Hybrid Control of the Berkeley Lower Extremity Exoskeleton (BLEEX)

2005 ◽  
Author(s):  
Lihua Huang ◽  
Ryan Ryan Steger ◽  
H. Kazerooni
Keyword(s):  
Position Control ◽  
Hybrid Control ◽  
System Sensitivity ◽  
Walking Gait ◽  
Mixed Control ◽  
Stance Control ◽  
Control Scheme ◽  
Load Carrying ◽  
Human Limb ◽  
Careful Design

The first functional load-carrying and energetically autonomous exoskeleton was demonstrated at U.C. Berkeley, walking at the average speed of 0.9 m/s (2 mph) while carrying a 34 kg (75 lb) payload. The original BLEEX sensitivity amplification controller, based on positive feedback, was designed to increase the closed loop system sensitivity to its wearer’s forces and torques without any direct measurement from the wearer. The controller was successful at allowing natural and unobstructed load support for the pilot. This article presents an improved control scheme we call “mixed” control that adds robustness to changing BLEEX backpack payload. The walking gait cycle is divided into stance control and swing control phases. Position control is used for the BLEEX stance leg (including torso and backpack) and the sensitivity amplification controller is used for the swing leg. The controller is also designed to smoothly transitions between these two schemes as the pilot walks. With mixed control, the controller does not require a good model of the BLEEX torso and payload, which is difficult to obtain and subject to change as payload is added and removed. As a tradeoff, the position control used in this method requires the human to wear seven inclinometers to measure human limb and torso angles. These additional sensors require careful design to securely fasten them to the human and increase the time to don (and doff) BLEEX.

Force-Controlled Assembly of two Objects with a Two-arm Robot

Robotica ◽  
1991 ◽  
Vol 9 (3) ◽  
pp. 299-306 ◽  
Author(s):  
Pierre Dauchez ◽  
Xavier Delebarre
Keyword(s):  
Position Control ◽  
Hybrid Control ◽  
Contact Forces ◽  
Rigid Object ◽  
Assembly Task ◽  
Control Scheme ◽  
The One ◽  
Theoretical Results ◽  
Hybrid Control Scheme ◽  
Approach Phase

SUMMARYThe use of a two-arm robot for assembling two objects, with each being held by one arm, is presented. The assembly task is decomposed into an approach phase and an assembly phase. For each phase, we propose a solution for describing the task. For the approach phase, we suggest to describe the task with respect to a mobile reference frame, attached to the end effector of one of the arms. This allows us to take advantage of the redundancy of the system. For the assembly phase, we propose two solutions, both involving some kind of force control. The first one is based upon a position control similar to the one used for the approach phase, with an updating of the reference position through a measurement of the contact forces. The second scheme is derived from a symmetrical hybrid control scheme initially proposed by Uchiyama and Dauchez to control a two-arm robot handling a single rigid object. The main results of this scheme are summarized, and the way of using it for an assembly task is presented. Finally, the experimental setup we have installed to validate our theoretical results is described.

Modeling and Control of a Novel High-Pressure Pneumatic Servo Valve Direct-Driven by Voice Coil Motor

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Li Baoren ◽  
Gao Longlong ◽  
Yang Gang
Keyword(s):  
High Pressure ◽  
Pid Controller ◽  
Gas Flow ◽  
Position Control ◽  
Hybrid Control ◽  
Voice Coil Motor ◽  
Direct Drive ◽  
Modeling And Control ◽  
Servo Valve ◽  
Control Scheme

High-pressure pneumatic control valves have been widely investigated during last decades. The published literature includes experimental and analytical studies on both constant value on–off valve and pressure reducing valve, but rarely on servo valve. In this paper, a novel voice coil motor (VCM) direct drive high-pressure pneumatic servo valve (HPPSV) is proposed. The mathematical model of the HPPSV including electromechanical and fluid subsystem is presented. Furthermore, the hybrid control scheme consisting of a proportional integral differential (PID) controller with velocity/acceleration feed-forward and a disturbance observer is proposed to improve the control performance of the HPPSV, taking into account the factors such as compressibility of high-pressure gas, high nonlinearity of gas flow force and friction force. The experimental results show that the spool position control system based on the proposed control scheme has strong robustness and disturbance rejection capability, and the control accuracy of the valve spool position can be enhanced greatly compared with the conventional PID controller. The study has general implications in the development of high-pressure pneumatic servo valves and high-pressure pneumatic precision control field.

Hybrid Control Scheme of a Hydraulically Actuated Lower Extremity Exoskeleton for Load-Carrying

2017 ◽  
Vol 91 (3-4) ◽  
pp. 493-500 ◽  
Author(s):  
Yi Long ◽  
Zhi-jiang Du ◽  
Chao-feng Chen ◽  
Wei-dong Wang ◽  
Long He ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Hybrid Control ◽  
Control Scheme ◽  
Load Carrying ◽  
Hydraulically Actuated ◽  
Hybrid Control Scheme

Assembly Strategies for Parts with a Plane of Symmetry

Robotica ◽  
1991 ◽  
Vol 9 (2) ◽  
pp. 189-195 ◽  
Author(s):  
N. A. Aspragathos
Keyword(s):  
Large Class ◽  
Position Control ◽  
Hybrid Control ◽  
Robotic System ◽  
Torque Sensor ◽  
Complex Assembly ◽  
Assembly Tasks

SUMMARYThis paper describes the development of assembly strategies based on hybrid force/position control. The assembly strategies developed are confined to the large class of assembly tasks defined as a peg-in-the-hole assembly having a plane of symmetry passing through the axis of insertion.The basic idea to develop a robotic system for programmable assembly is presented. This system can currently operate controlled manipulators with minor modifications, i.e. if a force/torque sensor and proper software for hybrid control are provided.The principles of writing assembly strategies are analysed and examples of more complex assembly tasks than the classic round peg-in-the-hole are discussed in detail.

scholarly journals Electronic Differential and Neuro-Fuzzy Sliding Mode Control with Extended State Observer for an Electric Vehicle System

2018 ◽  
Vol 61 ◽  
pp. 00007
Author(s):  
Ibrahim Farouk Bouguenna ◽  
Ahmed Azaiz ◽  
Ahmed Tahour ◽  
Ahmed Larbaoui
Keyword(s):  
Sliding Mode Control ◽  
Hybrid Control ◽  
Sliding Mode ◽  
Current Loop ◽  
Fuzzy Sliding Mode Control ◽  
Mode Control ◽  
Neuro Fuzzy ◽  
Control Scheme ◽  
Fuzzy Sliding Mode ◽  
Hybrid Control Scheme

In this paper a neuro-fuzzy-sliding mode control (NFSMC) with extended state observer (ESO) technique; is designed to guarantee the traction of an electric vehicle with two distinct permanent magnet synchronous motor (PMSM). Each PMSM systems (source-convertermotor) are attached to an electronic differential (ED), in order to adjust the senses of direction of the vehicle, and sustain a stable speed by adapting the difference in velocity of each motor-wheel according to the direction in the case of a turn. Two types of controllers are employed by a hybrid control scheme to assure the control and the performance of the vehicle. This hybrid control scheme guarantees the stability of the vehicle by ED, reduces the chattering phenomena in the PMSM electric motor, and improves the disturbance rejection ability which employs tow types of controllers. The neuro-fuzzy sliding mode control on the direct current loop and ESO controller on the speed loop, and the quadratic current loop; taking into account the dynamic of the vehicle. Simulation runs under Matlab/Simulink to assess the efficiency, and strength of the recommended control method on the closed loop system.

scholarly journals Design and Experimental Evaluation of a Robust Position Controller for an Electrohydrostatic Actuator Using Adaptive Antiwindup Sliding Mode Scheme

2013 ◽  
Vol 2013 ◽  
pp. 1-16 ◽  
Author(s):  
Ji Min Lee ◽  
Sung Hwan Park ◽  
Jong Shik Kim
Keyword(s):  
Control Systems ◽  
Pid Controller ◽  
Position Control ◽  
Sliding Mode ◽  
System Modeling ◽  
Modeling Error ◽  
Load Disturbance ◽  
Control Scheme ◽  
Position Controller ◽  
System Uncertainties

A robust control scheme is proposed for the position control of the electrohydrostatic actuator (EHA) when considering hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities. To reduce overshoot due to a saturation of electric motor and to realize robustness against load disturbance and lumped system uncertainties such as varying parameters and modeling error, this paper proposes an adaptive antiwindup PID sliding mode scheme as a robust position controller for the EHA system. An optimal PID controller and an optimal anti-windup PID controller are also designed to compare control performance. An EHA prototype is developed, carrying out system modeling and parameter identification in designing the position controller. The simply identified linear model serves as the basis for the design of the position controllers, while the robustness of the control systems is compared by experiments. The adaptive anti-windup PID sliding mode controller has been found to have the desired performance and become robust against hardware saturation, load disturbance, and lumped system uncertainties and nonlinearities.

Impedance Control of Dual-Arm Systems Based on the Object with Senseless Force

2013 ◽  
Vol 765-767 ◽  
pp. 1920-1923
Author(s):  
Li Jiang ◽  
Yang Zhou ◽  
Bin Wang ◽  
Chao Yu
Keyword(s):  
Numerical Simulations ◽  
Relative Position ◽  
Position Control ◽  
Impedance Control ◽  
Force Sensors ◽  
Operational Space ◽  
Novel Approach ◽  
Control Scheme ◽  
Statics And Dynamics ◽  
Dual Arm

A novel approach to impedance control based on the object is proposed to control dual-arm systems with senseless force. Considering the motion of the object, the statics and dynamics of the dual-arm systems are modeled. Extending the dynamics of dual-arm system and the impedance of object to the operational space, impedance control with senseless force is presented. Simulations on a dual-arm system are carried out to demonstrate the performance of the proposed control scheme. Comparing with position control, results of numerical simulations show that the proposed scheme realizes suitable compliant behaviors in terms of the object, and minimizes the error of the relative position between the manipulators even without force sensors.

scholarly journals Transient stability control by means of under-frequency load shedding and a hybrid control scheme

2017 ◽  
Vol 28 (4) ◽  
Author(s):  
P. F. Le Roux ◽  
R.C. Bansal
Keyword(s):  
Transient Stability ◽  
Hybrid Control ◽  
Stability Control ◽  
Load Shedding ◽  
Electrical Network ◽  
Traditional Methods ◽  
Transient Fault ◽  
System A ◽  
Control Scheme ◽  
Hybrid Control Scheme

An electrical network constantly faces unforeseen events such as faults on lines, loss of load and loss of generation. Under-frequency load shedding and generator tripping are traditional methods used to stabilise a network when a transient fault occurs. These methods will prevent any network instability by shedding load or tripping the most critical generator at a calculated time when required. By executing these methods, the network can be stabilised in terms of balancing the generation and the load of a power system. A hybrid control scheme is proposed where the traditional methods are combined to reduce the stress levels exerted on the network and to minimise the load to be shed.

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