The Experts below are selected from a list of 9378 Experts worldwide ranked by ideXlab platform
S Q Xie - One of the best experts on this subject based on the ideXlab platform.
-
Neural Network Adaptive Control of Hand Rehabilitation Robot Driven by Flexible Pneumatic Muscles
'Institute of Electrical and Electronics Engineers (IEEE)', 2021Co-Authors: Shao F, Meng W, Ai Q, S Q XieAbstract:The aim of this study is to design a reliable and stable controller for hand Rehabilitation Robot driven by flexible pneumatic muscles(FPMs) for post stroke patients. Position control is key to perform effective Rehabilitation Robotic exercise. However, it is difficult to achieve precise control due to the nonlinearity and hysteresis of the flexible muscles. The efficient control system is required to realize the high-precision control of the joint angle. In this paper, to achieve the stability and anti-interference ability of the system, an improved neural network adaptive control(INNAC) method is proposed. The neural network is used to estimate the unknown items and the adaptive control is used to realize the adaptive characteristics in the unknown environment, so as to realize the stability and high precision control of the control system when encountering human interferences. Finally, experiments were carried out on Robot with human participants for five fingers movement assistance. The results show that the control system can achieve good control effect and anti-interference ability
-
adaptive patient cooperative control of a compliant ankle Rehabilitation Robot carr with enhanced training safety
IEEE Transactions on Industrial Electronics, 2018Co-Authors: Mingming Zhang, S Q Xie, Guoli Zhu, Wei Meng, Xiaolin Huang, Allan J VealeAbstract:This paper proposes a new adaptive patient-cooperative control strategy for improving the effectiveness and safety of Robot-assisted ankle Rehabilitation. This control strategy has been developed and implemented on a compliant ankle Rehabilitation Robot (CARR). The CARR is actuated by four Festo Fluidic muscles located to the calf in parallel, has three rotational degrees of freedom. The control scheme consists of a position controller implemented in joint space and a high-level admittance controller in task space. The admittance controller adaptively modifies the predefined trajectory based on real-time ankle measurement, which enhances the training safety of the Robot. Experiments were carried out using different modes to validate the proposed control strategy on the CARR. Three training modes include: 1) a passive mode using a joint-space position controller, 2) a patient–Robot cooperative mode using a fixed-parameter admittance controller, and 3) a cooperative mode using a variable-parameter admittance controller. Results demonstrate satisfactory trajectory tracking accuracy, even when externally disturbed, with a maximum normalized root mean square deviation less than 5.4%. These experimental findings suggest the potential of this new patient-cooperative control strategy as a safe and engaging control solution for Rehabilitation Robots.
-
reconfigurable workspace and torque capacity of a compliant ankle Rehabilitation Robot carr
Robotics and Autonomous Systems, 2017Co-Authors: Mingming Zhang, Guoli Zhu, Jinghui Cao, Qing Miao, Xiangfeng Zeng, S Q XieAbstract:Abstract The novelty of this paper is the adjustable workspace and torque capacity of a compliant ankle Rehabilitation Robot (CARR). The Robot has three rotational degrees of freedom (DOFs) redundantly actuated by four compliant actuators. It suffers from conflicting workspace and actuation torque due to the use of a parallel mechanism and compliant actuators. To address this issue, also considering physical constraints imposed by human users, the CARR is designed with reconfigurability to make a trade-off between workspace and torque capacity for meeting different training requirements. Theoretical analysis indicates that varying kinematic and dynamic performance of the Robot can be achieved by reconfiguring the layout of the actuators. Experiments with/without load also demonstrate the validity of the reconfigurable Robotic design for practical applications.
-
three stage design analysis and multicriteria optimization of a parallel ankle Rehabilitation Robot using genetic algorithm
IEEE Transactions on Automation Science and Engineering, 2015Co-Authors: Prashant K Jamwal, Shahid Hussain, S Q XieAbstract:This paper describes the design analysis and optimization of a novel 3-degrees of freedom (DOF) wearable parallel Robot developed for ankle Rehabilitation treatments. To address the challenges arising from the use of a parallel mechanism, flexible actuators, and the constraints imposed by the ankle Rehabilitation treatment, a complete Robot design analysis is performed. Three design stages of the Robot, namely, kinematic design, actuation design, and structural design are identified and investigated, and, in the process, six important performance objectives are identified which are vital to achieve design goals. Initially, the optimization is performed by considering only a single objective. Further analysis revealed that some of these objectives are conflicting, and hence these are required to be simultaneously optimized. To investigate a further improvement in the optimal values of design objectives, a preference-based approach and evolutionary-algorithm-based nondominated sorting algorithm (NSGA II) are adapted to the present design optimization problem. Results from NSGA II are compared with the results obtained from the single objective optimization and preference-based optimization approaches. It is found that NSGA II is able to provide better design solutions and is adequate to optimize all of the objective functions concurrently. Finally, a fuzzy-based ranking method has been devised and implemented in order to select the final design solution from the set of nondominated solutions obtained through NSGA II. The proposed design analysis of parallel Robots together with the multiobjective optimization and subsequent fuzzy-based ranking can be generalized with modest efforts for the development of all of the classes of parallel Robots.
-
kinematic design optimization of a parallel ankle Rehabilitation Robot using modified genetic algorithm
Robotics and Autonomous Systems, 2009Co-Authors: Prashant K Jamwal, S Q XieAbstract:Rehabilitation Robotics is an evolving area of active research and recently novel mechanisms have been proposed to reinstate complex human movements. Parallel Robots are of particular interest to researchers since they are rigid and can provide enough load capacity for human joint movements. This paper proposes a soft parallel Robot (SPR) for ankle joint Rehabilitation. Kinematic workspace analysis is carried out and the singularity criterion of the SPR's Jacobian matrix is used to define the feasible workspace. A global conditioning number (GCN) is defined using the Jacobian matrix as a performance index for the evaluation of the Robot design. An optimization problem is formulated to minimize the GCN using modified genetic algorithm (GA). Results from simple GA and modified GA are compared and discussed. As a result of the optimization, an optimal Robot design is obtained which has a near unity GCN with almost uniform distribution in the entire feasible workspace of the Robot.
Prashant K Jamwal - One of the best experts on this subject based on the ideXlab platform.
-
impedance control of an intrinsically compliant parallel ankle Rehabilitation Robot
IEEE Transactions on Industrial Electronics, 2016Co-Authors: Prashant K Jamwal, Shahid Hussain, Mergen H Ghayesh, Svetlana V RogozinaAbstract:Robot-aided physical therapy should encourage subject’s voluntary participation to achieve rapid motor function recovery. In order to enhance subject’s cooperation during training sessions, the Robot should allow deviation in the prescribed path depending on the subject’s modified limb motions subsequent to the disability. In the present work, an interactive training paradigm based on the impedance control was developed for a lightweight intrinsically compliant parallel ankle Rehabilitation Robot. The parallel ankle Robot is powered by pneumatic muscle actuators (PMAs). The proposed training paradigm allows the patients to modify the Robot imposed motions according to their own level of disability. The parallel Robot was operated in four training modes namely position control, zero-impedance control, nonzero-impedance control with high compliance, and nonzero-impedance control with low compliance to evaluate the performance of proposed control scheme. The impedance control scheme was evaluated on 10 neurologically intact subjects. The experimental results show that an increase in Robotic compliance encouraged subjects to participate more actively in the training process. This work advances the current state of the art in the compliant actuation of parallel ankle Rehabilitation Robots in the context of interactive training.
-
three stage design analysis and multicriteria optimization of a parallel ankle Rehabilitation Robot using genetic algorithm
IEEE Transactions on Automation Science and Engineering, 2015Co-Authors: Prashant K Jamwal, Shahid Hussain, S Q XieAbstract:This paper describes the design analysis and optimization of a novel 3-degrees of freedom (DOF) wearable parallel Robot developed for ankle Rehabilitation treatments. To address the challenges arising from the use of a parallel mechanism, flexible actuators, and the constraints imposed by the ankle Rehabilitation treatment, a complete Robot design analysis is performed. Three design stages of the Robot, namely, kinematic design, actuation design, and structural design are identified and investigated, and, in the process, six important performance objectives are identified which are vital to achieve design goals. Initially, the optimization is performed by considering only a single objective. Further analysis revealed that some of these objectives are conflicting, and hence these are required to be simultaneously optimized. To investigate a further improvement in the optimal values of design objectives, a preference-based approach and evolutionary-algorithm-based nondominated sorting algorithm (NSGA II) are adapted to the present design optimization problem. Results from NSGA II are compared with the results obtained from the single objective optimization and preference-based optimization approaches. It is found that NSGA II is able to provide better design solutions and is adequate to optimize all of the objective functions concurrently. Finally, a fuzzy-based ranking method has been devised and implemented in order to select the final design solution from the set of nondominated solutions obtained through NSGA II. The proposed design analysis of parallel Robots together with the multiobjective optimization and subsequent fuzzy-based ranking can be generalized with modest efforts for the development of all of the classes of parallel Robots.
-
an iterative fuzzy controller for pneumatic muscle driven Rehabilitation Robot
Expert Systems With Applications, 2011Co-Authors: Prashant K JamwalAbstract:Pneumatic muscle actuators (PMA) show great potential in wearable and compliant Rehabilitation devices as they are flexible and lightweight. However, the varying and non-linear behavior of the actuators imposes modeling and control challenges, which are difficult to comprehend. This research proposes a new wearable ankle Rehabilitation Robot, first of its kind in the world driven by PMAs in a parallel form. The focus of this presented work is to develop an iterative controller to overcome the challenges for PMA driven devices. A fuzzy feedforward controller is proposed to accurately predict the behavior of PMA. A modified Genetic Algorithm (GA) is developed to identify the optimal set of parameters for the fuzzy controller. The iterative controller has been tested on the proposed PMA driven ankle Rehabilitation Robot, and is found capable of mapping the complex relationship in length, force and pressure of the PMA with high accuracy. Experimental results show excellent trajectory tracking performance of the controller when given various desired trajectories.
-
forward kinematics modelling of a parallel ankle Rehabilitation Robot using modified fuzzy inference
Mechanism and Machine Theory, 2010Co-Authors: Prashant K Jamwal, Y H Tsoi, Kean C AwAbstract:This article deals with forward kinematics (FK) mapping of a parallel Robot, especially designed for ankle joint Rehabilitation treatments. Parallel Robots exhibit highly coupled non-linear motions hence conventionally a unique closed form solution of their FK cannot be obtained. However, since FK is a key module in closed loop position and force control, its accurate and fast solution is indispensable. To solve the FK problem, a modified fuzzy inference system (FIS) is proposed in this paper for the first time which is time efficient and becomes very accurate when its parameters are optimized. In the proposed work, FIS has been optimized using three approaches namely: gradient descent (GD), genetic algorithm (GA) and modified genetic algorithm (MGA). The FIS, optimized by MGA has been found to be more accurate than the GD and GA optimized FIS. Performance of the MGA based fuzzy system has been found better both in terms of accuracy and computation time, when compared with Newton–Raphson iterative method and other fuzzy and neural approaches.
-
kinematic design optimization of a parallel ankle Rehabilitation Robot using modified genetic algorithm
Robotics and Autonomous Systems, 2009Co-Authors: Prashant K Jamwal, S Q XieAbstract:Rehabilitation Robotics is an evolving area of active research and recently novel mechanisms have been proposed to reinstate complex human movements. Parallel Robots are of particular interest to researchers since they are rigid and can provide enough load capacity for human joint movements. This paper proposes a soft parallel Robot (SPR) for ankle joint Rehabilitation. Kinematic workspace analysis is carried out and the singularity criterion of the SPR's Jacobian matrix is used to define the feasible workspace. A global conditioning number (GCN) is defined using the Jacobian matrix as a performance index for the evaluation of the Robot design. An optimization problem is formulated to minimize the GCN using modified genetic algorithm (GA). Results from simple GA and modified GA are compared and discussed. As a result of the optimization, an optimal Robot design is obtained which has a near unity GCN with almost uniform distribution in the entire feasible workspace of the Robot.
Herman Van Der Kooij - One of the best experts on this subject based on the ideXlab platform.
-
Sensing pressure distribution on a lower-limb exoskeleton physical human-machine interface
Sensors, 2011Co-Authors: Stefano Marco Maria De Rossi, Alessandro Persichetti, Herman Van Der Kooij, Bram Koopman, Fabrizio Vecchi, Renaud Ronsse, Tommaso Lenzi, Nicola Vitiello, Auke Jan Ijspeert, Maria Chiara CarrozzaAbstract:A sensory apparatus to monitor pressure distribution on the physical human-Robot interface of lower-limb exoskeletons is presented. We propose a distributed measure of the interaction pressure over the whole contact area between the user and the machine as an alternative measurement method of human-Robot interaction. To obtain this measure, an array of newly-developed soft silicone pressure sensors is inserted between the limb and the mechanical interface that connects the Robot to the user, in direct contact with the wearer's skin. Compared to state-of-the-art measures, the advantage of this approach is that it allows for a distributed measure of the interaction pressure, which could be useful for the assessment of safety and comfort of human-Robot interaction. This paper presents the new sensor and its characterization, and the development of an interaction measurement apparatus, which is applied to a lower-limb Rehabilitation Robot. The system is calibrated, and an example its use during a prototypical gait training task is presented.
-
A series elastic- and bowden-cable-based actuation system for use as torque actuator in exoskeleton-type Robots
International Journal of Robotics Research, 2006Co-Authors: Jan F. Veneman, Rik Kruidhof, Frans Van Der Helm, Ralf Ekkelenkamp, Herman Van Der KooijAbstract:Within the context of impedance controlled exoskeletons, common actuators have important drawbacks. Either the actuators are heavy, have a complex structure or are poor torque sources, due to gearing or heavy nonlinearity. Considering our application, an impedance controlled gait Rehabilitation Robot for treadmill-training, we designed an actuation system that might avoid these drawbacks. It combines a lightweight joint and a simple structure with adequate torque source quality. It consists of a servomotor, a flexible Bowden cable transmission, and a force feedback loop based on a series elastic element. A basic model was developed that is shown to describe the basic dynamics of the actuator well enough for design purpose. Further measurements show that performance is sufficient for use in a gait Rehabilitation Robot. The demanded force tracking bandwidths were met: 11 Hz bandwidth for the full force range (demanded 4 Hz) and 20 Hz bandwidth for smaller force range (demanded 12 Hz). The mechanical output impedance of the actuator could be reduced to hardly perceptible level. Maxima of about 0.7 Nm peaks for 4 Hz imposed motions appeared, corresponding to less than 2.5% of the maximal force output. These peaks were caused by the stick friction in the Bowden cables. Spring stiffness variation showed that both a too stiff and a too compliant spring can worsen performance. A stiff spring reduces the maximum allowable controller gain. The relatively low control gain then causes a larger effect of stick in the force output, resulting in a less smooth output in general. Low spring stiffness, on the other side, decreases the performance of the system, because saturation will occur sooner.
Jan F. Veneman - One of the best experts on this subject based on the ideXlab platform.
-
compliant actuation of Rehabilitation Robots
IEEE Robotics & Automation Magazine, 2008Co-Authors: Heike Vallery, Ralf Ekkelenkamp, Jan F. Veneman, E H F Van Asseldonk, Martin Buss, H Van Der KooijAbstract:This article discusses the pros and cons of compliant actuation for Rehabilitation Robots on the example of LOPES, focusing on the cons. After illustrating the bandwidth limitations, a new result has been derived: if stability in terms of passivity of the haptic device is desired, the renderable stiffness is bounded by the stiffness of the SEA's elastic component. In practical experiments with the VMC, the aforementioned limitations affected the control performance. Desired gait modifications were not tracked exactly, because the subjects were able to deviate from the prescribed pattern even in the stiffest possible configuration. Despite the limitations, the practical experiments also demonstrated the general effectiveness of the realization. Manipulation of selected gait parameters is possible, whereby other parameters are left unaffected. This high selectivity is made possible by the low level of undesired interaction torques, which is achieved by elastic decoupling of motor mass and a lightweight exoskeleton. The discrepancy between theoretical bounds and rendered stiffness indicated that healthy subjects might represent a stabilizing component of the coupled system, which could be different for patients. In light of the theoretical stability analysis and with the focus on patients, the LOPES actuation was slightly modified. The Robot was equipped with stiffer springs to obtain sufficient stiffness and to ensure stability without relying on stabilizing effects of the human. For this application, the disadvantages of compliant actuation can thus be tolerated or dealt with, and they are small compared with the advantages. Given that a Rehabilitation Robot, in the first place, is supposed to imitate therapist action, the limitations of bandwidth and stiffness do not pose severe problems. In contrast, safety and backdrivability are highly relevant, and they can be ensured easier with a compliant actuator. Therefore, we conclude that compliant actuation and a lightweight exoskeleton provide effective means to accomplish the desired AAN behavior of a Rehabilitation Robot. The next step is to evaluate the Robot behavior, control performance, and therapeutic effectiveness in patient studies.
-
A series elastic- and bowden-cable-based actuation system for use as torque actuator in exoskeleton-type Robots
International Journal of Robotics Research, 2006Co-Authors: Jan F. Veneman, Rik Kruidhof, Frans Van Der Helm, Ralf Ekkelenkamp, Herman Van Der KooijAbstract:Within the context of impedance controlled exoskeletons, common actuators have important drawbacks. Either the actuators are heavy, have a complex structure or are poor torque sources, due to gearing or heavy nonlinearity. Considering our application, an impedance controlled gait Rehabilitation Robot for treadmill-training, we designed an actuation system that might avoid these drawbacks. It combines a lightweight joint and a simple structure with adequate torque source quality. It consists of a servomotor, a flexible Bowden cable transmission, and a force feedback loop based on a series elastic element. A basic model was developed that is shown to describe the basic dynamics of the actuator well enough for design purpose. Further measurements show that performance is sufficient for use in a gait Rehabilitation Robot. The demanded force tracking bandwidths were met: 11 Hz bandwidth for the full force range (demanded 4 Hz) and 20 Hz bandwidth for smaller force range (demanded 12 Hz). The mechanical output impedance of the actuator could be reduced to hardly perceptible level. Maxima of about 0.7 Nm peaks for 4 Hz imposed motions appeared, corresponding to less than 2.5% of the maximal force output. These peaks were caused by the stick friction in the Bowden cables. Spring stiffness variation showed that both a too stiff and a too compliant spring can worsen performance. A stiff spring reduces the maximum allowable controller gain. The relatively low control gain then causes a larger effect of stick in the force output, resulting in a less smooth output in general. Low spring stiffness, on the other side, decreases the performance of the system, because saturation will occur sooner.
-
design of a series elastic and bowden cable based actuation system for use as torque actuator in exoskeleton type training
International Conference on Rehabilitation Robotics, 2005Co-Authors: Jan F. Veneman, Rik Kruidhof, Ralf Ekkelenkamp, F C T Van Der Helm, H Van Der KooijAbstract:Common actuators have important drawbacks for use in an exoskeleton type of Rehabilitation (training) Robot. Either the actuators are heavy, complex or poor torque sources. A new actuation system is proposed and tested that combines a lightweight joint and a simple structure with adequate torque source quality. It consists of a servomotor, a flexible Bowden cable transmission, and a force feedback loop based on a series elastic element. Measurements show that performance is sufficient for use in a gait Rehabilitation Robot.
Robert Riener - One of the best experts on this subject based on the ideXlab platform.
-
Feedforward model based arm weight compensation with the Rehabilitation Robot ARMin
2017 International Conference on Rehabilitation Robotics (ICORR), 2017Co-Authors: Fabian Just, Robert Riener, Özhan Özen, Stefano Tortora, Georg RauterAbstract:Highly impaired stroke patients at early stages of recovery are unable to generate enough muscle force to lift the weight of their own arm. Accordingly, task-related training is strongly limited or even impossible. However, as soon as partial or full arm weight support is provided, patients are enabled to perform arm Rehabilitation training again throughout an increased workspace. In the literature, the current solutions for providing arm weight support are mostly mechanical. These systems have components that restrict the freedom of movement or entail additional disturbances. A scalable weight compensation for upper and lower arm that is online adjustable as well as generalizable to any Robotic system is necessary. In this paper, a model-based feedforward weight compensation of upper and lower arm fulfilling these requirements is introduced. The proposed method is tested with the upper extremity Rehabilitation Robot ARMin V, but can be applied in any other actuated exoskeleton system. Experimental results were verified using EMG measurements. These results revealed that the proposed weight compensation reduces the effort of the subjects to 26% on average and more importantly throughout the entire workspace of the Robot.
-
control strategies and artificial intelligence in Rehabilitation Robotics
Ai Magazine, 2015Co-Authors: Domen Novak, Robert RienerAbstract:Rehabilitation Robots physically support and guide a patient's limb during motor therapy, but require sophisticated control algorithms and artificial intelligence to do so. This article provides an overview of the state of the art in this area. It begins with the dominant paradigm of assistive control, from impedance-based cooperative controller through electromyography and intention estimation. It then covers challenge-based algorithms, which provide more difficult and complex tasks for the patient to perform through resistive control and error augmentation. Furthermore, it describes exercise adaptation algorithms that change the overall exercise intensity based on the patient's performance or physiological responses, as well as socially assistive Robots that provide only verbal and visual guidance. The article concludes with a discussion of the current challenges in Rehabilitation Robot software: evaluating existing control strategies in a clinical setting as well as increasing the Robot's autonomy using entirely new artificial intelligence techniques.
-
enhancing patient freedom in Rehabilitation Robotics using gaze based intention detection
IEEE International Conference on Rehabilitation Robotics, 2013Co-Authors: Domen Novak, Robert RienerAbstract:Several design strategies for Rehabilitation Robotics have aimed to improve patients' experiences using motivating and engaging virtual environments. This paper presents a new design strategy: enhancing patient freedom with a complex virtual environment that intelligently detects patients' intentions and supports the intended actions. A `virtual kitchen' scenario has been developed in which many possible actions can be performed at any time, allowing patients to experiment and giving them more freedom. Remote eye tracking is used to detect the intended action and trigger appropriate support by a Rehabilitation Robot. This approach requires no additional equipment attached to the patient and has a calibration time of less than a minute. The system was tested on healthy subjects using the ARMin III arm Rehabilitation Robot. It was found to be technically feasible and usable by healthy subjects. However, the intention detection algorithm should be improved using better sensor fusion, and clinical tests with patients are needed to evaluate the system's usability and potential therapeutic benefits.
-
effects of intensive arm training with the Rehabilitation Robot armin ii in chronic stroke patients four single cases
Journal of Neuroengineering and Rehabilitation, 2009Co-Authors: Patricia Staubli, Tobias Nef, Verena Klamrothmarganska, Robert RienerAbstract:Robot-assisted therapy offers a promising approach to neuroRehabilitation, particularly for severely to moderately impaired stroke patients. The objective of this study was to investigate the effects of intensive arm training on motor performance in four chronic stroke patients using the Robot ARMin II. ARMin II is an exoskeleton Robot with six degrees of freedom (DOF) moving shoulder, elbow and wrist joints. Four volunteers with chronic (≥ 12 months post-stroke) left side hemi-paresis and different levels of motor severity were enrolled in the study. They received Robot-assisted therapy over a period of eight weeks, three to four therapy sessions per week, each session of one hour. Patients 1 and 4 had four one-hour training sessions per week and patients 2 and 3 had three one-hour training sessions per week. Primary outcome variable was the Fugl-Meyer Score of the upper extremity Assessment (FMA), secondary outcomes were the Wolf Motor Function Test (WMFT), the Catherine Bergego Scale (CBS), the Maximal Voluntary Torques (MVTs) and a questionnaire about ADL-tasks, progress, changes, motivation etc. Three out of four patients showed significant improvements (p < 0.05) in the main outcome. The improvements in the FMA scores were aligned with the objective results of MVTs. Most improvements were maintained or even increased from discharge to the six-month follow-up. Data clearly indicate that intensive arm therapy with the Robot ARMin II can significantly improve motor function of the paretic arm in some stroke patients, even those in a chronic state. The findings of the study provide a basis for a subsequent controlled randomized clinical trial.
-
patient cooperative control providing safe support without restricting movement
2009Co-Authors: Heike Vallery, Marco Guidali, Alexander Duschauwicke, Robert RienerAbstract:Patient-cooperative behavior of a Rehabilitation Robot can be seen as a tight interplay of three control components: The first and most important is the intervention paradigm, which can for example be assistance, resistance, or error augmentation. The second and third are more related to the underlying properties of the Robot: On the one hand the Robot should be transparent in “free” movements, and on the other hand it should provide a safe training frame with appropriate virtual constraints for the movement. In this paper, control strategies to enhance transparency and to constrain movement with virtual tunnels are presented using the examples of the ARMin and the Lokomat, which are Rehabilitation Robots for upper and lower extremities, respectively. Differences and similarities in control of these Robots are outlined in terms of the control strategies for transparency enhancement and movement constraints. The control concepts Generalized Elasticities and Path Control are described, which improve transparency in free movements inside an allowed spatial region, and which impose movement constraints to confine the user to this allowed region. Generalized Elastic Path Control unifies both control approaches within a single potential field, and preliminary results of this controller on the Lokomat are shown.