Increasing the power density and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing and deploying legged vehicles,especially for heavy-duty legged vehicles,in...Increasing the power density and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing and deploying legged vehicles,especially for heavy-duty legged vehicles,in which significant power fluctuations in energy supply exist with peak power several times surpassing the average value.Applying ESUs with high power density and high overload can compactly ensure fluctuating power source supply on demand.It can avoid the ultra-high configuration issue,which usually exists in the conventional lithium-ion battery-based or engine-generator-based ESUs.Moreover,it dramatically reduces weight and significantly increases the loading and endurance capabilities of the legged vehicles.In this paper,we present a hybrid energy-supply unit for a heavy-duty legged vehicle combining the discharge characteristics of lithium-ion batteries and peak energy release/absorption characteristics of supercapacitors to adapt the ESU to high overload power fluctuations.The parameters of the lithium-ion battery pack and supercapacitor pack inside the ESU are optimally matched using the genetic algorithm based on the energy consumption model of the heavy-duty legged vehicle.The experiment results exhibit that the legged vehicle with a weight of 4.2 tons can walk at the speed of 5 km/h in a tripod gait under a reduction of 35.39%in weight of the ESU compared to the conventional lithium-ion battery-based solution.展开更多
The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper propos...The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper proposes a leg design approach based on effective mechanical advantage(EMA)for developing the heavy-duty legged robot.The bio-inspired design approach can reduce the demand for joint actuation forces during walking by optimizing the ratio relationship between the joint driving force and ground contact force.A dimensionless EMA model of the leg for the heavy-duty legged robot is constructed in this paper.Leg dimensions and hinge point locations are optimized according to the EMA and energy-optimal criterion.Based on the optimal leg structure,an electrically driven tri-segmented leg prototype is developed.The leg's joint hinge points are located near the main support line,and the load-to-weight ratio is 15:1.The leg can realize a swing frequency of 0.63 Hz at the stride length of 0.8 m,and the maximum stride length can reach 1.5 m.展开更多
基金supported in part by the National Key R&D Program of China under Grant No.2019YFB1309502.
文摘Increasing the power density and overload capability of the energy-supply units(ESUs)is always one of the most challenging tasks in developing and deploying legged vehicles,especially for heavy-duty legged vehicles,in which significant power fluctuations in energy supply exist with peak power several times surpassing the average value.Applying ESUs with high power density and high overload can compactly ensure fluctuating power source supply on demand.It can avoid the ultra-high configuration issue,which usually exists in the conventional lithium-ion battery-based or engine-generator-based ESUs.Moreover,it dramatically reduces weight and significantly increases the loading and endurance capabilities of the legged vehicles.In this paper,we present a hybrid energy-supply unit for a heavy-duty legged vehicle combining the discharge characteristics of lithium-ion batteries and peak energy release/absorption characteristics of supercapacitors to adapt the ESU to high overload power fluctuations.The parameters of the lithium-ion battery pack and supercapacitor pack inside the ESU are optimally matched using the genetic algorithm based on the energy consumption model of the heavy-duty legged vehicle.The experiment results exhibit that the legged vehicle with a weight of 4.2 tons can walk at the speed of 5 km/h in a tripod gait under a reduction of 35.39%in weight of the ESU compared to the conventional lithium-ion battery-based solution.
基金supported in part by the National Key R&D Program of China under Grant No.2019YFB1309502in part by the project under Grant No.2019ZT08Z780.
文摘The leg structure is crucial to the legged robot's motion performance.With the size and load of the legged robot increasing,the difficulty of leg design increases sharply.Inspired by biomechanics,this paper proposes a leg design approach based on effective mechanical advantage(EMA)for developing the heavy-duty legged robot.The bio-inspired design approach can reduce the demand for joint actuation forces during walking by optimizing the ratio relationship between the joint driving force and ground contact force.A dimensionless EMA model of the leg for the heavy-duty legged robot is constructed in this paper.Leg dimensions and hinge point locations are optimized according to the EMA and energy-optimal criterion.Based on the optimal leg structure,an electrically driven tri-segmented leg prototype is developed.The leg's joint hinge points are located near the main support line,and the load-to-weight ratio is 15:1.The leg can realize a swing frequency of 0.63 Hz at the stride length of 0.8 m,and the maximum stride length can reach 1.5 m.
