A multi-degree-of-freedom platform

Abstract

The present invention discloses a multi-degree-of-freedom platform, including an arc frame, a rope, a rope driving mechanism, a crane mechanism, a guide device and a load frame. The upper and lower ends of the arc frame are respectively installed with arc guide rails, and a turntable is installed corresponding to the arc guide rails. Two rope driving mechanisms are synchronously controlled to generate yaw torque, and drive the turntable to realize yaw direction movement; eight ropes are arranged in a spatially symmetrical upper four and lower four manner, and the load frame realizes five degrees of freedom movement of X axis, Y axis, Z axis, pitch and roll in three-dimensional space as the extension length of the eight ropes changes. Through the above, the multi-degree-of-freedom platform provided by the present invention can simulate a low-gravity environment, realize six-degree-of-freedom movement in three-dimensional space, can realize a large range of displacement, and perform continuous axis movement on multiple axes to meet a large range of yaw requirements, and the load is shared by multiple branches. The single-channel drive power is small, the dynamic performance is high, and a large load can be driven.

Description

Technical Field

[0001] The present disclosure relates to the field of zero-gravity and low-gravity environment simulation, and in particular to a multi-degree-of-freedom platform. Background Art

[0002] Zero-gravity and low-gravity environment simulation test equipment can provide zero-gravity and low-gravity conditions for the equipment under test, and is widely needed in the aerospace field. It is usually used for adaptability testing of various performances of aerospace vehicles, assisting in the research and design of aerospace vehicles, and undertaking weightlessness training for pilots. The main methods and equipment for zero-gravity and low-gravity environment simulation currently include: (1) parabolic flight weightlessness simulation (2) buoyancy balance gravity method (3) rigid parallel mechanism simulation (4) cable mechanism simulation equipment.

[0003] (1) Parabolic flight weightlessness simulation method uses an airplane or a small rocket to make a parabolic flight to create a short-term microgravity environment. This method can only achieve a short-term microgravity environment, the working range is limited to the cabin, and the working cost is high, and it cannot achieve more complex working condition simulation.

[0004] (2) The buoyancy-balanced gravity method mainly uses the buoyancy of liquid and gas to offset gravity. Although it can establish a long-term stable gravity environment, this method is limited by liquid resistance. At the same time, the equipment of this method is bulky, and the center of gravity distribution and air resistance have great limitations on the operability and accuracy of the experiment.

[0005] (3) The rigid parallel mechanism simulation device is developed based on the hexapod motion platform and is driven by multiple groups of hydraulic cylinders or electric cylinders at different angles. Due to the limitation of the mechanical structure, it is impossible to achieve continuous motion on the multi-angle axis during the simulation process, and due to the limitation of the arm length of the hexapod telescopic cylinder, it is difficult to have a large range of motion in the vertical direction. Therefore, the performance of the simulation device is limited to a certain extent.

[0006] (4) The most commonly used cable mechanism simulation equipment is currently a single-degree-of-freedom cable drive mechanism, which can only simulate vertical motion and force. In order to achieve the simulation of multi-degree-of-freedom motion, an eight-cable traction configuration of "four up and four down" was proposed, which can achieve multi-degree-of-freedom motion simulation. However, due to the limitations of the external frame, cabin configuration, and the placement of traction points, the achievable yaw angle is very limited, and a large torque is required to achieve yaw. In some extreme working conditions, yaw cannot even be achieved. Therefore, the performance of the simulation device is limited to a certain extent.

[0007] The prior art discloses a cable-driven robot device for simulating zero-gravity and low-gravity environments (invention patent application publication number: CN104443448A), which relates to a cable-driven robot device for simulating zero-gravity and low-gravity environments, including a basic frame, ropes, a rope driving unit, a rope guiding device, a simulated load platform, a sensor and a control system. The eight ropes are arranged in a spatially symmetrical "four up and four down" manner. The extension or shortening of the ropes is driven by a motor-driven driving unit according to the instructions of the control system. The experimental device overcomes the problems of limited working space or insufficient dynamics of traditional simulation methods, and can realize 6-degree-of-freedom motion control and force simulation of the simulated load platform in zero-gravity or low-gravity environments.

[0008] The above-mentioned rope traction scheme of four on top and four on bottom realizes rope retraction and release through the cooperation of motor and drum to drive the load movement. When the eight ropes pull the load cabin, due to the limitations of the external frame, cabin configuration, and the placement of traction points, the achievable yaw angle is very limited, and a large torque is required to achieve yaw. Yaw cannot even be achieved under some extreme working conditions, which limits the performance of the motion platform to a certain extent.

[0009] Invention Disclosure

[0010] In view of the above-mentioned problems, the purpose of the present disclosure is to provide a multi-degree-of-freedom platform that can simulate zero gravity and low gravity environments, enable objects to perform a large range of displacement movements in space, and complete continuous axial movement on multiple axes, provide a larger effective load, and solve the problem that the yaw angle during movement is limited by the external frame, cabin configuration, and the placement of towing points, thereby achieving a large range of yaw and reducing the yaw load force of the rope.

[0011] To achieve the above-mentioned purpose, the present disclosure provides a multi-degree-of-freedom platform, including an arc frame, a rope and a load frame, the arc frame is a hollow cylindrical structure, and arc guide rails are respectively installed at the upper and lower ends of the arc frame, and a turntable is correspondingly installed on the arc guide rails, and rope driving mechanisms are respectively arranged at the upper and lower ends of the arc frame, and the two rope driving mechanisms are synchronously controlled and respectively connected to the turntable to drive the turntable to realize yaw direction movement, and the turntables at the upper and lower ends are respectively installed with four sets of crane mechanisms with an interval of 90°, and the turntable is provided with a plurality of guide devices corresponding to the positions of the crane mechanisms, and the ropes are arranged in a spatially symmetrical top-four and bottom-four manner, one end of each rope is wound around the crane mechanism, and the other end bypasses the guide device and is connected to the load frame, and the load frame realizes five degrees of freedom movement of X-axis, Y-axis, Z-axis, pitch and roll in three-dimensional space as the extension and retraction lengths of the eight ropes change.

[0012] Optionally, the rope drive mechanism includes a yaw motor and a rotating pair, and the yaw motor is connected to the turntable through the rotating pair, wherein the rotating pair is installed with an angle sensor, and the angle sensor feeds back the yaw angle in real time.

[0013] Optionally, the number of the crane mechanism and the number of the guide device are eight.

[0014] Optionally, each set of the crane mechanism includes a motor, a drum and an encoder, the drum is rotatably connected to the front end of the motor, and the encoder is arranged at the rear end of the motor. The motor drives the drum to rotate, and the length of the rope is changed as the drum rotates, and the encoder provides real-time feedback of the rope extension length.

[0015] Optionally, each set of the guide device includes a pulley, and a pressure sensor is installed on the pulley, and the pressure sensor provides real-time feedback of the tension of the rope.

[0016] Optionally, one end of each of the ropes is wound around a drum of the crane mechanism, and the other end is passed around a pulley of the guide device and connected to the load frame.

[0017] The beneficial effects of the present disclosure are: the multi-degree-of-freedom platform provided by the present disclosure can simulate a low-gravity environment, realize six-degree-of-freedom movement in three-dimensional space, can achieve a large range of displacement, and perform continuous axial movement on multiple axes, meet a large range of yaw requirements, share the load with multiple branches, have low single-channel drive power, high dynamic performance, and can drive larger loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a multi-degree-of-freedom platform according to an embodiment of the present disclosure;

[0019] The components in the accompanying drawings are marked as follows: 1. arc frame; 2. rope; 3. rope drive mechanism; 4. crane mechanism; 5. guide device; 6. load frame; 7. arc guide rail; 8. turntable; 31. yaw motor; 32. rotating pair; 33. angle sensor; 41. motor; 42. drum; 43. encoder; 51. pulley; 52. pressure sensor. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present disclosure are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present disclosure can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present disclosure.

[0021] See also Figure 1 , this embodiment includes:

[0022] The present disclosure provides a multi-degree-of-freedom platform, including an arc frame 1, a rope 2, a rope driving mechanism 3, a crane mechanism 4, a guide device 5 and a load frame 6.

[0023] The arc frame 1 is a hollow cylindrical structure, and an arc guide rail 7 is installed at its upper and lower ends respectively, and the yaw direction freedom degree is constrained by the upper and lower arc guide rails 7; a turntable 8 is installed corresponding to the arc guide rail 7, and two rope driving mechanisms 3 are arranged at the upper and lower ends of the arc frame 1 and connected to the turntable 8 accordingly. The two rope driving mechanisms 3 are synchronously controlled to generate yaw torque and drive the turntable 8 to realize yaw direction movement; four sets of vertical ceiling mechanisms are arranged on the turntable 8 at the upper end at an interval of 90°, and four sets of vertical ceiling mechanisms are arranged on the turntable 8 at the lower end at an interval of 90°. Eight sets of guide devices 5 are respectively installed on the two turntables 8 and correspond to the position of the crane mechanism 4. The eight ropes 2 are arranged in a spatially symmetrical upper four and lower four manner. One end of each rope 2 is wrapped around the crane mechanism 4, and the other end bypasses the guide device 5 and is connected to the load frame 6. The load frame 6 realizes five degrees of freedom movement of X-axis, Y-axis, Z-axis, pitch, and roll in three-dimensional space as the telescopic length of the eight ropes 2 changes.

[0024] The vertical crane mechanisms 4 being spaced 90° apart means that the angle between adjacent vertical crane mechanisms 4 in the same plane is 90°.

[0025] In the above, the rope drive mechanism 3 includes a yaw motor 31 and a rotating pair 32. The yaw motor 31 is connected to the turntable 8 through the rotating pair 32. The rotating pair 32 is equipped with an angle sensor 33, and the yaw angle is fed back in real time by the angle sensor 33. The two rope drive mechanisms 3 at the upper and lower ends of the arc frame 1 are synchronously controlled to generate a yaw torque, driving the turntable 8 to achieve yaw direction movement.

[0026] Each set of hoisting mechanism 4 includes a motor 41, a drum 42 and an encoder 43. The drum 42 is rotatably connected to the front end of the motor 41, and the encoder 43 is arranged at the rear end of the motor 41. The motor 41 drives the drum 42 to rotate, and the length of the rope 2 is changed with the rotation of the drum 42. The length of the rope is fed back in real time by the encoder 43. Each set of guide device 5 includes a pulley 51, and a pressure sensor 52 is installed on the pulley 51. The pressure sensor 52 feeds back the tension of the rope in real time.

[0027] Specifically, eight ropes 2, one end of each rope 2 is wound around a drum 42 of a crane mechanism 4, and the other end is passed through a pulley 51 in a guide device 5 in turn, and the other ends of the eight ropes 2 are connected to a load frame 6. The load frame 6 realizes five degrees of freedom movement in the three-dimensional space, namely, X-axis, Y-axis, Z-axis, pitch, and roll, as the other ends of the eight ropes 2 are extended and retracted. The motor 41 drives the drum 42 to rotate, and the length of the rope 2 is changed as the drum 42 rotates.

[0028] The control system obtains the position and posture of the load frame 6 through kinematic forward calculation according to the installation structure parameters of the platform and the measurement result of the length of the rope 2, analyzes the motion state of the load frame 6 in the zero gravity and low gravity environment in this posture, obtains the tension required to move to the next position and the extension and contraction amount of the rope 2 through dynamic and kinematic reverse calculation, and the controller outputs the instructions of the rope tension and length change, combined with the encoder 43 and the pressure sensor 52, thereby realizing the motion servo control of the low gravity environment simulation platform.

[0029] Working principle: Eight sets of crane mechanisms 4 and guide devices 5 are used to realize the retraction and release of eight ropes 2, thereby driving the load frame 6 to perform five degrees of freedom movement in X-axis, Y-axis, Z-axis, pitch and roll. The arc guide rail 7 installed on the arc frame 1 constrains the yaw degree of freedom movement. The yaw motor 31 installed on the arc guide rail 7 is synchronously controlled to generate a yaw torque, drive the turntable 8 to rotate, and realize yaw direction movement in three-dimensional space.

[0030] To sum up, the multi-degree-of-freedom platform provided by the present invention can simulate a low-gravity environment, realize six-degree-of-freedom movement in three-dimensional space, can achieve a large range of displacement, and perform continuous axial movement on multiple axes, meeting a large range of yaw requirements. The load is shared by multiple branches, the single-channel drive power is small, the dynamic performance is high, and a larger load can be driven.

[0031] The embodiments described above are merely descriptions of preferred implementation modes of the present disclosure and are not intended to limit the scope of the present disclosure. Without departing from the design spirit of the present disclosure, various modifications and improvements made to the technical solutions of the present disclosure by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present disclosure.

Claims

1. A multi-degree-of-freedom platform, characterized in that: It includes an arc frame, a rope and a load frame. The arc frame is a hollow cylindrical structure, and arc guide rails are respectively installed at the upper and lower ends of the arc frame. A turntable is installed corresponding to the arc guide rails. Rope driving mechanisms are respectively arranged at the upper and lower ends of the arc frame. The two rope driving mechanisms are synchronously controlled and respectively connected to the turntable to drive the turntable to realize yaw direction movement. The turntables at the upper and lower ends are respectively installed with four sets of crane mechanisms with an interval of 90°. The turntable is provided with a plurality of guide devices corresponding to the positions of the crane mechanisms. The ropes are arranged in a spatially symmetrical upper four and lower four manner. One end of each rope is wound around the crane mechanism, and the other end bypasses the guide device and is connected to the load frame. The load frame realizes five degrees of freedom movement in three-dimensional space, namely, X-axis, Y-axis, Z-axis, pitch, and roll, as the extension and contraction lengths of the eight ropes change. The rope drive mechanism comprises a yaw motor and a rotating pair, wherein the yaw motor is connected to the turntable via the rotating pair, wherein the rotating pair is equipped with an angle sensor, and the angle sensor provides real-time feedback of the yaw angle; Each set of the crane mechanism includes a motor, a drum and an encoder. The drum is rotatably connected to the front end of the motor, and the encoder is arranged at the rear end of the motor. The motor drives the drum to rotate, and the length of the rope is changed as the drum rotates. The encoder provides real-time feedback of the rope extension length.

2. The multi-degree-of-freedom platform according to claim 1, characterized in that: The number of the hoisting mechanism and the number of the guiding device are both eight.

3. The multi-degree-of-freedom platform according to claim 2, characterized in that: Each set of the guide device comprises a pulley, on which a pressure sensor is mounted, and the pressure sensor provides real-time feedback of the tension of the rope.

4. The multi-degree-of-freedom platform according to claim 3, characterized in that: One end of each of the ropes is wound around the drum of the hoist mechanism, and the other end is passed around the pulley of the guide device and connected to the load frame.

Images