This study investigates the tribological behavior of the attachment force between bio-inspired claw–spines and rough surfaces and conducts theoretical and model-based analyses of the corresponding attachment mechanism. Based on critical interfacial tribological theory, a frictional mechanics model for a single claw–spine interacting with an arbitrary rough surface was developed. Furthermore, a stiffness-matrix-based mechanical model of bio-inspired claw–spine attachment to arbitrary surfaces was established, together with a contact interaction model between the claw–spine and the contact surface. The force distribution during the contact and attachment of the claw–spine to arbitrary surfaces was analyzed in detail. Criteria for determining stable claw–spine attachment were formulated, and the safe range of frame displacement variation under the corresponding conditions was identified. Based on these analytical results, a test platform for the bio-inspired claw–spine attachment structure was designed. In the experiments, the developed attachment-force measurement system was used to measure and analyze the frictional attachment forces generated by the claw–spine foot on different rough surfaces. After the claw–spine entered the stable attachment stage, the maximum claw–spine attachment forces measured on 60-grit, 80-grit, and 120-grit sandpaper surfaces were 0.62 N, 0.54 N, and 0.61 N, respectively. The corresponding maximum attachment forces measured on horizontal and vertical brick surfaces were 0.92 and 0.99 N, respectively. The results provide a basis for the mechanical analysis and force sensing of bio-inspired claw–spine attachment states and establish theoretical and experimental foundations for subsequent research on attachment-state recognition and motion control based on attachment-force feedback.

The effect of different concentrations of oleic acid additive on the yield behavior of a magnetorheological fluid (MRF) was investigated from the perspective of tribology. Different concentrations of oleic acid (OA) influence the magnetorheological effect by altering the lubricating properties of the base carrier liquid. Good lubricity of the carrier fluids led to lower shear stresses. The friction between the particles and that between the particles and plates were a part of the shear stress. The structural evolution was promoted by both lubrication and shearing. The shearing thinning of the MRF was delayed under good lubricity, and the particles were easier to roll. The friction forces, along with Brownian forces, Stokes forces, and magnetic attraction, affect the structural evolution of MRF. This study provides a new theory for the formulation design of magnetorheological fluids, reducing design costs and improving production efficiency.

In order to provide a theoretical basis for the monitoring and control of the formation process of round bales, the friction test platform for the rolling formation of round bales was built to study the interaction between steel roll and material in the forming process. The results showed that the torque value of the steel roller at the lowest position (No. 2 steel roll) in the bale chamber was closely related to the forming process of the round bale. According to the change of the torque value, the forming process can be divided into an initial stage, straw core formation stage, compression stage and bale-forming stage. The change of torque value can be used for monitoring the forming process of round bales. During the forming process, materials were subject to sliding friction and rolling friction. From the initial stage to the forming stage, the friction of materials gradually changed from sliding friction to rolling friction, and the surface contacted between the material and the steel roll gradually changed to line contact. The interaction model of steel roll and material was established and verified; the model showed that the maximum error between the theoretical value and the experimental value of the forming density is 13.24% and the minimum error is 0.75%. The forming density of round bales was positively correlated with the mass of material fed per second and negatively correlated with the volume of the bale-forming chamber. The forming density of round bales can be expressed by the tangential force per unit length of No. 2 steel roll under the condition that the moisture content of material, the mass of material fed per second and the volume of the baling chamber were fixed. The model provides a theoretical basis for monitoring and controlling the forming process of round bales.