Jumping over obstacles with MIT Cheetah 2

Haewon, Park; Wensing, Patrick M.; Kim, Sangbae

doi:10.1016/j.robot.2020.103703

Cited by 60 publications

(35 citation statements)

References 33 publications

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“…The number of steps needed to recover from external disturbance is another critical quantity ensuring successful recovery. Following the simple approach used in [46], we propose to determine the number of steps by solving the above iterative QPs for a range of N and pick the one with smallest cost. In practice, we can simply set the number of steps N to be fixed and relatively large, and solve the corresponding planning problem.…”

Section: Number Of Steps Planningmentioning

confidence: 99%

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

Chen¹,

Hong²,

Yang³

et al. 2022

Preprint

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This paper studies capturability and push recovery for quadrupedal locomotion. Despite the rich literature on capturability analysis and push recovery control for legged robots, existing tools are developed mainly for bipeds or humanoids. Distinct quadrupedal features such as point contacts and multiple swinging legs prevent direct application of these methods. To address this gap, we propose a switched systems model for quadruped dynamics, and instantiate the abstract viability concept for quadrupedal locomotion with a time-based gait. Capturability is characterized through a novel specification of dynamically balanced states that addresses the time-varying nature of quadrupedal locomotion and balance. A linear inverted pendulum (LIP) model is adopted to demonstrate the theory and show how the newly developed quadrupedal capturability can be used in motion planning for quadrupedal push recovery. We formulate and solve an explicit model predictive control (EMPC) problem whose optimal solution fully characterizes quadrupedal capturability with the LIP. Given this analysis, an optimization-based planning scheme is devised for determining footsteps and center of mass references during push recovery. To validate the effectiveness of the overall framework, we conduct numerous simulation and hardware experiments. Simulation results illustrate the necessity of considering dynamic balance for quadrupedal capturability, and the significant improvement in disturbance rejection with the proposed strategy. Experimental validations on a replica of the Mini Cheetah quadruped demonstrate an up to 100% improvement as compared with state-of-the-art.

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Section: Number Of Steps Planningmentioning

confidence: 99%

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

Chen¹,

Hong²,

Yang³

et al. 2022

Preprint

Self Cite

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“…As the capabilities of quadrupedal robot rapidly grow, related researches have geared towards motions beyond locomotion on flat terrains. For example, ANYmal demonstrated the stair climbing capability [10]; MIT Cheetah 2 overcame obstacles by planning jumping trajectories online [11]; MIT Cheetah 3 achieved leaping onto high platforms [12]; MIT Mini Cheetah could execute 360 • backflips [13]. In general, the ability of quadrupedal robots is being developed towards applications that involve more dynamic maneuvers in increasingly complex scenarios.…”

Section: Introductionmentioning

confidence: 99%

Representation-Free Model Predictive Control for Dynamic Motions in Quadrupeds

Ding¹,

Pandala

et al. 2021

IEEE Trans. Robot.

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109

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This paper presents a novel Representation-Free Model Predictive Control (RF-MPC) framework for controlling various dynamic motions of a quadrupedal robot in three dimensional (3D) space. Our formulation directly represents the rotational dynamics using the rotation matrix, which liberates us from the issues associated with the use of Euler angles and quaternion as the orientation representations. With a variationbased linearization scheme and a carefully constructed cost function, the MPC control law is transcribed to the standard Quadratic Program (QP) form. The MPC controller can operate at real-time rates of 250 Hz on a quadruped robot. Experimental results including periodic quadrupedal gaits and a controlled backflip validate that our control strategy could stabilize dynamic motions that involve singularity in 3D maneuvers.

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“…The last two decades have seen the rapid research and development of legged robots to traversing rough terrain [1], [2], [3], [4], [5]. Among them, the research into jumping behaviors on legged robot has greatly drawn research attentions because of its remarkable advantages to navigate high obstacles [6], [7], [8], [9]. With recent advancement of hardware and well-established control strategies, quadruped robots has shown its impressive capabilities to perform various dynamic locomotion [10], [11], [12].…”

Section: Introductionmentioning

confidence: 99%

“…With recent advancement of hardware and well-established control strategies, quadruped robots has shown its impressive capabilities to perform various dynamic locomotion [10], [11], [12]. Regarding to jumping behaviors, the Cheetah 2 recently demonstrates jumping autonomously over obstacles while bounding at high-speed [7], and the Cheetah 3 is able to repeatably jump onto and jump down from a desk up to 30 in height [13].…”

Section: Introductionmentioning

confidence: 99%

Contact-timing and Trajectory Optimization for 3D Jumping on Quadruped Robots

Nguyen

2021

Preprint

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Performing highly agile acrobatic motions with a long flight phase requires perfect timing, high accuracy, and coordination of the whole body motion. To address these challenges, this paper presents a unified timing and trajectory optimization framework for legged robots performing aggressive 3D jumping. In our approach, we firstly utilize an effective optimization framework using simplified rigid body dynamics to solve for contact timings and a reference trajectory of the robot body. The solution of this module is then used to formulate a whole-body trajectory optimization based on the full nonlinear dynamics of the robot. This combination allows us to effectively optimize for contact timings while guaranteeing the accuracy of the jumping trajectory that can be realized in the hardware. We validate the efficiency of the proposed framework on the A1 robot model for various 3D jumping tasks such as double-backflips and double barrel roll off the high altitude of 2m and 0.8m respectively. Experimental validation was also successfully conducted for different 3D jumping motions such as barrel roll from a box or diagonal jumps.

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Jumping over obstacles with MIT Cheetah 2

Cited by 60 publications

References 33 publications

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

Quadruped Capturability and Push Recovery via a Switched-Systems Characterization of Dynamic Balance

Representation-Free Model Predictive Control for Dynamic Motions in Quadrupeds

Contact-timing and Trajectory Optimization for 3D Jumping on Quadruped Robots

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