Quantitative Feedback Input Shaping for Flexible-Joint Robot Manipulator

Chatlatanagulchai, Withit; Kijdech, Dumrongsak; Benjalersyarnon, Takat; Damyot, Supparat

doi:10.1115/1.4032931

Cited by 15 publications

(7 citation statements)

References 35 publications

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“…In the feed forward case, the effect of a command is estimated by means of a mechanical model, and the actuation is chosen in a way that the dynamic system performs the desired motion. Input shaping is a widely used feed forward control strategy that was first published in the 50s by Smith [29], and is still a research topic of control strategies [2,6,19,20]. In contrast, the feedback control approach measures the actual states of the system and acts based on the measured states.…”

Section: Introductionmentioning

confidence: 99%

Delay-induced bifurcations in collocated position control of an elastic arm

Szaksz

Stépàn

2021

Nonlinear Dyn

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The interference of the elasticity of a single robotic arm and the unavoidable time delay of its position control is analysed from nonlinear vibrations viewpoint. The simplified mechanical model of two blocks and a connecting spring considers the first vibration mode of the arm, while the collocated proportional-derivative (PD) control uses the state of the first block only and actuates also there. It is assumed that the relevant nonlinearity is the saturation of the delayed control force. The linear stability analysis proves that stabilizable and non-stabilizable parameter regions follow each other periodically even for large spring stiffnesses and for tiny time delays. Hopf bifurcation calculation is carried out after an infinite-dimensional centre manifold reduction, and closed-form algebraic expressions are given for the amplitudes of the emerging oscillations. These results support the experimental tuning of the control gains since the parameters of the arising and often unexpected self-excited vibrations can serve as a guide for this practical procedure.

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Section: Introductionmentioning

confidence: 99%

Delay-induced bifurcations in collocated position control of an elastic arm

Szaksz

Stépàn

2021

Nonlinear Dyn

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“…The Quantitative Feedback Input Shaping technique addresses nonlinear and time-varying systems even a trade-off to vibration induced by disturbance and noise can be quantifiable with this technique. Unfortunately, large and powerful computers are needed [ 25 ].…”

Section: Conceptualization: Robust Input Shapingmentioning

confidence: 99%

Dynamics and Embedded Internet of Things Input Shaping Control for Overhead Cranes Transporting Multibody Payloads

Peláez

Vaugan

Izquierdo

et al. 2018

Sensors

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Input shaping is an Optimal Control feedforward strategy whose ability to define how and when a flexible dynamical system defined by Ordinary Differential Equations (ODEs) and computer controlled would move into its operative space, without command induced unwanted dynamics, has been exhaustively demonstrated. This work examines the issue of Embedded Internet of Things (IoT) Input Shaping with regard to real time control of multibody oscillatory systems whose dynamics are better described by differential algebraic equations (DAEs). An overhead crane hanging a double link multibody payload has been appointed as a benchmark case; it is a multibody, multimode system. This might be worst scenario to implement Input Shaping. The reasons can be found in the wide array of constraints that arise. Firstly, the reliability of the multibody model was tested on a Functional Mock-Up Interface (FMI) with the two link payload suspended from the trolley by comparing the experimental video tapping signals in time domain faced with the signals extracted from the multibody model. The FFTs of the simulated and the experimental signal contain the same frequency harmonics only with somewhat different power due to the real world light damping in the joints. The application of this approach may be extended to other cases i.e., the usefulness of mobile hydraulic cranes is limited because the payload is supported by an overhead cable under tension that allows oscillation to occur during crane motion. If the payload size is not negligible small when compared with the cable length may introduce an additional oscillatory mode that creates a multibody double pendulum. To give the insight into the double pendulum dynamics by Lagrangian methods two slender rods as payloads are analyzed dealing with the overhead crane and a composite revolute-revolute joint is proposed to model the cable of the hydraulic crane, both assumptions facilitates an affordable analysis. This allows developing a general study of this type of multibody payloads dynamics including its normal modes, modes ratios plus ranges of frequencies expected. Input Shapers were calculated for those multimodes of vibration by convolving Specified Insensitivity (SI) shapers for each mode plus a novel Direct SI-SI shaper well suited to reduce the computational requirements, i.e., the number of the shaper taps, to carry out the convolution sum in real time by the IoT device based on a single microcontroller working as the command generator. Several comparisons are presented for the shaped and unshaped responses using both the multibody model, the experimental FMI set-up and finally a real world hydraulic crane under slewing motion commanded by an analog Joystick connected by two RF modules 802.15.4 to the IoT device that carry out the convolution sum in real time. Input Shaping improves the performances for all the cases.

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“…Fig. 5 shows the implementation of this type; the so-called outside-the-loop input shaping (OLIS) [13], where b r is the baseline reference signal, IS is the input shaping filter, s r is the shaped reference signal, e is the tracking error, G is the feedback controller, u is the control effort, P is the flexible plant, and y is the controlled output. The major advantage of the OLIS is that the time delay from the input shaping filter is outside the feedback loop; therefore, the time delay does not adversely affect the performance of the feedback system by limiting the controller bandwidth.…”

Section: A Implementation Of Input Shapingmentioning

confidence: 99%

Improving Manual Control of Two-Link Pendulum on Gantry Crane With Anti-Delay Closed-Loop Input Shaping

Chatlatanagulchai

Pongpanich

Yaemprasuan

2017

Volume 4B: Dynamics, Vibration, and Control

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This paper presents a novel and improved technique in manual control of flexible systems. Flexible systems, when subject to a rapid movement commanded by a human operator, exhibit severe oscillation, causing low positioning accuracy, high fatigue to the human operator, and unsafe accidents. Input shaping filter was proposed to reduce this oscillation by using the destructive interference principle where impulse responses cancel one another resulting in zero residual vibration. Recently, the input shaping filter was placed inside the feedback loop, so-called closed-loop signal shaping, to assist with the manual control of the flexible systems. The vibration was successfully suppressed. However, the input shaping filter also introduced time delays in the feedback loop, which limit the performance of the human operator. This paper offers a breakthrough idea by introducing an anti-delay algorithm called Smith predictor inside the feedback loop. When the plant model is perfect, it can be shown that the Smith predictor can entirely remove the effect of time delay from the feedback loop; therefore, improving the performance of the human operator. Experiments on manual control of a two-link pendulum on a gantry crane show the effectiveness of the proposed algorithm. The human operator was able to move the two-link pendulum with minimum residual vibration. Comparing to the currently world-best technique, the proposed technique could achieve faster maneuvering time, higher accuracy, and with less subjective difficulty.

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Quantitative Feedback Input Shaping for Flexible-Joint Robot Manipulator

Cited by 15 publications

References 35 publications

Delay-induced bifurcations in collocated position control of an elastic arm

Delay-induced bifurcations in collocated position control of an elastic arm

Dynamics and Embedded Internet of Things Input Shaping Control for Overhead Cranes Transporting Multibody Payloads

Improving Manual Control of Two-Link Pendulum on Gantry Crane With Anti-Delay Closed-Loop Input Shaping

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