real time.

[0100] The road feel feedback torque is:

[0101]

[0102] T m = k m I m

[0103] Wherein, T fb is the road feel feedback torque, B sw is the inherent damping coefficient of the steering wheel 1, θ sw is the rotation angle of the steering wheel 1, T s is the transmission torque of the transmission shaft of the steering wheel 1, T damp is the damping torque, T fric is the frictional torque, is the expected transmission torque of the transmission shaft of the steering wheel 1, d(t) is the disturbance quantity, is the control function, T m is the output torque of the road feel torque motor 2, I m is the current of the road feel torque motor 2, k m is the torque constant of the road feel torque motor 2, is the angular acceleration output by the road feel torque motor 2, ω m is the angular velocity output by the road feel torque motor 2, θ m is the angle output by the road feel torque motor 2, t is the time, g m is the transmission ratio.

[0104] Taking the expected transmission torque of the transmission shaft of the steering wheel 1 as the standard value, the steering control ECU6 adjusts the output torque of the road feel torque motor 2 by means of the PID control algorithm, and then adjusts the transmission torque of the transmission shaft of the steering wheel 1 to realize the real-time output of the road feel feedback torque.

[0105] Embodiment 2

[0106] This embodiment provides a road feel feedback method for an articulated hydraulically steer-by-wire vehicle. By adopting the road feel feedback system of the articulated hydraulically steer-by-wire vehicle described in Embodiment 1 for road feel feedback, the method includes the following steps:

[0107] S1. Collect the state variables during vehicle driving through the articulated hydraulic steering execution assembly 13.

[0108] The state variables include: the rotation angle of the steering wheel 1, the vehicle driving speed, the hydraulic pressure on the steering input side, the vehicle steering angle, etc.

[0109] The rotation angle of the steering wheel 1 is measured by the steering wheel encoder 4. The vehicle driving speed is measured by the wheel speed encoder 7. The hydraulic pressure on the steering input side is measured by the hydraulic pressure gauge 10. The vehicle steering angle is measured by the steering encoder 12.

[0110] S2. Obtain the expected transmission torque of the transmission shaft of the steering wheel 1 according to the state variables.

[0111] The expected transmission torque of the transmission shaft of the steering wheel 1 is:

[0112]

[0113] In the formula, is the expected transmission torque of the transmission shaft of the steering wheel 1, G is the driving preference gain coefficient, and T p is the hydraulic load feedback torque, and T c is the steering compensation torque, and T damp is the damping torque, and T at is the active return-to-center torque, and T lim is the limit control torque, B sw is the inherent damping coefficient of the steering wheel 1, θ sw is the rotation angle of the steering wheel 1, which is measured by the steering wheel encoder 4, and T fric is the frictional torque.

[0114] The specific values of each torque are obtained through state variables, and the expected transmission torque of the transmission shaft of the steering wheel 1 is calculated.

[0115] S3. According to the expected transmission torque of the transmission shaft of the steering wheel 1, the output torque of the road feel torque motor 2 is adjusted by the steering control ECU6, and then the transmission torque of the transmission shaft of the steering wheel 1 is adjusted to realize the real-time output of the road feel feedback torque.

[0116] The road feel feedback torque is:

[0117]

[0118] T m = k m I m

[0119] In the formula, T fb is the road feel feedback torque, B sw is the inherent damping coefficient of the steering wheel 1, θ sw is the rotation angle of the steering wheel 1, T s is the transmission torque of the transmission shaft of the steering wheel 1, T damp is the damping torque, T fric is the frictional torque, is the expected transmission torque of the transmission shaft of the steering wheel 1, d(t) is the disturbance quantity, is the control function, T m is the output torque of the road feel torque motor 2, I m is the current of the road feel torque motor 2, k m is the torque constant of the road feel torque motor 2, is the angular acceleration output by the road feel torque motor 2, ω m is the angular velocity output by the road feel torque motor 2, θ m is the angle output by the road feel torque motor 2, t is the time, g mIt is the transmission ratio.

[0120] Taking the expected transmission torque of the transmission shaft of the steering wheel 1 as the standard value, the steering control ECU 6 adjusts the output torque of the road feel torque motor 2 by means of the pid control algorithm, and then adjusts the transmission torque of the transmission shaft of the steering wheel 1 to achieve the real-time output of the road feel feedback torque.

[0121] The rest is the same as that of Embodiment 1.

[0122] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art shall fall within the protection scope determined by the claims.

Claims

1. A road feel feedback system for an articulated hydraulic steer-by-wire vehicle, characterized in that: include: An articulated hydraulic steering actuator assembly (13), a road sense feedback actuator assembly (14) and a steering control ECU (6), wherein the articulated hydraulic steering actuator assembly (13) comprises a wheel speed encoder (7), a hydraulic proportional reversing valve (8), a one-way overflow valve (9), a hydraulic pressure gauge (10), a steering actuator cylinder (11) and a steering encoder (12), and the articulated hydraulic steering actuator assembly (13) is used to collect state variables when the vehicle is traveling; the road sense feedback actuator assembly (14) comprises a steering wheel (1), a road sense torque motor (2), a steering wheel encoder (4) and a torque sensor (5), and the articulated hydraulic The hydraulic steering execution assembly (13) and the road sense feedback execution assembly (14) are connected via the steering control ECU (6); the steering control ECU (6) is used to obtain the expected transmission torque of the transmission shaft of the steering wheel (1) according to the state variables collected on the articulated hydraulic steering execution assembly (13), and adjust the output torque of the road sense torque motor (2) according to the expected transmission torque of the transmission shaft of the steering wheel (1); the road sense feedback execution assembly (14) is used to output the road sense feedback torque in real time according to the output torque of the road sense torque motor (2), and feed back the steering feel when the steering wheel (1) is turned to the driver.

2. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 1, characterized in that: The expected transmission torque of the transmission shaft of the steering wheel (1) is: In the formula, is the expected transmission torque of the transmission shaft of the steering wheel (1), G is the driving preference gain coefficient, T p is the hydraulic load feedback torque, T c is the steering compensation torque, T damp is the damping torque, T at is the active self-aligning torque, T lim is the limit control torque, B sw is the inherent damping coefficient of the steering wheel (1), θ sw is the turning angle of the steering wheel (1), measured by the steering wheel encoder (4), T fric is the friction torque.

3. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 2, characterized in that: The hydraulic load feedback torque is calculated based on the hydraulic pressure measured by the hydraulic pressure gauge (10): T p =k p (P l -P r ) Where P l is the hydraulic pressure on the left-turn input side, P r is the hydraulic pressure on the right-turn input side, k p is the steering torque coefficient.

4. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 2, characterized in that: The steering compensation torque is used to compensate for the nonlinear torque surge, and the steering compensation torque is: T c =k c (A1L l +A2L r )(P l -P r ) Where, T c is the steering compensation torque, A1 is the cross-sectional area of ​​the rodless cavity of the steering cylinder, A2 is the cross-sectional area of ​​the rod cavity of the steering oil tank, L l L is the lever arm of the steering actuator cylinder (11) on the left side, r is the force arm of the steering actuator cylinder (11) on the right side, θ is the vehicle steering angle, measured by the steering encoder (12), and d f is the front end joint width of the articulated hydraulic steering mechanism, d r h is the rear end joint width of the articulated hydraulic steering mechanism. f h is the vertical length of the front end of the articulated hydraulic steering mechanism, r It is the vertical length of the rear end of the articulated hydraulic steering mechanism.

5. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 2, characterized in that: The damping torque is: B d =k damp v+b damp Where, T damp is the damping torque, B d is the rotation damping coefficient, θ sw is the turning angle of the steering wheel (1), measured by the steering wheel encoder (4), k damp and b damp is the linear synthesis coefficient of the rotation damping coefficient, and v is the vehicle speed, which is measured by the wheel speed encoder (7).

6. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 2, characterized in that: The active self-aligning torque is matched to the steering wheel angle and the vehicle speed: Where, T at is the active self-aligning torque, v is the vehicle speed, measured by the wheel speed encoder (7), θ sw is the steering angle of the steering wheel (1), k v is the proportional coefficient of the return torque to speed, k θ is the proportional coefficient of the angular angle of the return torque.

7. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 2, characterized in that: The limit control torque is used to limit the maximum steering of the steering wheel (1), prompting the driver to reach the farthest steering angle, and preventing the steering wheel (1) from exceeding the steering range. The limit control torque is: i max =i(v,P)θ i(v,P)=i0+k vi v+k pi P Where, T lim is the limit control torque, k lim is the limiting torque proportional coefficient, θ sw is the steering wheel (1) angle, θ max is the maximum turning angle of the steering wheel (1), i(v,P) is the virtual steering ratio, i0 is the basic steering ratio, k vi is the transmission ratio speed coefficient, v is the vehicle speed, k pi is the transmission ratio hydraulic load coefficient, P is the steering load hydraulic pressure, and θ is the vehicle steering angle.

8. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 1, characterized in that: The road sense feedback torque is: T m =k m I m Where, T fb is the road feedback torque, B sw is the inherent damping coefficient of the steering wheel (1), θ sw is the turning angle of the steering wheel (1), T s is the transmission torque of the transmission shaft of the steering wheel (1), T damp is the damping torque, T fric is the friction torque, is the desired transmission torque of the transmission shaft of the steering wheel (1), d(t) is the disturbance, is the control function, T m is the output torque of the road-sensing torque motor (2), I m is the current of the road-sensing torque motor (2), k m is the torque constant of the road-sensing torque motor (2), is the angular acceleration output by the road-sensing torque motor (2), ω m is the angular velocity output by the road-sensing torque motor (2), θ m is the output angle of the road torque motor (2), t is the time, g m is the transmission ratio.

9. The road feel feedback system for an articulated hydraulic steer-by-wire vehicle according to claim 1, characterized in that: The dynamic scheme of the road feel feedback execution assembly follows the following steering wheel torque balance equation: Where, T sw is the torque applied by the driver on the steering wheel, J sw is the steering wheel moment of inertia, θ sw is the steering wheel angle, B sw is the inherent damping coefficient of the steering wheel (1), T s is the transmission torque of the transmission shaft of the steering wheel (1), measured by the torque sensor (5), T fric is the friction torque.

10. A road feel feedback method for an articulated hydraulic steer-by-wire vehicle, characterized in that: The method of performing road sense feedback by using the road sense feedback system of an articulated hydraulic steer-by-wire vehicle as claimed in any one of claims 1 to 9 comprises the following steps: The state variables of the vehicle when it is traveling are collected by means of an articulated hydraulic steering execution assembly (13); Obtaining a desired transmission torque of a transmission shaft of the steering wheel (1) according to the state variable; The output torque of the road sense torque motor (2) is adjusted through the steering control ECU (6) according to the expected transmission torque of the transmission shaft of the steering wheel (1), and the transmission torque of the transmission shaft of the steering wheel (1) is further adjusted to achieve the real-time output of the road sense feedback torque, and the steering feel when the steering wheel (1) is turned is fed back to the driver.

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