Force-controlled series elastic actuators (SEAs) are the widely used components of novel physical human–robot interaction applications such as assistive and rehabilitation robotics. Series Elastic Actuators (SEA), consisting of a conven-tional actuator connected in series through an elastic element to a load, offer several benets for PAFOs. First, they offer a safer human-machine interface than rigid PAFO actuators do because the actuated joint is back-driveable and capable of shock absorption. Second, expensive load cells For applications requiring interaction with humans or unstructured environments, robots are increasingly designed to leverage the intentional drivetrain compliance of series elastic actuators (SEAs). Impedance control, likewise, is of particular value in these applications, having long been considered an effective means of addressing dynamic
Series elastic actuators (SEAs) often use linear metal springs as the torque transmitting elements in their driv-etrains . As commercial, off-the-shelf products, metal springs can be easily bought at low prices. However, using series linear springs in the drivetrain requires com-promises between torque resolution and actuation bandwidth Series Elastic Actuators employ a novel mechanical design architecture which goes against the common machine design principal of “stiffer is better”. A compliant element is placed between the gear train and driven load to intentionally reduce the stiffness of the actuator. Continuously-Variable Series-Elastic Actuator Luke Mooney1 2and Hugh Herr 1Department of Mechanical Engineering 2MIT Media Lab Massachusetts Institute of Technology Cambridge, MA, USA [email protected] [email protected] Abstract— Actuator efficiency is an important factor in the design of powered leg prostheses, orthoses, exoskeletons, and Series Elastic Actuators and Virtual Model Control Series-Elastic Actuator hea.Mpg. The Leg Lab invented and developed several kinds of series-elastic actuator, which use an instrumented spring in series with the load to provide good characteristics for robots that execute natural tasks.
Actuator efficiency is an important factor in design of powered legged robots. A continuously variable series-elastic actuator (CV-SEA) is presented as an efficient actuator for legged locomotion. The CV-SEA implements a continuously variable transmission (CVT) between a motor and series elastic element. The CVT reduces the torque seen at the motor, allowing the motor to operate in speed regimes of higher efficiency, while the series-elastic …
High spring compliance with low damping in combination with a cascaded, motor velocity based, control structure was successfully tested in simulation and experiments. Final tests with the entire leg demonstrate that the system can perform a hopping motion providing only positive actuator power. Series 75 Electric Actuators from Worcester Actuation Systems add a new dimension of operational dependability and flexibility to modern processes controlled by computers, programmable controllers and other electric control equipment. A multi-function capability permits use of the Series 75 actuator throughout the process for on/off, throttling
The actuator presented in this thesis is designed from the premise that \Sti ness isn't everything". The actuator, which incorporates a series elastic element, trades o achievable bandwidth for gains in stable, low noise force control, and protection against shock loads. The upper arm joints S1, S2, S3, L1, L2 each includes a rotary series elastic actuator assembly 26. The rotary series elastic actuator assembly 26 for each of the upper arm joints S 1 , S 2 , S 3 , L 1 , L 2 may be sized according to the packaging, torque, and power requirements at that joint. A series elastic actuator is constructed, and pilot data are collected to compare with model predictions. 2. Simple models of actuator power and energy delivery For Case 1, we consider a simple model to look at how an actuator delivers energy to launch a mass. Here a linear This paper presents the development of a compact, modular rotary series elastic actuator (SEA) design that can be customized to meet the requirements of a wide range of applications.
Series elastic robots typically have fairly linear actuator dynamics compared to their joint dynamics. To exploit this in trajectory optimization, Rachel Schlossman and I designed an iterative linear programming based trajectory optimizer which uses trust regions only for the robot impedance portion of the problem.
After a discussion of the trade-offs inherent in series elastic actuators, the authors present a control system for their use under general force or impedance control. The authors conclude with test results from a revolute series-elastic actuator meant for the arms of … Of a series elastic actuator is shown below: Fig. 1. Block Diagram of Series-Elastic Actuator The ﬁrst beneﬁt of the series elasticity is to low-pass ﬁlter shock loads, thereby greatly reducing peak output gear forces. Although this also low-pass ﬁlters the actuator’s output, we believe this is a place for an engineering trade-off Series elastic actuator (SEA). Joint torque tracking of stan-dard SEA has known limitations that the torque dynamics has an relative order of two, and, as a consequence, the torque controller often requires acceleration feedback when the desired torque is deﬁned by a function of velocity (for Series Elastic Actuators differ from traditional actuation techniques in that we introduce a spring between the motor/gearing elements and the output of the actuator. This results in "gains in stable, low noise force control, and protection against shock loads".
In the field of robotics, Series Elastic Actuators (SEAs) have drawn great interest. Composed of a motor in series with an elastic element, they are capable of accurate force control, energy storage, and filtering shock to the motor. In addition, smaller, less sophisticated motors may be used with a high friction, low backlash gear train [11 Design and characterization of a magneto-rheological series elastic actuator for a lower extremity exoskeleton Bing Chen1,2, Xuan Zhao3, Hao Ma3, Ling Qin1,4 and Wei-Hsin Liao3,4 1Department of Orthopaedics and Traumatology and Innovative Orthopaedic Biomaterial and Drug Translational Research Laboratory of Li Ka Shing Institute of Health Sciences, The Chinese University of Actuators determine the performance of robotic systems at the most intimate of levels. As a result, much work has been done to assess the performance of different actuator systems. However, biomimetics has not previously been utilized as a pretext for tuning a series elastic actuator system with the purpose of designing an empirical testing platform. Thus, an artificial muscle tendon system
Series elastic actuators are used to provide force-sensing capabilities to the arms. The sensors embedded throughout the arms are linked up to the cognitive system. Hands. The design of a humanoid hand is required to incorporate some way to measure and output force. A few older designs had force sensors in the fingertips. A Series Elastic Actuator (SEA) [Robinson, 2000] deliberately introduces compliance via a spring between the motor-gearbox and the load, and so has intrinsic low impedance. The spring’s compression (measured simply with a distance sensor) is proportional to the spring torque.
The P170 Orion is a linear series elastic actuator (SEA) with a unique combination of power-density, efficiency, and safety in a compact package. It is extremely versatile and suitable in applications where force control and power density are a requirement. Robotics family, series elastic actuators (SEAs) demonstrate how elastic elements improve the functionality of prosthetic legs [2–4], humanoid robots , and manufacturing robots working in close contact with human users . In contrast to rigid actuators, SEAs have an elastic element connected in series between the actuator and the load [7 Alps Motion Series Elastic Actuator. Details. AM SEA-d10Seires. AM SEA-d10Seires Spec. Overview. Spec SEA-d10-100 SEA-d10-150 SEA-d10-200 Strok(mm) 100 150 200 Rated Power Output(W) 200 200/400 200/400 Cont. Output Force(N) 850 850/1700 850/1700 Peak Output Speed(cm/s)
Force/Torque*Sensor* Series*Elas(c*Actuator* Fig. 1. Three different electromagnetic (EM) actuator concepts. (a) High-ratio geared motor with torque sensor, (b) Series elastic actuator, (c) Proprioceptive force control actuator. Often conﬂicting requirements on the design of EM actua-tors. Design processes for EM components are traditionally
Series Elastic Actuators (SEAs) are systems that provide compliance for the joints . Robinson et al. Applied a series elastic actuator to a biomimetic walking robot , Pratt developed low-impedance walking robots with series elastic actuators . To secure the safety of a compliant actuation system, Wyeth demonstrated the safety and Series elastic actuators tend to have more stable force control because the spring filters out the high-frequency motion of the mechanism. A low frequency in the system dynamics means that you can use slower control techniques, which is important when using digital controllers with naive control implementations, and sensors with significant This paper presents a compact rotary Series Elastic Actuator (rSEA) with nonlinear stiffness for the drive of lower limb exoskeletons. The rSEA can change its stiffness from zero to a large value with respect to the external load. A sensitive force control around the zero-torque equilibrium and a good performance in the high external load can thus be expected.
In this paper we introduce a new mechanism known as a Clutchable Series-Elastic Actuator (CSEA). The purpose of this device is to take advantage of both the properties of an SEA, as well provide the ability to store energy in a tuned series spring, when the desired task dynamics are elastically conservative in the torque-angle domain.