Simultaneous Force and Stiffness Control of a Pneumatic Actuator

Shen, Xiangrong; Goldfarb, Michael

doi:10.1115/1.2745850

Cited by 61 publications

(48 citation statements)

References 8 publications

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“…The mapping in Tables III and IV We select the same values for the transition points γ 2 and γ 5 as in 5-mode (see (11)). Applying the same methodology to the venting profile, we select the following values for the transition points γ 4 and γ 3 in the venting profile:…”

Section: Duty Cycle Mapping For the 7-mode Systemmentioning

confidence: 99%

“…Pneumatic actuators are widely used in many different industries and offer many advantages such as low cost, good power/weight ratio, cleanliness, and safety [7], [8], [9]. Moreover, they permit to set actuators' compliance up more easily than with electric ones by controlling the amount of air inside both chambers [10], [11]. However, they suffer from drawbacks including friction and variation of the actuator dynamics to load and piston position along the cylinder stroke [12] and accurate position control of such actuators is difficult due to the nonlinear dynamics [13].…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear Discontinuous Dynamics Averaging and PWM-Based Sliding Control of Solenoid-Valve Pneumatic Actuators

Hodgson

Tavakoli

Pham

et al. 2015

IEEE/ASME Trans. Mechatron.

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Abstract-A pneumatic actuator with solenoid valves is a discontinuous-input system because each valve can be either in on or off state. For such an actuator, this paper proposes a slidingmode control scheme that is based on an averaged continuousinput model of the discontinuous-input open-loop system. The averaged model is obtained from the nonlinear dynamics of the open-loop system undergoing pulse-width-modulation (PWM) at the input (i.e., valve open/close action). The PWM duty cycle will be regarded as a continuous input to the proposed averaged model, and thus generated by the proposed slidingmode controller.For the sliding control design, we note that a pneumatic actuator has two chambers with a total of four on/off valves. Thus, there are sixteen possible combinations for valves' switching. Seven of these sixteen operating "modes" are considered both functional and unique. The proposed sliding control utilizes and switches between these seven modes of the open-loop system in order to select the ones with necessary and sufficient amounts of drive energy. In comparing the new 7-mode controller to previous controllers, we will demonstrate reductions in the position tracking error and the number of switches made by the actuator's on/off valves. The proposed control scheme is used in both position control of a pneumatic cylinder and bilateral control of a one degree of freedom teleoperation system. Experimental results are presented to validate our theoretical findings.

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Section: Duty Cycle Mapping For the 7-mode Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear Discontinuous Dynamics Averaging and PWM-Based Sliding Control of Solenoid-Valve Pneumatic Actuators

Hodgson

Tavakoli

Pham

et al. 2015

IEEE/ASME Trans. Mechatron.

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show abstract

“…In addition, dynamic stiffness of the cylinder can be expressed in terms of pressure and displacement as follows [20]:…”

Section: Comparison Of Closed-loop Performance Of Different Pwm Schemesmentioning

confidence: 99%

An experimental comparison of PWM schemes to improve positioning of servo pneumatic systems

Shiee

Sharifi

Fathi

et al. 2015

Int J Adv Manuf Technol

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Distinct advantages of the combination of the pneumatic actuated plants with "on/off" solenoid valves have motivated many researchers to conduct research in this scope. Pulse-width modulation (PWM) is a tool to use such combination in servo tasks. This paper studies the most frequent and well-reported PWM schemes. These PWM schemes have been applied for positioning tasks of the pneumatic actuators using solenoid on/off valves. In this study, the positioning performance of the servo pneumatic system, utilizing different PWM schemes, is investigated through several experiments with step and sinusoidal reference inputs. Rise time, overshoot, and steady-state error, in step input tests, and tracking performance in sinusoidal tests demonstrate the effectiveness of the deployed PWM schemes in the pneumatic system behaviors. Moreover, the closed-loop results demonstrate that the system robustness against the increase of the system's mass is associated with the applied PWM scheme. Based on the openloop results, two factors are found to be affecting PWM schemes performance, namely, the difference in the crosssectional areas on each side of the piston and the piston position, in which these factors have not been considered in the design procedure of the former studies. Taking into account the former factor, a modified version of the PWM schemes is proposed. Steady-state errors in closed-loop tests verify the effectiveness of the developed modified PWM schemes.

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“…4 Such research on human-robot physical interaction ranges from mechanical design, sensing, and motion control of a device to gait training and neuromuscular functional recovery. However, few research investigations have been conducted into selectively controlling individual muscle forces via human-robot interaction.…”

Section: Introductionmentioning

confidence: 99%

Pneumatically powered robotic exercise device to induce a specific force profile in target lower extremity muscles

Henderson

Ueda

2014

Robotica

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The goal of this research is to establish a methodology to actively control a pneumatically driven robotic device that can induce specific muscle force patterns in target muscles during a subject's voluntary movement. In this paper, the generation of constant forces in the rectus femoris muscle throughout the knee extension, i.e., isotonic contractions, was studied. Due to a highly nonlinear nature of mapping the joint torque to muscle force, a simple application of constant torques to the knee joint would not realize isotonic contractions. The proposed robotic exercise accounted for nonlinear moment arms of muscles as functions of joint angles and nonlinear coordination of multiple muscles in the neuromuscular system to accomplish individual muscle control. A pneumatically powered one degree-of-freedom device that can impose active force feedback control has been designed and built. An exercise-planning algorithm has been developed that involved a musculoskeletal model of the lower body, and the dynamics of a pneumatic actuator. Five constant force profiles were tested for 20 healthy volunteers and electromyographic signals were collected while the device was applying calculated force profiles.

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Simultaneous Force and Stiffness Control of a Pneumatic Actuator

Cited by 61 publications

References 8 publications

Nonlinear Discontinuous Dynamics Averaging and PWM-Based Sliding Control of Solenoid-Valve Pneumatic Actuators

Nonlinear Discontinuous Dynamics Averaging and PWM-Based Sliding Control of Solenoid-Valve Pneumatic Actuators

An experimental comparison of PWM schemes to improve positioning of servo pneumatic systems

Pneumatically powered robotic exercise device to induce a specific force profile in target lower extremity muscles

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