Design of a motion profile that provides nonvibrating operation of a system with hybrid input shaping method

Abstract

The present invention relates to a motion profile that reduces residual vibrations occurring both during and after motion.

Description

[0001] DESIGN OF A MOTION PROFILE THAT PROVIDES NONVIBRATING OPERATION OF A SYSTEM WITH HYBRID INPUT SHAPING METHOD

[0002] Technical Field of the Invention

[0003] The present invention relates to a motion profile method that reduces residual vibrations occurring both during and after motion.

[0004] The invention can be used for motion control in industrial robotic arms, crane systems, surgical robotic systems, robotic arms operating in space, autonomous vehicles, mobile robots, and electronic drive systems.

[0005] State of the Art

[0006] In order to perform the tasks performed in moving systems quickly, reliably and with high accuracy, different solutions have been studied. In control methods, closed-loop control methods are generally preferred for good motion control. In these methods, the output depending on an input applied to the system is observed and evaluated on the controller, and a second control signal is sent to the system.

[0007] In other methods, the outputs that the input signals applied to the systems will produce in the system are calculated and input signal designs are studied accordingly. Input signals are designed by looking at the dynamic parameters of the system such as natural frequency and damping. For systems using trapezoidal velocity profiles, it has been studied to reduce vibrations by determining the deceleration time of the trapezoidal input as integer multiples (n*Td / 2, n=1 ,2,3,... ) of half of the natural period (Td / 2).

[0008] The methods used to control the motions of systems are costly and include complex solutions. In particular, eliminating the vibrations that occur during and after the motion together is still a difficult problem.

[0009] In cases where robotic arms used in industry perform repetitive movements, the process repetition period needs not to coincide with the natural period of the robotic arm. This creates restrictions and difficulties in the operations to be performed. In methods using closed control, more equipment is required to measure the output and generate the control signal. Therefore, these applications both increase the cost of the systems and make them cumbersome. Although they can provide good motion control, these methods are difficult to apply in areas where both energy is limited and lightweight system designs are required, such as spacecraft.

[0010] In other methods, since the inputs applied to the system focus on the vibrations that occur after the motion, they cannot show sufficient success in the vibrations during the motion of the systems. Since the design is made depending on the system parameters, these methods show high sensitivity to the correct estimation of the system parameters. In addition, in load-carrying systems such as robotic arms, the dynamic system parameters also change since the amount of load changes according to the work done. In these cases, the input signals need to be redesigned for each situation.

[0011] In the designs where the deceleration time of the trapezoidal input is dependent on the natural period of the system, vibration reduction is provided to a certain extent. Although a significant reduction is provided in the even multiples of half of the period of the system (n*Td / 2, n=2,4,6, ... ), it has been observed that in the odd multiples (n*Td / 2, n=1 ,3,5, ... ), sufficient reduction is not provided. In addition, this method can only be effective on the residual vibrations that occur after the motion. It is not effective in the vibrations that occur during the motion.

[0012] The invention that is the subject of the application numbered “US6216058B1” in the state of the art relates to a system that provides reliable and numerically efficient generation of time-optimal trajectories with easy-to-follow or continuous acceleration profiles for simple and mixed movements of single and multi-arm robotic manipulators such as extension and retraction movements along a flat plane.

[0013] The invention that is the subject of the application numbered “US4916635A” in the state of the art relates to a method for generating input to a system to minimise undesirable dynamics. The first constraints limiting the available input are determined and the second constraints are established on the change in the system response with changes in the system properties.

[0014] The invention that is the subject of the application numbered “TR2020 / 07854” in the state of the art relates to a system that provides minimum vibration in rigid or flexible, translational or rotational, multi-degree-of-freedom systems during motion and when they reach the final position, by using the period calculated over the fundamental natural frequency and damping ratio of the controlled system.

[0015] Since the inputs applied to the system in the methods in the state of the art focus on the vibrations that occur after the motion, they cannot show sufficient success in the vibrations during the motion of the systems.

[0016] As a result, due to the negativities described above and the inadequacy of existing solutions on the subject, a new technology is needed in the relevant technical field.

[0017] Brief Description and Aims of the Invention

[0018] The present invention relates to a motion profile that reduces residual vibrations occurring both during and after motion. The invention can be used for motion control in industrial robotic arms, crane systems, surgical robotic systems, robotic arms operating in space, autonomous vehicles, mobile robots, and electronic drive systems.

[0019] The most important aim of the invention is to reduce vibrations both during and after the motion when the system is moved by using a hybrid open-loop control method that uses two different control methods together.

[0020] Another aim of the invention is to eliminate the need for an extra control system cost by using an open-loop control system.

[0021] Another aim of the invention is to reduce the sensitivity to system parameters calculated by experimental means such as damping. This ensures that the method works successfully even in small error margins or small changes in system dynamics.

[0022] Another aim of the invention is to reduce costs since it can be used without extra equipment compared to closed-loop control methods. It enables lighter system designs by means of needing the less equipment in the system.

[0023] Detailed Description of the Invention The present invention relates to a motion profile method that reduces residual vibrations occurring both during and after motion.

[0024] The invention can be used for motion control in industrial robotic arms, crane systems, surgical robotic systems, robotic arms operating in space, autonomous vehicles, mobile robots, and electronic drive systems.

[0025] With the invention, it is possible to reduce the residual vibrations that occur both during and after the motion of the systems. In the control method based on the design of the deceleration time of the trapezoidal input, it has also provided the reduction of residual vibrations for odd multiples of the natural period (n*Td / 2, n=1 ,3,5, ... ). The method used also reduces the sensitivity to the dynamic parameters of the system considered. Since the method used is an open-loop control system, it does not require an extra control system cost.

[0026] It has been observed that the vibrations that occur during the motion are eliminated by 60% with the invention, and the vibrations that occur after the motion are eliminated by 98%. The control method, which is based on the modification of the deceleration time of the commonly used input signal, has provided the reduction of vibrations in all multiples of its natural period.

[0027] The sensitivity to system parameters calculated by experimental means such as damping has been reduced. This ensures that the method works successfully even in small error margins or small changes in system dynamics.

[0028] It reduces the cost since it can be used without extra equipment compared to closed- loop control methods. It enables lighter system designs by means of needing the less equipment in the system.

[0029] The system is basically a hybrid open-loop control method that uses two different control methods together. First, the natural period and damping ratio of the system to be controlled are determined. Depending on the natural period of the system, the acceleration, constant and deceleration times of the trapezoidal input are calculated, and the input signal is produced. Depending on the natural period and damping ratio of the system, an input shaper using the three-step input shaping method is designed. The previously produced trapezoidal input signal is passed through this shaper, and a new input signal is obtained. The new input signal is the motion profile of the system. When the system is moved with this input, vibrations are reduced both during and after the motion.

[0030] The invention works successfully in vibrations that occur both during and after the motion. In addition, it also reduces sensitivity to system parameters. It is a method that can offer all these features together. The invention can be implemented as a program adapted to the computer or an electronic circuit or integrated circuit.

[0031] It has been observed that the invention works successfully at the current level. It is planned to be brought to a state that provides solutions by also taking into account the changing system parameters. In addition, it is desired to transform the system into a system that can determine the parameters autonomously and determine the control signal within the framework of the reported constraints.

[0032] The invention can be used in industrial robotic arms, robotic arms in space vehicles, mobile robots, crane systems, etc. It can be used by robotic arm companies (such as KUKA, ABB). It can be used in robotic systems in the space and aviation sector. Companies working in this field can benefit from this invention since it can be used in light and flexible systems. It can be preferred in robotic vehicles to be produced in the space field, where new steps are being taken. It can be used in mobile robot and drone systems. Since it can also be used in auxiliary home robots, relevant companies can prefer it. It can be used in all electric motor machine areas that work stop-start.

[0033] The invention can be implemented as a program adapted to the computer or an electronic circuit or integrated circuit. In the preferred implementation of the invention, it works on a processor.

[0034] Motion profile method that provides nonvibrating operation of a system with hybrid input shaping method, comprises the following process steps that work on the processor:

[0035] - determining the natural period and damping ratio of the system to be controlled,

[0036] - producing the input signal by calculating the acceleration, constant and deceleration times of the trapezoidal input depending on the natural period of the system, - designing an input shaper using a three-step input shaping method depending on the natural period and damping ratio of the system, and

[0037] - passing the generated trapezoidal input signal through the shaper to obtain a new input signal which is the motion profile of the system.

Claims

CLAIMS1. Motion profile method that provides nonvibrating operation of a system with hybrid input shaping method, comprises the following process steps that work on the processor:- determining the natural period and damping ratio of the system to be controlled,- producing the input signal by calculating the acceleration, constant and deceleration times of the trapezoidal input depending on the natural period of the system,- designing an input shaper using a three-step input shaping method depending on the natural period and damping ratio of the system, and passing the generated trapezoidal input signal through the shaper to obtain a new input signal which is the motion profile of the system.