Biped Robot With Heterogeneous Legs Research Articles

A new virtual-real gravity compensated inverted pendulum model and ADAMS simulation for biped robot with heterogeneous legs

Our research team combined humanoid robots with intelligent lower limb prostheses to study the dynamic characteristics of intelligent lower extremity prostheses for disabled people in the walking process, and proposed a biped robot with heterogeneous legs (BRHL). This paper proposes a new virtual-real inverted pendulum system model to unify the models for both single support phase and double support phase in walking process and builds a special simulation platform which can acquire the real-time center of mass (COM) trajectory. Initially, a gravity-compensated inverted pendulum model was built and improved the stability of gait, a natural ZMP trajectory improved the anthropomorphism of the gait. Furthermore, in double support phase, a virtual inverted pendulum model was established and a virtual-real inverted pendulum model was proposed and used to plan the gait of both single support phase and double support phase in the walking process. Additionally, the joint angles were obtained by inverse kinematics; the stability of the system was analyzed to be feasible and effective by phase trajectories. A special ADAMS simulation platform was built to simulate the walking process and acquire real-time COM trajectory. The feasibility of the gait planning was also verified. Finally, the trajectory of COM was optimized based on the minimum energy criterion according to the geodesic equation.

Design, Modeling and Control of Bionic Knee in Artificial Leg

The biped robot with heterogeneous legs (BRHL) greatly facilitates the development of intelligent lower-limb prosthesis (ILLP). In the BRHL, the remaining leg of the amputee is simulated by an artificial leg, which provides the bionic leg with the precise gait following trajectory. Therefore, the artificial leg must closely mimic the features of the human leg. After analyzing the motion mechanism of the human knee, this paper designs a four-link bionic knee in light of the coexistence of rolling and sliding between the femur, the meniscus and the tibia. Drawing on the driving mechanism of leg muscles, two pneumatic artificial muscles (PAMs) were adopted to serve as the extensor and flexor muscles on the thigh. The two PAMs move in opposite direction, driving the knee motions in the artificial leg. To overcome the complexity of traditional PAM modelling methods, the author set up a PAM feature test platform to disclose the features of the PAMs, and built static and dynamic nonlinear mathematical models of the PAMs based on the test data. Next, a proportional-integral-derivative (PID) closed loop controller and sliding mode controller was designed for the bionic knee, referring to the kinetics equation of the knee. Through experimental simulation, it is confirmed that the proposed controller can accurately control the position of the four-link bionic knee, and that the designed bionic knee and PAM driving mode are both correct.

Virtual Prototype Modeling of Biped Robot with Heterogeneous Legs

Biped robot with heterogeneous legs (BRHL) can simulate amputees dressed with intelligent above/knee (A/K) prosthesis and can be used to evaluate intelligent prosthesis (IP) performance. First the concept of virtual prototype technology and BRHL is introduced. Then virtual prototypes of BRHL mechanical system, ground environment, perception and control system are established. In the end, the continuously walking simulation of BRHL based on virtual prototype is done. The research indicates that virtual prototype modeling based on Pro/E, ADAMS and MATLAB/Simulink is feasible.

A coordinated control strategy for stable walking of biped robot with heterogeneous legs

Purpose – The purpose of this paper is to present a coordinated control strategy for stable walking of biped robot with heterogeneous legs (BRHL), which consists of artificial leg (AL) and intelligent bionic leg (IBL).Design/methodology/approach – The original concentrated control in common biped robot system is replaced by a master‐slave dual‐leg coordinated control. P‐type open/closed‐loop iterative learning control is used to realize the time‐varying gait tracking for IBL to AL.Findings – The new control architecture can simplify gait planning scheme of BRHL system with complicated closed‐chain mechanism and mixed driving mode.Research limitations/implications – Designing and constructing a suitable magneto‐rheological damper can greatly improve the control performance of IBL.Practical implications – Master‐slave coordination strategy is suitable for BRHL stable walking control.Originality/value – The concepts and methods of dual‐leg coordination have not been explicitly proposed in single biped robot ...

The Design and Modeling of Multi-axis Knee Artificial Leg

To provide an ideal test-base for the development of an intelligent bionic leg, a new pattern humanoid robot – biped robot with heterogeneous legs (BRHL) was designed. To simulate a normal human gait, a multi-axis knee mechanism was included into the artificial leg design that was different from the artificial leg of a common biped robot. The conception and research purposed for the BRHL was developed. Based on human bioscience, the bionic design of multi-axis knee artificial leg was analyzed and a virtual prototype was made. The kinematics model and dynamics model were deduced in detail. Based on human normal gait data, a simulation of dynamics model was carried. An optimized mechanical design of multi-axis knee artificial leg is discussed and a simulation was done. The optimal mechanism parameters for the multi-axis knee artificial leg and a BRHL prototype were given. This research indicated that a multi-axis knee artificial leg can simulate a human leg.

Intelligent Control of BRHL Based on MR Damper

Biped robot with heterogeneous legs (BRHL) is a new pattern humanoid robot. This paper first introduces the conception, research purpose and configuration of HRHL. Then coordinated dynamics model and magneto-rheological (MR) damper model are given. In the end, this paper discusses the control model of BRHL and gives combined control simulation. The result indicates that intelligent bionic leg controlled by MR damper can track artificial leg’s gait well.

Biped robot control strategy and open-closed-loop iterative learning control

Master-slaver dual-leg coordination control was proposed for the biped robot with heterogeneous legs (BRHL), in order to reduce gait planning and to get a good tracking performance. The key to coordination is gait trajectory tracking control. Bionic knee joint with closed-chain 4links makes robot walking more humanlike, but the model is complex and tracking of the bionic leg to the artificial leg is more difficult. P-type open-closed-loop iterative learning control (ILC) is not based on model parameters and has advantages in both open-loop and closed-loop ILC; so this paper proposes a complex robot gait trajectory tracking. The convergence is proved by using functional analysis and the stability condition is given. A tracking simulation based on the virtual prototype pe was done. The results show that this control strategy and algorithm are effective and robust, and the convergence speed is better than separate open-loop or closed-loop ILC.

INTELLIGENT CONTROL OF BIPED ROBOT WITH HETEROGENEOUS LEGS

Intelligent bionic leg (IBL) is important for above-knee amputees. Biped robot with heterogeneous legs (BRHL) including artificial leg and bionic leg is proposed as a good test-bed for IBL. Mechanism and virtual prototype of BRHL is designed and built. Model of BRHL is established. Based on the complex differential algebraic equation of bionic leg, computed torque and PD feedback control of joint angle are introduced for gait tracking. The iterative learning control is applied in conjunction with computed torque and PD control law for good tracking performance. Control simulation is done and shows intelligent control is good for BRHL.