Mechanical Design of a Low-Impedance 6-Degree-of-Freedom Displacement Sensor for Intuitive Physical Human-Robot Interaction

2020 ◽  
pp. 1-15
Author(s):  
Gabriel Boucher ◽  
Thierry Laliberte ◽  
Clement Gosselin
Keyword(s):  
Mechanical Design ◽  
Human Robot Interaction ◽  
Degree Of Freedom ◽  
Displacement Sensor ◽  
Robot Interaction ◽  
Serial Robot ◽  
Kinematic Sensitivity ◽  
Impedance Sensor ◽  
Forward Kinematic ◽  
Six Degree Of Freedom

Abstract This paper presents the mechanical design of a six-degree-of-freedom low-impedance displacement sensor. The sensor is mounted around a link of a serial robot and used as an interface for physical human-robot interaction. The motivation for the use of a low-impedance sensor is first discussed. The mechanical design of each of the elastic components of the sensor is then presented. The kinematic architecture of the mechanism is introduced and the inverse and forward kinematic problems are solved. The kinematic sensitivity is then used to characterize the accuracy of the mechanism. Finally, the design of a prototype is presented and experimental results are provided.

Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

2015 ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Human Robot Interaction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Robot Interaction ◽  
End Effector ◽  
Serial Robots ◽  
Serial Robot ◽  
Maximum Contact ◽  
Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human-robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

Force Capabilities of Two-Degree-of-Freedom Serial Robots Equipped With Passive Isotropic Force Limiters

2016 ◽  
Vol 8 (5) ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Human Robot Interaction ◽  
Contact Forces ◽  
Degree Of Freedom ◽  
Practical Implementation ◽  
Robot Interaction ◽  
End Effector ◽  
Serial Robots ◽  
Serial Robot ◽  
Maximum Contact ◽  
Two Degree Of Freedom

This paper proposes the use of passive force and torque limiting devices to bound the maximum forces that can be applied at the end-effector or along the links of a robot, thereby ensuring the safety of human–robot interaction. Planar isotropic force limiting modules are proposed and used to analyze the force capabilities of a two-degree-of-freedom (2DOF) planar serial robot. The force capabilities at the end-effector are first analyzed. It is shown that, using isotropic force limiting modules, the performance to safety index remains excellent for all configurations of the robot. The maximum contact forces along the links of the robot are then analyzed. Force and torque limiters are distributed along the structure of the robot in order to ensure that the forces applied at any point of contact along the links are bounded. A power analysis is then presented in order to support the results. Finally, examples of mechanical designs of force/torque limiters are shown to illustrate a possible practical implementation of the concept.

Design and Static Analysis of Elastic Force and Torque Limiting Devices for Safe Physical Human-Robot Interaction

2016 ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Static Analysis ◽  
Robotic Manipulator ◽  
Numerical Results ◽  
Elastic Force ◽  
Human Robot Interaction ◽  
Degree Of Freedom ◽  
Elastic Component ◽  
Robot Interaction ◽  
Nonlinear Relationships

This paper presents the static analysis of elastic force and torque limiters that aim at limiting the forces that a robotic manipulator can apply on its environment. First, the design of one-degree-of-freedom force and torque limiting mechanisms is presented. It is shown that a single elastic component (spring) can be used to provide a prescribed preload and stiffness in both directions of motion along a given axis. Then, the mechanisms are analyzed in order to determine the nonlinear relationships between the motion of the mechanism and the extension of the spring. These relationships can then be used in the design of the force and torque limiters. Finally, the force capabilities of the mechanisms are investigated and numerical results are provided for example designs.

Design and Static Analysis of Elastic Force and Torque Limiting Devices for Safe Physical Human–Robot Interaction

2017 ◽  
Vol 9 (2) ◽  
Author(s):  
Meiying Zhang ◽  
Thierry Laliberté ◽  
Clément Gosselin
Keyword(s):  
Static Analysis ◽  
Robotic Manipulator ◽  
Numerical Results ◽  
Elastic Force ◽  
Human Robot Interaction ◽  
Degree Of Freedom ◽  
Elastic Component ◽  
Robot Interaction ◽  
Nonlinear Relationships

This paper presents the static analysis of elastic force and torque limiters that aim at limiting the forces that a robotic manipulator can apply on its environment. First, the design of one-degree-of-freedom force and torque limiting mechanisms is presented. It is shown that a single elastic component (spring) can be used to provide a prescribed preload and stiffness in both directions of motion along a given axis. Then, the mechanisms are analyzed in order to determine the nonlinear relationships between the motion of the mechanism and the extension of the spring. These relationships can then be used in the design of the force and torque limiters. Finally, the force capabilities of the mechanisms are investigated and numerical results are provided for example designs.

scholarly journals Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

2021 ◽  
Author(s):  
Yiwei Liu ◽  
Shipeng Cui ◽  
Yongjun Sun
Keyword(s):  
Modular Design ◽  
Mechanical Design ◽  
Bending Moment ◽  
Variable Stiffness ◽  
Fast Response ◽  
Human Robot Interaction ◽  
Asymmetric Structure ◽  
Robot Interaction ◽  
Collaborative Robotics ◽  
Variable Stiffness Actuator

AbstractThe safety of human-robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human-robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional-derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

Geometric Error Compensation With a Six Degree-of–Freedom Rotary Magnetic Actuator

2018 ◽  
Vol 140 (11) ◽  
Author(s):  
Alexander Yuen ◽  
Yusuf Altintas
Keyword(s):  
Real Time ◽  
Kinematic Model ◽  
Geometric Error ◽  
Degree Of Freedom ◽  
Geometric Errors ◽  
Working Volume ◽  
Quintic Polynomial ◽  
Gradient Descent Algorithm ◽  
Forward Kinematic ◽  
Six Degree Of Freedom

This paper presents a methodology to compensate the tooltip position errors caused by the geometric errors of a three-axis gantry type micromill integrated with a six degree-of-freedom (6DOF) rotary magnetic table. A geometric error-free ideal forward kinematic model of the nine-axis machine has been developed using homogenous transformation matrices (HTMs). The geometric errors of each linear axis, which include one positioning, two straightness, pitch, roll, and yaw errors, are measured with a laser interferometer and fit to quintic polynomial functions in the working volume of the machine. The forward kinematic model is modified to include the geometric errors which, when subtracted from the ideal kinematic model, gives the deviation between the desired tooltip position with and without geometric errors. The position commands of the six degree-of-freedom rotary magnetic table are modified in real time to compensate for the tooltip deviation using a gradient descent algorithm. The algorithm is simulated and verified experimentally on the nine-axis micromill controlled by an in-house developed virtual/real-time open computer numerical controlled (CNC) system.

Mechanical Design and Evaluation of a Novel Knee-Ankle-Foot Robot for Rehabilitation

2015 ◽  
Author(s):  
Gong Chen ◽  
Zhao Guo ◽  
Haoyong Yu
Keyword(s):  
Mechanical Design ◽  
Gait Training ◽  
Human Robot Interaction ◽  
Robot Interaction ◽  
Gait Patterns ◽  
Gait Biomechanics ◽  
Leg Muscles ◽  
In Series ◽  
Translational Spring ◽  
Selection Of

This paper presents the mechanical design and evaluation of a knee-ankle-foot robot, which is compact, modular, and portable for stroke patients to carry out overground gait training at outpatient and home settings. The robot is driven by a novel series elastic actuator (SEA) for safe human-robot interaction. The SEA employs one soft translational spring in series with a stiff torsion spring to achieve high intrinsic compliance and the capacity of providing peak force. The robotic joint mechanism and the selection of the actuator springs are optimized based on gait biomechanics to achieve portability and capability. The robot demonstrated stable and accuracy force control in experiments conducted on healthy subjects with overground walking. Major leg muscles of the subjects showed reduced level of activations (Electromyography, EMG) while maintaining normal gait patterns with robotic assistances, indicating the robot’s capability of providing effective gait assistance.

scholarly journals MECHANICAL DESIGN OF THE HUGGABLE ROBOT PROBO

2011 ◽  
Vol 08 (03) ◽  
pp. 481-511 ◽  
Author(s):  
KRISTOF GORIS ◽  
JELLE SALDIEN ◽  
BRAM VANDERBORGHT ◽  
DIRK LEFEBER
Keyword(s):  
Facial Expressions ◽  
High Precision ◽  
Mechanical Design ◽  
Human Robot Interaction ◽  
Nonverbal Cues ◽  
Special Focus ◽  
Robot Interaction ◽  
Communicative Skills ◽  
Face To Face ◽  
Safety Aspects

This paper reports on the mechanical design of the huggable robot Probo. Its intentions include human–robot interaction (HRI), both physical and cognitive, with a special focus on children. Since most of the communication passes through nonverbal cues and since people rely on face-to-face communication, the focus of Probo's communicative skills lies initially on facial expressions. The robot has 20 high-precision motors in its head and body. They are used to actuate the ears, eyebrows, eyelids, eyes, trunk, mouth, and neck. To build safety aspects intrinsically in the robot's hardware, all the motors are linked with flexible components. In case of a collision, the robot will be elastic and safety will be ensured. The mechanics of Probo are covered by protecting plastic shells, foam, and soft fur. This gives Probo's animal-like look and makes the robot huggable.

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