Exoskeletons are attracting great attention as a new means of rehabilitation devices. In such applications, control algorithms ofexoskeletons are often inspired by nature for natural and effective assistance for patients. In this paper, a control algorithm inspired by aquatic therapy is introduced. Aquatic therapy provides various beneficial effects for rehabilitation based on useful properties of water, e.g., buoyancy and drag. The proposed controller calculates joint torques equivalent to the buoyant and drag forces. Then, an exoskeleton-type assistive device generates the calculated joint torques to provide the similar effects as aquatic therapy. In this paper, the Sogang University biomedical assist robot is utilized as a testbed. This paper also discusses the mechanical impedance of actuators, which obstructs implementation of controllers in practice. The resistive forces generated by actuators are precisely modeled and compensated to realize the control algorithm inspired by aquatic therapy correctly and effectively.

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In this paper we describe the design and evaluation of a passive lower limb assistive exoskeleton based on omnidirectional rehabilitation vehicle. According to the leg dynamics during assisted walking, we optimize the design parameters to make the lower limb obtain the most positive energy. We employ MACCEPA (mechanically adjustable compliance and controllable equilibrium position actuator) in design which generates the constant torque in knee joint. Experiments were performed on injured people and their results verify the system effect in reducing physical power.

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In this paper, the exoskeleton robot is first briefly introduced, the mathematical model for the upper limb exoskeleton robot and the force and position double-closed-loop control system are discussed. Then the authors discuss the type design of all sectors for the control system, and the various components of the system are given. Lastly, through the use of Matlab’s Simulink software, the simulation of the upper limb exoskeleton robot is carried out and the response characteristics of the brushless DC motor PID control system are analyzed. The results show that the use of the PID control system has good characteristics of fast responsibility and stable signal output.

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In this paper, a new type of master finger in exoskeleton type has been developed to implement master-slave operation for DLR/HIT dexterous hand. The finger has three novel characteristics. Firstly, the exoskeleton mechanism uses ldquofour-bar mechanism jointrdquo, which rotates about an instant center that coincides with joint center of operator’s finger. Secondly, the master finger can distinguish the contact and non-contact mode. The two modes enable free motion and natural contact sensation between operator and master finger respectively. Thirdly, the master finger can exert forces in the direction of extension and flexion because it can make active motion in the two directions. In order to assure faster data transmission and near zero delay in master-slave operation, a digital signal processing/field programmable gate array (DSP/FPGA-FPGA) structure is proposed to control the master finger. The kernel of the hardware system consists of a peripheral component interface (PCI)-based DSP/FPGA board configured as high-level and a FPGA board configured as low-level. By utilizing low-voltage differential signaling (LVDS) serial data bus and PCI bus, the high-level can communicate with the low-level and PC. Using the principle of Virtual work, the relationship between driving torque and the force acting at the tip of master finger is acquired and validated by an experiment conducted to the operation of master finger and DLR/HIT dexterous finger. Experimental results also demonstrate that the master finger can augment telepresence.

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A control methodology is developed for modulating shoulder impedance in an arm exoskeleton during physical therapy. Setting the remote center of compliance at the shoulder will allow the exoskeleton to enact resistance training protocols that strengthen the rotator cuff and other joint musculature supporting the shoulder complex. The rotational kinematics for the shoulder are first derived, and then the torques applied at the shoulder are estimated using force sensors placed at the hand and elbow interfaces. Impedance and admittance control schemes are both developed for realizing isolateral strengthening exercises, and some preliminary experimental results are presented for implementation on an arm exoskeleton currently under development.

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