A Hybrid Actuation Approach for Haptic Devices (original) (raw)

A New Actuation Approach for Haptic Interface Design

The International Journal of Robotics Research, 2009

Traditional haptic interfaces available today use motors to generate forces, while a more recent class of devices uses passive elements to constrain movement. This paper presents a new hybrid actuation approach that combines the use of brakes, springs and motors. The proposed actuation design is potentially safer and more energy efficient than haptic devices that only rely on motors for actuation, and also overcomes many of the rendering limitations displayed by existing passive haptic displays. Applications of this new technology range from devices where safety and reliability are of prime concerns (e.g. large force-feedback interfaces) to devices which can only be powered by limited energy sources such as small batteries (e.g. portable haptic interfaces).

A new hybrid actuator approach for force-feedback devices

2012 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2012

A new concept of hybrid actuator for haptic devices is proposed. This system combines a controllable magnetorheological brake with a conventional DC motor. Both actuators are linked through an overrunning clutch. Thus, the motor is connected to the handle while the brake can exert a resistive force only in a defined direction. This configuration enables the brake and the motor to be engaged at the same time because the torque imposed by the motor is not canceled by the brake. The concept and its control laws have been investigated using a 1-DOF haptic device. The experimental results show that is possible to combine a powerful brake with a small DC motor. This approach reduces the power consumption, expand the range of forces, achieve global stability in the system providing thereby safety to the user. Besides, the proposed independent control laws enable the actuator to be adaptable in many different haptic applications.

Design and Control of a Dual Unidirectional Brake Hybrid Actuation System for Haptic Devices

IEEE Transactions on Haptics, 2014

Hybrid actuators combining brakes and motors have emerged as an efficient solution to achieve high performance in haptic devices. In this paper an actuation approach using two unidirectional brakes and a DC motor is proposed. The brakes are coupled to overrunning clutches and can apply a torque in only one rotational direction. The associated control laws, that are independent of the virtual environment model, calculate the control gains in real time in order limit the energy and the stiffness delivered by the motor to ensure stability. The reference torque is respected using the combination of the motor and the brake. Finally, an user experiment has been performed to evaluate the influence of passive and active torque differences in the perception of elasticity. The proposed actuator has a torque range of 0.03 Nm to 5.5 Nm with a 17.75 kNm −2 torque density.

Advanced DC Motor Drive for Haptic Devices

Electronics ETF, 2012

Haptics covers many different forms of mechanical interaction with human senses by engaging, touch, vibrations and forces/torques, established for the purpose of augmenting the feedback structure during human-machine interaction. A haptic device has mechanical part, moved by actuators from one and human hand or fingers from the other, actuators, drives, sensing elements, as well as algorithms designed to control the interaction between human and machine in positioning and motion control tasks. With such a system, motors can be controlled in a way to simulate various environments, defined by their material and dynamics, for example pushing soft ball uphill. Haptic devices are becoming more popular in medical applications after introduction of modern medical robots with many different extensions for minimally invasive surgery or diagnostics based on palpation. This paper discusses one DC motor driver custom designed for the purpose of designing a haptic device for medical applications.

Performance analysis of a 2-link haptic device with electric brakes

11th Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems, 2003. HAPTICS 2003. Proceedings.

Passive haptic devices have better stability than active ones, but usually have limited capability of haptic display. In this paper a 2-link passive haptic device equipped with electric brakes is discussed. Since passive devices cannot generate forces in all directions, determination of the region available for force reflection is important to their design and operation. This analysis can be done by a socalled force manipulability ellipsoid (FME). In some haptic applications, the endpoint of a device is required to move along a certain trajectory (e.g., the surface of a virtual wall) and haptic display plays a role of path guide. Performance of path guidance is also investigated in this research. Finally, guideline for the design of more efficient passive haptic devices is briefly discussed.

Stable haptic interaction using passive and active actuators

2013 IEEE International Conference on Robotics and Automation, 2013

This paper presents a stable control method for a hybrid haptic device comprising a brake and a motor. A review of stability condition via describing function analysis is first presented. The results show that while brakes are intrinsically stable, an active device is limited in terms of stiffness. The stability is however improved if the brake simulates a physical damping. Subsequently, the stability condition is obtained via passivity condition analysis. The results demonstrate that the stiffness is improved by engaging both actuators to create resistive forces and the passivity is respected assuming a passive virtual environment. An energy and a stiffness-bounding algorithms have been developed in order to assure the stability of the coupled system in this case. It has been tested and validated using a 1-DOF hybrid haptic device by the simulation of an unstable and an active virtual environments respectively. Experimental results show that the displayable stiffness is improved under stability conditions using the control method. Furthermore, it allows the hybrid system to simulate nonlinear and unstable virtual environments and the controller remains independent of the virtual environment model.

Portable haptic interface with active functional design

Smart Structures and Materials 1999: Smart Structures and Integrated Systems, 1999

Haptic rendering is the process of computing and generating forces in response to user interactions with virtual objects. The interaction modality of haptic feedback gains more and more of importance for simulation tasks in virtual environments. However there are only very few portable haptic interfaces, with which the user can experience in a natural way the sensation of force feedback. The scope of this paper is to present a new portable haptic interface using shape memory alloy wires as actuators. Shape memory alloys (SMA), and especially the nickel-titanium compositions, offer a number of engineering properties available in no other material. The ability to respond with significant force and motion to small changes in ambient temperature and the capability to convert heat energy into mechanical work provide the designer with a new array of possibilities. Beside some application specific characterization of the actuator material with respect to energy consumption and dynamic behavior for loading, the mechanical layout of the interface is discussed in detail. To realize a light and compact design of the interface, a flexure hinge is considered as an essential part of interface.

The ultimate haptic device: First step

World Haptics 2009 - Third Joint EuroHaptics conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems, 2009

We describe a single-axis haptic interface which is based on a dualstage actuator technique and which is aimed at achieving perfect transparency to a human user. The paper shows how all parasitic forces arising from inertia and friction can be brought below human detection thresholds, yet, the system is able to output significant torque. It has a stage with a large motor coupled to a distal stage with a smaller motor via a viscous coupler based on the principle of eddy current induction. The paper also describes its control principle and preliminary results.

Design and performance of a high fidelity, low mass, linear haptic display

2005

We built a high fidelity, low mass, linear haptic display, with a peak force output of 8.5 Newtons, continuous force output of 1.3 Newtons, range of motion of approximately 15 millimeters, sensing resolution of 0.5 microns, and a -3dB bandwidth of approximately 550 Hz. By having low apparent mass of approximately 5 grams, we can realistically render linear switches, which themselves have a moving mass of only a few grams. This device utilizes a low inertia rotary motor, but over only a limited range of motion, allowing it to be driven without commutation. We constructed a linear, current controlled amplifier to drive the system. Additionally, the motor windings allow us to use electrical damping to add physical damping to the system to improve its performance.

Interaction Power Flow Based Control of a 1-DOF Hybrid Haptic Interface

Lecture Notes in Computer Science, 2012

A control method based on instantaneous interaction energy is used to control a hybrid haptic actuator, comprising magnetorheological brake and a DC motor, linked in parallel. We have combined this method with a quantitative analysis of interaction forces to develop two control variants, which can determine an optimal sharing of efforts between the active and dissipative actuators and make the system more reactive. The proposed control laws have been validated in a rotary 1-DOF force-feedback device.