Walking trajectory control for a biped robot

A not trivial problem in bipedal robot walking is the instability produced by the violent transition between the different dynamic walk phases. In this work an dynamic algorithm to control a biped robot is proposed. The algorithm is based on cubic polynomial interpolation of the initial conditions for the robot’s position, velocity and acceleration. This guarantee a constant velocity an a smooth transition in the control trajectories. The algorithm was successfully probed in the bipedal robot “Dany walker” designed at the Freie Universität Berlin, finally a briefly mechanical description of the robot structure is presented

Asymptotically Stable Walking of a Five-Link Underactuated 3D Bipedal Robot

This paper presents three feedback controllers that achieve an asymptotically stable, periodic, and fast walking gait for a 3D (spatial) bipedal robot consisting of a torso, two legs, and passive (unactuated) point feet. The contact between the robot and the walking surface is assumed to inhibit yaw rotation. The studied robot has 8 DOF in the single support phase and 6 actuators. The interest of studying robots with point feet is that the robot's natural dynamics must be explicitly taken into account to achieve balance while walking. We use an extension of the method of virtual constraints and hybrid zero dynamics, in order to simultaneously compute a periodic orbit and an autonomous feedback controller that realizes the orbit. This method allows the computations to be carried out on a 2-DOF subsystem of the 8-DOF robot model. The stability of the walking gait under closed-loop control is evaluated with the linearization of the restricted Poincar\'e map of the hybrid zero dynamics. Three strategies are explored. The first strategy consists of imposing a stability condition during the search of a periodic gait by optimization. The second strategy uses an event-based controller. In the third approach, the effect of output selection is discussed and a pertinent choice of outputs is proposed, leading to stabilization without the use of a supplemental event-based controller

Experimental Estimation of Slipping in the Supporting Point of a Biped Robot

When developing a gait cycle on a low-friction surface, a biped robot eventually tends to slip. In general, it is commonto overcome this problem by means of either slow movements or physical adaptations of the robot at the contact pointwith the walking surface in order to increase the frictional characteristics. In the case of slipping, several types ofsensors have been used to identify the relative displacement at the contact point of the supporting leg with the walkingsurface for control purposes. This work is focused on the experimental implementation of a low-cost force sensor as ameasurement system of the slipping phenomenon. It is shown how, supported on a suitable change of coordinates,the force measurement at the contact point is used to obtain the total displacement at the supporting point due to thelow-friction conditions. This is an important issue when an accurate Cartesian task is required

Control of biomimetic locomotion via averaging theory

Based on a recently developed "generalized averaging theory", we present a generic approach for the design of stabilizing feedback controller for biomimetic locomotive systems. The control laws exponentially stabilize in the average, and they apply to a very wide class of systems. Two examples are given: a "kinematic biped" that demonstrates how our theory handles discontinuities, and the snakeboard, which is an underactuated mechanical system with drift

3D Simulator for a Biped Walking Robot

In this paper, a 3D simulator was developed to reduce experimental problems of dangerous, economical and time element for locomotion of the biped walking robot (BWR) with joint actuators using the Open graphics library (OpenGL) and physical engine so called Open Dynamics Engine (ODE). The database of 3D models for robot body？s elements using the Milkshape 3D ascii format was set up, and using them, 3D locomotion was simulator with mass, length of robot body？s elements to 3D. The 3D simulator was develop to have function of calculation of load torque of the drive motor to show the 3D simulator and to have ZMP function for stable walk of robot. The robot model adapted for the 3D simulator shows gesture of walk cycle of 8 steps, and it？s trajectories are generated based on the data of joint angles that from the motion capture system. To track the specified trajectories, the PID control algorithm is applied. Finally, the joint angle from the simulator was applied to the actual BWR, and which showed similar walking results.제 1 장. 서론 1 제 2 장. 이족보행 로봇의 동역학 해석 4 2.1. 하체의 순기구학 해석 5 2.2. 하체의 역기구학 해석 7 2.3. 관절 구동부의 동역학 해석 11 2.4. 관절 구동부의 부하 토크 계산 16 제 3 장. 3D 시뮬레이터의 구성 21 3.1. 시뮬레이터의 설계 22 3.2. 3D 이족보행 로봇의 모델링 25 3.3. 물리 엔진의 소개 28 3.4. 제어부의 구성 29 제 4 장. 보행 시뮬레이션 31 5.1. 보행의 안정도 분석 31 5.2. 보행 주기의 결정 34 5.3. 보행을 위한 각 관절의 궤적 생성 37 5.4. 궤적을 이용한 로봇의 구동 48 제 5 장. 결론 49 참고문헌 5